Clamp tool and inner runner crack repairing and deformation control method

Abstract

The invention relates to the technical field of aero-engine turbine rear casings, in particular to a clamp tool and an inner runner crack repairing and deformation control method. The clamp tool comprises a supporting mechanism, an expansion mechanism, a pressing ring mechanism and a center shaft; the center shaft sequentially penetrates through the supporting mechanism, the expansion mechanism and the ring pressing mechanism. The expansion mechanism is arranged above the supporting mechanism, and the ring pressing mechanism is arranged above the expansion mechanism; the method comprises the steps of pre-welding treatment, deformation simulation of an inner runner workpiece, clamping of the inner runner workpiece, welding repair and post-welding quality and size inspection. According to the method, simplified simulation analysis is conducted on workpiece welding before welding, the deformation trend and the main deformation or residual stress area of the part are rapidly judged, the welding clamp tool is designed to achieve pre-deformation before welding and rigid fixing of the mounting edge, post-welding deformation can be effectively reduced, size out-of-tolerance is prevented, the rejection rate is reduced, and the repair cost is saved; and the post-weld heat treatment or vibration destressing procedure is omitted, the part machining time is shortened, and the repairing efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engine turbine rear casing, and in particular to a fixture, an inner flow channel crack repair and deformation control method. Background Art

[0002] The turbine component is one of the key components of afterburner aircraft engines and has a significant impact on the performance of the entire engine. The turbine rear support plate and rear casing are important components of the turbine component. Their main aerodynamic function is to fold the deflected airflow to the axial direction, create reasonable inlet airflow conditions for the afterburner combustion chamber, and achieve efficient operation of the engine. The turbine rear casing has a high operating temperature and complex working conditions. It is prone to fatigue cracks under high temperature and vibration conditions. Among the related parts of the turbine rear casing, the number of welds in the inner flow channel exceeds 100, so the problem rate is high and the replacement rate exceeds 90%. Regarding the welding repair of thin-walled cylinder structural parts, Patent CN201811423266.1 proposes a method for repairing spot welding cracks in aircraft engine diverter ring parts, but does not mention a method for controlling the installation deformation of the structural parts; Patent CN202211300526.2 mentions a method for repairing cracks on the installation edge of a titanium alloy thin-walled casing, which allows the installation edge crack problem of the titanium alloy thin-walled casing of an aircraft engine to be repaired, while ensuring that the welding deformation of the installation edge during welding meets the requirements, but this solution requires additional materials for performance testing, and additional processing steps are required after welding; Patent CN202010807265.8 mentions a method for welding repair of crack defects in an aircraft engine flame diverter, which uses the method of replacing welding materials to repair crack defects, but due to the mixture of multiple materials, subsequent inspections may result in repair failures and require re-grinding and repair, and no deformation control method for the components is mentioned. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a fixture, an inner flow channel crack repair and deformation control method, which can control the deformation of the inner flow channel crack repair through the fixture, thereby solving the problem of high scrap rate.

[0004] The specific technical solutions are as follows:

[0005] A clamping tool comprises a supporting mechanism, an expanding mechanism, a pressing ring mechanism and a central axis; the central axis passes through the supporting mechanism, the expanding mechanism and the pressing ring mechanism in sequence; the expanding mechanism is arranged above the supporting mechanism, and the pressing ring mechanism is arranged above the expanding mechanism;

[0006] The support mechanism includes a base, a support plate arranged on the base, and a positioning ring; the support plate is positioned on the base by the positioning ring, and the base and the support plate are fixed by a positioning pin A passing through the central axis and a fastening screw;

[0007] The expansion mechanism includes an expansion cone, a fan-shaped expansion block, an expansion nut, and a retaining ring; the expansion cone is sleeved on the central axis, and the expansion block is arranged along the circumference of the expansion cone to fit the cone wall of the expansion cone; the expansion nut is arranged on the expansion cone and is threadedly connected with the central axis, and the expansion nut can move up and down on the central axis through the thread; the expansion cone and the retaining ring are connected by screws, and the expansion cone and the expansion nut form a movable connection;

