A high speed grinding method for directionally solidified high temperature alloy turbine blade

Abstract

The application discloses a high-speed grinding method for directionally cast high-temperature alloy turbine working blades, which comprises the following processes: grinding directionally cast high-temperature alloy turbine working blades by using a grinding wheel; the grinding line speed Vs is not less than 43 m / s and the feeding speed Vw is not less than 1000 mm / min in each grinding process; the cutting depth of the first cutter is 0.5 mm, and the cutting depth of subsequent grinding processes is sequentially decreased; and the grinding wheel is a single-crystal corundum grinding wheel. The method solves the problem of low processing efficiency of the grinding method for directionally cast high-temperature alloy turbine working blades in the prior art, and seriously affects the production speed. By adopting the single-crystal corundum grinding wheel, the grinding line speed Vs is not less than 43 m / s, the feeding speed Vw is not less than 1000 mm / min, and the cutting depth of the grinding process is limited, the grinding efficiency is improved by 3.6 times, and the surface integrity requirement is met.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically to a high-speed grinding method for directional casting high-temperature alloy turbine blades. Background Technology

[0002] Turbine blades are an important component of the turbine section in a gas turbine engine. They are subjected to high-temperature thermal shock from the combustion chamber. To improve the heat resistance of turbine blades, new aero-engine turbine blades now use DZ125 cast high-temperature alloy.

[0003] Turbine blades are currently ground using a five-axis grinding center with a hybrid corundum wheel (WA / PA) for profile grinding. The typical grinding parameters are: linear velocity Vs = 18–22 m / s, feed rate Vw = 200–250 mm / min, and depth of cut a. p Grinding methods with a thickness of ≤0.3mm are used, but this grinding method has low processing efficiency, which seriously restricts the production needs.

[0004] In summary, the existing grinding methods for directional casting high-temperature alloy turbine blades suffer from low processing efficiency, which seriously affects production speed. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a high-speed grinding method for directional casting high-temperature alloy turbine working blades, which solves the problem of low processing efficiency and serious impact on production speed in the existing grinding methods for directional casting high-temperature alloy turbine working blades.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A high-speed grinding method for directionally cast high-temperature alloy turbine blades includes the following processes:

[0008] The working blades of the directional casting high-temperature alloy turbine are ground using a grinding wheel; the grinding linear speed Vs is not less than 43m / s and the feed speed Vw is not less than 1000mm / min during each grinding process;

[0009] The cutting depth of the first cut is 0.5 mm, and the cutting depth of subsequent grinding processes decreases sequentially.

[0010] The grinding wheel is a single-crystal corundum grinding wheel.

[0011] Preferably, when the number of cutting tools in the grinding process is 7, the cutting depth of each pass in the processing sequence is 0.5mm, 0.5mm, 0.3mm, 0.15mm, 0.05mm, 0.01mm, and 0.0mm respectively.

[0012] Preferably, cooling is achieved by flushing with coolant during the grinding process.

[0013] Furthermore, the cooling pressure of the coolant flushing is not less than 8 atmospheres.

[0014] Preferably, the dimensional tolerance of the tenon profile of the directional cast high-temperature alloy turbine blade is no greater than 0.02 mm.

[0015] Preferably, when grinding the directional casting high-temperature alloy turbine blades with a grinding wheel, a roller is used for follow-up correction to correct the profile of the grinding wheel.

[0016] Furthermore, the roller spindle speed is greater than 5879 r / min.

[0017] Furthermore, the correction amount for the grinding wheel is 0.10 μm / r.

[0018] Preferably, the grinding wheel spindle speed is greater than 7349 r / min.

[0019] Preferably, the working surface profile of the tenon teeth of the directional casting high-temperature alloy turbine working blade is 0.02mm, the roughness Ra is 0.8mm, the non-working surface profile is 0.07mm, the roughness Ra is 1.6mm, the tenon tooth roller size tolerance is ±0.04mm, the tooth taper is not greater than 0.02mm, and the maximum misalignment is 0.013mm.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention provides a high-speed grinding method for directional casting high-temperature alloy turbine blades. By employing a single-crystal corundum grinding wheel and grinding parameters suitable for directional casting high-temperature alloy turbine blades, the grinding linear velocity Vs is not less than 43 m / s, the feed rate Vw is not less than 1000 mm / min, and the depth of cut is precisely defined. This method improves grinding efficiency by 3.6 times and meets the surface integrity requirements of Q / 5B691. By selecting a single-crystal corundum grinding wheel, which possesses characteristics such as sharp grinding edge, good self-sharpening properties, high durability, good toughness, and low cost, it can adapt to these grinding parameters, improving the machining quality and efficiency of directional casting high-temperature alloy turbine blades. Attached Figure Description

[0022] Figure 1 This is a front view of the tenon teeth on a turbine blade of a certain machine.

[0023] Figure 2 This is a side view of the tenon teeth on a turbine blade of a certain machine.

