CN115781175A - A method for cavitation repair of the flow surface of the runner chamber - Google Patents

Abstract

The invention provides a method for repairing the cavitation on the flow surface of the runner chamber, which includes the following steps: turning the cavitation part about 920mm long on the cavitation deep part of the flow surface at the lower part of the runner chamber, and inserting a stainless steel liner Rear plug welding, strictly control the amount of deformation, the welding process of the steel plate must be knocked to ensure that it is close to the base material of the runner chamber, the flow surface of the runner chamber is processed by numerical control programming, the cutting depth of one side is up to 8mm deep, and the surface waviness is less than 0.5 mm, material selection: use anti-cavitation material 1Cr18Ni9Ti steel plate, the steel plate is blanked by numerical control, and several segments are used in the height direction and circumference, and spliced to make segmented and block liner surface molds. The invention provides a method for repairing cavitation on the overflow surface of a runner chamber. A positioning component and a fixing component are arranged on the surface of the stainless steel liner to cooperate with a blocking component to facilitate the splicing and fixing of multiple stainless steel liners, which can be installed in the runner chamber. The stainless steel liners can be replaced one by one after prolonged contact with water.

Description

A method for cavitation repair of the flow surface of the runner chamber

technical field

The invention relates to the field of hydroelectric power generation, in particular to a cavitation repair method for the flow surface of a runner chamber.

Background technique

Hydropower is a science and technology that studies technical and economic issues such as engineering construction and production operation that convert water energy into electrical energy. The water energy used by hydropower is mainly the potential energy stored in water bodies. In order to convert water energy into electrical energy, it is necessary Construct different types of hydropower stations.

A runner chamber and impeller are currently used in hydroelectric power for auxiliary operations.

The long-term immersion of the current runner chamber in water will cause erosion on the surface, but the current runner chamber needs to be replaced after being eroded, and the current eroded runner chamber will cause The maintenance project is large, and it will also result in high replacement costs and long operating hours.

Therefore, it is necessary to provide a cavitation repair method for the flow surface of the runner chamber to solve the above technical problems.

Contents of the invention

The invention provides a cavitation repair method for the flow surface of the runner chamber, which solves the problem that the existing runner chamber will be corroded when it is in contact with water for a long time, resulting in large cost and maintenance engineering for the replacement of the runner chamber. The problem of long operation time.

In order to solve the above technical problems, the present invention provides a cavitation repair method for the flow surface of the runner chamber, which includes the following steps:

S1. For the deep cavitation part of the flow surface in the lower part of the runner chamber, which is about 920mm long, the cavitation part is cut off, and the stainless steel liner is inlaid with the rear plug for repair welding. The deformation is strictly controlled. The steel plate welding process must be struck to ensure tightness Paste the base material of the runner chamber;

S2. Using CNC programming to process the flow surface of the runner chamber, the cutting depth on one side can reach 8mm deep, and the surface waviness is less than 0.5mm;

S3. Material selection: use anti-cavitation material 1Cr18Ni9Ti steel plate, and anti-cavitation material can also be 304 stainless steel, Cr18Ni9Ti steel plate and 0Cr1 3Ni5Mot steel plate with a thickness of 9mm to 12mm as the lining plate material of the flow surface of the runner chamber 1. This material is used in the manufacture of hydraulic turbine flow parts, and has good comprehensive performance. This steel has unique cavitation resistance, and an appropriate amount of inverted austenite can improve the comprehensive performance of the steel, reduce the crack sensitivity of the matrix, and improve welding. Performance, the thickness of the steel plate needs to consider the margin of the turning of the spherical surface inside the runner chamber and the tightness of the inlay, and no void is allowed between the base metal and the liner after inlay;

S4. Material forming process:

S41. The steel plate is blanked by numerical control, and the laser punching process plugs the welding hole φ21mm. Several segments are used in the height direction and circumference, and several segments are used for splicing and circumference. CNC machining surface molded segmented and segmented liner plate assembly runner chamber flow surface liner gas shielded welding, process measures to reduce deformation, CNC machining runner chamber flow surface;

