Manufacturing, sleeving and dynamic balancing method of surface lining ECTFE impeller

Abstract

The invention discloses a method for manufacturing, sleeving and dynamically balancing a surface lining ECTFE impeller, which comprises the following steps of: (1) controlling the thicknesses of blades, a wheel cover and a wheel disc, and unifying the weight, molding datum line, cambered surface length and boundary dimension of symmetrical blades; (2) carrying out stable aging treatment on the blade; (3) the wheel cover is in a natural state when attached to the blades, then the inner side circle of the wheel cover is inspected at different heights, and the impeller is welded through a welding robot; (4) sequentially carrying out annealing treatment, magnetic powder inspection, overall turning, sand blasting treatment and primary dynamic balance on the whole impeller; (5) carrying out ECTFE coating by adopting a hot melting leveling method; (6) the impeller is heated, the main shaft is lifted after an inner hole of the impeller expands, and the impeller is sleeved with the main shaft through the dead weight; and (7) carrying out overall dynamic balance by adopting a method of combining membrane material heat sealing and a dynamic balance block method. According to the method, the ECTFE coating is not damaged on the premise that the assembly precision is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of wind turbine technology, specifically to a method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller. Background Technology

[0002] Under different operating conditions and in different operating systems, fans need to withstand the influence of different media. For clean air fans, the system contains media such as weak acids and alkalis, chloride ions, fluoride ions, and organic solvents, which are corrosive to a certain extent. As a load-bearing component, the impeller needs to withstand a certain torque force. In addition to considering corrosion resistance, the material selection principle during operation also needs to consider factors such as the strength of the base material and manufacturing cost.

[0003] Under normal temperature, clean air, and low-corrosion conditions, conventional austenitic stainless steels such as 304 and 316L cannot meet the impeller design requirements due to strength limitations. Therefore, the process of using low-alloy high-strength steel lined with ECTFE coating was proposed.

[0004] For large impellers, the assembly with the main shaft uses an interference fit design. To ensure assembly quality, the main shaft is typically horizontally fixed and its center height adjusted before the impeller is lifted, heated, and then fitted onto the main shaft. However, ECTFE material softens above 150°C. During impeller heating, the flame temperature of the heating torch generally exceeds 150°C and is difficult to control, easily damaging the ECTFE coating during lifting, potentially rendering it unusable. To ensure long-term operation of the impeller in corrosive media, the ECTFE coating thickness must be at least 0.3mm. The ECTFE application process requires a hot-melt leveling method. Therefore, to avoid heat deformation of precision-machined parts such as the main shaft, it is impossible to assemble them with the impeller before overall application. Furthermore, the ECTFE coating thickness exhibits a uniformity error of ±5% to ±10% after application, significantly impacting the subsequent rotor dynamic balance. Therefore, how to achieve full lining of large impellers with ECTFE coating has become a pressing problem. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for manufacturing, assembling and dynamically balancing an ECTFE-lined impeller, which can ensure assembly accuracy without damaging the ECTFE coating and ensure the dynamic balance accuracy of the rotor, thereby improving the overall service life of the impeller.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention provides a method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller, the innovation of which lies in including the following steps: (1) First, during the impeller manufacturing process, the thickness of the blades, wheel cover and wheel disk is strictly controlled. At the same time, the weight of the symmetrical blades, the forming baseline of the blades, the arc length of the blades and the external dimensions are uniformly controlled. (2) When the blade is rolled into shape by sheet metal method, the blade needs to be stabilized and aged to release the stress during sheet metal forming and put the blade in a natural state. (3) The wheel cover is made by spinning, and it must be in a natural state when it is attached to the blade. The maximum gap must not exceed 2mm. Then, the pile head is fixed at the center of the impeller and the inner circle of the wheel cover is inspected from the inlet position of the wheel cover at different heights. The radius error of the inner circle of the wheel cover at each height position must not exceed ±2mm. Then, the impeller is welded using a welding robot, and the parameters of each weld are set to be consistent to ensure that the welding amount and welding deformation are consistent. (4) Then the impeller is annealed as a whole. After annealing, the impeller is inspected by magnetic particle testing. After passing the inspection, it is machined as a whole. Then it is sandblasted and initially dynamically balanced. (5) Then the impeller is coated with ECTFE by hot melt leveling method, and the coating thickness must be ≥0.3mm, and leveling is achieved by its own gravity; (6) Then the impeller is placed upside down in the heat treatment furnace, suspended and then the impeller is heated as a whole. After the inner hole of the impeller expands, the main shaft is lifted and the main shaft is used to fit together with the impeller by its own weight. (7) Then, the overall dynamic balance of the assembly consisting of the impeller and the main shaft is carried out by combining the membrane material heat sealing and the dynamic balance block method.

