Large hydrogen-cooled steam turbine generator end cover closing surface gap out-of-tolerance repairing method

Abstract

The invention discloses a large hydrogen-cooled steam turbine generator end cover closing surface gap out-of-tolerance repairing method. The problems that in a traditional repairing method, the machining amount is large, an end cover and a stator need to be centered again, positioning pin holes and positioning pins of the end cover and the stator need to be machined again, and end shaft oil assembling needs to be conducted again are solved. According to the characteristics of the generator end cover with a bearing bush top block structure, after the end cover closing surface is repaired by adopting a numerical control boring machine processing mode, the bearing bush top block on the end cover is matched and processed, so that the problem of out-of-tolerance of the gap of the end cover closing surface within a certain deviation range is solved; a series of additional work such as large machining amount of the end cover and re-centering of the end cover and the stator can be avoided, and the bearing bush top clearance meets the technical requirement after the end shaft oil is assembled. The method has the advantages of being short in repair period, controllable in repair range, easy to machine and the like, the repair efficiency is remarkably improved, and the construction period is shortened.

Description

Technical Field

[0001] The invention relates to the field of steam turbine generators, in particular to a method for repairing excessive clearance of a joint surface of an end cover of a large hydrogen-cooled steam turbine generator. Background Art

[0002] When installing the end cover of a large hydrogen-cooled steam turbine generator on site, the gap between the end cover joint surface needs to be re-measured. Once the gap between the joint surface is out of tolerance, the end cover needs to be repaired, otherwise there may be a risk of leakage during the subsequent operation of the unit. In the past, when the gap between the end cover joint surface of a large hydrogen-cooled steam turbine generator on site was out of tolerance, it was necessary to first smooth the joint surface of the upper end cover and the joint surface of the lower end cover, and then re-process the inner circle of the end cover after combining the upper and lower end covers, re-center the end cover with the stator, re-process the locating pin holes and locating pins, re-assemble the end cover bearing oil seal, re-grind the end cover bearing shell, etc. Repairing the gap between the end cover joint surface will generate a lot of additional work, with low work efficiency, complex work content, and a long repair cycle. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method for repairing the gap of the end cover of a large hydrogen-cooled steam turbine generator with an excessive tolerance. For a hydrogen-cooled steam turbine generator with a bearing top block structure, the present invention is used to repair the end cover joint surface, which can avoid the end cover and stator re-centering and re-processing new positioning pin holes, positioning pins, etc. The assembly relationship between the bearing and oil seal assembly parts and the end cover remains consistent with that before the end cover repair, and there is no need to re-grind the bearing, which can achieve the repair of the end cover joint surface in the smallest range and the shortest time and meet the performance requirements. The method is implemented by the following steps:

[0004] Step 1: Place the upper end cover and the lower end cover on the processing platform of the CNC boring machine respectively and align them, and measure and record the flatness A of the joint surface of the upper end cover and the flatness B of the joint surface of the lower end cover respectively.

[0005] Step 2: Calculate the processing volume. The sum of the alignment and processing accuracy errors of the CNC boring machine is C. If A+B+2C≤1.5mm, subsequent judgment and processing can be carried out. If A>0.03mm, the joint surface of the upper half end cover is processed by the CNC boring machine with the minimum amount to see flatness, and the flatness is processed to less than or equal to 0.03mm, and the processing volume D is recorded. If B>0.03mm, the joint surface of the lower half end cover is processed by the CNC boring machine with the minimum amount to see flatness, and the flatness is processed to less than or equal to 0.03mm, and the processing volume E is recorded.

[0006] Step 3: Grind the upper and lower end cover joint surfaces separately, and check the grinding effect by combining the upper and lower end covers and re-measuring the joint surface gap value until the joint surface gap value is less than or equal to 0.03mm. Match the thickness of the bearing top block, and match the processing size F=D+E.

[0007] In the above-mentioned large hydrogen-cooled steam turbine generator end cover gap tolerance repair method, in step 1, the upper half end cover and the lower half end cover are respectively placed horizontally on the processing platform of the CNC boring machine for clamping and alignment. The CNC boring machine is used to measure the flatness A and B of the upper half end cover joint surface and the lower half end cover joint surface respectively.