S5. Welding process: Gas shielded welding is used for welding to reduce welding deformation;

S51. Selection of welding wire diameter, use welding wire with a diameter of 1.2mm;

S52, welding current (A);

S53, welding voltage (V);

S54, welding speed;

S55, selection of CO2 gas flow rate;

S56, welding wire selection;

S57. Welding external inspection;

S58. When welding dissimilar steel plates, the welding process of high-strength steel should be used for welding. The welding materials should be specified in the drawings and should be evaluated by the welding process test;

S59. Before welding, the rust, slag, oil stains, water marks, etc. within the range of 10-20mm on both sides of the groove should be cleaned;

S510. Welding materials should be baked and stored according to the following requirements;

Welding rods and welding should be placed in a specially designed warehouse with ventilation, drying, and room temperature not lower than 5°C. Special personnel should be assigned to store, bake and distribute. The actual temperature and welding rod distribution records should be made in time, and H08MnSi should be selected according to requirements such as design. CrM0A or H08MnSi CrM0VA;

S511. Steel plate material requirements: Material steel plate and welding wire must have a factory quality certificate, and its chemical composition and mechanical properties and other indicators should meet the standards.

Preferably, when thick wire welding is used in S52, the upper limit of the current depends on the shape of the welding wire, and the lower limit depends on the stability of the welding process.

Preferably, the arc voltage in S53 should not be too high. If it is too high, pores and splashes will easily occur. If the arc voltage is too low, it will affect the weld formation.

Preferably, the main indicator for measuring productivity in S54, if the welding speed is too high, the shielding gas will be destroyed, and poor weld formation will cause the weld to cool too fast, so as to reduce the plasticity and toughness of the weld. If the speed is too low, it is easy to cause the weld seam to burn through or form a thick weld seam structure. Therefore, the welding speed of CO2 gas shielded welding semi-automatic welding generally does not exceed 0.5m/min.

Preferably, in order to ensure that the welding is free from air pollution in the S55, the gas flow rate is 30-50 liters/min when the welding wire diameter>1.2mm CO2 is used for welding. In order to effectively protect the welding surface and obtain high-quality welds, the CO2 used for welding The purity of the gas should not be lower than 99.5%. When the pressure in the CO2 gas cylinder is lower than 10kg/cm2, it should be stopped to avoid air holes.

Preferably, in the S56, H08MnSiCrMOA or H08MnSiCrMOVA is selected according to the composition of the welding material, the arc of the weld and the design requirements.

Preferably, the external inspection in S57 uses a template to check the appearance size of the weld or check the surface defects with the naked eye or a magnifying glass. Defects such as cracks, incomplete fusion, incomplete penetration, a large number of pores, and slag inclusions are not allowed in the weld. The seams should be beautiful, with scale-like ripples, and the transition between the welds and the base metal should be smooth. b All welds should be subjected to non-destructive testing.

Preferably, a plurality of steel rings are welded on the surface of the runner chamber.

Preferably, a positioning assembly is provided on the side of the surface of the stainless steel liner, the positioning assembly includes a positioning block, and a positioning groove matching the positioning block is opened inside the stainless steel liner, and the stainless steel liner A fixing assembly is provided inside the plate and on one side of the positioning groove, the fixing assembly includes a sliding cavity, a fixing piece is arranged inside the sliding cavity, and a fixed piece corresponding to the fixing piece is opened inside the positioning block. A suitable fixing hole, the surface of the fixing member is provided with a limit bolt.

Preferably, a blocking assembly is provided on the top of the stainless steel liner, the blocking assembly includes a slot, and a block is provided inside the slot, and the top of the stainless steel liner is located on a side opposite to the slot. There is an active groove on the side, and a stopper is arranged inside the movable groove, a placement groove matching the stopper is opened on the top of the stainless steel liner, and a threaded bolt is provided on one side of the stopper surface. .

