Method for removing broken shaft of large motor rotor

Abstract

The present application relates to motor spindle processing technical field, specifically relates to a kind of large motor rotor broken shaft extraction method, comprising the following steps: fixed rotor;The periphery of the cross section of rotor spindle is polished and protruding burr part is removed;Actual size and shape and the distance of the cross section distance the deformation place of rotor spindle are surveyed on site, and the data obtained by surveying and mapping are recorded;According to surveying and mapping results, drill several deformation holes on the cross section, the depth of all deformation holes is greater than or equal to the distance of cross section distance the deformation place of rotor spindle;The cross section is pressed using pressing equipment, and the rotor spindle is ejected from rotor core, i.e. broken shaft extraction can be completed.This large motor rotor broken shaft extraction method can effectively protect rotor core and effectively extract broken shaft from rotor core, and high practicability.

Description

Technical Field

[0001] This invention relates to the field of large motor rotor spindle disassembly technology, specifically to a method for removing a broken shaft from a large motor rotor. Background Technology

[0002] With the development of social productivity, the requirements for power output of power equipment are becoming increasingly higher, thus the application range of large motors is expanding. Long-term overload or fatigue operation can lead to rotor shaft breakage in large motors, which is a common mechanical failure.

[0003] The motor rotor shaft and rotor core are both installed using an interference fit, making it difficult to disassemble them under normal conditions. For example, Chinese patent ZL201621207303.1, "An Auxiliary Removal Device for a Broken Motor Shaft," discloses a method of using a screw to push the broken shaft out of the motor rotor core. However, this patent has limited applicability, only suitable for removing broken shafts from small motors, and cannot be used for removing broken shafts from large motors.

[0004] Large motors are significantly larger and heavier than conventional small motors. The rotor shaft of a large motor is typically over 2 meters long and over 0.25 meters in diameter, with a single rotor weighing several tons. Due to the relatively large size of the rotor, conventional pressing equipment is difficult to use. Furthermore, if the rotor shaft breaks, the stress at the fracture point causes deformation in the cross-sectional area, leading to cracking, localized deformation, or even complete deformation and enlargement of the end of the rotor shaft near the cross-section. Therefore, in practice, disassembling and assembling the rotor shaft of a large motor is significantly more difficult than that of a conventional small motor. If large hydraulic equipment is used for ejection, the irregular edges of the rotor shaft's cross-section under stress can scratch the inner ring of the rotor core. Simultaneously, the deformation of the rotor shaft's cross-section may damage the inner ring of the rotor core, or even cause the two parts to jam together. Since components of large motors are generally custom-made and non-standard products, replacing a damaged rotor core with a new one not only involves a long manufacturing cycle but also increases costs. Therefore, there is an urgent need for a method that can effectively protect the rotor core and safely remove the broken shaft from it to solve the aforementioned problems. Summary of the Invention

[0005] To overcome one of the shortcomings of existing technologies, the present invention aims to provide a method for removing a broken shaft from a large motor rotor. This method effectively protects the rotor core and safely removes the broken shaft from the rotor core, making it highly practical.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] A method for removing a broken shaft from a large motor rotor includes the following steps:

[0008] Preparation steps: Fix the rotor;

[0009] Finishing steps: Grind the periphery of the cross section of the rotor spindle and remove any protruding burrs.

[0010] Measurement steps: On-site measurement of the actual size and shape of the cross-section, as well as the distance from the cross-section to the point where the rotor spindle begins to deform, and recording the measured data;

[0011] Drilling steps: Based on the survey results, drill several deformation holes on the cross section. The depth of all deformation holes is greater than or equal to the distance from the cross section to the point where the rotor main shaft begins to deform.

[0012] Pressing step: Use pressing equipment to press the cross section and push the rotor main shaft out of the rotor core to complete the removal of the broken shaft;

[0013] Wherein, the total diameter d of all deformed holes n for:

[0014]

[0015] Where D is the diameter of the rotor spindle, in meters (m); τ u σ is the ultimate shear stress of the rotor spindle, in Pa; α is the coefficient of thermal expansion of the material used in the rotor spindle; t is the temperature of the rotor spindle, in °C; T is room temperature (23 °C); σ maxc This represents the ultimate compressive stress on the rotor spindle, expressed in Pa.