[0008] In the above-mentioned method for repairing the gap of the joint surface of the end cover of a large hydrogen-cooled steam turbine generator, in the step 2, when the calculated total of the expected processing volume A+B+2C is ≤1.5mm, it can be further determined whether A and B are less than or equal to 0.03mm. If A or B is greater than 0.03mm, the minimum processing is to flatten the corresponding end cover joint surface, and the joint surface flatness is processed to be less than or equal to 0.03mm. Record the processing volume D and E.

[0009] In the above-mentioned large hydrogen-cooled steam turbine generator end cover joint surface gap out-of-tolerance repair method, in step three, the thickness of the bearing top block is matched with the processing dimension F equal to the actual total processing amount D+E of the upper end cover joint surface and the lower end cover joint surface.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] In the present invention, when the estimated processing amount of the end cover joint surface does not exceed 1.5 mm, the end cover joint surface is processed and ground so that the clearance after assembly meets the requirement, and then the requirements of on-site end cover bearing oil seal assembly are met by matching and processing the bearing shell top block, avoiding additional work such as re-centering the end cover with the stator, re-processing the locating pin holes and locating pins of the end cover and the stator, and re-grinding the bearing shell caused by re-processing the inner circle of the end cover, thereby significantly improving the repair efficiency and ensuring the assembly quality while saving the repair time. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the upper end cover and the joint surface of the upper end cover in the present invention.

[0013] Figure 2 It is a schematic diagram of the joint surface of the upper and lower end covers and the lower and upper end covers in the present invention.

[0014] Figure 3 It is a schematic diagram of the bearing top block of the present invention.

[0015] Markings in the figure: 1-upper end cover; 2-upper end cover joint surface; 3-lower end cover; 4-lower end cover joint surface; 5-bearing shell top block. DETAILED DESCRIPTION

[0016] The present application is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present application.

[0017] This embodiment provides a method for repairing excessive clearance between joint surfaces of an end cover of a large hydrogen-cooled steam turbine generator, and the method is implemented through the following steps.

[0018] Step 1: If Figure 1 and Figure 2 As shown, the upper end cover 1 and the lower end cover 3 are placed horizontally on the processing platform of the CNC boring machine and clamped and aligned, and the flatness A of the joint surface 2 of the upper end cover and the flatness B of the joint surface 4 of the lower end cover are measured and recorded respectively.

[0019] Step 2: Calculate the expected processing volume. The sum of the alignment and processing accuracy errors of the CNC boring machine is C. If A+B+2C≤1.5mm, subsequent judgment and processing can be carried out. If A>0.03mm, the upper half end cover joint surface 2 is processed by the CNC boring machine with the minimum amount to see flatness, and the flatness is processed to less than or equal to 0.03mm, and the processing volume D is recorded. If B>0.03mm, the lower half end cover joint surface 4 is processed by the CNC boring machine with the minimum amount to see flatness, and the flatness is processed to less than or equal to 0.03mm, and the processing volume E is recorded.

[0020] Step 3: Grind the upper end cover joint surface 2 and the lower end cover joint surface 4 respectively, and check the grinding effect by combining the upper end cover 1 and the lower end cover 3 and re-measuring the joint surface gap until the joint surface gap is less than or equal to 0.03mm. Match the thickness of the bearing top block 5, and match the processing size F=D+E.

[0021] Preferably, the upper end cover 1 and the lower end cover 3 in step 1 are placed horizontally on the processing platform of the CNC boring machine. The flatness A and B of the joint surface 2 of the upper end cover and the joint surface 4 of the lower end cover are measured respectively.

[0022] Measuring the flatness of the end cover joint surface by using a CNC boring machine can effectively estimate the processing amount of the end cover joint surface, and provide data basis for subsequent judgment on whether the present invention can be used to repair the end cover.

[0023] Preferably, the sum of the alignment and machining accuracy errors of the CNC boring machine in step 2 is C. If A+B+2C≤1.5mm, subsequent judgment and processing can be performed. Compare A and B with 0.03mm respectively. If A or B is greater than 0.03mm, use the CNC boring machine to process the corresponding joint surface with the minimum amount, and record the processing amount D and E.

[0024] Compare A+B+2C with 1.5mm, and decide whether to use the present invention for subsequent processing according to the comparison result. If A+B+2C does not exceed 1.5mm, the present invention can be used to further determine whether the upper half end cover joint surface 2 and the lower half end cover joint surface 4 need to be processed. Compare the flatness A and the flatness B with 0.03mm respectively, and only process the end cover joint surface with a flatness greater than 0.03mm.