[0008] The expansion block is provided with a cavity inside, a reset spring is connected to the near end of the cavity, a stop pin is provided at the end of the reset spring away from the central axis, the lower end of the stop pin is fixed on the support plate, and the upper end is inserted into the cavity to block the reset spring, and when no expansion is required, the reset spring is in the original length state;

[0009] A sliding mechanism is provided between the expansion block and the support plate, and the sliding mechanism includes a guide block and a slide rail; the guide block can move along the slide rail provided on the support plate, and the expansion block and the guide block are fixedly connected by a positioning pin B and a tightening mechanism screw;

[0010] The pressure ring mechanism comprises an inner pressure ring and an outer pressure ring; the inner pressure ring and the outer pressure ring are moved and positioned by means of studs and pressure ring nuts arranged on the support plate.

[0011] The supporting mechanism, the expanding mechanism and the pressing ring mechanism are all circular.

[0012] A cover plate is arranged above the reset spring, and the end of the cover plate close to the center axis is connected to the expansion block through a countersunk screw.

[0013] A lifting eye screw is arranged on the top end of the central shaft.

[0014] A method for repairing cracks in an inner flow channel and controlling deformation using the above-mentioned fixture comprises the following steps:

[0015] Step 1: Pre-welding treatment

[0016] Measure and count the size of the cracks in the inner flow channel, the circumferential distribution state, the overall workpiece size of the inner flow channel, and the position of the installation edge; grind the crack position and grind the edge of the notch to a smooth transition;

[0017] Step 2: Internal flow channel workpiece deformation simulation

[0018] According to the crack size and circumferential distribution obtained in step 1, the residual stress distribution and deformation of the inner flow channel workpiece repaired by the crack are simulated according to the heat input of welding current and welding speed, and the main stress area and main deformation area are determined. According to the stress / deformation data prediction given by the welding simulation software, it is compared with the actual measurement data of the parts to determine the difference between the stress / deformation prediction values ​​of each area;

[0019] Step 3: Inner channel workpiece clamping

[0020] According to the main stress area and main deformation area positions determined in step 2, the inner flow channel workpiece is installed on the inner flow channel workpiece fixture, stress and pre-deformation are applied to a part of the inner flow channel workpiece, the inner pressure ring and the outer pressure ring are pressed on the two pressing parts of the inner flow channel on the multiple studs above the inner flow channel workpiece, and the welding parts are cleaned and prepared for welding;

[0021] Step 4: Welding Repair

[0022] Welding parameters and welding sequence setting;

[0023] Step 5: Post-welding quality and dimension inspection

[0024] The repaired welds are cleaned and polished until there is a smooth transition between the welds and the substrate, and 100% visual inspection and penetration inspection are carried out. The weld quality meets the requirements of the corresponding welding standards; the size of the inner flow channel workpiece after welding repair meets the installation requirements.

[0025] In step 1, after grinding away the crack notch, the width of the notch does not exceed 5 mm.

[0026] In step 2, the width of each area is 8-12 cm.

[0027] In step three, the main stress area is preferentially placed in the gap of the expansion block, and the expansion block is used to support the preset tensile stress. The main deformation area is preferentially placed in the center of the expansion block, and the guide block is used to increase the supporting force to achieve pre-deformation. When the positions of multiple areas conflict, the maximum principal stress and main deformation area shall prevail. If the difference in the predicted stress / deformation values ​​between multiple areas exceeds 40%, the welding is completed at one time. If the difference in the predicted stress / deformation values ​​between multiple areas is less than 40%, after completing partial welding, the part is rotated to the next main stress / deformation area and then welding is continued.