[0007] Preferably, in step (1) above, the thickness error of the blade, wheel cover and wheel disk body shall not exceed 0.1 mm.

[0008] Preferably, in step (1) above, in order to ensure that the forming reference line of the blade is consistent, the inlet end face and the outlet end face of the blade need to be processed by machining to ensure that there is no cutting damage on the inlet and outlet reference surfaces of the blade and to ensure that the reference is consistent; during forming, the blade thickness direction neutral line needs to be used for positioning, and the blade thickness neutral layer position needs to be marked with a punch before forming; after machining, the blade length needs to be ensured that the length error does not exceed 0.1mm; after the blade is rolled into shape, it needs to be inspected with a chuck template and feeler gauge, and the error between each blade and the chuck template should not exceed 0.1mm; in addition, each blade needs to be weighed and the weight error needs to be controlled within ±10g.

[0009] Preferably, in step (2) above, the blade is stabilized and aged for 48 hours to release stress naturally. After aging, the blade needs to be re-inspected according to the requirements of step (1) above. If it fails to meet the requirements, it needs to be reworked and stabilized and aged again until the re-inspection is qualified.

[0010] Preferably, in step (3) above, the fit error between the pile head and the impeller center hole needs to be controlled within 0.2~0.5mm, and the inner circle of the wheel cover is divided into three groups for height inspection, namely the highest point position, the lowest point position and the center point position. If the wheel cover error is large, it needs to be reworked. When welding the impeller, the cross-shaped symmetrical welding method should be adopted, and before welding, the process impeller and the actual impeller need to be combined. The process impeller can only be disassembled after the overall annealing is completed.

[0011] Preferably, in step (4) above, the temperature of the overall annealing treatment of the impeller is set to 560℃±10℃, and after reaching the specified temperature, it needs to be kept at the temperature for 3~4 hours, and then cooled to 200℃ in the furnace before air cooling; after it is completely cooled to room temperature, the impeller is inspected by magnetic particle testing; when the impeller is machined, the outer end face of the blade is aligned with the plane of the impeller disk, and the inner hole of the impeller needs to be protected before sandblasting, and sandblasted to Sa2.5 grade; the impeller is initially dynamically balanced using a process balance shaft, and the process balance shaft needs to be heat-treated so that its surface hardness value reaches HB200-HB250 after heat treatment; a gap of 0.01mm needs to be left between the outer diameter of the process balance shaft and the inner hole of the impeller on one side, and it is fixed by key blocks and lock nuts.

[0012] Preferably, in step (5) above, the inner diameter of the impeller needs to be measured before hot melting, and the inner diameter of the impeller needs to be remeasured after the hot melting is completely cooled to ensure that the inner diameter of the impeller is restored to the original size. At the same time, the inner diameter of the impeller needs to be protected. After hot melting, the impeller is slowly cooled to room temperature in the furnace. When the impeller is hot melted as a whole, the main shaft and the impeller are not assembled.

