A hollow part machining method with high wall thickness machining precision

Abstract

This invention relates to the field of machining technology, and in particular to a method for machining hollow parts with high wall thickness machining accuracy. The method comprises the following steps: fixing a support rod to one side of a hollow part formed by vacuum diffusion welding; placing the hollow part on a first positioning table and fixing it with the support rod, and machining the upper blade surface using CNC milling; removing the support rod and placing the hollow part on a second positioning table and fixing it with a shaped limiting component, with the upper blade surface facing downwards, and machining the lower blade surface using CNC milling; after machining the upper and lower blade surfaces, using a heat treatment fixture for shaping, thus completing the machining of the hollow part. This method for machining hollow parts with high wall thickness machining accuracy ensures the machining accuracy of the outer wall thickness of the hollow part.

Description

Technical Field

[0001] This invention relates to the field of machining technology, and in particular to a method for machining hollow parts with high wall thickness accuracy. Background Technology

[0002] As the performance of new aero engines becomes increasingly sophisticated, higher demands are placed on the weight reduction of components, leading to the emergence of many hollow parts. A typical hollow part is shown in Figure 1. Figure 1 , Figure 2 as well as Figure 3 As shown. Connecting ends 11 are provided at both ends for connection with other parts. In the middle is a hollow structure 12 with an airfoil-shaped surface. The airfoil wall thickness is 1-2 mm, with a tolerance of +0.1 / 0. The existing processing method involves welding two semi-cavity workpieces (dividing the hollow part into a left part 2 and a right part 3 from the middle surface) before machining the outer surface, such as... Figures 4-5 As shown, half a cavity 4 is machined on both the left part 2 and the right part 3. Reasonable machining allowances are left at both ends, and reasonable machining allowances are also left on the left and right blade surfaces. The left part 2 and right part 3 are aligned and assembled in a welding fixture, then placed in a vacuum diffusion welding machine. Using the vacuum diffusion welding process, under a high temperature of several hundred degrees and reasonable pressure, the contact surfaces of the left part 2 and right part 3 are diffusion welded together. The welded hollow parts are then machined by CNC milling to remove the allowances at both ends and on the blade surfaces. In reality, the hollow parts undergo high-temperature and high-pressure diffusion welding, resulting in stress that causes welding deformation. The theoretical welding surface 5 is a plane, but the actual welding surface 5 is a curved surface, causing some deformation in the hollow parts. Some hollow parts experience significant deformation. After subsequent CNC milling of the blade surfaces, the wall thickness of some hollow parts' blade surfaces becomes uneven, exceeding tolerances. Summary of the Invention

[0003] The purpose of this invention is to provide a method for machining hollow parts with high wall thickness accuracy, thereby solving the above-mentioned technical problems.

[0004] To achieve the above objectives, the present invention provides a method for machining hollow parts with high wall thickness machining accuracy, the specific steps of which are as follows: Step S1: Fix a support rod on one side of the hollow part formed by vacuum diffusion welding; Step S2: Place the hollow part on the first positioning table and fix the hollow part with the support rod, and use CNC milling to process the upper blade surface; Step S3: After removing the support rod, place the hollow part on the second positioning table and fix it with the irregular limiting part, with the upper blade surface facing down, and use CNC milling to process the lower blade surface; Step S4: After the upper and lower blade surfaces are machined, a heat treatment fixture is used for shaping to complete the machining of the hollow part.

[0005] Preferably, the hollow part formed by vacuum diffusion welding has a margin of 1mm-3mm on its outer surface.

[0006] Preferably, the support rods are arranged in a matrix, the spacing between adjacent support rods is positively correlated with the wall thickness of the hollow part, and the number of support rods is positively correlated with the size of the hollow part.

[0007] Preferably, the first positioning platform includes two first positioning uprights. The upper surface of the first positioning uprights is provided with an inwardly oriented first positioning groove. The first positioning groove is used to accommodate the connecting ends of the hollow parts and to make the hollow parts in a compressed state, thereby limiting the position of the hollow parts in the X-axis direction. A first positioning horizontal plate is provided between the two first positioning uprights. The first positioning horizontal plate has a first limiting hole that is opened and closed relative to the position of the support rod.

[0008] Preferably, one end of the support rod is fixed to the outer surface of the hollow part by argon arc welding, and the other end of the support rod is provided with an adjusting nut after passing through the first limiting hole. The position of the outer surface of the hollow part is measured while rotating the adjusting nut until the wall thickness tolerance of the blade surface is met. Then, the rotation of the adjusting nut is stopped, thereby fixing the position of the hollow part in the Y-axis direction and the Z-axis direction.

[0009] Preferably, the second fixed platform includes two second positioning plates. The upper surface of the second positioning plates is provided with an outwardly arranged second positioning groove. The second positioning groove is used to accommodate the connecting ends of the hollow parts and to make the hollow parts in a stretched state. It is used to limit the position of the hollow parts in the X-axis direction. A second positioning horizontal plate is provided between the two second positioning plates. The second positioning horizontal plate has a second limiting hole that is arranged opposite to the position of the support rod.