[0028] In step 4, according to the positions of the main stress area and the main deformation area determined in step 2, welding starts first in the area of ​​minimum stress and deformation, adopting the principle of symmetry and maximum distance. After one symmetrical welding is completed, rotate 90° to start the next symmetrical welding; under the conditions of meeting the welding repair forming, appropriately reduce the welding current and increase the welding speed in the main deformation area.

[0029] In step 4, welding parameters: low stress / deformation welding current: 50~70A, welding gun argon flow: 12~15L / min, back argon protection: 10~12L / min, welding speed: 0.1-0.2m / min, wire feeding speed 0.2~0.3m / min, pre-ventilation 2~6s before welding; high stress / deformation area welding current: 30~40A, welding gun argon flow: 8~10L / min, back argon protection: 8~10L / min, welding speed: 0.2-0.3m / min, wire feeding speed: 0.2~0.3m / min.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention can solve the problems of insufficient spare parts and high scrap rate, save repair costs, ensure production progress, and achieve a repair qualification rate of 100%, while the replacement rate will be reduced to 0. The present invention has been applied to 37 sets of flow passages in the rear casing of turbines, saving the cost of the flow passages that have reached the scrap standard due to cracks by no less than RMB 420,000 / set × 100 sets = RMB 42 million.

[0032] 2. Through simplified simulation analysis of workpiece welding before welding, the deformation trend of parts and the main deformation or residual stress area can be quickly determined. The welding fixture is designed to achieve pre-deformation before welding and rigid fixation of the installation edge, which can effectively reduce deformation after welding and prevent dimensional deviation.

[0033] 3. By using preset internal stress, welding repair parameters and welding sequence to simultaneously optimize, the overall stress distribution trend of the inner flow channel workpiece is reduced, the unbalanced deformation of the inner flow channel workpiece is reduced, the dimensional accuracy is ensured, and secondary cracking is prevented during use.

[0034] 4. It reduces the post-weld heat treatment or vibration stress relief process, reduces the parts processing time, and improves the repair efficiency.

[0035] 5. The present invention is suitable for repairing cracks in the thin-walled structure of the turbine rear casing and has been put into mass application. At the same time, it can also serve as a reference for welding and repairing support plates and heat shields of other types of turbine rear casings, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the top view of the inner flow channel fixture in the present invention;

[0037] Figure 2 For the present invention Figure 1 AA section view;

[0038] Figure 3 For the present invention Figure 1 BB-direction cross-sectional view;

[0039] Figure 4 It is a schematic diagram of the local structure of the clamping position of the inner flow channel in the present invention;

[0040] 1. Base; 2. Support plate; 3. Expansion cone; 4. Expansion block; 5. Expansion nut; 6. Retaining ring; 7. Center axis; 8. Cover plate; 9. Retaining pin; 10. Stud; 11. Guide block; 12. Positioning ring; 13. Inner pressure ring; 14. Outer pressure ring; 15. Positioning pin A; 16. Expansion mechanism screw; 17. Screw; 18 Eye screw; 19. Pressure ring nut; 20. Reset spring; 21. Countersunk screw; 22. Positioning pin B; 23. Fastening screw; 24. Inner mounting edge; 25. Outer mounting edge; 26. Inner profile. DETAILED DESCRIPTION

[0041] In order to better explain the present invention and facilitate understanding, the technical solutions and effects of the present invention are described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0042] like Figure 1-3 As shown, this embodiment provides a fixture for welding and clamping an inner flow channel workpiece, including a supporting mechanism, an expansion mechanism, a pressure ring mechanism and a center axis 7; the center axis 7 passes through the supporting mechanism, the expansion mechanism and the pressure ring mechanism in sequence; they are positioned and connected; the expansion mechanism is arranged above the supporting mechanism, and the pressure ring mechanism is arranged above the expansion mechanism; the supporting mechanism, the expansion mechanism and the pressure ring mechanism are all circular.

