A machining tool and method for a gas turbine tangential shroud casting

Abstract

The application provides a processing method of a tangential protective cover casting of a gas turbine, which is completed through the steps of analyzing the structure of the casting, processing the tooling, marking the size of the casting, clamping the casting and processing the casting, etc., in the processing of the casting, an auxiliary tooling structure is designed, which comprises: an upper tooling and a lower tooling, the split surface of the upper tooling and the lower tooling is located below the position of the maximum contour line of the outer contour of the casting, the top surface of the upper tooling is provided with a first supporting structure for supporting the casting, and the side surface of the lower tooling is provided with a second supporting structure for clamping the casting, through the method and the tooling structure, the position of the casting in the tooling can be accurately set, a center frame is not needed, the size tolerance of the product is ensured, the processing cost is greatly reduced, and the processing cycle is shortened.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of casting and machining, and relates to a machining process for a tangential protective cover casting, in particular to a machining process for a tangential protective cover casting of a special-shaped gas turbine. BACKGROUND

[0002] The tangential protective cover of a gas turbine exhaust cylinder has a tensile strength of not less than 620 Mpa, a hardness of 180-280 HB, a casting body blank size tolerance of 0-2.5 mm, and a machining surface machining tolerance of +0.3 mm. The tangential protective cover of the gas turbine exhaust cylinder is currently a forged piece, and the forged piece is changed into a casting piece due to procurement cost, but the casting piece is a special-shaped structure casting piece, and the scribing and machining are difficult, and the casting body blank profile size is 1280*580*480 mm. Although the existing machining scheme is to use a larger five-axis numerical control machining center for machining, the size tolerance requirement of the casting piece can be met, but the machining cost is high, the cycle is long, and the economy is not strong. Therefore, a new machining method for the tangential protective cover casting piece of the gas turbine is developed. SUMMARY

[0003] In order to solve the technical problems existing in the prior art, the application provides a machining method and machining tool for a tangential protective cover casting piece of a gas turbine, the structure characteristics of the type of casting piece are analyzed, the machining tool is designed, the scribing detection scheme of the product is optimized, and the auxiliary tool is designed to ensure the size tolerance of the product. The application is as follows:

[0004] A machining tool for a tangential protective cover casting piece of a gas turbine, the tool structure comprises: an upper tool and a lower tool, the split surface of the upper tool and the lower tool is located below the position of the maximum contour line of the outer contour of the casting piece, the top surface of the upper tool is provided with a first supporting structure for supporting the casting piece through an upper supporting plate, and the side surface of the lower tool is provided with a second supporting structure for clamping the casting piece through a lower supporting frame; the upper tool and the lower tool are respectively provided with an upper positioning structure and a lower positioning structure on one side of the split surface.

[0005] The application is applied to machining the type of castings on a three-axis numerical control boring / milling machine, needs to be processed twice, and after one side is processed with the help of an auxiliary machining tool, the other side is clamped and processed after turning over, the tool design is an upper tool and a lower tool, according to the maximum range that can be machined by the three-axis boring / milling machine, the split surface of the upper tool and the lower tool is selected at a position where the maximum profile line of the outer profile of the casting is moved downward by a certain distance, the downward movement distance can be determined according to the height of the casting, while ensuring that the height of the lower tool is convenient for clamping the workpiece. The upper tool and the lower tool are cooperatively positioned through 4 to 6 positioning references, and a certain gap is reserved at the split surface position except the position of the positioning reference. The first supporting structure and the second supporting structure are used to fix the casting, the first supporting structure is used to adjust the bottom surface reference of the casting and the end surface of the lower tool to be flush, the second supporting structure is used to clamp the casting, the casting is connected with the tool, and it is ensured that the casting does not move between the lower tool during machining and turning over, and it is ensured that the machining reference does not move.

[0006] In order to adapt to castings with different shapes, the clamping of the castings is adjusted, and further, the length of the first supporting structure and the second supporting structure inside the upper tool and the lower tool is adjustable.

[0007] Preferably, the first supporting structure and the second supporting structure are both bolts, and the bolts are used to conveniently adjust the extension amount of the supporting structure.

[0008] Further, in order to combine the upper tool and the lower tool, ensure that the upper tool and the lower tool are tightly connected, ensure that the top surface of the upper tool and the bottom surface of the lower tool are parallel, and ensure that the tool is tightly matched with the casting, a connecting plate for connecting the upper tool and the lower tool is arranged on the outer side surface of the upper tool and the lower tool.