[0016] Furthermore, the measurement steps specifically include:

[0017] Measure the actual distance between the periphery of the cross section of the rotor spindle and the center line of the rotor spindle rotation, and record the measurement data;

[0018] Based on the above measurement data, the actual horizontal plane projection of the cross section is drawn, thus obtaining the first projection diagram of the cross section;

[0019] Draw a diagram showing the positional relationship between the projection graphic and the cross-sectional graphic of the rotor spindle;

[0020] Divide the cross section into at least four equal parts, and measure the average projected distance of each divided region on the cross section from the horizontal plane where the rotor main shaft begins to deform, and record the measurement data.

[0021] Furthermore, the drilling step specifically includes:

[0022] Based on the positional relationship diagram, project the point markings onto the cross-section of the rotor main shaft;

[0023] Smooth out the marked area;

[0024] Using a small-diameter drilling machine, drilling positioning holes are made on the point markings on the cross-section;

[0025] Replace with a larger diameter drilling device and drill the deformation hole based on the positioning hole;

[0026] The distance between the outer peripheries of any two adjacent deformation holes shall be less than one-third of the diameter of any one of the deformation holes.

[0027] Furthermore, the specific steps of projecting and marking the point positions onto the cross-section of the rotor spindle based on the positional relationship diagram include the following steps:

[0028] Draw equally divided regions on the first projection pattern, and mark the drilling points within the equally divided regions on the first projection pattern. The more points are marked in the equally divided regions with larger average projection distances.

[0029] The point markers on the primary projection pattern are transferred onto the cross-section of the rotor spindle using a stamping method.

[0030] Furthermore, in the above-mentioned step of marking the drilling points, the number of points in the equally divided area where the deviation between the primary projection pattern and the rotor spindle cross-sectional pattern is greater is increased.

[0031] Furthermore, in the above-mentioned step of marking the drilling points, the drilling points are not marked in the areas where the projected image deviates from the cross-sectional image of the rotor spindle.

[0032] Furthermore, the diameter of the deformation hole closer to the edge of the cross section is smaller, and the distance between the deformation hole closer to the edge of the cross section and the edge of the cross section is greater than the diameter of the corresponding deformation hole.

[0033] Furthermore, the pressing step specifically includes the following steps:

[0034] The gap between the outer wall of the rotor spindle and the inner ring of the rotor core is filled with lubricating oil, and lubricating oil is also applied to the outer wall of the rotor spindle near the cross section.

[0035] The cross section of the rotor spindle is pressed forward by the pressing equipment, causing the rotor spindle to slide relative to the rotor core until the part of the rotor spindle that begins to deform contacts the end face of the rotor core. The pressing speed is 3-10 mm / min.

[0036] Re-map the cross-section of the rotor spindle on the horizontal plane as a secondary projection. Compare the secondary projection with the primary projection. If the overlap ratio between the secondary and primary projections is less than 95%, increase the number of deformation holes or use tools to break the connection between two adjacent deformation holes in the area with the largest relative deviation. If the overlap ratio between the secondary and primary projections is greater than or equal to 95%, continue pressing at a speed of 2-6 mm / min, with each pressing session lasting no more than 4 minutes.

[0037] Repeat the measurement and projection comparison operations multiple times until the cross-section of the rotor spindle does not protrude from the end face of the inner ring of the rotor core.

[0038] The pressing device continuously presses the cross section of the rotor main shaft in the forward direction at a pressing speed of 3-10 mm / min until the rotor main shaft is completely pushed out of the rotor core.

[0039] Furthermore, when the pressing device presses the cross section of the rotor spindle, the cooling device is used to cool the rotor spindle, and the cooling temperature is below zero degrees Celsius.