[0043] The support mechanism includes a base 1, a support plate 2 arranged on the base 1, and a positioning ring 12; the support plate 2 is positioned on the base 1 by the positioning ring 12, and the base 1 and the support plate 2 are fixed by a positioning pin B22 passing through the central axis 7 and a fastening screw 23.

[0044] The expansion mechanism includes an expansion cone 3, a fan-shaped expansion block 4, an expansion nut 5, and a retaining ring 6; the expansion cone 3 is sleeved on the central axis 7, and the six expansion blocks 4 are arranged to fit the cone wall of the expansion cone 3 along the circumference of the expansion cone 3; the expansion nut 5 is arranged on the expansion cone 3 and is threadedly connected to the central axis 7, and the expansion nut 5 can move up and down on the central axis 7 by rotation; the expansion cone 3 and the retaining ring 6 are connected by screws 17, and the expansion cone 3 and the expansion nut 5 form a movable connection; when the workpiece is expanded, the expansion nut 5 rotates downward, driving the expansion cone 3 to move downward, and the expansion block 4 expands radially outward under the action of the expansion cone 3; when expansion is not required, the expansion nut 5 rotates upward, and the retaining ring 6 drives the expansion cone 3 to move upward.

[0045] A cavity is provided inside the expansion block 4, and a reset spring 20 is connected to the end of the cavity close to the central axis 7, and a stop pin 9 is provided at the end of the reset spring 20 away from the central axis 7. The lower end of the stop pin 9 is fixed on the support plate 2, and the upper end is inserted into the cavity to block the reset spring 20; when no expansion is required, the reset spring 20 is in the original length state, and when the workpiece is expanded, the reset spring 20 is in a compressed state. When no expansion is required, after the expansion cone 3 moves upward, the reset spring 20 drives the expansion block 4 to move toward the central axis 7 in order to restore the original length state, so that the expansion block 4 fits the cone wall of the expansion cone 3; a cover plate 8 is provided above the reset spring 20 to prevent foreign matter from falling into the reset spring 20, and the end of the cover plate 8 close to the central axis 7 is connected to the expansion block by a countersunk screw 21 to avoid restricting the movement of the reset spring 20.

[0046] A guide block 11 is provided between the expansion block 4 and the support plate 2. The guide block 11 can move along a slide rail provided on the support plate 2. The expansion block 4 and the guide block 11 are fixedly connected by a positioning pin A15 and a tightening mechanism screw 16.

[0047] The pressure ring mechanism includes an inner pressure ring 13 and an outer pressure ring 14; the inner pressure ring 13 and the outer pressure ring 14 are moved and positioned by means of a stud 10 and a pressure ring nut 19 arranged on the support plate 2; a lifting eye screw 18 is arranged at the top end of the central shaft 7 for lifting the clamp.

[0048] The inner flow channel workpiece is a tapered thin-walled circular ring. When clamping, first remove the inner pressure ring 13 and the outer pressure ring 14. Figure 4 As shown, the large end of the inner flow channel workpiece is turned downward and fastened on the outer edge of the expansion block 4, and the expansion nut 5 is rotated downward to drive the expansion cone 3 to move downward. The expansion block 4 expands radially outward under the action of the expansion cone 3, fits and expands with the inner profile 26 of the inner flow channel workpiece, thereby realizing self-centering of the inner flow channel workpiece and supporting the round inner profile 26, thereby controlling and reducing the profile deformation during the workpiece welding repair process; then the inner pressure ring 13 and the outer pressure ring 14 are installed on the fixture, and the inner pressure ring 13 and the outer pressure ring 14 are respectively pressed on the inner and outer pressing parts of the inner flow channel workpiece, which are the inner mounting edge 24 and the outer mounting edge 25, respectively; the deformation of the end face during the welding repair process is controlled.