[0009] The application also provides a machining method for a tangential protective cover casting of a gas turbine, characterized in that the machining tool is used, and when the casting is actually machined, the method specifically includes the following steps:

[0010] Firstly, the structure of the casting is analyzed: according to the characteristics of the inner and outer surfaces of the casting, the tool structure is determined,

[0011] The tool structure includes an upper tool and a lower tool, and the split surface of the upper tool and the lower tool is located on the lower side of the maximum profile line of the outer profile of the casting.

[0012] Secondly, the tool is machined.

[0013] Thirdly, the size of the casting is marked, the size of the casting blank is measured, the height direction reference is determined after the allowance of each surface of the casting is adjusted, and the actual allowance of each surface of the casting is marked on the surface of the casting according to the size measurement result.

[0014] Fourth step, the clamping of the casting, the reference boring / milling plane of the casting bottom plane in the height direction Z is taken as the reference surface, the upper tooling and the lower tooling are opened, the upper tooling top surface is downward, the casting is supported through the first support structure on the upper tooling top surface, and the height of the casting is adjusted, after ensuring that the reference in the height direction is flush with the bottom surface of the lower tooling, the second support structure on the side of the lower tooling and the upper tooling and the lower tooling are fastened;

[0015] Fifth step, the processing of the casting, the tooling and the casting are turned over, the upper tooling, the casting and the lower tooling are sequentially arranged from top to bottom, the bottom surface of the lower tooling is taken as the reference for clamping, then the upper tooling is removed, the tool setting device is used, the machining reference in other directions is determined according to the machining allowance of each surface marked during the size marking, and then the machining program is compiled according to the three-dimensional model of each machining surface of the casting by using the programming software to perform the machining.

[0016] Further, a gap is reserved at the position of the split surface between the upper tooling and the lower tooling.

[0017] In the preferred scheme, in the third step, the size marking of the casting, the three-dimensional measuring arm or the three-dimensional scanning, the three-dimensional camera or any one of the measurement methods is used to measure the size of the casting blank.

[0018] Further, in the fourth step, when the casting is clamped, the distance of the first support structure arranged on the upper support plate inside the upper tooling is adjusted, the casting bottom surface reference is adjusted flush with the end surface of the lower tooling, the distance of the second support structure on the lower support frame inside the lower tooling is adjusted, and the casting is clamped.

[0019] Further, in the fifth step, in the processing of the casting, the three-axis numerical control boring / milling machine is used to process the casting.

[0020] The application has the following technical effects:

[0021] 1. The application as a whole designs a processing method of a gas turbine tangential protective cover casting, the application designs a tooling structure for processing of a special-shaped casting, the tooling structure is designed as an upper tooling and a lower tooling, the split surface of the upper tooling and the lower tooling is arranged according to the outer contour line of the casting, 4 to 6 positioning references are arranged for cooperation and positioning, the first support structure and the second support structure respectively located inside the upper tooling and the lower tooling are used to adjust the position of the casting, the movement between the casting and the lower tooling during the processing and turning over is avoided, the processing reference is prevented from being misaligned, and the processing precision of the casting is ensured.

[0022] 2. In the size marking step of the casting, the reference in the height direction Z is determined after the allowance of each surface of the casting is adjusted to the optimal state, and the actual allowance of each surface of the casting is marked at intervals on the surface of the casting according to the size measurement result, so that the tool setting is facilitated before processing.

[0023] 3. The process method can be used for batch processing of special-shaped products with high size accuracy requirements, ensuring product size tolerance, reducing the dependence of special-shaped castings on machining centers, greatly reducing machining cost, and shortening the machining cycle. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A tangential protective cover casting for a gas turbine exhaust cylinder;

[0025] Figure 2 A tangential protective cover casting for a gas turbine exhaust cylinder;

[0026] Figure 3 An upper tooling;

[0027] Figure 4 A lower tooling;

[0028] Figure 5 A casting and tooling assembly view;

[0029] Figure 6 Another assembly view of the casting and tooling;

[0030] In the figure, the upper tooling 110, the upper support plate 111, the first support structure 112, the lower tooling 120, the lower support frame 121, the second support structure 122, the upper positioning structure 113, the lower positioning structure 123, the connecting plate 130, the casting 200, 300, and the tooling split surface. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0032] In the specific embodiment, an M701AJ type gas turbine exhaust cylinder tangential protective cover casting is made, the casting material is 13Cr-1Ni stainless steel, the tensile strength of the body is required to be not less than 620Mpa, the hardness is required to be 180-280HB, the casting structure is as shown in Figure 1 and Figure 2 The casting contour size is 1250*550*450mm, the casting blank contour size is 1280*580*480mm. The net weight of the casting is 232kg, the casting body blank size tolerance is 0-2.5mm, and the processing tolerance is required to be ±0.3mm.