[0013] Preferably, in step (6) above, the heat treatment furnace must be a calibrated Class II or higher heat treatment furnace, that is, the temperature uniformity of the effective heating zone must be controlled within ±5℃; after the impeller is placed upside down in the heat treatment furnace, the inner hole size of the impeller is measured, 4 sets of points are measured, the minimum value is taken and recorded as ΦA; at the same time, the level of the impeller is checked and adjusted with a level; the heat treatment furnace is set to 130℃, kept at 4 hours, and the heating rate is set to 100℃ / h; after the furnace is opened, the inner hole size of the impeller is measured, 4 sets of points are measured, the minimum value is taken and recorded as ΦB; if ΦB-ΦA≥0.15mm, the main shaft and impeller can be assembled.

[0014] Preferably, in step (6) above, the main shaft is lifted to a natural vertical position and then assembled with the impeller; before assembly, the bearing must be installed on the main shaft body, and the bearing housing side cover must be designed as a split type; after assembly, the assembly of the impeller and the main shaft is allowed to cool naturally together. At this time, the impeller must not be lifted, and the impeller body must be protected to avoid damage to the ECTFE coating by foreign objects; the assembly of the impeller and the main shaft is lifted after it has completely cooled to room temperature.

[0015] Preferably, in step (7) above, when the assembly of the impeller and the main shaft is dynamically balanced as a whole, the bearings are already installed and therefore need to be secured with tooling to ensure that it is perpendicular to the main shaft and does not wobble; the overall dynamic balancing is performed according to G2.5 grade, specifically as follows: (7.1) When the imbalance exceeds 10g, titanium alloy steel plate is used as a dynamic balancing block. After drilling holes at the locations where the wheel disc and wheel cover need to be counterweighted, it is connected to the titanium alloy steel plate and connected with titanium alloy bolts. When selecting titanium alloy steel plate and titanium alloy bolts, the weight needs to be calculated, and titanium alloy steel plate of corresponding thickness and titanium alloy bolts of different sizes and nuts should be selected. In order to avoid corrosion of the low alloy steel surface exposed in the hole after drilling, PTFE polytetrafluoroethylene is wrapped around the outer ring of the titanium alloy bolt for protection. Double nuts are used for tightening. After tightening, the anti-reverse groove is tapped on the thread at the tail of the titanium alloy bolt. (7.2) When the imbalance is less than or greater than 10g, use a hot air gun to spot-fill the corresponding ECTFE flat strip at the position where counterweight is required. The counterweight area must be smoothly connected with the base ECTFE coating and present a regular circular appearance. During the melting process, pressure must be applied evenly, and the pressure holding time for each layer is between 10s and 20s.

[0016] The beneficial effects of this invention are: (1) The present invention can ensure the assembly accuracy without damaging the ECTFE coating and ensure the dynamic balance accuracy of the rotor, thereby improving the overall service life of the impeller; (2) This invention improves the control of blade area size, weight and profile, and at the same time performs stabilization aging treatment on the blade, effectively reducing the imbalance caused by uneven weight change after subsequent ECTFE coating coverage; (3) By controlling the arc line of the wheel cover and the thickness requirements of the wheel cover and the wheel disc, the present invention further reduces the skewness of the impeller body; at the same time, the use of robotic welding improves the consistency of heat input during the welding process and makes the stress release uniform after annealing. (4) The present invention adopts the method of vertically sleeved impeller on main shaft, which avoids the problem of damage to coating when lifting after the impeller is fully lined with ECTFE coating; and adopts a calibrated Class II or above heat treatment furnace, which can effectively avoid the phenomenon of coating melting due to temperature deviation; (5) The present invention uses a combination of titanium alloy balance blocks and membrane material heat treatment to achieve dynamic balancing, which solves the problems of not being able to remove weight and not being able to weld dynamic balance blocks. The use of PTFE tape to wrap the bolts can effectively prevent corrosive media from directly contacting the low alloy steel surface base layer, thereby improving the service life of the impeller body. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram illustrating the manufacturing, assembly, and dynamic balancing method of an ECTFE-lined impeller according to the present invention. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below through specific embodiments.

