A method for correcting the bending and torsion size of turbine blades

Abstract

The present invention provides a method for correcting the bending and torsion size of a turbine blade, and the method comprises the following steps: Step 1, fixing wax sheets with a thickness of 0.4-1 mm at both ends of a blade shape correction membrane that meets the back of the turbine blade to be corrected, to obtain a processed blade shape correction membrane; Step 2, placing a wax mold corresponding to the turbine blade to be corrected on the processed blade shape correction membrane; Step 3, placing a weight that matches the shape of the wax mold in Step 2 at the center of the wax mold in Step 2 along the width direction of the wax mold in Step 2 to press the wax mold to obtain a wax mold with corrected bending and torsion size, and using the obtained wax mold with corrected bending and torsion size to perform investment casting to obtain a turbine blade with corrected bending and torsion size. Through the wax mold pre-deformation method, the reverse deformation amount of the bending and torsion size can be obtained quickly and effectively, and qualified castings can be manufactured and applied to the early wax mold control, thereby reducing the trial production cost and improving production efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of investment casting, in particular to a method for correcting the bending and torsion dimensions of turbine blades. Background Art

[0002] Gas turbines are the power source of modern manufacturing industry, and precision-cast turbine blades are one of the core components of gas turbines. Generally, investment casting method is used to produce precision-cast turbine blades with no excess of high-temperature alloy. Due to the structure of precision-cast turbine blades and the setting of the gating system, precision-cast turbine blades will produce large thermal stress during solidification and cooling, resulting in deformation of the surface of precision-cast turbine blades, bending and twisting tolerances, and high scrap rate of precision-cast turbine blades. Therefore, how to solve the problem of bending and twisting tolerances and deformation of precision-cast turbine blades during the casting process is one of the key technologies in the manufacture of precision-cast turbine blades.

[0003] Because precision-cast turbine blades are generally not allowed to be corrected during the casting stage, correction or anti-deformation technology is used in the wax mold stage to reduce the bending and torsion tolerance of precision-cast turbine blades. Anti-deformation technology is based on three-coordinate measurement, and the surface of precision-cast turbine blades is parametrically designed. The deformation of bending and torsion is characterized by parameter deviation. The average deformation of precision-cast turbine blades is determined by statistically analyzing the size of a certain batch of precision-cast turbine blades. The wax mold anti-deformation model of the precision-cast turbine blade is designed according to the average deformation. Then, the corresponding wax mold correction mold is designed and manufactured. The process is verified according to the anti-deformed model. The anti-deformation model is corrected by the measurement results of the turbine blades. This is repeated iteration to finally determine the wax mold correction mold corresponding to the turbine blade.

[0004] This anti-deformation technology has two shortcomings when dealing with out-of-tolerance dimensions of precision-cast turbine blades: first, it is necessary to count the dimensions of a certain batch of precision-cast turbine blades to determine the average deformation of the precision-cast turbine blades, which results in high initial investment costs; second, the process of statistical deformation-verification-trim takes a lot of time and has a long cycle. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention proposes a method for correcting the bending and torsion dimensions of turbine blades. Through the wax mold pre-deformation method, the bending and torsion dimension reverse deformation amount can be obtained quickly and effectively, and qualified castings can be manufactured and applied to the early wax mold control, thereby reducing the trial production cost and improving production efficiency.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for correcting the bending and torsion size of a turbine blade comprises the following steps:

[0008] Step 1, fixing wax sheets with a thickness of 0.4-1 mm at both ends of a blade shape correction membrane that conforms to the back of the turbine blade to be corrected, to obtain a processed blade shape correction membrane;

[0009] Step 2, placing a wax model corresponding to the turbine blade to be corrected on the processed blade correction membrane;

[0010] Step 3, placing a heavy object that matches the shape of the wax model in step 2 at the center of the wax model in step 2 along the width direction of the wax model in step 2 to press it to obtain the wax model with corrected bending and torsion dimensions, and using the obtained wax model with corrected bending and torsion dimensions for investment casting to obtain the turbine blade with corrected bending and torsion dimensions.