[0010] Preferably, the irregularly shaped limiting component includes an irregularly shaped protective pad, the upper surface of which is adapted to the upper blade surface, and the lower surface of which is opposite to the tightening screw in the second limiting hole. While rotating the tightening screw, the position of the lower outer surface of the hollow part is measured until the wall thickness tolerance of the blade surface is met. Then, the rotation of the tightening screw is stopped, thereby fixing the position of the hollow part in the Y-axis direction and the Z-axis direction.

[0011] Therefore, the above-mentioned method for processing hollow parts with high wall thickness accuracy has the following advantages: multiple support rods are used to generate tension to straighten the blade surface before CNC milling, ensuring the wall thickness accuracy of the upper blade surface; according to the size of the hollow part, a certain number of irregular protective pads are arranged on the blade surface, and multiple tightening screws are used to straighten the blade surface before CNC milling, ensuring the wall thickness accuracy of the lower blade surface, so that the overall wall thickness processing accuracy meets the production needs.

[0012] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0013] Figure 1 This is a typical hollow part structure diagram of the present invention; Figure 2 This is a front view of a typical hollow part of the present invention; Figure 3 For the present invention Figure 2 Cross-sectional view of the AA section; Figure 4 This is a structural diagram of the hollow part of the present invention before welding; Figure 5 This is a structural diagram of the left component of the present invention; Figure 6 This is a structural diagram of the hollow part of the present invention after diffusion welding; Figure 7 This is a cross-sectional view of the hollow part of the present invention after diffusion welding; Figure 8 This is a diagram showing the distribution structure of the support rods in this invention; Figure 9 This is a schematic diagram of the assembly of the hollow part of the present invention with the first positioning table; Figure 10 For the present invention Figure 9 Cross-sectional view of the AA section; Figure 11 This is a structural diagram of the upper blade surface after machining according to the present invention; Figure 12 This is a schematic diagram of the assembly of the hollow part and the second positioning stage of the present invention; Figure 13 For the present invention Figure 12 Cross-sectional view of the middle BB plane.

[0014] Figure Labels 1. Hollow part; 11. Connecting end; 12. Cavity structure; 13. Upper blade surface; 14. Lower blade surface; 2. Left part; 3. Right part; 4. Cavity; 5. Welding surface; 6. First positioning platform; 61. First positioning vertical plate; 611. First positioning groove; 62. First positioning horizontal plate; 621. First limiting hole; 7. Support rod; 8. Adjusting nut; 9. Second positioning platform; 91. Second positioning vertical plate; 911. Second positioning groove; 92. Second positioning horizontal plate; 921. Second limiting hole; 10. Irregularly shaped protective pad; 101. Tightening screw. Detailed Implementation

[0015] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0016] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0017] A method for machining hollow parts with high wall thickness accuracy, characterized by the following specific steps: Step S1: Fix the support rod 7 on one side of the hollow part formed by vacuum diffusion welding.

[0018] Hollow parts formed by vacuum diffusion welding, such as Figures 6-7 As shown, the hollow parts formed by vacuum diffusion welding have a margin of 1mm-3mm on their outer surface.

[0019] like Figure 8 As shown, the support rods 7 are arranged in a matrix. One end of each support rod 7 is fixed to the outer surface of the hollow part using argon arc welding. The spacing between adjacent support rods 7 is positively correlated with the wall thickness of the hollow part; that is, the greater the wall thickness of the hollow part, the larger the spacing. The number of support rods 7 is positively correlated with the size of the hollow part; the longer (wider) the hollow part, the more support rods are required. Based on the size of the hollow part, a certain number of support rods are arranged on the blade surface and fixed using manual argon arc welding with process parameters that do not damage the final blade surface.

[0020] Step S2: Place the hollow part on the first positioning platform 6 and fix the hollow part with the support rod 7, such as... Figure 9 and Figure 10As shown, the first positioning table 6 includes two first positioning plates 61. The upper surface of each first positioning plate 61 has an inwardly oriented first positioning groove 611. The first positioning groove 611 accommodates the connecting ends of the hollow part and keeps the hollow part in a compressed state, thus defining the X-axis position of the hollow part. A first positioning horizontal plate 62 is positioned between the two first positioning plates 61. The first positioning horizontal plate 62 has a first limiting hole 621 positioned opposite to the support rod 7. One end of the support rod 7 is fixed to the outer surface of the hollow part using argon arc welding. The other end of the support rod 7 passes through the first limiting hole 621 and is fitted with an adjusting nut 8. Rotating the adjusting nut 8 while simultaneously measuring the position of the outer surface of the hollow part until the blade wall thickness tolerance is met, then stopping the rotation of the adjusting nut 8, thus fixing the Y-axis and Z-axis positions of the hollow part. After fixing, the upper blade surface is machined using CNC milling, as shown... Figure 11 As shown, multiple support rods are used to generate tension to straighten the blade surface, which is then CNC milled to ensure the wall thickness accuracy of the upper blade surface.