[0049] The present invention provides a method for repairing cracks in an inner flow channel and controlling deformation by using the above-mentioned fixture, and the specific steps are as follows:

[0050] Step 1: Pre-welding treatment

[0051] Measure and count the size of the cracks in the inner flow channel, the circumferential distribution state, the overall workpiece size of the inner flow channel, and the position of the installation edge; grind the crack position and grind the edge of the notch to a smooth transition;

[0052] Specifically, the present technical solution uses TIG wire-filling welding technology, and other automated welding technologies are also applicable. Due to the particularity of the structure of the inner flow channel itself and the particularity of the assembly position, the impact on the assembly quality after repair must be considered before TIG welding, otherwise it will cause difficulties in the subsequent assembly of parts. After grinding away the crack notch, the notch width should not exceed 5mm, and the notch width should be minimized as much as possible.

[0053] Step 2: Internal flow channel workpiece deformation simulation

[0054] According to the crack size and circumferential distribution obtained in step 1, the residual stress distribution and deformation of the inner flow channel workpiece that was repaired while the crack was simulated according to the heat input of welding current: 50A, welding speed: 0.3m / min, and the positions of the main stress area and the main deformation area were determined. The stress / deformation data predicted by the welding simulation software (MARC) were compared with the actual measured data of the parts to determine whether the difference between the predicted stress / deformation values ​​of each area was less than 40%.

[0055] Specifically, welding simulation software (MARC) is used. In this embodiment, simufact welding software is used to simulate the residual stress and deformation distribution of the inner flow channel workpiece after simultaneous welding of the crack welding repair position and the two clamping parts near the welding repair position, so as to quickly determine the main stress area (the three areas with the largest stress) and the main deformation area (the two areas with the largest deformation). The width of each area is 8-12 cm. In this embodiment, the width of each area is 10 cm.

[0056] Step 3: Internal flow channel workpiece clamping

[0057] According to the positions of the main stress area and the main deformation area determined in step 2, the inner flow channel workpiece is installed on the inner flow channel workpiece fixture; stress and pre-deformation are applied to a part of the inner flow channel workpiece, and the inner pressure ring 13 and the outer pressure ring 14 are pressed on the two pressing parts of the inner flow channel on the multiple studs 10 above the inner flow channel workpiece, and the welding parts are cleaned and prepared for welding.

[0058] Specifically, Figure 2As shown, the clamp is designed with a tightening mechanism and a pressure ring mechanism to improve the overall rigidity of the parts during the processing of the parts, reduce the deformation of the inclined surface after welding and control the warping deformation of the installation edge; first, the expansion nut 5 of the central axis 7 is rotated to drive the expansion cone 3 on the central axis to slide downward along the central axis 7, and the fan-shaped expansion blocks 4 evenly distributed at 6 positions along the circumference are synchronously radially expanded and tightened under the restriction of the cone wall of the expansion cone 3. The expansion force on the inner surface 26 of the inner flow channel workpiece is 6-12KN, so as to achieve the purpose of supporting the round inner surface 26 and controlling welding deformation; a guide block 11 for guiding sliding is installed in the center of each expansion block 4, which drives the expansion block 4 to slide radially, and preferentially places the main stress area in the gap of the expansion block 4 In the process, the expansion block 4 is used to support the preset tensile stress, the main deformation area is preferentially placed at the center of the expansion block 4, and the guide block 11 is used to increase the supporting force to achieve pre-deformation. When the positions of multiple areas conflict, the maximum principal stress and the main deformation area shall prevail. If the difference in the predicted stress / deformation values ​​between the multiple areas exceeds 40%, the welding is completed at one time. If the difference in the predicted stress / deformation values ​​between the multiple areas is less than 40%, after completing partial welding, the parts are rotated to the next principal stress / deformation area and then welding is continued; in addition, the inner pressure ring 13 and the outer pressure ring 14 press the two clamping parts of the inner flow channel on the multiple studs 10 above the inner flow channel workpiece, while achieving clamping stability, the warping deformation of the installation edge is controlled to the maximum extent.

