A rough milling and fillet processing method for an integral impeller

Abstract

The present invention discloses a method for rough milling and rounding of an integral impeller, which adopts a milling process with cutting tools fed from both sides to reduce tool overhang, and adopts a U-shaped milling process to reduce the cutting depth of each cut. The method comprises the following steps: S1. Dividing the processing area; S2. Selecting the diameter of the processing tool according to the upper and lower limit selection principle of the tool diameter; S3. Selecting the processing step range; S4. Selecting the U-shaped milling parameters. Compared with the traditional rough milling and rounding process, the technology of the present invention can effectively avoid abnormal wear of the tool tip and the reduction of cutting efficiency due to the increase of the allowance distribution to reduce wear. The same processing area can reduce tool consumption by 50% and improve tool cutting efficiency by more than 40%, which has a very high application value.

Description

Technical Field

[0001] The invention relates to the technical field of numerical control milling of integral impellers of aircraft engines, and in particular to a method for rough milling and rounding of integral impellers. Background Art

[0002] The integral structure impeller is a key component used in aircraft engines. The integral impeller blades are usually processed by CNC milling. When the tool overhang is greater than five times the tool diameter during rough milling of the integral impeller, the tool will vibrate during the processing, affecting the tool life and processing efficiency. When the reference tool diameter is too large and the rough milling tool diameter is small, the processed material will wrap more than one-half of the tool diameter, the tool will produce edge chipping, and the tool life and processing efficiency will be greatly reduced.

[0003] The characteristic of the fan's integral impeller is that the blade length is greater than the blade height. When the tool aspect ratio is less than five times, radial processing is usually used in rough milling of fillets. Since the tool before rough milling fillets often uses a larger diameter tool for rough processing to improve processing efficiency, a large amount of material residue will be caused in the fillet. When radial processing is used, the tool tip is easily wrapped by the material, resulting in instantaneous vibration, which will cause the tip to break and the tool to fail. In order to avoid wrapping around the tip, the excess material to be processed can be decomposed into multiple steps for processing, but the cutting efficiency will be significantly reduced. When the machining tool overhang is more than five times the diameter, the axial milling method along the impeller is adopted. This processing method can reduce the tool overhang, but the problem of the tool tip being wrapped by material will also occur during processing. In order to improve the tool life, the excess material to be processed can only be decomposed, sacrificing cutting efficiency. Summary of the Invention

[0004] To address the challenges of existing technologies, this invention provides a method for rough milling and rounding the corners of integral impellers for aircraft engines. This method effectively increases tool life, reduces abnormal wear at the tool tip, and improves cutting parameters, thereby increasing machining efficiency, ultimately achieving the goal of efficiently and cost-effectively manufacturing integral impellers.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for rough milling and rounding the corners of an integral impeller uses a butt milling process with two-sided feeds to reduce tool overhang and a zigzag milling process to reduce the depth of cut per cut. The method includes the following steps:

[0007] S1. Divide the processing area;

[0008] S2. Select the diameter of the machining tool according to the upper and lower limits of the tool diameter;

[0009] S3. Select the processing step range;

[0010] S4. Select the U-shaped milling parameters for processing.

[0011] In step S1, the processed area is divided into two halves along the axial direction, and the tool overhang lengths of the upper and lower halves are as close as possible, and preferably the same tool overhang length is used to reduce the number of tool changes during processing.

[0012] In step S2, the principle for selecting the tool diameter is to use the tool diameter for rough grooving of the blade as the reference upper limit and the final fillet diameter of the blade as the reference lower limit, and the diameter size between the upper and lower limits is selected as the machining tool diameter of this invention.

[0013] In step S3, since the linear velocity of the midpoint of the tool tip is zero, according to the tool diameter selected in step S2, a step distance of 0.04-0.08 times the tool diameter is selected to ensure that the midpoint of the tool tip does not contact the surface of the part, so that the tool is not wrapped in the processed material, and to avoid excessive cutting stress causing tool chipping.