[0011] Preferably, the turbine blade to be corrected in step 1 is a precision cast turbine blade.

[0012] Preferably, the wax sheet described in step 1 is pasted to both ends of the leaf-shaped correction fetal membrane.

[0013] Preferably, in step 2, the wax mold blade back corresponding to the turbine blade to be corrected is placed on the corresponding position of the blade shape correction membrane described in step 1.

[0014] Preferably, the heavy object described in step 3 is a sand bag.

[0015] Furthermore, the width of the contact between the sand bag and the wax model in step 2 is 50-100 mm.

[0016] Preferably, the weight of the weight in step 3 is 500-1000g.

[0017] Preferably, in step 3, a weight of 500-1000 g is used to press the center of the wax mold for 3-5 minutes.

[0018] Preferably, in step 3, the wax mold after the bending and torsion dimensions are corrected is reshaped before investment casting.

[0019] Preferably, the bending and torsion of the turbine blades after the bending and torsion dimension correction in step 3 is controlled within ±0.2 mm.

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

[0021] The present method is a method for correcting the bending and torsion dimensions of turbine blades. First, wax sheets of a certain thickness are fixed at both ends of a blade shape correction membrane that conforms to the back of the turbine blade to be corrected. Then, a wax mold corresponding to the turbine blade to be corrected is placed on the blade shape correction membrane. In this way, a heavy object that conforms to its shape can be placed in the center of the wax mold along the width direction to press it, so that the wax mold has a certain pre-deformation to control the subsequent bending and torsion dimensions of the turbine blade, and the wax mold after the bending and torsion dimensions are corrected is obtained. Through the wax mold pre-deformation method, the reverse deformation amount of the bending and torsion dimensions can be obtained quickly and effectively, and qualified castings can be manufactured and applied to the early wax mold control, which reduces the trial production cost and improves production efficiency. By adopting this invention, after the first round of trial production, the precision-cast turbine blade can obtain a suitable wax mold pre-deformation amount, and the cast turbine blade has qualified and stable bending and torsion dimensions, which not only solves the problem of bending and torsion control of slender and large turbine blades, but also effectively shortens the development cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the precision-cast turbine blades of a certain machine described in the present invention.

[0023] Figure 2 for Figure 1 A cross-sectional view along a certain width direction.

[0024] Figure 3 This is a 3D blue light scan of an uncorrected leaf.

[0025] Figure 4 This is a three-dimensional blue light scanning image of the blade described in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0027] The present invention provides a method for correcting the bending and torsion dimensions of a precision-cast turbine blade, which comprises the following steps:

[0028] Step 1: Manufacturing a blade shape correction membrane that conforms to the back of the precision-cast turbine blade;

[0029] Step 2: Paste 0.1mm-0.2mm thick wax sheets on both ends of the leaf-shaped correction membrane;

[0030] Step 3: Press the precision-cast turbine blade wax model, and immediately take it out and place the back of the blade on the corresponding position of the blade shape correction membrane with the wax sheet attached;

[0031] Step 4: Place a 500g-1000g sandbag in the middle of the precision casting turbine blade wax mold. The sandbag can be deformed to adapt to the different shapes of the blades. Form 50mm to 100mm strips along the width of the precision casting turbine blade wax mold and keep it for 3 minutes to 5 minutes, so that the precision casting turbine blade wax mold can form a certain deformation under the action of the gravity of the sandbag.

[0032] Step 5: Remove the corrected precision casting turbine blade wax model and make correction marks on the tenon of the precision casting turbine blade wax model. You can also mark other positions to remember the thickness value of the wax sheet in step 2.

