Milling method for titanium alloy edge covering of composite material blade

Abstract

The present application relates to a kind of milling processing methods of composite material blade titanium alloy edge covering, adopt clamp a and clamp b, process flow includes: pretreatment→first time glue application→first time solidification→first time milling processing→first time sol→second time glue application→second time solidification→second time milling processing→second time sol→post-processing;Composite material blade titanium alloy edge covering is connected by thin-walled portion I (inner and outer surface is region a, a *), node portion (inner and outer surface is region b, b *) And thin-walled portion II (inner and outer surface is region c, c *) Connection is made;The inner and outer side surface of composite material blade titanium alloy edge covering is connected by region a~c, region a*~c* respectively;Groove is provided in clamp a, its inner surface is sequentially connected by region a'~c', convex is provided in clamp b, its outer surface is connected by region a^~c^.The present application improves clamping strength and clamping accuracy and the clamping stiffness and clamping stability of processing.

Description

Technical Field

[0001] This invention belongs to the technical field of cold-end blade processing for high bypass ratio aero-engines, and relates to a milling method for titanium alloy edging of composite blades. Background Technology

[0002] Currently, aero-engine components are developing towards higher temperatures, higher pressure ratios, and higher reliability, while aero-engine structures are evolving towards lighter weight, integration, and composite designs. Composite materials, due to their excellent specific strength and vibration resistance, have become the preferred material for improving efficiency and reducing weight at the fan end of high-bypass turbofan engines. However, due to the anisotropic mechanical properties and brittleness of resin-based composite materials, fan blades made solely of resin-based composite materials have poor impact and erosion resistance, failing to meet current airworthiness standards. Therefore, facing the lightweight and high-efficiency design requirements of advanced aero-engines, and to avoid the fatal defects of carbon fiber materials in fan blade applications, major aero-engine manufacturers have adopted a manufacturing scheme of carbon fiber cores and titanium alloy leading-edge edging.

[0003] Titanium alloys, being a material with high machining difficulty, exhibit significant challenges during milling due to high cutting forces and temperatures, as well as severe work hardening. This leads to rapid tool wear, chattering during machining, and poor machining quality. Furthermore, titanium alloy structural components used for the leading edge edging of aero-engine blades have complex, non-uniform thin-walled curved surfaces with narrow, deep grooves, making machining extremely difficult. Existing mechanical clamping systems, when faced with the large-area curved thin walls and narrow, deep cavity shapes of titanium alloy edgings, often only provide localized clamping, failing to offer full-coverage support. This results in uneven clamping stiffness distribution, insufficient clamping stability, and severely impacts product machining quality.

[0004] For example, patent CN114888608B discloses a clamp for processing the metal reinforcing edge of the leading edge of composite fan blades. The clamp described in this patent consists of left and right clamps. During operation, it only clamps the two ends of the edge, without clamping the large area of ​​thin-walled side of the edge.

[0005] For example, patent CN108466079B discloses a dual-purpose fixture for machining two types of blanks: a metal reinforcing edge on the leading edge of a composite material fan blade. This fixture mainly consists of a metal base, two square grooves on both sides, and an array of bolts. The bolts arranged in an array on the sides clamp the curved surface of the edge by setting different bolt tightening depths. However, this patent still utilizes existing mechanical structure fixture systems, achieving the machining purpose through the assembly of standardized mechanical parts.

[0006] Furthermore, to ensure the service performance of titanium alloy leading edge trimmings, higher requirements have been placed on the machining quality and surface integrity of the inner and outer surfaces of titanium alloy structural components. The machinability of titanium alloy materials and the complexity of the blade leading edge trimming structure together result in high machining costs, long manufacturing cycles, and significant machining difficulties in the high-precision manufacturing of titanium alloy leading edge trimmings for aero-engine blades. Summary of the Invention

[0007] The purpose of this invention is to solve the problems existing in the prior art and to provide a milling method for titanium alloy edging of composite blades.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A milling method for titanium alloy edging of composite blades, using fixture a and fixture b, the process flow includes: pretreatment → first adhesive application → first curing → first milling → first sol-gel → second adhesive application → second curing → second milling → second sol-gel → post-treatment;

[0010] The titanium alloy edging of the composite blade is formed by sequentially connecting thin-walled part I, nodal part and thin-walled part II; the inner surface of the titanium alloy edging of the composite blade is formed by sequentially connecting region a, region b and region c, and the outer surface is formed by sequentially connecting region a*, region b* and region c*; region a and region a* are the inner and outer surfaces of thin-walled part I, region b and region b* are the inner and outer surfaces of nodal part, and region c and region c* are the inner and outer surfaces of thin-walled part II.