[0014] In step S4, the machining cutting parameters of the rounded corners are determined by the part material. The linear speed range for stainless steel is 40-60 m / min, the linear speed range for titanium alloy is 80-120 m / min, and the linear speed range for high-temperature alloy is 30-45 m / min. The feed per tooth is selected as 0.05-0.08 mm.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] Compared with traditional rough milling and fillet processing, the technology of the present invention can effectively avoid abnormal wear of the tool tip and the reduction of cutting efficiency due to increased allowance distribution to reduce wear. The same processing area can reduce tool consumption by 50% and improve tool cutting efficiency by more than 40%, which has very high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a method for rough milling and rounding of an integral impeller according to the present invention;

[0018] Figure 2 The figure is a schematic diagram of the U-shaped tool path used in the rough milling fillet processing method of an integral impeller of the present invention.

[0019] Among them, 1 is the cutter, 2 is the blade. DETAILED DESCRIPTION

[0020] In order to solve the problems existing in the prior art, such as Figure 1-Figure 2As shown, the present invention provides a method for rough milling and rounding an integral impeller, including a tool 1 and a blade 2. In this embodiment, the fan integral impeller component is made of titanium alloy material with a material grade of TC17, an impeller diameter of Φ450mm, a blade length of 177mm, 35 blades, and a final rounded corner radius of R5.25. The processing method includes the following steps:

[0021] S1. Divide the processing area;

[0022] S2. Select the diameter of the machining tool 1 according to the upper and lower limits of the tool diameter selection principle;

[0023] S3. Select the processing step range;

[0024] S4. Select the U-shaped milling parameters for processing.

[0025] In step S1 , the area to be processed is divided into two halves along the axial direction, with a ratio of 0.5. The tools in the upper and lower halves use the same tool overhang length to reduce the number of tool changes during processing.

[0026] In step S2, the slot width between blades is 31 mm, the previous slotting tool diameter is an R9.5 mm ball cutter, the final fillet is R5.25 mm, and the processing tool selected is an R6 ball end milling cutter.

[0027] In step S3, the length of the blade from the root to 90% is selected as the cutting range, and a step distance of 0.05 times the tool diameter is selected, that is, the cutting depth of each cut is 0.6mm, which can ensure that the tip of the tool does not contact the surface of the processed part, avoiding abnormal wear due to vibration.

[0028] In step S4, a machining program is compiled according to the determined machining layer depth, and a machining cutting speed of 100 m / min and a feed per tooth of 0.07 mm are selected based on the material.

Claims

1. A method for rough milling of an integral impeller, characterized by: The method adopts a butt milling process from both sides to reduce tool overhang, and adopts a round milling process to reduce the depth of cut of each cut. The method includes the following steps: S1. Divide the processing area; S2. Select the diameter of the machining tool according to the upper and lower limits of the tool diameter; S3. Select the processing step range; S4. Select the round milling parameters for processing; In step S1, the processing area is divided into two halves along the axial direction, and the tool overhang lengths in the upper and lower halves are close; In step S2, the principle for selecting the tool diameter is to use the tool diameter for rough grooving of the blade as the reference upper limit and the final fillet diameter of the blade as the reference lower limit, and select the diameter size between the upper and lower limits as the machining tool diameter.

2. The method for rough milling of an integral impeller according to claim 1, characterized in that: In step S1, the same tool overhang length is used.

3. The method for rough milling corners of an integral impeller according to claim 1, characterized in that: In step S3, based on the tool diameter selected in step S2, a tool diameter with a step size of 0.04-0.08 times is selected.

4. The method for rough milling corners of an integral impeller according to claim 1, characterized in that: In step S4, the machining cutting parameters of the rounded corners are determined by the part material. The linear speed range for stainless steel is 40-60 m / min, the linear speed range for titanium alloy is 80-120 m / min, and the linear speed range for high-temperature alloy is 30-45 m / min. The feed per tooth is selected as 0.05-0.08 mm.

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