Compared with related technologies, a method for repairing cavitation on the flow surface of the runner chamber provided by the present invention has the following beneficial effects:

The invention provides a cavitation repair method for the flow surface of the runner chamber. A positioning component and a fixing component are arranged on the surface of the stainless steel lining plate to cooperate with the blocking component to facilitate splicing and fixing between multiple stainless steel lining plates. After prolonged contact with water, the stainless steel liners can be replaced one by one.

Description of drawings

Fig. 1 is a structural schematic diagram of the first embodiment of a method for repairing cavitation on the flow surface of a runner chamber provided by the present invention;

Fig. 2 is a structural schematic diagram of a second embodiment of a method for repairing cavitation on the flow surface of a runner chamber provided by the present invention;

Fig. 3 is an enlarged schematic diagram of part A shown in Fig. 2;

FIG. 4 is an enlarged schematic diagram of part B shown in FIG. 2 .

Numbers in the figure: 1. Runner chamber, 2. Steel ring, 3. Stainless steel liner,

4, positioning assembly, 41, positioning block, 42, positioning groove,

5. Fixing assembly, 51, sliding cavity, 52, fixing piece, 53, fixing hole, 54, limit bolt,

6. Blocking assembly, 61, draw-in slot, 62, block, 63, movable slot, 64, stopper, 65, placement slot, 66, threaded bolt.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

first embodiment

Please refer to FIG. 1 , wherein FIG. 1 is a schematic structural diagram of a first embodiment of a method for repairing cavitation on the flow surface of a runner chamber provided by the present invention. A method for repairing cavitation on the flow surface of a runner chamber, comprising the following steps:

S1. For the deep cavitation part of the lower part of the runner chamber 1, which is about 920mm long, the cavitation part is removed by turning, and the stainless steel lining plate 3 is inlaid with the rear plug for repair welding. The deformation is strictly controlled. The steel plate welding process should be knocked Ensure that it is close to the base material of the runner chamber;

S2. Using CNC programming to process the flow surface of the runner chamber, the cutting depth on one side can reach 8mm deep, and the surface waviness is less than 0.5mm;

S3. Material selection: use anti-cavitation material 1Cr18Ni9Ti steel plate, and anti-cavitation material can also be 304 stainless steel, Cr18Ni9Ti steel plate and 0Cr1 3Ni5Mot steel plate with a thickness of 9mm to 12mm as the lining plate material of the flow surface of the runner chamber 1. This material is used in the manufacture of hydraulic turbine flow parts, and has good comprehensive performance. This steel has unique cavitation resistance, and an appropriate amount of inverted austenite can improve the comprehensive performance of the steel, reduce the crack sensitivity of the matrix, and improve welding. Performance, the thickness of the steel plate needs to consider the margin of the turning of the spherical surface inside the runner chamber and the tightness of the inlay, and no void is allowed between the base metal and the liner after inlay;

The parameters of cutting depth and steel plate thickness are determined by the severity of cavitation in the runner chamber of the power station and the model and size of the unit.

S4. Material forming process:

S41. The steel plate is blanked by numerical control, and the laser punching process plugs the welding hole φ21mm. Several segments are used in the height direction and circumference, and several segments are used for splicing and circumference. CNC machining surface molded segmented and segmented liner plate assembly runner chamber flow surface liner gas shielded welding, process measures to reduce deformation, CNC machining runner chamber flow surface;

S5. Welding process: Gas shielded welding is used for welding to reduce welding deformation;

S51. Selection of welding wire diameter, use welding wire with a diameter of 1.2mm;

S52, welding current (A);

S53, welding voltage (V);

S54, welding speed;

S55, selection of CO2 gas flow rate;

S56, welding wire selection;

S57. Welding external inspection;

S58. When welding dissimilar steel plates, the welding process of high-strength steel should be used for welding. The welding materials should be specified in the drawings and should be evaluated by the welding process test;

S59. Before welding, the rust, slag, oil stains, water marks, etc. within the range of 10-20mm on both sides of the groove should be cleaned;

