A method for finish milling a blade tip of a blisk

Abstract

The application provides a whole-blade-disc tip precision milling method, which uses a chamfering milling cutter as a precision cutter. In the precision milling process, the cutting edge of the chamfering milling cutter is tangent to the tip, and the direction of the precision cutter is controlled to be along the milling direction. When the precision cutter rotates, the cutting force is directed towards the blade root rather than the blade side. Therefore, the machined part of the tip has sufficient rigidity, and the precision milling of the tip can be completed based on the chamfering milling cutter. The more complex high-speed grinding method is not needed for the machining of the tip, the machining process of the tip is simplified, and the machining cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of impeller disc machining, in particular to a precision milling method for a blade tip of a blisk. BACKGROUND

[0002] In the field of turbomachinery and aerospace, compressor centrifugal impellers and blisks are becoming more and more popular. The blade tip machining of fan discs, compressor discs, centrifugal impellers and other compressor products has always been a technical difficulty in the industry. For example, Figure 1 and Figure 2 As shown in the structural schematic diagram of an embodiment of a blade disc 1 and an impeller 2. Generally, in the process of machining the blade, rough milling is performed first, and then precision milling is performed. However, after the blade profile is precisely machined, the thickness of the blade is only a few millimeters, and the rigidity is weak. If a common milling cutter such as a round corner milling cutter is used to continue to rotate the blade tip, the blade will vibrate left and right, and the blade tip will be overcut. Therefore, in the prior art, after the blade is precisely machined, a combined grinding machining technology / high-speed grinding composite machining technology is used to machine the blade tip of the rotor blade based on high-speed grinding. However, this machining process is relatively complex, and the equipment used has a relatively high cost, resulting in a relatively high blade machining cost. SUMMARY

[0003] In order to solve the problem of complex machining method and high machining cost for the blade tip in the prior art, the present application provides a precision milling method for a blade tip of a blisk, which can reduce the machining cost while ensuring the machining precision of the blade tip.

[0004] The technical scheme of the present application is as follows: a precision milling method for a blade tip of a blisk, comprising the following steps:

[0005] S1: analyzing the blade disc and the impeller to be machined, measuring the height size of the blade profile of the blade disc and the impeller, and analyzing the torsion direction of the blade to be machined;

[0006] characterized in that it further comprises the following steps:

[0007] S2: using modeling software to model the blade tip to be machined to obtain a profiled surface of the blade tip to be machined;

[0008] S3: selecting a machining tool;

[0009] The machining tool comprises a chamfering milling cutter;

[0010] The length of the cutting edge of the machining tool is greater than the thickness of the blade tip to be machined;

[0011] S4: preparing a precision milling machining program for the blade tip to be machined based on the machining tool;

[0012] When the fine milling machining program is constructed, the machining tool is selected, a variable profile milling command is used, a surface area driving method is used, the blade tip to be machined is used to generate a blade tip fine machining track;

[0013] In the fine milling machining program, when the blade to be machined is clockwise twisted, the cutting direction of the machining tool moves from the inlet side leading edge to the outlet side trailing edge; when the blade to be machined is counterclockwise twisted, the cutting direction of the machining tool moves from the outlet side trailing edge to the inlet side leading edge; when the angle of the machining tool is set, the cutting edge of the machining tool is tangent to the blade tip to be machined, and the tool path of the machining tool is controlled to be down milling, and the cutting force of the machining tool rotates towards the blade root;

[0014] S5: debugging based on a five-axis linkage machine tool simulation machining process to obtain a debugged machining program;

[0015] S6: running the machining program to complete machining of the blade tip to be machined using a five-axis linkage numerical control machining machine tool.