[0020] The present invention provides a method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller, such as... Figure 1 As shown, it includes the following steps: (1) First, during the impeller manufacturing process, the thickness of the blades, wheel cover and wheel disk is strictly controlled. At the same time, the weight of the symmetrical blades, the forming baseline of the blades, the arc length of the blades and the external dimensions are uniformly controlled. The thickness error of each of the blades, wheel covers, and wheel discs must not exceed 0.1 mm.

[0021] In the above steps, to ensure that the forming baseline of the blades is consistent, the inlet and outlet end faces of the blades need to be machined to ensure that there are no cut edges on the inlet and outlet reference surfaces and to ensure that the references are consistent. During forming, the blade thickness neutral line must be used for positioning, and the position of the blade thickness neutral layer must be marked with a center punch before forming. After machining, the blade length must be ensured to have a length error of no more than 0.1 mm. After the blades are rolled into shape, they must be inspected with a chuck template and feeler gauge, and the error between each blade and the chuck template must not exceed 0.1 mm. In addition, each blade must be weighed, and the weight error must be controlled within ±10g.

[0022] (2) When the blade is rolled and formed by sheet metal method, stress is easily formed inside the blade and it takes a certain amount of time to release. Therefore, the blade needs to be stabilized and aged to release the stress during sheet metal forming and put the blade in a natural state. In the above steps, the blade is stabilized and aged for 48 hours to release stress naturally. After aging, the blade needs to be re-inspected according to the requirements of step (1) above. If it fails, it needs to be reworked and stabilized and aged again until the re-inspection is qualified.

[0023] (3) The wheel cover is made by spinning, and it must be in a natural state when it is attached to the blade. The maximum gap must not exceed 2mm. Then, the pile head is fixed at the center of the impeller and the inner circle of the wheel cover is inspected from the inlet position of the wheel cover at different heights. The radius error of the inner circle of the wheel cover at each height position must not exceed ±2mm. Then, the impeller is welded using a welding robot, and the parameters of each weld are set to be consistent to ensure that the welding amount and welding deformation are consistent. In the above steps, the fit error between the pile head and the impeller center hole must be controlled within 0.2~0.5mm, and the inner circle of the impeller cover should be checked in three groups, namely the highest point, the lowest point and the center point. If the impeller cover error is large, it needs to be reworked. When welding the impeller, a cross-shaped symmetrical welding method should be used, and before welding, the process impeller and the actual impeller should be combined. The process impeller can only be disassembled after the overall annealing is completed.

[0024] (4) Then the impeller is annealed as a whole. After annealing, the impeller is inspected by magnetic particle testing. After passing the inspection, it is machined as a whole. Then it is sandblasted and initially dynamically balanced. In the above steps, the temperature for the overall annealing of the impeller is set to 560℃±10℃, and after reaching the specified temperature, it needs to be held for 3~4 hours, and then cooled in the furnace to 200℃ before air cooling. After it has completely cooled to room temperature, the entire impeller is inspected by magnetic particle testing. When machining the impeller, the outer end face of the blade is aligned with the plane of the impeller disk. Before sandblasting, the entire inner hole of the impeller needs to be protected and sandblasted to Sa2.5 grade. The initial dynamic balancing of the impeller is performed using a process balance shaft. The process balance shaft needs to be heat-treated so that its surface hardness value reaches HB200-HB250 after heat treatment. A gap of 0.01mm needs to be left between the outer diameter of the process balance shaft and the inner hole of the impeller on one side, and it is fixed by key blocks and lock nuts.

[0025] (5) Then the impeller is coated with ECTFE by hot melt leveling method, and the coating thickness must be ≥0.3mm, and leveling is achieved by its own gravity; In the above steps, the inner diameter of the impeller needs to be measured before hot melting. After the hot melting is completely cooled, the inner diameter of the impeller needs to be remeasured to ensure that the inner diameter of the impeller is restored to the original size. At the same time, the inner diameter of the impeller needs to be protected. After hot melting, the impeller is slowly cooled to room temperature in the furnace. When the impeller is hot melted as a whole, the main shaft and the impeller are not assembled.