S510. Welding materials should be baked and stored according to the following requirements;

Welding rods and welding should be placed in a specially designed warehouse with ventilation, drying, and room temperature not lower than 5°C. Special personnel should be assigned to store, bake and distribute. The actual temperature and welding rod distribution records should be made in time, and H08MnSi should be selected according to requirements such as design. CrM0A or H08MnSi CrM0VA;

S511. Steel plate material requirements: material steel plate and welding wire must have a factory quality certificate, and its chemical composition and mechanical properties and other indicators should meet the standards;

When thick wire welding is used in S52, the upper limit of the current depends on the shape of the welding wire, and the lower limit depends on the stability of the welding process.

The arc voltage in S53 should not be too high, if it is too high, pores and spatter will easily occur, and if the arc voltage is too low, it will affect the weld formation.

The main indicator of productivity in the above S54, if the welding speed is too high, the shielding gas will be destroyed, poor weld formation will make the weld cool too fast, so as to reduce the plasticity and toughness of the weld, and the welding speed is too low , It is easy to cause the weld to burn through or form a thick weld structure. Therefore, the welding speed of CO2 gas shielded welding semi-automatic welding generally does not exceed 0.5m/min.

In order to ensure that the welding is free from air pollution in the S55, the gas flow rate is 30-50 liters/min when the welding wire diameter>1.2mm is used for CO2 welding. In order to effectively protect the welding surface and obtain high-quality welds, the purity of the CO2 gas used for welding It should not be lower than 99.5%. When the pressure in the CO2 gas cylinder is lower than 10kg/cm2, it should be stopped to avoid air holes.

In the S56, H08MnSi CrM0A or H08MnSi CrM0VA is selected according to the composition of the welding material, the arc of the weld and the design requirements.

The external inspection in a of S57 uses a sample to check the appearance size of the weld or check the surface defects with the naked eye or a magnifying glass. Defects such as cracks, incomplete fusion, incomplete penetration, a large number of pores and slag inclusions are not allowed in the weld, and the weld should be beautiful. , fish scale-like corrugation, smooth transition between the weld and the base metal, b non-destructive testing for all welds.

A plurality of steel rings 2 are welded on the surface of the runner chamber 1 .

Stainless steel is used to improve its cavitation resistance. However, due to the high installation elevation of the power station unit, the cavitation in the runner chamber of the unit is very serious, and the cavitation part is far beyond the range where the runner chamber is made of stainless steel. The scope of cavitation repair for the runner chamber is getting wider and more difficult. Since the installation elevation of the unit cannot be changed, the only way to improve the anti-cavitation performance of the runner chamber itself is to completely solve the problem of the cavitation of the runner chamber. The larger the area, the more difficult it is to repair, and the large-scale repair will lead to the loss of reference of the surface after repair welding due to relief grinding, and the deviation of the flow surface profile and the accuracy of roundness cannot be controlled. In addition, due to the existence of these problems, the uniformity of the gap between the outer diameter of the runner and the runner chamber will be damaged. At the same time, the gap between the runner chamber and the runner needs to be increased to avoid interference, resulting in hydraulic energy loss and hydraulic imbalance of the unit. The vibration of the unit is aggravated, burying hidden dangers to the operation of the unit, so it is urgent to use all stainless steel materials for anti-abrasion renovation of the entire flow surface of the runner chamber.

In view of the cavitation existing in the current runner chamber of the power station, the basic material of the flow surface in the original runner chamber is ordinary steel. Due to its low carbon content in the structure, fatigue damage will occur soon when it is hit by the impact force of cavitation, and there is no The martensitic structure of stainless steel has extremely poor anti-cavitation performance. In order to completely solve the problem of easy cavitation in the runner chamber, the solution adopts the flow-type surface section to be all stainless steel and wear-resistant materials, and the flange of the runner chamber The half surface adopts ordinary steel material to overcome the sealing defect of the contact surface caused by the easy deformation of stainless steel material, and to reduce the use of stainless steel as much as possible to reduce the cost of technical transformation. The structural design of the runner chamber is mainly based on Improve the rigidity and reduce horizontal vibration to avoid cracks due to vibration to improve reliability.

material selection:

Choose 06Cr19Ni10 stainless steel material with high corrosion resistance, which has excellent anti-cavitation performance. Its choice is based on the following three points:

①The chemical composition of 06Cr19Ni10 is as follows, its carbon content is 0.08, it belongs to high carbon steel, its strength and wear resistance are higher, and its harmful component (P) is low in phosphorus. has obvious advantages.