[0016] It is further characterized in that:

[0017] The modeling process of the blade tip to be machined includes the following steps:

[0018] a1: extracting the profile curve of the blade tip to be machined to determine the inner arc curve and the back arc curve of the blade tip to be machined;

[0019] a2: based on the inner arc curve and the back arc curve, modeling a curve from the two curves, i.e., obtaining the blade tip to be machined;

[0020] The chamfering milling cutter includes a pointed chamfering milling cutter and a flat-headed chamfering milling cutter;

[0021] The size range of the chamfering milling cutter includes a diameter of 3mm to 30mm and a single edge angle of 15 degrees to 75 degrees;

[0022] The machining tool specifications include a diameter of 6mm, a single edge angle of 45 degrees, a diameter of 8mm, a single edge angle of 45 degrees, a diameter of 10mm, a single edge angle of 45 degrees, a diameter of 12mm, a single edge angle of 45 degrees, and a diameter of 16mm, a single edge angle of 45 degrees.

[0023] The application provides a whole-blade-disc-blade-tip fine milling processing method, which uses a chamfering milling cutter as a fine processing cutter, in the fine processing procedure, the cutting edge of the chamfering milling cutter is tangent to the blade tip, and the direction of the fine processing cutter is controlled to be along the milling direction, the cutting force of the fine processing cutter is directed to the blade root instead of the blade side when the fine processing cutter rotates, so that the machined part of the blade tip has enough rigidity, and the fine processing of the blade tip can be completed based on the chamfering milling cutter, without using a more complex high-speed grinding method to process the blade tip, so that the processing procedure of the blade tip is simplified, and the processing cost is reduced. Meanwhile, in the processing procedure, when the blade is twisted clockwise, the cutting direction of the fine processing cutter should be moved from the air inlet side leading edge to the air outlet side trailing edge, and when the blade is twisted counterclockwise, the cutting direction of the fine processing cutter should be moved from the air outlet side trailing edge to the air inlet side leading edge, so that the cutting force can be borne by the structure of the blade twist direction, the cutting force is reduced, the processing vibration is reduced, the probability of overcutting of the milling cutter is reduced, and the quality of the blade tip processing is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Fig. 1 is a structural schematic diagram of a blade disc;

[0025] Figure 2 Fig. 2 is a structural schematic diagram of an impeller;

[0026] Figure 3 Fig. 3 is a schematic diagram of a round milling cutter;

[0027] Figure 4 Fig. 4 is a schematic diagram of a flat chamfering cutter;

[0028] Figure 5 Fig. 5 is a schematic diagram of a sharp chamfering cutter;

[0029] Figure 6 Fig. 6 is a processing schematic diagram of the round milling cutter;

[0030] Figure 7 Fig. 7 is a processing schematic diagram of the flat chamfering cutter used in the application;

[0031] Figure 8 Fig. 8 is a processing schematic diagram of the sharp chamfering cutter used in the application;

[0032] Figure 9 Fig. 9 is a modeling process schematic diagram of a profile surface to be processed of a blade tip;

[0033] Figure 10 Fig. 10 is a flowchart of the whole-blade-disc-blade-tip milling processing method of the application. DETAILED DESCRIPTION

[0034] As shown in Fig. 1, Figure 10 the application includes a whole-blade-disc-blade-tip fine milling processing method, which includes the following steps.

[0035] S1: Analyzing the blade disc and impeller to be processed, obtaining the height size of the blade profile of the blade disc and impeller, and obtaining the torsion direction of the blade to be processed.

[0036] As Figure 1 For an example of the blade disc 1 to be processed, it includes: the inner arc 1-1 of the blade of the blade disc, the back arc 1-2 of the blade of the blade disc, the blade passage surface 1-3 of the blade disc, the leading edge 1-4 of the blade disc, the trailing edge 1-5 of the blade disc, and the blade tip 1-6 of the blade disc. Figure 2 For an example of the impeller 2 to be processed, it includes: the leading edge 2-1 of the impeller, the main blade 2-2, the impeller passage surface 2-3, the back arc 2-4 of the blade of the impeller, the inner arc 2-5 of the blade of the impeller, the blade tip 2-6 of the impeller, the trailing edge 2-7 of the impeller, and the splitter blade 2-8. It is necessary to ensure the accuracy of all sizes to ensure the accuracy of subsequent processing.