[0025] Preferably, in step 3, the upper end cover joint surface 2 and the lower end cover joint surface 4 are fully ground and then the upper end cover 1 and the lower end cover 3 are assembled, and the joint surface gap is measured to be less than or equal to 0.03 mm. The thickness of the bearing top block 5 is matched with the processing amount F=D+E.

[0026] By fully grinding the joint surface 2 of the upper end cover and the joint surface 4 of the lower end cover, the roughness of the joint surface of the end cover is further reduced, so that the gap value of the joint surface after the upper end cover 1 and the lower end cover 3 are controlled to be no more than 0.03mm. The thickness matching processing amount of the bearing top block is the sum of the processing amount of the joint surface 2 of the upper end cover and the joint surface 4 of the lower end cover. The processing amount of the end cover joint surface is offset by matching the bearing top block, so as to ensure that the gap between the bearing and the bearing top block meets the technical requirements during the subsequent assembly of the end cover bearing oil seal, and the center height of the end cover remains the same as before the repair.

[0027] The present invention is only an exemplary description of the present invention and does not limit its protection scope. Those skilled in the art may also make partial changes thereto, which are within the protection scope of the present invention as long as they do not exceed the spirit of the present invention.

Claims

1. A method for repairing the gap out of tolerance on the joint surface of a large hydrogen-cooled steam turbine generator end cover, which is characterized by comprising the following steps: Step 1: The upper end cover (1) and the lower end cover (3) are respectively placed on the processing platform of the CNC boring machine and clamped and aligned, and the flatness A of the joint surface (2) of the upper end cover and the flatness B of the joint surface (4) of the lower end cover are measured and recorded; Step 2: Calculate the estimated machining workload. The sum of the alignment and machining accuracy errors of the CNC boring machine is C. If A+B+2C≤1.5mm, perform subsequent judgment and machining; if A>0.03mm, the joint surface (2) of the upper end cover is machined flat by the minimum amount of the CNC boring machine, and the flatness is machined to be less than or equal to 0.03mm, and the machining volume D is recorded; if B>0.03mm, the joint surface (4) of the lower end cover is machined flat by the minimum amount of the CNC boring machine, and the flatness is machined to be less than or equal to 0.03mm, and the machining volume E is recorded; Step 3: Fully grind the joint surface (2) of the upper end cover and the joint surface (4) of the lower end cover respectively, check the grinding effect by combining the upper end cover (1) and the lower end cover (3) and re-measuring the joint surface gap value until the joint surface gap value is less than or equal to 0.03mm; match the thickness of the bearing top block (5) and match the processing dimension F=D+E.

2. A method for repairing excessive clearance of joint surface of end cover of a large hydrogen-cooled steam turbine generator according to claim 1, characterized in that: In the step 1, the upper end cover (1) and the lower end cover (3) need to be placed horizontally on the processing platform of the CNC boring machine. After the end covers are clamped and aligned, the CNC boring machine is used to measure the flatness A of the joint surface (2) of the upper end cover and the flatness B of the joint surface (4) of the lower end cover.

3. The method for repairing excessive gap between joint surfaces of a large hydrogen-cooled steam turbine generator end cover according to claim 1 is characterized in that: In the step 2, if the sum of the errors 2C of the alignment and processing of the upper end cover (1) and the lower end cover (3), the flatness A of the joint surface (2) of the upper end cover, and the sum of the flatness B of the joint surface (4) of the lower end cover (4) A+B+2C is less than or equal to 1.5 mm, the next step of judgment and repair is carried out.

4. The method for repairing excessive gap between joint surfaces of a large hydrogen-cooled steam turbine generator end cover according to claim 1 is characterized in that: In the step three, after the upper end cover joint surface (2) and the lower end cover joint surface (4) are fully ground respectively, the upper end cover (1) and the lower end cover (3) are assembled, and the joint surface gap value is re-measured to be less than or equal to 0.03 mm. If the gap value is greater than 0.03 mm, it is necessary to continue to grind the upper end cover joint surface (2) and the lower end cover joint surface (4) respectively until the gap value is less than or equal to 0.03 mm. The thickness F of the bearing top block (5) is matched according to the value of the total end cover processing amount D+E.

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