②06Cr19Ni10 has the characteristics of relatively uniform structure, which is beneficial to anti-cavitation performance, and has a relatively uniform low-carbon martensitic structure, which significantly improves the anti-cavitation performance. The cavitation structure load is microscopic and has "selection" for different structures. However, conventional mechanical properties can only reflect the macroscopic properties of materials, so the cavitation resistance of materials cannot be measured by conventional mechanical properties. When subjected to cavitation, the strip ferrite is destroyed first, thereby accelerating the destruction of the austenite matrix.

③Inclusions and harmful components (P) High phosphorus content is not good for anti-cavitation performance, so in order to improve anti-cavitation performance, the purity of steel should be increased. 06Cr19Ni10 stainless steel has high cavitation resistance.

Based on the above reasons, the flow surface in the runner chamber is fully made of 06Cr19Ni10 material with excellent cavitation resistance

Features of Structural Design

The structure of the runner chamber includes a cylindrical body, which is divided into a semi-cylindrical upper split-valve chamber and a lower split-valve chamber. The upper split-valve chamber and the lower split-valve chamber are connected by flanges. The outer walls are all provided with reinforcing ring ribs along the arc direction. The tubular body located downstream is provided with a rigid body ring at its outlet. The runner chamber of the bulb tubular water turbine is horizontal when in use. The interior of the runner chamber is filled with water under the operating condition of the unit. The petal runner chamber is affected by the gravity of the water, so the vibration is small; the upper petal wheel chamber and the lower half wheel chamber are connected by flanges, which reduces the horizontal vibration and strengthens the connection stiffness of the waist of the runner chamber; thus, the The runner chamber reduces the vibration of the unit's operating conditions and improves the structural rigidity, so its structural reliability is high, cracks and water leakage problems are reduced, and the safe and stable operation of the unit can be effectively guaranteed; there is no need to specially set longitudinal ribs to improve the rigidity, Thereby reducing the amount of materials and improving the utilization rate of materials.

Its main manufacturing process regulations are as follows.

The process structure of the runner chamber adopts segmental splicing, which is divided into upper profile section and lower cone pipe section.

Reinforcing ring ribs are arranged around the runner chamber to increase rigidity.

Material molding process:

The steel plate is blanked by numerical control, and the upper profile section and the lower conical section are used in the height direction.

The upper section is divided into semicircles and quartered, and molded with a special mold. The mold surface is processed by numerical control.

The lower conical section is formed by coiling with a coiling machine.

Gas shielded welding is used for welding, and welding deformation is reduced in strict accordance with dissimilar steel welding specifications and process measures.

After welding, stress relief annealing is carried out in strict accordance with the company's heat treatment specifications.

All mechanical processing is programmed and processed on a CNC boring machine to strictly ensure the accuracy of dimension accuracy, surface profile and waviness. After rough machining, flaw detection is carried out according to technical requirements. If defects are found, they are processed according to the process flow. After finishing machining, kerosene penetration test is performed. .

Runner room after renovation

The flow surface of the modified runner chamber is all made of 06Cr19Ni10 material with excellent anti-cavitation performance, which ensures the safety and stability of the unit, improves the efficiency and life of the unit; the structure of the runner chamber is connected by flanges to the upper lobe chamber and the lower half chamber , the horizontal vibration is reduced, and the connection rigidity of the waist of the runner chamber is strengthened; the vibration of the operating condition of the unit is reduced, the structural rigidity is improved, and the reliability is high; modern numerical control programming is adopted, the flow surface is accurate, the size and position The deviation is small, and the gap between the runner chamber and the runner is uniform after installation, which effectively improves the hydraulic efficiency of the turbine, reduces the vibration caused by hydraulic imbalance, and greatly improves the stability of operation.