[0040] Furthermore, the point where the rotor spindle begins to deform in the measurement step specifically refers to the area where the circular runout of one end of the rotor spindle in the cross-section begins to exceed the specified circular runout standard value.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] This invention provides a method for removing a broken rotor shaft from a large motor. Through a measurement step, the specific deformation and length of the deformation at the end of the rotor shaft near the cross-section can be effectively understood, facilitating the drilling of deformation holes. Specifically, this application drills several deformation holes on the cross-section to break the internal stress of the rotor shaft at that end. This effectively prevents damage to the inner ring of the rotor core during subsequent ejection. Simultaneously, all deformation holes reduce the strength of the rotor shaft at the cross-section end to a certain extent. During ejection, the inner ring of the rotor core compresses and forces the rotor shaft at that end to deform inwards, preventing damage to the inner ring of the rotor core or jamming within it during the ejection process. Furthermore, the finishing step effectively grinds the edges of the cross-section, preventing burrs or protrusions from scratching or damaging the inner ring of the rotor core, ensuring smooth installation of the rotor core later.

[0043] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0044] Figure 1This is a flowchart illustrating the process of an embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0046] See Figure 1 This application provides a method for removing a broken shaft from a large motor rotor, comprising the following steps:

[0047] S100, Preparation steps: Fix the rotor;

[0048] S200, Finishing steps: Grind the periphery of the cross section of the rotor spindle and remove any protruding burrs.

[0049] S300, Measurement steps: On-site measurement of the actual size and shape of the cross-section, as well as the distance from the cross-section to the point where the rotor main shaft begins to deform, and recording the measured data;

[0050] S400, Drilling steps: Drill several deformation holes on the cross section according to the survey results. The depth of all deformation holes is greater than or equal to the distance from the cross section to the point where the rotor main shaft begins to deform.

[0051] S500, Top Pressing Step: Use the top pressing equipment to press the cross section and push the rotor main shaft out of the rotor core to complete the removal of the broken shaft;

[0052] The total diameter d of all deformation holes n for:

[0053]

[0054] Where D is the diameter of the rotor spindle, in meters (m); τ u σ is the ultimate shear stress of the rotor spindle, in Pa; α is the coefficient of thermal expansion of the material used in the rotor spindle; t is the temperature of the rotor spindle, in °C; T is room temperature (23 °C); σ maxc This represents the ultimate compressive stress on the rotor spindle, expressed in Pa.

[0055] Furthermore, in step S100, the entire rotor is hoisted onto the workbench using hoisting equipment. The workbench can be a specially designed platform to easily support the entire rotor. The workbench can also be designed with fixing slots or other fixing structures to facilitate relative positioning of the rotor. Additionally, the broken end of the rotor shaft faces upwards. If both ends of the rotor core are broken, the end with less deformation and a relatively regular end face can be observed by examining the cross-sections at both ends; the end facing upwards is the one with the smaller deformation. The pressing equipment mentioned in step S500 is actually a hydraulic pressing device, which can be installed as a whole on the workbench, thus assembling a large stamping machine.

[0056] It should be noted that in step S200 above, burrs will be generated on the periphery of the cross section of the rotor spindle during the fracture process. Therefore, it is necessary to grind and remove the burrs in advance. In addition to effectively reducing the resistance of the top pressure and protecting the inner ring of the rotor core, this can also protect the workers to a certain extent and prevent the burrs from scratching them during the operation.

[0057] Furthermore, in step S400, the principle utilized in this application is based on the Mohr-Coulomb strength theory. During actual pressing, if the broken end of the rotor shaft can be ejected from the inner ring of the rotor core, it will be subjected to radial clamping force, axial pressing force, and friction between the outer surface and the inner ring of the rotor core. In fact, the radial clamping force corresponds to shear stress, and the difference between the axial pressing force and the friction between the outer surface and the inner ring of the rotor core is the normal stress. Therefore, if the internal friction of the rotor shaft is not considered during actual pressing, when the normal stress is appropriate, the rotor shaft with the deformation hole will deform inward under radial shear stress. Therefore, this application is formally based on this principle in designing its solution.

[0058] Furthermore, the distance between the cross section and the starting deformation point of the rotor spindle obtained in step S300 is actually used as the main basis for the depth of the deformation hole in step S400. Its main purpose is to eliminate or reduce the internal stress of the rotor spindle between the cross section and the starting deformation point through the deformation hole in the later stage, so that the pressing device in step S500 can push the rotor spindle out of the rotor core.