[0037] When analyzing the torsion direction of the blade, from the perspective of the forward direction, when the blade is twisted clockwise, the cutting direction of the tool should move from the inlet side leading edge to the outlet side trailing edge, and when the blade is twisted counterclockwise, the cutting direction of the tool should move from the outlet side trailing edge to the inlet side leading edge. This can be achieved by the structure of the torsion direction of the blade to accept the cutting force, which can be used to reduce the cutting force and reduce the processing vibration.

[0038] S2: Using modeling software to model the blade tip to be processed to obtain the profile surface of the blade tip to be processed.

[0039] In this application, the machining range and machining length of the blade are adjusted and controlled by the profile surface of the blade tip to be processed. Therefore, the profile surface of the blade tip to be processed is made to generate a suitable machining trajectory. In specific implementation, a curve can be extracted from the surface to drive the machining program, or the surface can be directly used to drive the machining program.

[0040] The modeling process of the profile surface of the blade tip to be processed specifically includes the following steps:

[0041] a1: Extracting the contour curve of the blade tip to be processed to determine the inner arc curve and the back arc curve of the blade tip to be processed.

[0042] a2: Based on the inner arc curve and the back arc curve, modeling a curve from the two curves to obtain a surface, i.e. the profile surface of the blade tip to be processed.

[0043] In specific implementation, the CAD software in the prior art can be used for surface modeling. In this embodiment, UG software is used, for example, Figure 9The steps shown are as follows: First, import the impeller and blade disk model into UG software. Use the curve command to extract the blade tip contour curve. Then, use the curve length or trim command to separate the inner and outer arc curves of the blade tip, thus obtaining two curves. Next, use UG's mesh surface or ruled surface command to shape the two curves into a single surface, which is the blade tip contour surface to be processed. In actual production, there is a probability of error between the blade tip contour surface and the actual blade tip arc surface. However, as long as the error between the two surfaces is less than 0.005mm, it can be used as the model surface for the design program, meeting the subsequent processing accuracy requirements.

[0044] S3: Select machining tool. In this application, the machining tool selected for finish milling the blade tip is a chamfering end mill; the length of the cutting edge of the chamfering end mill is greater than the thickness of the blade tip to be machined.

[0045] like Figure 3 The rounded end mill 3 shown has a concave rounded cutting edge 3-1 on one or both sides. The rounded end mill 3 can be used for roughing. Before the blade is finished, the blade has not yet been formed and the product has very good rigidity. The rounded end mill can be used directly for rough milling.

[0046] However, the fillet end mill 3 is not suitable for finishing blade tips. For example... Figure 6 As shown, the blade tip 1-6 of the impeller is used as an example for explanation. A standard rounded end mill 3 is used to finish the rough-machined blade tip 1-6. Because after the blade shape is finished, the blade thickness is only a few millimeters, and its rigidity is weak, when using the rounded end mill 3, the cutting force of the concave cutting edge 3-1 is directed towards the adjacent blade, which will cause the machined blade to vibrate left and right, easily leading to overcutting.

[0047] Therefore, this application uses a chamfering end mill for finishing the blade tip. The chamfering end mills used as finishing tools include: pointed chamfering end mills and flat chamfering end mills; the diameter of the chamfering end mill is between 3 mm and 30 mm, and the angle of one side is between 15 degrees and 75 degrees.

[0048] like Figure 4 and Figure 5 The following are two embodiments of chamfering end mills. The single-sided angle of the frustum-shaped cutting edge 4-1 of the flat-end chamfering cutter 4 and the conical cutting edge 5-1 of the pointed-end chamfering cutter 5 is 45 degrees. Taking the blade tip 1-6 of the impeller as an example, when machining the blade tip using these two types of chamfering end mills, the specific machining angle of the cutting edge is as follows... Figure 7 and Figure 8 As shown.