[0024] Figure 3 This is a schematic diagram of metallographic testing. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0026] The present invention discloses a high-speed grinding method for directional casting high-temperature alloy turbine working blades, comprising the following processes: grinding the directional casting high-temperature alloy turbine working blades with a grinding wheel; the grinding linear velocity Vs is not less than 43 m / s and the feed rate Vw is not less than 1000 mm / min in each grinding process; the cutting depth of the first cut is 0.5 mm, and the cutting depth of subsequent grinding processes decreases sequentially; the grinding wheel is a single-crystal corundum grinding wheel.

[0027] This invention, through a combination of grinding wheel, equipment function, processing materials, and working blade processing stroke, establishes a high-speed grinding method for directional turbine working blades, improving efficiency by 3.6 times. This grinding method is economical and effective, effectively preventing burning of the working blades and reducing grinding wheel consumption. By selecting a single-crystal corundum grinding wheel, which possesses characteristics such as sharp grinding edge, good self-sharpening properties, high durability, good toughness, and low price, it can adapt to the grinding parameters, improving the processing quality and efficiency of directional cast high-temperature alloy turbine working blades.

[0028] Example

[0029] This embodiment uses a DZ125 cast high-temperature alloy turbine blade as an example to illustrate a high-speed grinding method for a directionally cast high-temperature alloy turbine blade (including equipment parameters, grinding wheel, grinding parameters, etc.). In this embodiment, the preferred grinding speed is Vs = 43 m / s, feed rate Vw = 1000 mm / min, and depth of cut a... p With a thickness of ≤0.5mm, grinding efficiency is increased by 3.6 times, meeting the surface integrity requirements of Q / 5B691.

[0030] like Figure 1 and Figure 2 As shown, the directionally cast high-temperature alloy turbine blades of a certain machine employ multi-station integrated machining technology during processing. The main grinding parts are the tenons and end faces. The tenons serve as the assembly datum for the blades, with a serrated profile. The working surface profile is 0.02 mm with a surface roughness Ra of 0.8 mm, while the non-working surface profile is 0.07 mm with a surface roughness Ra of 1.6 mm. The tenon hob dimensions have a tolerance of ±0.04 mm, a tooth taper of no more than 0.02, and a maximum misalignment of 0.013, requiring strict machining specifications.

[0031] The entire grinding process uses a linear speed of Vs = 43 m / s. Considering the high dimensional accuracy of the tenon profile (0.02 tolerance) and the relatively small width of the tenon relative to the guide vane edge size, the feed rate of the entire machining process is set to Vw = 1000 mm / min, which is slower than that of the guide vane. This maintains the high dimensional accuracy of the grinding wheel profile. The first few passes of grinding the part use a large depth of cut ap = 0.5 mm, and the depth of cut decreases gradually in subsequent passes to prevent overheating and burning of the part surface during rapid feed grinding and to improve the surface integrity of the part.

[0032] The present invention discloses a high-speed grinding method for directional casting high-temperature alloy turbine blades, which specifically includes the following steps.

[0033] Step 1, Grinding wheel selection:

[0034] For the production of single-crystal corundum grinding wheels with a maximum linear velocity of 50m / s, and considering the machinability of DZ125 material, the grinding wheel grade 88A46-3E16-QV36-50S, manufactured by Fenghang (Handan) Grinding Wheel Products Co., Ltd., was selected. This grinding wheel's single-crystal abrasive has the characteristics of strong cutting ability, high hardness and toughness, and is particularly suitable for grinding easily deformable and hard-damaged parts. The outer diameter of this grinding wheel is 300mm, the inner diameter is 76.2mm, and the grinding wheel thickness is available in different specifications from 10mm, 13mm, 15mm... to 60mm, depending on the workpiece position.

[0035] Step 2, Equipment Selection:

[0036] ① Grinding wheel spindle speed requirement. The linear velocity of the grinding wheel is Vs = 50m / s. When the minimum grinding wheel diameter is 130mm, the grinding wheel spindle speed needs to be greater than 7349r / min (n = linear velocity Vs / π minimum grinding wheel diameter D × 60 × 1000).

[0037] ② Grinding wheel dressing method. Because the ratio of feed rate Vw / grinding linear speed Vs in high-speed grinding is larger than that in conventional grinding, and the working blade teeth are longer (approximately 30mm-50mm), the abrasive breakage and self-sharpening properties of the grinding wheel are poor. Even with a grinding wheel possessing strong cutting ability, high hardness, and high toughness, a roller is still needed to follow the grinding wheel in a dressing process to break up the abrasive and improve self-sharpening, ensuring the high precision of the grinding wheel in profile grinding of parts and guaranteeing the surface quality of the parts. To reduce grinding wheel consumption and improve economy, the grinding wheel dressing amount is reduced from the original 0.25μm / r to 0.10μm / r, which is relatively low compared to the high-speed grinding dressing amount of the working blades.