Compared with related technologies, a method for repairing cavitation on the flow surface of the runner chamber provided by the present invention has the following beneficial effects:

The present invention provides a method for repairing the cavitation on the overflow surface of the runner chamber. When the runner chamber 1 is undergoing erosion processing, the cavitation position is removed by turning, and the stainless steel liner 3 is inlaid with the rear plug for repair welding, so as to strictly control the amount of deformation. During the welding process of the steel plate, it is necessary to tap to ensure that it is close to the base material of the runner chamber, which can replace the current operation of the overall replacement of the runner chamber, which can facilitate the reduction of processing costs and also play a convenient role in the replacement of the runner chamber.

second embodiment

Please refer to Fig. 2, Fig. 3 and Fig. 4 in combination. Based on the cavitation repair method for the flow surface of the runner chamber provided by the first embodiment of the application, the second embodiment of the application proposes another method for the flow of the runner chamber. Flow surface cavitation repair method. The second embodiment is only a preferred mode of the first embodiment, and the implementation of the second embodiment will not affect the independent implementation of the first embodiment.

Specifically, the difference between the cavitation repair method for the flow surface of the runner chamber provided by the second embodiment of the present application is that the method for cavitation repair of the flow surface of the runner chamber is that the surface of the stainless steel liner 3 The side of the positioning assembly 4 is provided, and the positioning assembly 4 includes a positioning block 41. The inside of the stainless steel liner 3 is provided with a positioning groove 42 that is compatible with the positioning block 41. The stainless steel liner 3 Inside and on one side of the positioning groove 42, a fixing assembly 5 is provided. The fixing assembly 5 includes a sliding cavity 51, and a fixing member 52 is arranged inside the sliding cavity 51. The inside of the positioning block 41 is provided with a The fixing member 52 is matched with the fixing hole 53 , and the surface of the fixing member 52 is provided with a limiting bolt 54 .

The positioning block 41 is connected to the bottom of the stainless steel liner 3, and the positioning groove 42 is set inside another stainless steel liner 3. Using the positioning block 41 and the positioning groove 42 facilitates the positioning of multiple stainless steel liner 3 when splicing vertically. , to prevent displacement during fixation, the sliding chamber 51 is set on the surface of the stainless steel liner 3, the fixing part 52 includes two chute, the inside of the two chute is slidably connected with sliders, and there is a connection between the two sliders plate, and a fixing bolt is arranged inside the connecting plate.

The top of the stainless steel liner 3 is provided with a blocking assembly 6, the blocking assembly 6 includes a card slot 61, and the inside of the card slot 61 is provided with a block 62, and the top of the stainless steel liner 3 is located on the card The opposite side of the groove 61 is provided with a movable groove 63, and the inside of the movable groove 63 is provided with a stopper 64, and the top of the stainless steel liner 3 is provided with a placement groove 65 matching the stopper 64, so One side of the surface of the blocking member 64 is provided with a threaded bolt 66 .

The use of the clamping block 62 and the clamping groove 61 can play a fixed role when multiple stainless steel lining plates 3 are spliced horizontally. .

The working principle of a cavitation repair method for the flow surface of the runner chamber provided by the present invention is as follows:

When in use, when splicing between a plurality of stainless steel liners 3, firstly connect the stainless steel liner 3 with the positioning block 41 and the block 62 with the stainless steel liner 3 with the positioning groove 42 and the stainless steel liner with the slot 61 of the stainless steel liner 3 coincides, when the positioning block 41 is overlapped with the positioning groove 42 and connected, then the fixing member 52 inside the sliding chamber 51 is pushed to connect with the fixing hole 53 inside the stainless steel liner 3 with the positioning block 41, when After the fixing member 52 is overlapped with the fixing hole 53 and connected, the limit bolt 54 is used to pass through the surface of the fixing member 52 and connect with the limit hole provided on the inner wall of the sliding cavity 51 .