[0033] Embodiment 1

[0034] As Figures 3-5 The gas turbine tangential protective cover casting processing tool of the present application comprises: an upper tool 110 and a lower tool 120, the split surface of the upper tool 110 and the lower tool 120 is located below the position of the maximum contour line of the outer contour of the casting, the top surface of the upper tool 110 is provided with a first support column 112 for supporting the casting through an upper support plate 111, and the side surface of the lower tool 120 is provided with a second support column 122 for clamping the casting 200 through a lower support frame 121; the upper tool 110 and the lower tool 120 are respectively provided with an upper positioning structure 113 and a lower positioning structure 123 on one side of the split surface, the upper positioning structure 113 and the lower positioning structure 123 can be male and female positioning columns and can be installed in a nested manner. The length of the first support column and the second support column inside the upper tool and the lower tool is adjustable. The first support column and the second support column are both bolts, in the embodiment, the first support column and the second support column are both M32 bolts, of course, they can also be other adjustable fixing structures such as studs and screw rods, and the outer side surface of the upper tool 110 and the lower tool 120 is provided with a connecting plate 130 for connecting the upper tool 110 and the lower tool 120.

[0035] Embodiment 2,

[0036] As Figures 3-6 The processing method for realizing the gas turbine tangential protective cover casting by using the processing tool of claim embodiment 1 comprises the following steps:

[0037] Step 1: determining the tool structure: analyzing the structure of the casting, determining the tool structure according to the characteristics of the inner and outer surfaces of the casting, the tool structure comprising: an upper tool and a lower tool, the split surface of the upper tool and the lower tool being located below the position of the maximum contour line of the outer contour of the casting;

[0038] Step 2: tool processing;

[0039] Step 3: casting size marking, measuring the size of the casting blank, determining the height direction reference after adjusting the allowance of each surface of the casting, and marking the actual allowance of each surface of the casting on the casting surface according to the size measurement result;

[0040] Step 4: casting clamping, boring / milling the casting bottom plane as the reference surface according to the height direction Z reference, opening the upper tool and the lower tool, placing the upper tool top surface downward, supporting the casting through the first support structure of the upper tool top surface, adjusting the height of the casting, ensuring that the height direction reference is flush with the bottom surface of the lower tool, and then fastening the second support structure of the side surface of the lower tool and the upper tool and the lower tool;

[0041] In the fifth step, the casting is processed, the turning tool and the casting are arranged from top to bottom as the upper tool, the casting and the lower tool, and the lower tool is used as the reference to clamp, and then the upper tool is removed. The tool is used to mark the machining allowance of each surface according to the size line, and then the machining program is compiled according to the three-dimensional model of each machining surface of the casting to process.

[0042] Specifically, in the first step, as Figures 3-4 Specifically, the three-axis numerical control boring / milling machine processes the type of casting twice, and after processing one side with the help of the auxiliary tool, the other side is clamped and processed. Therefore, the structure of the casting is analyzed first, and the auxiliary tool manufacturing scheme is determined according to the characteristics of the inner and outer surfaces. The auxiliary tool structure of the embodiment is formed by welding steel plates into upper and lower tools.

[0043] The determination of the split surface of the upper tool and the lower tool is based on the maximum range that can be machined by the three-axis boring / milling machine, and is selected below the contour line at the maximum position of the casting contour to ensure that the height of the lower tool is determined according to the purpose of easy clamping of the workpiece.

[0044] As Figures 3-6 The upper tool and the lower tool are positioned and matched by four positioning references, and a gap is reserved at the split surface position in addition to the positioning reference position. The top surface of the upper tool is equipped with M32 bolts for supporting the casting, and the bottom surface reference of the casting is adjusted to be flush with the end surface of the lower tool by using the bolts.

[0045] The four sides of the lower tool are equipped with M32 bolts for clamping the casting, connecting the casting and the tool, ensuring that the casting does not move during processing and turning, and ensuring that the machining reference does not shift. The outer side of the upper tool and the lower tool is provided with a connecting plate for connecting the upper tool and the lower tool, and the connecting plate is connected by bolts to ensure precise connection of the upper tool and the lower tool.

[0046] In the second step of tool processing, the size of the welded upper and lower tools is marked according to the tool design size to determine the size reference. The positioning reference of the split surface position of the upper tool and the lower tool is matched with a gap of less than 0.1 mm. During tool processing, it is necessary to ensure that the upper tool and the lower tool are combined, the connecting bolts on the sides are tightened to ensure that the upper tool and the lower tool are tightly connected, and the top surface of the upper tool and the bottom surface of the lower tool are parallel.