[0026] (6) Then the impeller is placed upside down in the heat treatment furnace, suspended and then the impeller is heated as a whole. After the inner hole of the impeller expands, the main shaft is lifted and the main shaft is used to fit together with the impeller by its own weight. In the above steps, the heat treatment furnace must be a calibrated Class II or higher heat treatment furnace, meaning the temperature uniformity of the effective heating zone must be controlled within ±5℃. After the impeller is placed upside down in the heat treatment furnace, the inner diameter of the impeller is measured at 4 points, and the minimum value is recorded as ΦA. At the same time, the level of the impeller is checked and adjusted using a level. The heat treatment furnace is set to 130℃, held for 4 hours, and the heating rate is set to 100℃ / h. After the furnace is opened, the inner diameter of the impeller is measured at 4 points, and the minimum value is recorded as ΦB. If ΦB-ΦA≥0.15mm, the main shaft and impeller can be assembled.

[0027] In the above steps, the main shaft is lifted to a naturally vertical position and then assembled with the impeller. Before assembly, the bearing must be installed on the main shaft body, and the bearing housing side cover must be designed as a split type. After assembly, allow the assembly of the impeller and the main shaft to cool naturally together. At this time, the impeller must not be lifted, and the impeller body must be protected to avoid damage to the ECTFE coating by foreign objects. Lifting can only be carried out after the assembly of the impeller and the main shaft has completely cooled to room temperature.

[0028] (7) Then, the overall dynamic balance of the assembly consisting of the impeller and the main shaft is carried out by combining the membrane material heat sealing and the dynamic balance block method.

[0029] In the above steps, when performing overall dynamic balancing of the impeller and main shaft assembly, since the bearings are already installed, tooling is needed to secure them to ensure they are perpendicular to the main shaft and do not wobble; the overall dynamic balancing is performed according to G2.5 grade, specifically as follows: (7.1) When the imbalance exceeds 10g, titanium alloy steel plate is used as a dynamic balancing block. After drilling holes at the locations where the wheel disc and wheel cover need to be counterweighted, it is connected to the titanium alloy steel plate and connected with titanium alloy bolts. When selecting titanium alloy steel plate and titanium alloy bolts, the weight needs to be calculated, and titanium alloy steel plate of corresponding thickness and titanium alloy bolts of different sizes and nuts should be selected. In order to avoid corrosion of the low alloy steel surface exposed in the hole after drilling, PTFE polytetrafluoroethylene is wrapped around the outer ring of the titanium alloy bolt for protection. Double nuts are used for tightening. After tightening, the anti-reverse groove is tapped on the thread at the tail of the titanium alloy bolt. (7.2) When the imbalance is less than or greater than 10g, use a hot air gun to spot-fill the corresponding ECTFE flat strip at the position where counterweight is required. The counterweight area must be smoothly connected with the base ECTFE coating and present a regular circular appearance. During the melting process, pressure must be applied evenly, and the pressure holding time for each layer is between 10s and 20s.

[0030] The beneficial effects of this invention are: (1) The present invention can ensure the assembly accuracy without damaging the ECTFE coating and ensure the dynamic balance accuracy of the rotor, thereby improving the overall service life of the impeller; (2) This invention improves the control of blade area size, weight and profile, and at the same time performs stabilization aging treatment on the blade, effectively reducing the imbalance caused by uneven weight change after subsequent ECTFE coating coverage; (3) By controlling the arc line of the wheel cover and the thickness requirements of the wheel cover and the wheel disc, the present invention further reduces the skewness of the impeller body; at the same time, the use of robotic welding improves the consistency of heat input during the welding process and makes the stress release uniform after annealing. (4) The present invention adopts the method of vertically sleeved impeller on main shaft, which avoids the problem of damage to coating when lifting after the impeller is fully lined with ECTFE coating; and adopts a calibrated Class II or above heat treatment furnace, which can effectively avoid the phenomenon of coating melting due to temperature deviation; (5) The present invention uses a combination of titanium alloy balance blocks and membrane material heat treatment to achieve dynamic balancing, which solves the problems of not being able to remove weight and not being able to weld dynamic balance blocks. The use of PTFE tape to wrap the bolts can effectively prevent corrosive media from directly contacting the low alloy steel surface base layer, thereby improving the service life of the impeller body.