[0059] Step 4: Welding Repair

[0060] Welding parameters and welding sequence setting; welding parameters: low stress / deformation welding current: 50-70A, welding gun argon flow: 12-15L / min, back argon protection: 10-12L / min, welding speed: 0.1-0.2m / min, wire feeding speed 0.2-0.3m / min, pre-ventilation 2-6s before welding, high stress / deformation area welding current: 30-40A, welding gun argon flow: 8-10L / min, back argon protection: 8-10L / min, welding speed: 0.2-0.3m / min, wire feeding speed: 0.2-0.3m / min. The welding sequence is based on the main stress area and main deformation area position determined in step 2. When welding, start in the minimum stress and deformation area first. When there are many welding positions, the principle of symmetry and the farthest distance is adopted. After one symmetrical welding is completed, rotate 90° to start the next symmetrical welding; under the conditions of meeting the welding repair forming, appropriately reduce the welding current and speed up the welding speed in the main deformation area.

[0061] In this embodiment, welding parameters are as follows: welding current in low stress / deformation area: 50A, welding gun argon flow: 15L / min, back argon protection: 10L / min, welding speed: 0.2m / min, wire feeding speed: 0.3m / min, pre-ventilation for 2s before welding. Welding current in high stress / deformation area: 40A, welding gun argon flow: 10L / min, back argon protection: 10L / min, welding speed: 0.3m / min, wire feeding speed: 0.2m / min. Step 5: Post-welding quality and size inspection

[0062] The repaired welds are cleaned and polished until there is a smooth transition between the welds and the substrate, and 100% visual inspection and penetration inspection are carried out. The weld quality meets the requirements of the corresponding welding standards. The size of the inner flow channel workpiece after welding repair should meet the installation requirements, and the warping of the installation edge should not exceed 0.05mm.

Claims

1. A fixture, characterized in that: It includes a supporting mechanism, an expanding mechanism, a pressing ring mechanism and a central axis; the central axis passes through the supporting mechanism, the expanding mechanism and the pressing ring mechanism in sequence; the expanding mechanism is arranged above the supporting mechanism, and the pressing ring mechanism is arranged above the expanding mechanism; The support mechanism includes a base, a support plate arranged on the base, and a positioning ring; the support plate is positioned on the base by the positioning ring, and the base and the support plate are fixed by a positioning pin A passing through the central axis and a fastening screw; The expansion mechanism includes an expansion cone, a fan-shaped expansion block, an expansion nut, and a retaining ring; the expansion cone is sleeved on the central axis, and the expansion block is arranged along the circumference of the expansion cone to fit the cone wall of the expansion cone; the expansion nut is arranged on the expansion cone and is threadedly connected with the central axis, and the expansion nut can move up and down on the central axis through the thread; the expansion cone and the retaining ring are connected by screws, and the expansion cone and the expansion nut form a movable connection; The expansion block is provided with a cavity inside, a reset spring is connected to the near end of the cavity, a stop pin is provided at the end of the reset spring away from the central axis, the lower end of the stop pin is fixed on the support plate, and the upper end is inserted into the cavity to block the reset spring, and when no expansion is required, the reset spring is in the original length state; A sliding mechanism is provided between the expansion block and the support plate, and the sliding mechanism includes a guide block and a slide rail; the guide block can move along the slide rail provided on the support plate, and the expansion block and the guide block are fixedly connected by a positioning pin B and a tightening mechanism screw; The pressure ring mechanism comprises an inner pressure ring and an outer pressure ring; the inner pressure ring and the outer pressure ring are moved and positioned by means of studs and pressure ring nuts arranged on the support plate.

2. A fixture according to claim 1, characterized in that: The supporting mechanism, the expanding mechanism and the pressing ring mechanism are all circular.