[0011] The fixture a has a groove, and the inner surface of the groove is formed by the sequential connection of region a', region b' and region c'.

[0012] The fixture b has a protrusion, and the outer surface of the protrusion is formed by sequentially connecting regions a^, b^ and c^.

[0013] The first application of adhesive involves laying adhesive dots in areas a* and c*, and simultaneously laying an adhesive film in area b*.

[0014] The first curing step involves fully bonding area a* to area a', fully bonding area b* to area b', and simultaneously fully bonding area c* to area c', allowing the adhesive to cure.

[0015] The first milling operation is to mill the inner side of the titanium alloy edging of the composite blade.

[0016] The second application of adhesive involves laying adhesive dots in areas a and c, while simultaneously laying an adhesive film in area b.

[0017] The second curing process involves fully bonding region a with region a^, fully bonding region b with region b^, and simultaneously fully bonding region c with region c^, allowing the adhesive to cure.

[0018] The second milling process involves milling the outer surface of the titanium alloy edging on the composite blade.

[0019] The two areas connected by each adhesive dot have an adhesive bond strength of greater than or equal to 35MPa after curing. Only when the adhesive bond strength is large can the clamping stability during the milling process be guaranteed and the edge-wrapping processing requirements be met. Otherwise, adhesive sticking is likely to occur, resulting in poor processing quality, uneven surface, and obvious processing chatter marks and burrs.

[0020] If adhesive film is laid on regions a* and c*, the thickness of the adhesive film will affect the positioning accuracy of thin-walled parts I and II on fixture a, thus affecting the processing quality; if adhesive dots are laid on region b*, the adhesive bonding strength cannot meet the requirements, and clamping failures such as delamination and displacement are likely to occur. Compared with adhesive dots, adhesive film is more suitable for bonding large curvature structures at joints.

[0021] If adhesive film is laid in regions a and c, the thickness of the adhesive film will affect the positioning accuracy of thin-walled parts I and II on fixture b, thus affecting the processing quality. If adhesive dots are laid in region b, the adhesive bonding strength will not meet the requirements, and clamping failures such as delamination and displacement are likely to occur. Compared with adhesive dots, adhesive film is more suitable for bonding large curvature structures at joints.

[0022] As a preferred technical solution:

[0023] As described above, in the milling process of titanium alloy edging for composite blades, the adhesive bonding strength between the two areas connected by each adhesive dot after curing does not exceed 50 MPa.

[0024] In the milling method for titanium alloy edging of composite blades as described above, when adhesive dots are laid on regions a*, c*, a, or c, the adhesive dots are distributed in a rectangular array with a row spacing of L, a column spacing of T, a volume of V for each adhesive dot, an adhesive strength per unit volume of adhesive of η, and an adhesive bond strength of σ between the two regions connected by the adhesive dots after curing. Where L, T, V, η, and σ are in mm, mm, and mm units, respectively. 3 N / mm 3 MPa.

[0025] In the milling process of titanium alloy edging for composite blades as described above, when the adhesive film is laid on region b* or region b, the thickness of the adhesive film is 0.015-0.030 mm.

[0026] The milling process for titanium alloy edging of composite blades as described above involves placing the bonded fixture and titanium alloy edging of the composite blades at a temperature of 40-45℃ and a pressure of 95-98kPa for 20-25 minutes to cure the adhesive. The curing step ensures that the adhesive is completely cured and that the adhesive and adhesive film tightly fill the gaps between the edging and the fixture, achieving the expected adhesive bonding strength.

[0027] As described above, the milling process for titanium alloy edging of composite blades involves the following steps: First, the bonded fixture and the titanium alloy edging of the composite blade are immersed together in the sol, heated to 70-75°C by vibration and held at that temperature until the fixture and the titanium alloy edging of the composite blade separate. Then, the adhesive film is removed. Finally, the fixture and the titanium alloy edging of the composite blade are immersed separately in the sol, heated to 70-75°C by vibration and held at that temperature for 30-35 minutes to remove residual adhesive and other impurities from the surface.

[0028] The milling method for titanium alloy edging of composite blades as described above has a roughness Ra<0.8μm for the inner surface of the groove and the outer surface of the protrusion, and a surface hardness HRC of 55-60.