[0031] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, all modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope of the present invention. The technical content for which protection is sought in the present invention has been fully described in the technical requirements.

Claims

1. A method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller, characterized in that... Includes the following steps: (1) First, during the impeller manufacturing process, the thickness of the blades, wheel cover and wheel disk is strictly controlled. At the same time, the weight of the symmetrical blades, the forming baseline of the blades, the arc length of the blades and the external dimensions are uniformly controlled. (2) When the blade is rolled into shape by sheet metal method, the blade needs to be stabilized and aged to release the stress during sheet metal forming and put the blade in a natural state. (3) The wheel cover is made by spinning, and it must be in a natural state when it is attached to the blade. The maximum gap must not exceed 2mm. Then, the pile head is fixed at the center of the impeller and the inner circle of the wheel cover is inspected from the inlet position of the wheel cover at different heights. The radius error of the inner circle of the wheel cover at each height position must not exceed ±2mm. Then, the impeller is welded using a welding robot, and the parameters of each weld are set to be consistent to ensure that the welding amount and welding deformation are consistent. (4) Then the impeller is annealed as a whole. After annealing, the impeller is inspected by magnetic particle testing. After passing the inspection, it is machined as a whole. Then it is sandblasted and initially dynamically balanced. (5) Then the impeller is coated with ECTFE by hot melt leveling method, and the coating thickness must be ≥0.3mm, and leveling is achieved by its own gravity; (6) Then the impeller is placed upside down in the heat treatment furnace, suspended and then the impeller is heated as a whole. After the inner hole of the impeller expands, the main shaft is lifted and the main shaft is used to fit together with the impeller by its own weight. (7) Then, the overall dynamic balance of the assembly consisting of the impeller and the main shaft is carried out by combining the membrane material heat sealing and the dynamic balance block method.

2. The method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller according to claim 1, characterized in that: In step (1) above, the thickness error of the blade, wheel cover and wheel disk shall not exceed 0.1 mm.

3. The method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller according to claim 1, characterized in that: In step (1) above, in order to ensure that the forming reference line of the blade is consistent, the inlet end face and the outlet end face of the blade need to be processed by machining to ensure that there is no cutting damage on the inlet and outlet reference surfaces of the blade and to ensure that the reference is consistent; during forming, the blade thickness direction neutral line needs to be used for positioning, and the blade thickness neutral layer position should be marked with a punch before forming. After machining, the blade length must be ensured to have an error of no more than 0.1 mm. After the blade is rolled into shape, it must be inspected with a chuck template and feeler gauge. The error between each blade and the chuck template must not exceed 0.1 mm. In addition, each blade must be weighed and the weight error must be controlled within ±10g.

4. The method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller according to claim 1, characterized in that: In step (2) above, the blade is stabilized and aged for 48 hours to release stress naturally. After aging, the blade needs to be re-inspected according to the requirements of step (1) above. If it fails to meet the requirements, it needs to be reworked and stabilized and aged again until the re-inspection is qualified.

5. The method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller according to claim 1, characterized in that: In step (3) above, the fit error between the pile head and the impeller center hole needs to be controlled within 0.2~0.5mm, and the inner circle of the wheel cover is divided into three groups for height inspection, namely the highest point position, the lowest point position and the center point position. If the wheel cover error is large, it needs to be reworked. When welding the impeller, the cross-shaped symmetrical welding method should be used, and before welding, the process impeller and the actual impeller should be combined. The process impeller can only be disassembled after the overall annealing is completed.