[0033] like Figure 1 and Figure 2 The precision-cast turbine blade of a certain machine has a total length of about 310 mm, a blade body length of about 270 mm, a maximum blade thickness of 15 mm, an exhaust edge thickness of 1 mm, an average chord width of 52 mm, a smaller thickness difference at the crown, and a larger thickness difference at the tenon.

[0034] Step 6: After pressing the required number of 0.2mm thick wax sheets for precision casting of turbine blade wax models, you can press several more precision casting turbine blade wax models in the same way according to actual needs. Generally, 4 pieces are more common.

[0035] Step 7: Change the thickness of the wax sheet pasted in step 2 from 0.2mm to 0.2×2mm, and repeat steps 3-5 to press out 4 precision casting turbine blade wax molds for testing with 0.4mm thick wax sheets pasted, and make correction marks on the tenons of each precision casting turbine blade wax mold.

[0036] Four more precision-cast turbine blade wax models were pressed out using the same method for testing with wax sheets of 0.2×3mm, 0.2×4mm, and 1.0mm thickness.

[0037] Step 8: Place the rectified precision-cast turbine blade wax model with the air inlet side facing upward and the exhaust side facing downward on a tray padded with sponge. Do not stack them.

[0038] Step 9: Take out the precision-cast turbine blade wax model from the tray padded with sponge for trimming. After trimming, put it back into the tray padded with sponge and keep it flat. Do not stack it.

[0039] The shaping operation inevitably requires holding the blade, and deformation in this process is inevitable, so the operator is required to wear nylon gloves and operate carefully during the shaping operation.

[0040] Step 10: Follow up with normal investment casting modification, assembly, shell making, pouring, cleaning, three-coordinate detection and three-dimensional blue light scanning detection. Qualified castings will be checked and correction marks will be found. Subsequent castings can be corrected by pasting wax sheet thickness corresponding to qualified castings.

[0041] Step 11: When the production demand is large, the corresponding durable correction mold made of aluminum or the like can be designed and manufactured according to the thickness of the wax sheet to be pasted, that is, the correction data. Similarly, the reverse correction wax mold can be obtained to achieve the purpose of controlling the bending and torsion size of the casting.

[0042] Embodiment 1:

[0043] The maximum height of a certain type of gas turbine turbine blade is 290mm, the chord width is 49-53mm, the maximum thickness of the blade is 5.5-13mm, the twisting of each section of the blade relative to its own theoretical profile is no more than ±15', and the bending is within ±0.25mm.

[0044] When the precision casting turbine blade is corrected for bending and torsion, the implementation steps are as follows:

[0045] Step 1: Manufacturing a blade shape correction membrane that conforms to the back of the precision-cast turbine blade;

[0046] Step 2: Paste 0.2mm wax sheets on both ends of the leaf-shaped correction membrane;

[0047] Step 3: Press the wax mold corresponding to the precision-cast turbine blade, and immediately take it out and place the back of the blade on the corresponding position of the blade shape correction membrane with the wax sheet attached;

[0048] Step 4: Place a 500g sandbag in the middle of the precision casting turbine blade wax model and keep it there for 5 minutes.

[0049] Step 5: Remove the corrected precision casting turbine blade wax model and make correction marks on the tenon of the precision casting turbine blade wax model.

[0050] Step 6: After pressing the required number of 0.2 mm thick wax sheets for the precision casting turbine blade wax model test, press another 3 pieces;

[0051] Step 7: Change the thickness of the wax sheet pasted in step 2 from 0.2mm to 0.4mm, and repeat steps 3-5 to press out 4 precision casting turbine blade wax models for testing with 0.4mm thick wax sheets pasted, and make correction marks at the tenon. Use the same method to press out 4 precision casting turbine blade wax models for testing with 0.6mm and 0.8mm thick wax sheets pasted.

[0052] Step 8: Place the corrected precision-cast turbine blades with the air intake side facing upward and the exhaust side facing downward, flat on a tray lined with sponge. Do not stack them.

[0053] Step 9: Take out the wax model from the tray padded with sponge for reshaping. After reshaping, put it back into the tray padded with sponge and keep it flat. Do not stack it.