[0029] The milling method for titanium alloy edging of composite blades as described above includes the following pretreatment process: First, the entire titanium alloy edging of the composite blade is immersed in 75% alcohol and cleaned with an ultrasonic cleaner at a frequency of 20-25KHz for 15-20 minutes. Then, the entire titanium alloy edging of the composite blade is placed in an oven and heated to 80-85℃ for 5-10 minutes to allow all the alcohol on the surface to evaporate. Finally, the surface cleaning effect of the titanium alloy edging of the composite blade is checked to ensure that there are no oil stains, dust, or other impurities remaining on the surface of the titanium alloy edging of the composite blade.

[0030] The milling process for the titanium alloy edge of the composite blade described above includes the following post-processing steps: placing the titanium alloy edge of the composite blade in an oven at 70-75℃, gradually cooling it to room temperature, and then letting it stand for 2-3 hours to achieve stress relief aging treatment of the titanium alloy edge of the composite blade.

[0031] Beneficial effects:

[0032] (1) The present invention uses adhesive film and adhesive dots distributed in a rectangular array to make the clamp and titanium alloy edge fit more completely, effectively improving the adhesive strength and clamping stability.

[0033] (2) This invention utilizes the thin-walled and narrow-cavity structural features of titanium alloy edging, and combines customized fixtures with adhesive clamping methods. While ensuring clamping strength and clamping accuracy, it achieves full-fit support for the thin-walled structure of the edging, effectively improving the clamping rigidity and clamping stability of the edging process. Attached Figure Description

[0034] Figure 1 This is a process flow diagram of the present invention;

[0035] Figure 2 This is a schematic diagram of the titanium alloy edging structure of the composite blade of the present invention;

[0036] Figure 3 Figure a is a schematic diagram of the machining and clamping of the inner side of the titanium alloy edging of the composite blade according to the present invention; Figure a is a perspective view of the machining and clamping of the inner side of the titanium alloy edging of the composite blade, and Figure b is a front view of the machining and clamping of the inner side of the titanium alloy edging of the composite blade.

[0037] Figure 4 This is a schematic diagram showing the distribution of adhesive dots processed on the inner side of the titanium alloy edging of the composite blade of the present invention.

[0038] Figure 5 Figure a is a schematic diagram of the milling and clamping of the outer side of the titanium alloy edge of the composite blade according to the present invention; Figure a is a perspective view of the milling and clamping of the outer side of the titanium alloy edge of the composite blade, and Figure b is a front view of the milling and clamping of the outer side of the titanium alloy edge of the composite blade.

[0039] Figure 6 This is a schematic diagram showing the distribution of adhesive dots processed on the outer side of the titanium alloy edge of the composite blade of the present invention.

[0040] Figure 7 This is a schematic diagram of the adhesive film bonding on the top of the titanium alloy edge of the composite blade of the present invention;

[0041] Wherein, 1-thin-walled part I, 2-nodal part, 3-thin-walled part II, 4-clamp a, 5-clamp b, 6-inner side of titanium alloy edging of composite blade, 7-outer side of titanium alloy edging of composite blade, 8-titanium alloy edging of composite blade, 9-adhesive film, 10-adhesive dot. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] A milling method for the titanium alloy edging of composite blades, such as... Figures 1-7 As shown, clamp a4 and clamp b5 are used;

[0044] like Figure 3 As shown, the fixture a4 has a groove, and the inner surface of the groove is formed by the sequential connection of region a', region b' and region c'. Its roughness Ra is <0.8μm and its surface hardness HRC is 55-60.

[0045] like Figure 5 As shown, fixture b 5 has a protrusion. The outer surface of the protrusion is formed by the sequential connection of region a^, region b^ and region c^. Its roughness Ra is <0.8μm and its surface hardness HRC is 55-60.

[0046] like Figure 2 As shown, the titanium alloy edging 8 of the composite blade has a narrow, deep cavity, and thin-walled structure. The main areas to be processed are the inner and outer sides of the edging. The titanium alloy edging 8 of the composite blade is formed by sequentially connecting the thin-walled part I1, the node part 2, and the thin-walled part II 3.

[0047] like Figure 3 As shown, the inner surface 6 of the titanium alloy edging of the composite blade is formed by connecting regions a, b and c in sequence, and the outer surface 7 of the titanium alloy edging of the composite blade is formed by connecting regions a*, b* and c* in sequence.

[0048] Region a and region a* are the inner and outer surfaces of thin-walled portion I1, region b and region b* are the inner and outer surfaces of node portion 2, and region c and region c* are the inner and outer surfaces of thin-walled portion II3.