3. A fixture according to claim 1, characterized in that: A cover plate is arranged above the reset spring, and the end of the cover plate close to the center axis is connected to the expansion block through a countersunk screw.

4. A fixture according to claim 1, characterized in that: A lifting eye screw is arranged on the top end of the central shaft.

5. A method for repairing cracks and controlling deformation of an inner flow channel using the fixture described in any one of claims 1 to 4, characterized in that: The steps include: Step 1: Pre-welding treatment Measure and count the size of the cracks in the inner flow channel, the circumferential distribution state, the overall workpiece size of the inner flow channel, and the position of the installation edge; grind the crack position and grind the edge of the notch to a smooth transition; Step 2: Internal flow channel workpiece deformation simulation According to the crack size and circumferential distribution obtained in step 1, the residual stress distribution and deformation of the inner flow channel workpiece repaired by the crack are simulated according to the heat input of welding current and welding speed, and the main stress area and main deformation area are determined. According to the stress / deformation data prediction given by the welding simulation software, it is compared with the actual measurement data of the parts to determine the difference between the stress / deformation prediction values ​​of each area; Step 3: Internal flow channel workpiece clamping According to the main stress area and main deformation area positions determined in step 2, the inner flow channel workpiece is installed on the inner flow channel workpiece fixture, stress and pre-deformation are applied to a part of the inner flow channel workpiece, the inner pressure ring and the outer pressure ring are pressed on the two pressing parts of the inner flow channel on the multiple studs above the inner flow channel workpiece, and the welding parts are cleaned and prepared for welding; Step 4: Welding Repair Welding parameters and welding sequence setting; Step 5: Post-welding quality and dimension inspection Clean and polish the repaired welds until they have a smooth transition between the welds and the substrate, and conduct 100% visual inspection and penetration inspection to ensure that the weld quality meets the requirements of the corresponding welding standards; After welding repair, the size of the inner flow channel workpiece meets the installation requirements.

6. The inner flow channel crack repair and deformation control method according to claim 5, characterized in that: In step 1, after grinding away the crack notch, the width of the notch does not exceed 5 mm.

7. The inner flow channel crack repair and deformation control method according to claim 5, characterized in that: In step 2, the width of each area is 8-12 cm.

8. The inner flow channel crack repair and deformation control method according to claim 5, characterized in that: In step three, the main stress area is preferentially placed in the gap of the expansion block, and the expansion block is used to support the preset tensile stress. The main deformation area is preferentially placed in the center of the expansion block, and the guide block is used to increase the supporting force to achieve pre-deformation. When the positions of multiple areas conflict, the maximum principal stress and main deformation area shall prevail. If the difference in the predicted stress / deformation values ​​between multiple areas exceeds 40%, the welding is completed at one time. If the difference in the predicted stress / deformation values ​​between multiple areas is less than 40%, after completing partial welding, the part is rotated to the next main stress / deformation area and then welding is continued.

9. The inner flow channel crack repair and deformation control method according to claim 5, characterized in that: In step 4, the welding sequence is based on the positions of the main stress area and the main deformation area determined in step 2. When welding, start first in the area of ​​minimum stress and deformation, adopt the principle of symmetry and maximum distance. After one symmetrical welding is completed, rotate 90° to start the next symmetrical welding; under the conditions of meeting the welding repair forming, reduce the welding current and increase the welding speed in the main deformation area.

10. The inner flow channel crack repair and deformation control method according to claim 5, characterized in that: In step 4, welding parameters: low stress / deformation welding current: 50~70A, welding gun argon flow: 12~15L / min, back argon protection: 10~12L / min, welding speed: 0.1-0.2m / min, wire feeding speed 0.2~0.3m / min, pre-ventilation 2~6s before welding, high stress / deformation area welding current: 30~40A, welding gun argon flow: 8~10L / min, back argon protection: 8~10L / min, welding speed: 0.2-0.3m / min, wire feeding speed: 0.2~0.3m / min.

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