[0049] The chamfering cutter is a single-edge 45-degree chamfering cutter. When the cutting edge of the chamfering cutter is tangent to the blade tip surface, the cutting force of the rotating cutting edge is directed towards the tangent surface, and the cutting force is absorbed by the blade, reducing the vibration of the blade and ensuring that the blade tip can be machined by fine milling. When selecting the chamfering cutter, the length of the cutting edge of the chamfering cutter must be greater than the thickness of the blade tip to be machined, otherwise there will be a residual step after one-time machining, and the second-time machining surface will have traces of tool joint, affecting the machining precision. The specific specifications of the machining tool selected in the application include: a diameter of 6 mm, a single-edge angle of 45 degrees, a diameter of 8 mm, a single-edge angle of 45 degrees, a diameter of 10 mm, a single-edge angle of 45 degrees, a diameter of 12 mm, a single-edge angle of 45 degrees, and a diameter of 16 mm, a single-edge angle of 45 degrees.

[0050] S4: Compiling a blade tip machining program based on the machining tool.

[0051] According to product requirements, the size of the blade tip must be strictly controlled, and the blade tip must be machined after the blade profile is precisely machined. Therefore, the blade must be rough machined first, then precisely machined, and then the blade tip is precisely machined. Therefore, for the blade tip, the blade tip machining program includes a rough machining program and a fine milling machining program. The rough machining program can be realized based on the blade rough machining program in the prior art.

[0052] When a single-edge 45-degree chamfering cutter is selected for fine milling machining, a suitable machining program trajectory is needed to achieve better results. When constructing the fine milling machining program, a fine machining tool is selected, a variable contour milling command is used, a curve region driving method is used, a blade tip to be machined is used to generate a blade tip fine machining trajectory.

[0053] In the fine milling machining program, when the blade to be machined is twisted clockwise, the cutting direction of the fine machining tool moves from the inlet side leading edge to the outlet side trailing edge; when the blade to be machined is twisted counterclockwise, the cutting direction of the fine machining tool moves from the outlet side trailing edge to the inlet side leading edge; when setting the angle of the fine machining tool, the cutting edge of the fine machining tool is tangent to the blade tip to be machined, and the tool path is controlled to be down milling, and the cutting force is directed towards the blade root when the tool rotates. Specifically, the tool is inclined at an angle of 45 degrees, the cutting edge of the chamfering cutter is tangent to the material surface of the blade tip to be machined, and the machining method is down milling. At the same time, five-axis linkage machining is required to ensure that the cutting edge of the tool and the blade tip surface always remain tangent.

[0054] In the implementation, the program is compiled by using computer programming software, and the general CAM programming software can be used. In the embodiment, UG software is used. After selecting the finishing tool, in the programming module of UG, the selected chamfer milling cutter is established, the VARIABLE_CONTOUR variable profile milling command is selected, the surface area driving method is selected, then the profiled surface of the blade tip to be machined constructed in step S2 is selected, the machining trajectory is generated by using the profiled surface to drive the cutter, and the machining direction is as follows: from the forward direction of the blade, when the blade is twisted clockwise, the cutter cutting direction should be moved from the leading edge of the inlet side to the trailing edge of the outlet side, when the blade is twisted counterclockwise, the cutter cutting direction should be moved from the trailing edge of the outlet side to the leading edge of the inlet side, and the machining angle is shown in the figure. Figure 7 and Figure 8 .

[0055] S5: In the method, the cutting edge of the cutter is always tangent to the blade tip machining surface during cutting, only a five-axis linkage machine tool can meet the requirement, therefore, the machining program is a five-axis linkage program, and the selected machine tool must be a five-axis linkage machine tool.