[0049] like Figure 1 As shown, the process flow includes: pretreatment → first application of adhesive → first curing → first milling → first sol-gel → second application of adhesive → second curing → second milling → second sol-gel → posttreatment;

[0050] The pretreatment process is as follows: First, the titanium alloy edging 8 of the composite blade is immersed in 75% alcohol and cleaned with an ultrasonic cleaner at a frequency of 20-25KHz for 15-20 minutes. Then, the titanium alloy edging 8 of the composite blade is placed in an oven and heated to 80-85℃ for 5-10 minutes to allow all the alcohol on the surface to evaporate. Finally, the surface cleaning effect of the titanium alloy edging 8 of the composite blade is checked to ensure that there is no oil, dust or other impurities remaining on the surface of the titanium alloy edging 8 of the composite blade.

[0051] The first application of adhesive involves laying adhesive dots on areas a* and c*, such as... Figure 4As shown, the adhesive dots are distributed in a rectangular array with a row spacing of L and a column spacing of T. The volume of each adhesive dot is V, the adhesive strength per unit volume of adhesive is η, and the bond strength between the two regions connected by the adhesive dots after curing is σ. Where L, T, V, η, and σ are in mm, mm, and mm units, respectively. 3 N / mm 3 MPa, and at the same time, a film 9 with a thickness of 0.015-0.030mm is laid on the area b*;

[0052] The first curing process involves fully bonding regions a* and a', fully bonding regions b* and b', and simultaneously fully bonding regions c* and c'. After this process, the adhesive is left to cure for 20-25 minutes at a temperature of 40-45℃ and a pressure of 95-98kPa. The adhesive strength of region a* is 35-50MPa, and the adhesive strength of region b* is also 35-50MPa.

[0053] The first milling operation is to mill the inner side 6 of the titanium alloy edge of the composite blade. During this process, the fixture a is glued to the outer side 7 of the titanium alloy edge of the composite blade, providing a fully fitted fixed clamping for the titanium alloy edge of the composite blade, and exposing the inner side 6 of the titanium alloy edge of the composite blade to the outside for processing.

[0054] The first sol process is as follows: First, the bonded clamp a 4 and the titanium alloy edge of the composite blade 8 are immersed together in the sol, shaken and heated to 70-75℃ and kept at the temperature until clamp a 4 and titanium alloy edge of the composite blade 8 separate. Then, the adhesive film 9 is removed. Finally, clamp a 4 and titanium alloy edge of the composite blade 8 are separated and immersed in the sol, shaken and heated to 70-75℃ and kept at the temperature for 30-35 minutes.

[0055] The second application of adhesive involves laying adhesive dots in areas a and c, such as... Figure 6 , 7 As shown, the adhesive dots are distributed in a rectangular array with a row spacing of L and a column spacing of T. The volume of each adhesive dot is V, the adhesive strength per unit volume of adhesive is η, and the bond strength between the two regions connected by the adhesive dots after curing is σ. Where L, T, V, η, and σ are in mm, mm, and mm units, respectively. 3 N / mm 3 MPa, and at the same time, a film 9 with a thickness of 0.015-0.030mm is laid on area b;

[0056] The second curing process involves fully bonding region a with region a^, fully bonding region b with region b^, and fully bonding region c with region c^. After this process, the adhesive is left to cure for 20 minutes at a temperature of 40-45℃ and a pressure of 95-98kPa. The adhesive strength of region a* is 35-50MPa, and the adhesive strength of region b* is 35-50MPa.

[0057] The second milling process involves milling the outer surface 7 of the titanium alloy edging of the composite blade. During this process, the fixture b is glued to the inner surface 6 of the titanium alloy edging of the composite blade, providing a fully fitted and fixed clamping for the titanium alloy edging of the composite blade, and exposing the outer surface 7 of the titanium alloy edging of the composite blade to facilitate processing.

[0058] The second sol-gel process is as follows: First, the bonded clamp b5 and the titanium alloy edge of the composite blade 8 are immersed together in the sol, shaken and heated to 70-75℃ and kept at that temperature until the clamp b5 and the titanium alloy edge of the composite blade 8 separate. Then, the adhesive film 9 is removed. Finally, the clamp b5 and the titanium alloy edge of the composite blade 8 are separated and immersed in the sol, shaken and heated to 70-75℃ and kept at that temperature for 30-35 minutes.

[0059] The post-processing procedure is as follows: place the titanium alloy edge of the composite blade in an oven at 70-75℃, gradually cool it to room temperature, and then let it stand for 2-3 hours.