[0047] In the third step, the casting size marking, the three-dimensional measuring arm or three-dimensional scanning, three-dimensional camera and other measurement methods are used to measure the size of the casting blank, and the height direction (Z direction) reference is determined after adjusting the excess of each surface of the casting to the optimal state. Meanwhile, according to the size measurement results, the actual excess of each surface of the casting is marked on the casting surface at intervals of 100-200 mm, which is convenient for tool setting before machining.

[0048] As Figures 5-6 In the fourth step, the casting clamping, the height direction (Z direction) reference is used to bore / mill the bottom plane of the casting as the reference surface, and the machining deviation is less than 0.1 mm. The upper tooling and the lower tooling are opened, the upper tooling top surface is downward, the casting is supported by the bolts on the upper tooling top surface, the height of the casting is adjusted, and the reference in the height direction Z is flush with the bottom surface of the lower tooling after the fastening of the bolts on the side of the lower tooling and the connecting bolts of the upper and lower toolings, so as to ensure that the tooling and the casting are tightly matched and have sufficient strength.

[0049] In the fifth step, the casting machining. The NX programming software is used to compile the machining program for machining, and the conventional shaft numerical control boring / milling machine is used for machining the casting.

[0050] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions described in the foregoing examples can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A method for machining a tangential protective cover casting for a gas turbine, characterized in that, Includes the following steps: The first step is to determine the tooling structure: Analyze the structure of the casting and determine the tooling structure based on the characteristics of the inner and outer surfaces of the casting; The second step is tooling processing; The third step is to scribing the dimensions of the casting blank. After adjusting the allowances on each side of the casting, the reference in the height direction is determined. At the same time, based on the dimensional measurement results, the actual allowances on each side of the casting are marked at intervals on the surface of the casting. The fourth step is to clamp the casting. Using the Z-direction height reference as the reference plane, bore / mill the bottom plane of the casting. Open the upper and lower fixtures, with the top surface of the upper fixture facing down. Support the casting through the first support structure on the top surface of the upper fixture, and adjust the height of the casting to ensure that the reference in the height direction is flush with the bottom surface of the lower fixture. Then, tighten the second support structure on the side of the lower fixture, as well as the upper and lower fixtures. The fifth step is casting machining. The fixture and casting are flipped over, and from top to bottom, they are the upper fixture, the casting, and the lower fixture. The bottom surface of the lower fixture is used as the reference for clamping. Then the upper fixture is removed. A tool setter is used to determine the machining reference in other directions based on the machining allowance of each surface marked when scribing the dimensions. Finally, based on the three-dimensional model of each machining surface of the casting, the machining program is compiled using programming software for machining. The tooling structure includes an upper tooling (110) and a lower tooling (120). The dividing surface of the upper tooling (110) and the lower tooling (120) is located below the maximum outline of the outer contour of the casting. The top surface of the upper tooling (110) is provided with a first support structure (112) for supporting the casting through an upper support plate (111). The lower tooling (120) is provided with a second support structure (122) that passes through the lower support frame (121) for clamping the casting (200). The upper tooling (110) and the lower tooling (120) are respectively provided with an upper positioning structure (113) and a lower positioning structure (123) on one side of the dividing surface.

2. The processing method of the gas turbine tangential protective cover casting as described in claim 1, characterized in that, The lengths of the first and second support structures inside the upper and lower tooling are adjustable.

3. The processing method for the gas turbine tangential protective cover casting as described in claim 2, characterized in that, Both the first and second support structures are bolts.

4. The machining method of the gas turbine tangential protective cover casting as described in claim 1, characterized in that, The outer surfaces of the upper tooling (110) and the lower tooling (120) are provided with connecting plates (130) for connecting the upper tooling (110) and the lower tooling (120).

5. The machining method of the gas turbine tangential protective cover casting as described in claim 1, characterized in that, Includes the following steps: A gap is reserved at the position of the dividing surface between the upper tooling and the lower tooling.

6. The machining method of the gas turbine tangential protective cover casting as described in claim 1, characterized in that, In the third step, when scribing the dimensions of the casting, the dimensions of the casting blank are measured using a three-dimensional measuring arm or any measurement method such as three-dimensional scanning or three-dimensional imaging.

7. The method for machining the gas turbine tangential protective cover casting as described in claim 1, characterized in that, In the fourth step, when clamping the casting, the distance between the first support structure (112) on the upper support plate (111) and the inner side of the upper tooling is adjusted so that the bottom surface reference of the casting is aligned with the end face of the lower tooling. The distance between the second support structure (122) on the lower support frame (121) and the inner side of the lower tooling is adjusted so that the casting is clamped.

8. The method for machining the gas turbine tangential protective cover casting as described in claim 1, characterized in that, In the fifth step, during casting processing, a three-axis CNC boring / milling machine is used to process the casting.

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