6. The method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller according to claim 1, characterized in that: In step (4) above, the temperature for the overall annealing of the impeller is set to 560℃±10℃, and after reaching the specified temperature, it needs to be kept at the temperature for 3~4 hours, and then cooled to 200℃ in the furnace before air cooling. After it is completely cooled to room temperature, the impeller is then subjected to magnetic particle inspection. When machining the impeller, the outer end face of the blade is aligned with the plane of the impeller disk. Before sandblasting, the inner hole of the impeller needs to be protected and sandblasted to Sa2.5 grade. The impeller is initially dynamically balanced using a process balance shaft. The process balance shaft needs to be heat-treated so that its surface hardness value reaches HB200-HB250 after heat treatment. A gap of 0.01mm needs to be left between the outer diameter of the process balance shaft and the inner hole of the impeller on one side, and it is fixed by a key block and a locking nut.

7. The method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller according to claim 1, characterized in that: In step (5) above, the inner diameter of the impeller needs to be measured before hot melting. After the hot melting is completely cooled, the inner diameter of the impeller needs to be remeasured to ensure that the inner diameter of the impeller is restored to its original size. At the same time, the inner diameter of the impeller needs to be protected. After hot melting, the impeller is slowly cooled to room temperature in the furnace. When the impeller is hot melted as a whole, the main shaft and the impeller are not assembled.

8. The method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller according to claim 1, characterized in that: In step (6) above, the heat treatment furnace must be a calibrated Class II or above heat treatment furnace, that is, the temperature uniformity of the effective heating zone must be controlled within ±5℃; after the impeller is placed upside down in the heat treatment furnace, the inner hole size of the impeller is measured, 4 sets of points are measured, the minimum value is taken and recorded as ΦA; at the same time, the level of the impeller is checked and adjusted with a level; the heat treatment furnace is set to 130℃, held for 4 hours, and the heating rate is set to 100℃ / h; after the furnace is opened, the inner hole size of the impeller is measured, 4 sets of points are measured, the minimum value is taken and recorded as ΦB; if ΦB-ΦA≥0.15mm, the main shaft and impeller can be assembled.

9. The method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller according to claim 1, characterized in that: In step (6) above, the main shaft is lifted to a natural vertical position and then assembled with the impeller. Before assembly, the bearing must be installed on the main shaft body, and the bearing housing side cover must be designed as a split type. After assembly, the assembly of the impeller and the main shaft is allowed to cool naturally. At this time, the impeller must not be lifted, and the impeller body must be protected to avoid damage to the ECTFE coating by foreign objects. The assembly of the impeller and the main shaft is lifted after it has completely cooled to room temperature.

10. The method for manufacturing, assembling, and dynamically balancing an ECTFE-lined impeller according to claim 1, characterized in that: In step (7) above, when the assembly of the impeller and the main shaft is dynamically balanced as a whole, the bearings are already installed and therefore need to be secured with tooling to ensure that they are perpendicular to the main shaft and do not wobble; the overall dynamic balancing is carried out according to G2.5 grade, specifically as follows: (7.1) When the imbalance exceeds 10g, titanium alloy steel plate is used as a dynamic balancing block. After drilling holes at the locations where the wheel disc and wheel cover need to be counterweighted, it is connected to the titanium alloy steel plate and connected with titanium alloy bolts. When selecting titanium alloy steel plate and titanium alloy bolts, the weight needs to be calculated, and titanium alloy steel plate of corresponding thickness and titanium alloy bolts of different sizes and nuts should be selected. In order to avoid corrosion of the low alloy steel surface exposed in the hole after drilling, PTFE polytetrafluoroethylene is wrapped around the outer ring of the titanium alloy bolt for protection. Double nuts are used for tightening. After tightening, the anti-reverse groove is tapped on the thread at the tail of the titanium alloy bolt. (7.2) When the imbalance is less than or greater than 10g, use a hot air gun to spot-fill the corresponding ECTFE flat strip at the position where counterweight is required. The counterweight area must be smoothly connected with the base ECTFE coating and present a regular circular appearance. During the melting process, pressure must be applied evenly, and the pressure holding time for each layer is between 10s and 20s.

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