[0038] ③ Roller spindle speed. Since the speed ratio between the grinding wheel and the roller is 0.8, and the conventional roller diameter is 130mm, the roller spindle speed needs to be greater than 5879r / min (n=linear velocity Vs / π roller diameter D1×60×1000×0.8).

[0039] ④ Cooling pressure.

[0040] Because the grinding feed speed Vw = 1000 mm / min is relatively fast, in order to prevent the parts from being burned during grinding, and to ensure that the abrasive and iron filings generated during grinding are removed from the air holes of the grinding wheel in a timely manner, it is necessary to increase the cooling pressure to no less than 8 atmospheres to reduce the heat generated during grinding and flush away the iron filings.

[0041] Step 3, Grinding parameter selection:

[0042] If the surface allowance of the tenon teeth of a directional high-temperature alloy turbine blade is 1.5mm, the grinding parameters are obtained through repeated orthogonal experiments and iterations on various parameters, including the characteristics of the part material, equipment, and grinding wheel. The entire grinding process uses a linear velocity Vs = 43m / s. Considering the high dimensional accuracy of the tenon teeth (0.02 tolerance) and the relatively small width of the tenon teeth compared to the guide vane edge, the feed rate Vw = 1000mm / min is set relatively slower than that of the guide vane to maintain the high dimensional accuracy of the grinding wheel. The first few passes of grinding the part use a large depth of cut ap = 0.5mm, and the depth of cut decreases gradually in subsequent passes to prevent overheating and burning of the part surface during rapid feed grinding and to improve the surface integrity of the part.

[0043] The parameters for the entire processing are shown in the table below:

[0044]

[0045] The operation method of this invention includes the following steps: clamping the part onto the fixture, using a feeler gauge to check and ensure that the gap between the part and the fixture positioning point is no greater than 0.03mm, and using a torque-limiting wrench to tighten the bolts to secure the part. Using a roller to dress the grinding wheel until the required surface profile is achieved; while dressing the part, ensure that the roller simultaneously dresses the grinding wheel; simultaneously using the grinding parameters in the table above, perform grinding on the surface of the part; after machining, disassemble the part.

[0046] Surface integrity test results of parts:

[0047] Test items Standard value Original processing method Method of the present invention White layer / remelted layer none Not seen Not seen Surface deformation layer ≤0.005 Not seen Not seen redeposition layer none Not seen Not seen Foreign objects none Not seen Not seen Pulling ≤0.013 ≤0.013 ≤0.004 Peeling ≤0.013 ≤0.009 ≤0.003 wrinkles ≤0.008 Not seen Not seen work hardening ≤0.025 Not seen Not seen crack none Not seen Not seen .

Claims

1. A high speed grinding method for directionally cast high temperature alloy turbine work blades, characterized by, The process comprises the following steps, Grinding is performed on the directional casting high-temperature alloy turbine working blade by using a grinding wheel; the grinding line speed Vs is not less than 43 m / s and the feed speed Vw is not less than 1000 mm / min in each grinding process; The cutting depth of the first cutter is 0.5 mm, and the cutting depth of the subsequent grinding processes is sequentially decreased; when the number of cutters in the grinding process is 7, the cutting depth of each process in the processing order is 0.5 mm, 0.5 mm, 0.3 mm, 0.15 mm, 0.05 mm, 0.01 mm and 0.0 mm; cooling liquid flushing is used for cooling during the grinding process; the cooling pressure of the cooling liquid flushing is not less than 8 atmospheres. The grinding wheel is a single-crystal corundum grinding wheel.

2. A high speed grinding method of directionally solidified high temperature alloy turbine blade according to claim 1, wherein, The size precision tolerance of the tenon tooth profile of the directional casting high-temperature alloy turbine working blade is not greater than 0.02 mm.

3. A high speed grinding method of a directionally solidified high temperature alloy turbine blade according to claim 1, wherein, When the directional casting high-temperature alloy turbine working blade is ground by using the grinding wheel, a roller is used for following correction to correct the profile of the grinding wheel.

4. A high speed grinding method of directionally solidified high temperature alloy turbine blade according to claim 3, wherein The roller spindle speed is greater than 5879 r / min.

5. A high speed grinding method of directionally solidified high temperature alloy turbine blade according to claim 3, wherein The correction amount of the grinding wheel is 0.10 μm / r.

6. A high speed grinding method of directionally solidified high temperature alloy turbine blade according to claim 1, wherein The grinding wheel spindle speed is greater than 7349 r / min.

7. A high speed grinding method of directionally cast high temperature alloy turbine work blade according to claim 1, characterized by, The working surface profile of the tenon tooth of the directional casting high-temperature alloy turbine working blade is 0.02 mm, the roughness Ra is 0.8 mm, the non-working surface profile is 0.07 mm, the roughness Ra is 1.6 mm, the tenon tooth roller size tolerance is 0.04 mm, the tooth taper is not greater than 0.02 mm, and the maximum tooth error is 0.013 mm.

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