[0021] Step S3: After removing the support rod 7 and grinding the weld points, place the hollow part on the second positioning table 9 and fix it with the irregularly shaped limiting component, with the upper blade-shaped surface facing downwards. Figures 12-13 As shown, the lower blade profile is machined using CNC milling. The second fixed table includes two second positioning plates 91. The upper surface of the second positioning plates 91 is provided with an outwardly oriented second positioning groove 911. The second positioning groove 911 is used to accommodate the connecting ends of the hollow part and to keep the hollow part in a stretched state. It is used to limit the position of the hollow part in the X-axis direction. A second positioning horizontal plate 92 is provided between the two second positioning plates 91. The second positioning horizontal plate 92 has a second limiting hole 921 that is positioned opposite to the support rod 7. The irregularly shaped limiting component includes an irregularly shaped protective pad 10. The upper end face of the irregularly shaped protective pad 10 is adapted to the upper blade surface, and the lower end face of the irregularly shaped protective pad 10 is positioned opposite to the tightening screw 101 in the second limiting hole 921. The irregularly shaped protective pad 10 prevents the tightening screw 101 from directly damaging the blade surface and maintains stable and uniform support. While rotating the tightening screw 101, the position of the lower outer surface of the hollow part is measured until the blade surface wall thickness tolerance requirement is met. Rotation of the tightening screw 101 is then stopped, thus fixing the position of the hollow part in the Y-axis and Z-axis directions. According to the size of the hollow part, a certain number of irregularly shaped protective pads are arranged on the blade surface, and the blade surface is straightened with multiple tightening screws and then CNC milled to ensure the wall thickness accuracy of the lower blade surface.

[0022] Step S4: After the upper and lower blade surfaces are machined, a heat treatment fixture is used for shaping to complete the machining of the hollow part.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for machining hollow parts with high wall thickness accuracy, characterized in that, The specific steps are as follows: Step S1: Fix a support rod on one side of the hollow part formed by vacuum diffusion welding; Step S2: Place the hollow part on the first positioning table and fix the hollow part with the support rod, and use CNC milling to process the upper blade surface; Step S3: After removing the support rod, place the hollow part on the second positioning table and fix it with the irregular limiting part, with the upper blade surface facing down, and use CNC milling to process the lower blade surface; Step S4: After the upper and lower blade surfaces are machined, a heat treatment fixture is used for shaping to complete the machining of the hollow part.

2. The method for machining hollow parts with high wall thickness accuracy according to claim 1, characterized in that: The hollow parts formed by vacuum diffusion welding have a margin of 1mm-3mm on their outer surface.

3. The method for machining hollow parts with high wall thickness accuracy according to claim 2, characterized in that: The support rods are arranged in a matrix. The spacing between adjacent support rods is positively correlated with the wall thickness of the hollow part, and the number of support rods is positively correlated with the size of the hollow part.

4. The method for machining hollow parts with high wall thickness accuracy according to claim 3, characterized in that: The first positioning platform includes two first positioning uprights. The upper surface of the first positioning uprights is provided with an inwardly positioned first positioning groove. The first positioning groove is used to accommodate the connecting ends of the hollow parts and to put the hollow parts in a compressed state. It is used to limit the position of the hollow parts in the X-axis direction. A first positioning horizontal plate is provided between the two first positioning uprights. The first positioning horizontal plate has a first limiting hole that is set opposite to the position of the support rod.

5. The method for machining hollow parts with high wall thickness accuracy according to claim 4, characterized in that: One end of the support rod is fixed to the outer surface of the hollow part by argon arc welding. The other end of the support rod passes through the first limiting hole and is equipped with an adjusting nut. Rotating the adjusting nut while measuring the position of the outer surface of the hollow part until the wall thickness tolerance of the blade surface is met, then stopping the rotation of the adjusting nut, thereby fixing the position of the hollow part in the Y-axis and Z-axis directions.

6. The method for machining hollow parts with high wall thickness accuracy according to claim 5, characterized in that: The second fixed platform includes two second positioning plates. The upper surface of the second positioning plates is provided with an outwardly positioned second positioning groove. The second positioning groove is used to accommodate the connecting ends of the hollow parts and to make the hollow parts in a stretched state. It is used to limit the position of the hollow parts in the X-axis direction. A second positioning horizontal plate is provided between the two second positioning plates. The second positioning horizontal plate has a second limiting hole that is provided opposite to the position of the support rod.

7. The method for machining hollow parts with high wall thickness accuracy according to claim 6, characterized in that: The irregularly shaped limiting component includes an irregularly shaped protective pad. The upper surface of the irregularly shaped protective pad is adapted to the upper blade surface, and the lower surface of the irregularly shaped protective pad is positioned opposite to the tightening screw in the second limiting hole. While rotating the tightening screw, the position of the lower outer surface of the hollow part is measured until the wall thickness tolerance of the blade surface is met. Then, the rotation of the tightening screw is stopped, thereby fixing the position of the hollow part in the Y-axis direction and the Z-axis direction.

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