[0054] The shaping operation inevitably requires holding the blade, and deformation in this process is inevitable, so the operator is required to wear nylon gloves and operate carefully during the shaping operation.

[0055] Step 10: After normal investment casting, the casting is subjected to molding, assembly, shell making, pouring, cleaning, three-coordinate and three-dimensional blue-light scanning inspections. After the casting is placed with a 0.8 mm wax sheet, the bending and torsion of the casting can meet the design requirements.

[0056] The 3D blue light scan of an uncorrected leaf is shown below: Figure 3 As shown in FIG. 1 , the casting has a bending deformation of 1.0 mm and a torsional deformation of 0.51 mm. However, after the blades of this embodiment are corrected, as shown in FIG. Figure 4 The bending and torsion shown are controlled within the range of ±0.2mm.

[0057] Step 11: Based on the thickness of the wax sheet, design and manufacture an aluminum correction mold with 0.8mm at both ends and 0 in the middle to produce castings to achieve the purpose of correcting the bending and torsion of the castings.

[0058] Embodiment 2:

[0059] The maximum height of a certain type of precision-cast turbine blade for a gas turbine is 320 mm, the chord width is 48-53 mm, the maximum thickness of the blade is 5-12 mm, the torsion of each section of the blade relative to its own theoretical profile is no more than ±15', and the bending is within ±0.25 mm.

[0060] When the precision casting turbine blade is corrected for bending and torsion, the implementation steps are as follows:

[0061] Step 1: Manufacturing a blade shape correction membrane that conforms to the back of the precision-cast turbine blade;

[0062] Step 2: Paste 0.2mm wax sheets on both ends of the leaf-shaped correction membrane;

[0063] Step 3: Press the wax mold corresponding to the precision-cast turbine blade, and immediately take it out and place the back of the blade on the corresponding position of the blade shape correction membrane with the wax sheet attached;

[0064] Step 4: Place a 500g sandbag in the middle of the precision casting turbine blade wax model and keep it there for 5 minutes.

[0065] Step 5: Remove the corrected precision casting turbine blade wax model and make correction marks on the tenon of the precision casting turbine blade wax model.

[0066] Step 6: After pressing the required number of 0.2 mm thick wax sheets for the precision casting turbine blade wax model test, press another 3 pieces;

[0067] Step 7: Change the thickness of the wax sheet pasted in step 2 from 0.2mm to 0.4mm, and repeat steps 3-5 to press out 4 precision casting turbine blade wax molds for testing with 0.4mm thick wax sheets pasted, and make correction marks at the tenon. Use the same method to press out 4 precision casting turbine blade wax molds for testing with 0.6mm, 0.8mm and 1.0mm thick wax sheets pasted on the correction mold.

[0068] Step 8: Place the corrected precision-cast turbine blades with the air intake side facing upward and the exhaust side facing downward, flat on a tray lined with sponge. Do not stack them.

[0069] Step 9: Take out the wax model from the tray padded with sponge for reshaping. After reshaping, put it back into the tray padded with sponge and keep it flat. Do not stack it.

[0070] The shaping operation inevitably requires holding the blade, and deformation in this process is inevitable, so the operator is required to wear nylon gloves and operate carefully during the shaping operation.

[0071] Step 10: After normal investment casting, modification, assembly, shell making, pouring, cleaning, three-coordinate and three-dimensional blue-light scanning inspection, it is found that the bending and torsion of the casting can meet the design requirements after placing a 1.0 mm wax sheet.

[0072] Step 11: Based on the thickness of the wax sheet, design and manufacture an aluminum correction mold with 1.0mm at both ends and 0 in the middle to produce castings to achieve the purpose of correcting the bending and torsion of the castings.