[0056] After the machining program trajectory is generated, the corresponding post-processing is designed according to the structure of the machining equipment. Since the cutting edge of the chamfer milling cutter is always tangent to the blade tip machining surface in the method, the whole machining process is five-axis linkage machining. The machining trajectory is post-processed into an NC machining program that can be recognized by the machine tool by using post-processing, the model of the blade disc or the impeller is imported into the Vericut simulation software, the simulated cutter is established, the post-processed NC program is imported into the Vericut, the machining state of the five-axis linkage machine tool is simulated, and the program is gradually debugged until it is confirmed that the program is correct.

[0057] S6: The machining program is run, and the five-axis linkage numerical control machining machine tool is used to complete the machining of the blade tip to be machined.

[0058] When the technical solution of the application is used, the chamfer milling cutter with a blade length greater than the thickness of the blade is selected according to the thickness of the blade, the blade tip is finely machined, in the machining process, the programming command in the existing CAM software is matched, when the cutting edge of the chamfer milling cutter is tangent to the blade tip surface, it is ensured that the cutting edge of the chamfer rotates and keeps the cutting force towards the tangent surface, the vibration of the blade in the machining process is reduced, the whole blade disc blade tip is finely machined, the machining process is simplified, and the machining cost is reduced on the basis of ensuring the machining precision.

Claims

1. A method for precision milling the tip of an integral bladed disk, comprising the following steps: S1: Analyze the impeller and bladed disk to be processed, measure the height dimensions of the blade profile of the impeller and bladed disk, and analyze the torsion direction of the blade to be processed; Its characteristic is that it further includes the following steps: S2: Use modeling software to shape the blade tip to be processed, and obtain the contoured curved surface of the blade tip to be processed; S3: Select machining tool; The machining tools include: a chamfering milling cutter; The cutting tool used for finish milling the blade tip is a chamfering end mill; The length of the cutting edge of the machining tool is greater than the thickness of the blade tip to be machined; S4: Compile a precision milling program for the blade tip to be machined based on the machining tool; When constructing the precision milling program, the machining tool is selected, the variable profile milling command is used, and the blade tip precision machining trajectory is generated using the contoured surface of the blade tip to be machined based on the surface region driving method. In the precision milling process, when the blade to be processed is rotated clockwise, the cutting direction of the machining tool moves from the leading edge of the inlet side to the trailing edge of the outlet side; when the blade to be processed is rotated counterclockwise, the cutting direction of the machining tool moves from the trailing edge of the outlet side to the leading edge of the inlet side; when setting the angle of the machining tool, the cutting edge of the machining tool is made tangent to the tip of the blade to be processed, and the direction of the tool is controlled to be climb milling, and the cutting force is directed towards the root of the blade when the tool rotates; S5: Based on the simulation of the machining process of a five-axis linkage machine tool, the machining program is debugged to obtain the debugged machining program; S6: Run the machining program and use a five-axis CNC machining tool to complete the machining of the blade tip to be machined; The chamfering cutter includes: a pointed chamfering cutter and a flat chamfering cutter; The chamfering cutter's size range includes: diameters between 3 mm and 30 mm, and single-sided angles between 15 degrees and 75 degrees.

2. The precision milling method for the tip of an integral bladed disk according to claim 1, characterized in that: The shaping process of the blade tip contour surface to be processed specifically includes the following steps: a1: Extract the contour curve of the blade tip to be processed, and determine the inner arc curve and back arc curve of the blade tip to be processed; a2: Based on the inner arc curve and the back arc curve, the two curves are shaped into a curved surface, which is the blade tip contour surface to be processed.

3. The precision milling method for the tip of an integral bladed disk according to claim 1, characterized in that: The specifications of the machining tools include: 6 mm diameter tool tip with a single-sided angle of 45 degrees, 8 mm diameter tool tip with a single-sided angle of 45 degrees, 10 mm diameter tool tip with a single-sided angle of 45 degrees, 12 mm diameter tool tip with a single-sided angle of 45 degrees, and 16 mm diameter tool tip with a single-sided angle of 45 degrees.

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