[0060] The milling method for titanium alloy edge banding of composite blades based on the present invention can achieve full-fit effective support for large-area curved thin walls. Compared with the existing clamping scheme, it effectively improves clamping rigidity and processing stability. The surface roughness index is improved from Ra1.2 to Ra0.8, and the dimensional accuracy index is improved from 0.6mm to 0.4mm, realizing high-precision manufacturing of titanium alloy leading edge banding.

Claims

1. A milling method for the titanium alloy edging of composite blades, characterized in that, Using fixtures a and b, the process flow includes: pretreatment → first application of adhesive → first curing → first milling → first sol-gel → second application of adhesive → second curing → second milling → second sol-gel → posttreatment; The titanium alloy edging of the composite blade is formed by sequentially connecting thin-walled part I, nodal part and thin-walled part II; the inner surface of the titanium alloy edging of the composite blade is formed by sequentially connecting region a, region b and region c, and the outer surface is formed by sequentially connecting region a*, region b* and region c*; region a and region a* are the inner and outer surfaces of thin-walled part I, region b and region b* are the inner and outer surfaces of nodal part, and region c and region c* are the inner and outer surfaces of thin-walled part II. The fixture a has a groove, and the inner surface of the groove is formed by the sequential connection of region a', region b' and region c'. The fixture b has a protrusion, and the outer surface of the protrusion is formed by sequentially connecting regions a^, b^ and c^. The first application of adhesive involves laying adhesive dots in areas a* and c*, and simultaneously laying an adhesive film in area b*. The first curing step involves fully bonding area a* to area a', fully bonding area b* to area b', and simultaneously fully bonding area c* to area c', allowing the adhesive to cure. The first milling operation is to mill the inner side of the titanium alloy edging of the composite blade. The second application of adhesive involves laying adhesive dots in areas a and c, while simultaneously laying an adhesive film in area b. The second curing process involves fully bonding region a with region a^, fully bonding region b with region b^, and simultaneously fully bonding region c with region c^, allowing the adhesive to cure. The second milling process involves milling the outer surface of the titanium alloy edging on the composite blade. The adhesive bond strength of the two areas connected by each adhesive dot after curing is greater than or equal to 35 MPa; The thickness of the adhesive film is 0.015-0.030mm.

2. The milling method for titanium alloy edging of composite blades according to claim 1, characterized in that, The bond strength between the two areas connected by each adhesive dot after curing shall not exceed 50 MPa.

3. The milling method for titanium alloy edging of composite blades according to claim 1, characterized in that, When applying adhesive dots to regions a*, c*, a, or c, the dots are arranged in a rectangular array with row spacing of L and column spacing of T. The volume of each dot is V, and the adhesive strength per unit volume of adhesive is [value missing]. The adhesive bond strength between the two areas connected by the adhesive dots after curing is: , Among them, L, T, V, , The units are mm, mm, and mm respectively. 3 N / mm 3 MPa.

4. A milling method for the titanium alloy edging of composite blades according to any one of claims 1 to 3, characterized in that, After the adhesive has cured, the clamps and composite blades with titanium alloy edging are placed at a temperature of 40-45℃ and a pressure of 95-98kPa for 20-25 minutes to allow the adhesive to cure.

5. The milling method for titanium alloy edging of composite blades according to claim 1, characterized in that, The process of the first or second sol is as follows: First, immerse the bonded fixture and the titanium alloy edge of the composite blade together in the sol, shake and heat to 70-75℃ and keep warm until the fixture and the titanium alloy edge of the composite blade separate. Then remove the adhesive film. Finally, immerse the fixture and the titanium alloy edge of the composite blade separately in the sol, shake and heat to 70-75℃ and keep warm for 30-35 minutes.

6. The milling method for titanium alloy edging of composite blades according to claim 1, characterized in that, The surface roughness Ra of the inner surface of the groove and the outer surface of the protrusion is <0.8μm, and the surface hardness HRC is 55-60.

7. The milling method for titanium alloy edging of composite blades according to claim 1, characterized in that, The pretreatment process is as follows: First, the titanium alloy edge of the composite blade is immersed in 75% alcohol and cleaned with an ultrasonic cleaner at a frequency of 20-25KHz for 15-20 minutes. Then, the titanium alloy edge of the composite blade is placed in an oven and heated to 80-85℃ for 5-10 minutes. Finally, the surface cleaning effect of the titanium alloy edge of the composite blade is checked to ensure that there are no impurities remaining on the surface of the titanium alloy edge of the composite blade.

8. The milling method for titanium alloy edging of composite blades according to claim 1, characterized in that, The post-processing procedure is as follows: place the titanium alloy edge of the composite blade in an oven at 70-75℃, gradually cool it to room temperature, and then let it stand for 2-3 hours.

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