[0073] Embodiment three:

[0074] The precision-cast turbine blades for a certain type of gas turbine are about 245mm long, 75-85mm wide, and have a maximum blade thickness of about 13mm. The twist of each section of the blade relative to its theoretical profile is no more than ±15', and the bending is within ±0.30mm.

[0075] When the precision casting turbine blade is corrected for bending and torsion, the implementation steps are as follows:

[0076] Step 1: Manufacturing a blade shape correction membrane that conforms to the back of the precision-cast turbine blade;

[0077] Step 2: Paste 0.2mm wax sheets on both ends of the leaf-shaped correction membrane;

[0078] Step 3: Press the wax mold corresponding to the precision-cast turbine blade, and immediately take it out and place the back of the blade on the corresponding position of the blade shape correction membrane with the wax sheet attached;

[0079] Step 4: Place a 500g sandbag in the middle of the precision casting turbine blade wax model and keep it there for 5 minutes.

[0080] Step 5: Remove the corrected precision casting turbine blade wax model and make correction marks on the tenon of the precision casting turbine blade wax model.

[0081] Step 6: After pressing the required number of 0.2 mm thick wax sheets for the precision casting turbine blade wax model test, press another 3 pieces;

[0082] Step 7: Change the thickness of the wax sheet pasted in step 2 from 0.2mm to 0.4mm, and repeat steps 3-5 to press out 4 precision casting turbine blade wax models for testing with 0.4mm thick wax sheets pasted, and make correction marks at the tenons. Use the same method to press out 4 precision casting turbine blade wax models for testing with 0.6mm thick wax sheets pasted on the correction molds.

[0083] Step 8: Place the corrected precision-cast turbine blades with the air intake side facing upward and the exhaust side facing downward, flat on a tray lined with sponge. Do not stack them.

[0084] Step 9: Take out the wax model from the tray padded with sponge for reshaping. After reshaping, put it back into the tray padded with sponge and keep it flat. Do not stack it.

[0085] The shaping operation inevitably requires holding the blade, and deformation in this process is inevitable, so the operator is required to wear nylon gloves and operate carefully during the shaping operation.

[0086] Step 10: After normal investment casting, modification, assembly, shell making, pouring, cleaning, three-coordinate and three-dimensional blue-light scanning inspection, it is found that the bending and torsion of the casting can meet the design requirements after placing a 0.4mm wax sheet.

[0087] Step 11: Based on the thickness of the wax sheet, design and manufacture an aluminum correction mold with 1.0mm at both ends and 0 in the middle to produce castings to achieve the purpose of correcting the bending and torsion of the castings.

Claims

1. A method for correcting the bending and torsion dimensions of a turbine blade, characterized in that: The following steps are involved: Step 1, pasting wax sheets with a thickness of 0.4 mm on both ends of the blade shape correction membrane that meets the back of the precision cast turbine blade to obtain the blade shape correction membrane processed in the first way; Step 2, placing the wax mold blade back corresponding to the precision-cast turbine blade on the corresponding position of the blade shape correction membrane processed in the first way; Step 3: Place a 500-1000g sandbag that is adapted to the shape of the wax model in step 2 at the center of the wax model in step 2 along the width direction of the wax model in step 2 and press for 3-5 minutes. The width of the contact between the sandbag and the wax model in step 2 is 50-100mm, and obtain the wax model after the bending and torsion size correction in the first way; Step 4, replacing the thickness of the wax sheet in step 1 with 0.6 mm, 0.8 mm and 1.0 mm respectively, and then performing steps 1 to 3 in sequence to obtain the wax model after the bending and torsion size correction in the second way, the wax model after the bending and torsion size correction in the third way and the wax model after the bending and torsion size correction in the fourth way respectively; Step 5, after the wax molds have been corrected for bending and torsion in the four ways obtained in steps 3 and 4, they are modified and then respectively subjected to investment casting, and then three-coordinate detection and three-dimensional blue light scanning detection are respectively performed to select the turbine blades after bending and torsion correction with bending and torsion controlled within ±0.2mm.

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