[0059] Furthermore, in one embodiment, the measurement step in step S300 specifically includes:

[0060] S310. Measure the actual distance between the periphery of the cross section of the rotor spindle and the center line of the rotor spindle rotation axis, and record the measurement data;

[0061] S320. Based on the above measurement data, draw the actual horizontal plane projection of the cross section, thus obtaining the first projection diagram of the cross section;

[0062] S330. Draw the positional relationship diagram of the first projection graphic relative to the cross-sectional graphic of the rotor main shaft;

[0063] S340. Divide the cross section into at least four equal parts, and measure the average projected distance of each equal part on the cross section from the horizontal plane where the rotor main shaft begins to deform, and record the measurement data.

[0064] In step S320, the positional relationship between the projected image and the cross-sectional image of the rotor spindle allows us to determine the specific deviation of the broken end of the rotor spindle relative to the inner ring of the rotor core. This helps workers determine which side of the rotor core experiences the greatest compressive force during the subsequent pressing process, and also identifies the main stress concentration point at the broken end of the rotor spindle during the pressing process. Using this positional relationship diagram, workers can drill deformation holes to release the internal stress at the broken end of the rotor spindle in advance, reducing the reaction force exerted on the rotor core by the rotor spindle during the subsequent pressing process and minimizing damage to the rotor core.

[0065] Furthermore, since the rotor spindle is primarily made of high-strength carbon steel or alloy steel, it undergoes carburizing and quenching treatment according to specific requirements, achieving a hardness of 42-52 HRC. Therefore, in step S340, dividing the cross-section into several equal regions primarily facilitates the subsequent determination by the operator of the actual distance between the average cross-section of each region and the point where the rotor spindle begins to deform. This allows for the separate drilling of deformation holes at different depths in each region, thereby reducing the overall workload of drilling deformation holes in the rotor spindle and significantly improving work efficiency.

[0066] Furthermore, based on the above embodiments, in step S300, the operator needs to use a circular runout measuring device to measure the external circular runout of one end of the rotor spindle located in the cross section. If the area where the rotor spindle at one end of the cross section begins to exceed the specified circular runout standard value can be determined as the point where the rotor spindle begins to deform.

[0067] Furthermore, in one embodiment of this application, step S400 specifically includes:

[0068] S410. Based on the positional relationship diagram, project and mark the points on the cross-section of the rotor main shaft.

[0069] S420, smooth out the marked area;

[0070] S430. Use a small-diameter drilling device to drill positioning holes on the point markings on the cross section.

[0071] S440. Replace with a larger diameter drilling device and drill the deformation hole based on the positioning hole;

[0072] S450, the distance between the outer peripheries of any two adjacent deformation holes shall be less than one-third of the diameter of any one of the deformation holes.

[0073] The main purpose of point marking is to preliminarily calculate the total diameter d of the final drilled deformation hole using specific points. n Whether it meets the design requirements can ensure that, to the greatest extent possible, the broken end of the rotor spindle will deform inward under the reaction force of the inner ring of the rotor core during the pressing process, thus protecting the inner ring of the rotor core. In this application, when drilling deformation holes at each point, different diameter drill bits can be used depending on the actual situation, or the same drill bit can be used to drill all deformation holes. In this application, a large diameter drill bit is used to drill deformation holes in the area near the rotor spindle center, mainly to improve the efficiency of drilling deformation holes; while a small diameter drill bit is used to drill deformation holes in the edge area of ​​the cross section, which can avoid deformation of the rotor spindle sidewall caused by an excessively large drill bit when drilling deformation holes, thus protecting the edge of the cross section.

[0074] In step S450 above, the distance between the outer peripheries of any two adjacent deformation holes is less than one-third of the diameter of any one of the deformation holes. This design can be considered as designing the weakest point of the entire rotor spindle under internal stress, so that the end of the rotor spindle that breaks during the pressing process can automatically deform inward when subjected to the extrusion force of the inner ring of the rotor core. At this time, the isolation part between the outer peripheries of the two deformation holes is more easily deformed by the extrusion force than other areas, thereby ensuring that the entire rotor spindle deforms inward and reducing the extrusion force on the rotor core, which can effectively protect the rotor core.