When the card slot 61 and the card block 62 are overlapped and connected, the stopper 64 inside the movable slot 63 is moved to coincide with the stainless steel liner 3 with the card slot 61 and the placement slot 65, and then the threaded bolt 66 is used to pass through the stop The surface of part 64 is connected with the threaded hole at the bottom of the inner wall of placement groove 65 and gets final product.

Compared with related technologies, a method for repairing cavitation on the flow surface of the runner chamber provided by the present invention has the following beneficial effects:

The present invention provides a method for repairing cavitation on the flow surface of a runner chamber. A positioning component 4 and a fixing component 5 are arranged on the surface of a stainless steel liner 3 to cooperate with a blocking component 6 to facilitate the splicing and fixing of a plurality of stainless steel liner 3 . The stainless steel liner 3 can be replaced one by one after the runner chamber 1 has been in contact with water for a long time.

The above is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process conversion made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related technologies fields, all of which are equally included in the scope of patent protection of the present invention.

Claims (10)

1. A cavitation repair method for an overflow surface of a runner chamber is characterized by comprising the following steps:

s1, turning a part which is about 920mm long than a deep part of an overflow surface at the lower part of a runner chamber, removing a cavitation position, embedding a stainless steel lining plate, then performing plug repair welding, strictly controlling deformation, knocking a steel plate in a welding process to ensure that the steel plate is tightly attached to a runner chamber base metal;

s2, machining the overflowing surface of the runner chamber by adopting numerical control programming, wherein the unilateral cutting depth reaches 8mm, and the waviness of the molded surface is less than 0.5 mm;

s3, selecting materials: the material is characterized in that a cavitation-resistant material 1Cr18Ni9Ti steel plate is adopted, meanwhile, the cavitation-resistant material can also be 304 stainless steel, cr18Ni9Ti steel plate and 0Cr1 3Ni5Mot steel plate, and the thickness of the material is 9mm to 12mm, and the material is used as a lining plate material of a runner chamber 1 overflowing surface, is applied to the manufacturing of a water turbine overflowing part, has good comprehensive performance, has unique cavitation-resistant capability, can improve the comprehensive performance of the steel by proper amount of inverted austenite, reduces the crack sensitivity of a base body, improves the welding performance, needs to consider the surplus of turning of a spherical surface in the runner chamber and the inlaid adhesion degree of the steel plate, and does not allow a cavity between a base material and the lining plate after being inlaid;

s4, a material forming process:

s41, numerical control blanking is adopted for a steel plate, a process plug welding hole phi is formed by laser punching, a plurality of sections are adopted in the height direction and the circumference, a plurality of sections are adopted in the splicing direction and the circumference, a sectional block lining plate profile mold is manufactured by splicing, a numerical control machining profile mold pressing sectional block lining plate is used for splicing a runner chamber overflow surface lining plate for gas shielded welding, deformation is reduced by technological measures, and an overflow curved surface of the runner chamber is machined by a numerical control machine;

s5, welding process: welding is carried out by adopting gas shielded welding, so that welding deformation is reduced;

s51, selecting the diameter of a welding wire, wherein the diameter of the welding wire is 1.2 mm;

s52, welding current (A);

s53, welding voltage (V);

s54, welding speed;

s55, selecting the CO2 gas flow;

s56, selecting welding wires;

s57, welding external inspection;

s58, when welding the dissimilar steel plates, welding by adopting a welding process of high-strength steel, wherein welding materials are specified according to patterns and are evaluated by a welding process test;

s59, before welding, cleaning the groove and rust, slag, oil dirt, water marks and the like within the range of 10-20mm on two sides of the groove;

s510, baking and storing the welding materials according to the following requirements;

the welding rod and the welding are placed in a special storehouse which is ventilated, dry and has the room temperature of not less than 5 shots, a special person is arranged for keeping, baking and issuing, and the requirements of actually measured temperature, welding rod issuing record, counting and the like are selected in time, and H08MnSi CrM0A or H08MnSi CrM0VA is selected;

s511, steel plate material requirement: the steel plates and the welding wires of the materials have delivery quality certification, and the chemical components, the mechanical properties and other indexes of the steel plates and the welding wires meet the standards;

2. the method for repairing cavitation of the overflow surface of the runner chamber as claimed in claim 1, wherein when the thick wire welding is adopted in S52, the upper limit of the current depends on the formation of the welding wire, and the lower limit depends on the stability of the welding process.

3. The method for repairing the overflow surface of the runner chamber by cavitation according to claim 1, wherein the arc voltage in S53 is not too high, which is liable to generate blowholes and spatters, and the arc voltage is too low which is liable to affect the formation of the weld.

4. The method for repairing the overflow surface of the runner chamber by cavitation erosion of the runner chamber as recited in claim 1, wherein the main indicator for measuring the productivity in S54 is that if the welding speed is too high, the shielding gas is damaged, the weld is cooled too fast due to poor formation of the weld, so that the plasticity and toughness of the weld are reduced, and the welding speed is too low, so that the weld is easily burnt through or a coarse weld structure is formed, and therefore the welding speed of the general semi-automatic CO2 gas shielded welding is not more than 0.5m/min.

5. The method for repairing the flow surface of the runner chamber by cavitation erosion of the flow surface of the runner chamber as recited in claim 1, wherein in S55, in order to ensure that the welding is free from air pollution, when the diameter of the welding wire is larger than 1.2mm 2, the gas flow is 30-50 l/min, in order to effectively protect the welding surface and obtain a high-quality welding seam, the purity of the CO2 gas for welding is not lower than 99.5%, and when the pressure in the CO2 gas cylinder is lower than 10kg/cm2, the use is stopped so as to avoid blowholes.

6. The runner chamber flow surface cavitation repair method according to claim 1, characterized in that in S56, H08MnSi CrM0A or H08MnSi CrM0VA is selected according to the requirements of the composition of welding materials, the radian of welding seams, design and the like.

7. The runner chamber overflow surface cavitation repair method according to claim 1, characterized in that in S57, an external inspection in a adopts a sample plate to inspect the appearance size of the weld or inspects surface defects with naked eyes and a magnifier, the weld is not allowed to have defects such as cracks, unfused, incomplete penetration, a large number of pores and slag inclusion, the weld is beautiful and has a fish scale-shaped ripple, the weld is in smooth transition with the base material, and b, all welds are subjected to nondestructive inspection.

8. The method for repairing the flow surface of the runner chamber by cavitation according to claim 1, wherein a plurality of steel rings are welded to the surface of the runner chamber.

9. The runner chamber overflow surface cavitation repair method according to claim 1, characterized in that a positioning assembly is arranged on the edge side of the surface of the stainless steel lining plate, the positioning assembly comprises a positioning block, a positioning groove matched with the positioning block is formed in the stainless steel lining plate, a fixing assembly is arranged in the stainless steel lining plate and on one side of the positioning groove, the fixing assembly comprises a sliding cavity, a fixing part is arranged in the sliding cavity, a fixing hole matched with the fixing part is formed in the positioning block, and a limit bolt is arranged on the surface of the fixing part.

10. The method for repairing cavitation of the overflowing surface of the runner chamber according to claim 9, wherein a blocking component is arranged on the top of the stainless steel lining plate, the blocking component comprises a clamping groove, a clamping block is arranged inside the clamping groove, a movable groove is arranged on the top of the stainless steel lining plate and on the side opposite to the clamping groove, a blocking piece is arranged inside the movable groove, a placing groove matched with the blocking piece is formed in the top of the stainless steel lining plate, and a threaded bolt is arranged on one side of the surface of the blocking piece.

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