[0075] Furthermore, in one embodiment of this application, step S410 includes the following steps:

[0076] S411. Draw equally divided regions on the primary projection pattern and mark the drilling points within the equally divided regions on the primary projection pattern, wherein the more points are marked in the equally divided regions with larger average projection distances.

[0077] S412. The point markers on the primary projection pattern are transferred to the cross-section of the rotor spindle using a stamping method.

[0078] In step S411, a larger average projection distance indicates greater deformation of the entire rotor spindle on that side, and a greater concentration of stress in that area. Therefore, drilling more deformation holes later eliminates this internal stress, facilitating inward deformation of that area during subsequent pressing. In step S412, the stamping method can be understood as the position of the point markers on the primary projection pattern being essentially consistent with the position of the point markers on the cross-section of the rotor spindle, achieving the same effect as a stamp.

[0079] It should be further explained that the location of the point markers in this application needs to be selected based on the size of the drill bit and the periphery of the cross section. The selection of the point markers in this application follows the principle that there are fewer points closer to the center of the rotor spindle, and large drill bits are used to drill deformation holes in this area later; while point markers closer to the periphery of the cross section are drilled with small diameter drill bits to drill deformation holes. Therefore, the internal stress in this area can be reduced by increasing the number of point markers.

[0080] Furthermore, in one embodiment of this application, in step S410, the number of points on the equally divided regions with larger deviations between the primary projection pattern and the rotor spindle cross-sectional pattern is increased. The main reason for this is that the equally divided regions with larger deviations are also the regions experiencing the greatest deformation, and therefore accumulate the greatest stress. If the internal stress in these regions is not eliminated beforehand during the pressing process, these regions are prone to exerting a reaction force on the inner ring of the rotor core, thus easily causing damage to the inner ring of the rotor core. Therefore, this embodiment of the application sets more points on the equally divided regions with larger deviations so that the total diameter of the deformation holes in these regions is larger later, resulting in more eliminated internal stress and facilitating inward deformation of these regions under stress.

[0081] Furthermore, in step S410, the drilling points are not marked in the area where the projected pattern deviates from the cross-sectional pattern of the rotor spindle. Since the area where the cross-section deviates from the cross-sectional pattern of the rotor spindle is actually the area of ​​bending deformation, if the drilling points are marked in this area and deformation holes are drilled, deformation in this area is likely to occur. Although the internal stress in this area can be released to a certain extent, the deformation caused by this area has a greater impact on the subsequent pressing step and on the inner ring of the rotor core. Therefore, this application will not mark the drilling points in this area in actual use.

[0082] Similarly, to better protect the rotor core and prevent the broken end of the rotor shaft from deforming inward, in one embodiment of this application, the diameter of the deformation hole closer to the edge of the cross-section is smaller, and the distance between the deformation hole near the edge of the cross-section and the edge of the cross-section is greater than the diameter of the corresponding deformation hole. This design effectively ensures that the broken end of the rotor shaft deforms inward under the compressive force of the inner ring of the rotor core, preventing the connection area between the outer wall of the rotor shaft and the nearby deformation hole from breaking and the fracture opening from turning outward. This avoids the outward-turned fracture opening scratching or damaging the inner wall of the inner ring of the rotor core.

[0083] Furthermore, in one embodiment of this application, since the rotor spindle of a large motor generally fractures due to gravitational concentration and fatigue at both ends of the rotor core, but a section of the rotor spindle remains between the cross-section and the end face of the rotor core, and there may be an unaffected portion on the rotor spindle between the cross-section and the end face of the rotor core, this portion does not deform, and the circular runout of the outer periphery of this portion meets the requirements, for such a rotor spindle, step S500 of this application, i.e., the pressing step, adopts the following steps:

[0084] S510, The gap between the outer wall of the rotor spindle and the inner ring of the rotor core is filled with lubricating oil and lubricating oil is applied to the outer wall of the rotor spindle near the cross section.

[0085] S520. Use the pressing device to press the cross section of the rotor spindle in the forward direction, so that the rotor spindle slides relative to the rotor core until the part of the rotor spindle that begins to deform contacts the end face of the rotor core. The pressing speed is 3-10 mm / min.

[0086] S530. Re-map the cross-section of the rotor spindle in a secondary projection on the horizontal plane; compare the secondary projection with the primary projection. If the overlap ratio between the secondary and primary projections is less than 95%, increase the number of deformation holes or use tools to break the connection between two adjacent deformation holes in the area with the largest relative deviation; if the overlap ratio between the secondary and primary projections is greater than or equal to 95%, continue pressing at a speed of 2-6 mm / min, with each pressing session lasting no more than 4 minutes.

[0087] S540. Repeat the measurement and projection comparison operations multiple times until the cross section of the rotor spindle does not protrude from the end face of the inner ring of the rotor core.

[0088] The S550 pressing device continuously presses the cross-section of the rotor main shaft in a positive direction at a pressing speed of 3-10 mm / min until the rotor main shaft is completely pushed out of the rotor core.

[0089] It should be noted that if the cross-section of the rotor spindle is very short from the end face of the rotor core, or if the starting deformation point of the rotor spindle coincides with or nearly coincides with the end face of the rotor core, then step S520 can be omitted. Furthermore, in this application, the lubricating oil impregnation operation in step S510 needs to be performed beforehand so that the lubricating oil can penetrate into the gap between the outer wall of the rotor spindle and the inner ring of the rotor core. In reality, impregnating the gap between the outer wall of the rotor spindle and the inner ring of the rotor core in step S510 is not very effective, mainly because the outer wall of the rotor spindle and the inner ring of the rotor core use an interference fit, making lubricating oil impregnation time too long or difficult. However, impregnating this area with lubricating oil mainly facilitates the introduction of lubricating oil when the rotor spindle slides relative to the rotor core, reducing the friction between them. In step S540, the cross-section of the rotor spindle is completely located within the inner ring of the rotor core. This can be simply understood as the broken end of the rotor spindle being completely sunk into the rotor core, with the cross-section not extending beyond the end face of the rotor core.

[0090] In addition, before step S510, it is necessary to clean the metal debris on the end face of the rotor core and the gap between the outer wall of the rotor spindle and the inner ring of the rotor core to prevent these metal debris from being carried into the gap between the outer wall of the rotor spindle and the inner ring of the rotor core by the rotor spindle, which can effectively protect the inner ring of the rotor core.

[0091] In the above embodiments, under normal circumstances, because the rotor spindle has several deformation holes at one end of the cross section, the mass of this end is not uniform, and the area with deformation holes is relatively weak. Under the combined action of compressive force and top pressure, it is prone to inward deformation, that is, the entire rotor spindle at one end of the cross section deforms towards the axis of the rotor spindle. The main purpose of steps S530 and S540 is to effectively monitor and prevent deformation at the broken end of the rotor spindle. In the actual top pressing process, the broken end of the rotor spindle will inevitably undergo irregular deformation due to the top pressure and the reaction force of the inner ring of the rotor core. If the deformation exceeds the amount that can be automatically recovered later is not dealt with in time during the top pressing process, these deformations will cause the rotor spindle and rotor core to jam each other or scratch or damage the inner ring of the rotor core. Therefore, during the pressing process, it is necessary to continuously adjust the internal stress at the broken end of the rotor spindle according to the deformation of the rotor spindle, and artificially eliminate some of the stress. This can be achieved by increasing the number of deformation holes in the equally divided area with the largest relative deviation, or by using tools to destroy the connection between two adjacent deformation holes. This operation allows the broken end of the rotor spindle to deform according to the preset weak area under the dual action of extrusion pressure and pressing pressure, ensuring the safety and reliability of the entire pressing process.

[0092] Furthermore, to increase the pressing speed and reduce the friction between the rotor spindle and the rotor core, this application can utilize the principle of thermal expansion and contraction to change the diameter of the broken end of the rotor spindle or the diameter of the inner ring of the rotor core. Based on the above embodiments, in one embodiment of this application, when the pressing device presses the cross-section of the rotor spindle, a cooling device is used to cool the rotor spindle to a temperature below zero degrees Celsius. Since several deformation holes are formed on the broken end of the rotor spindle, the cooling section of the cooling device can be directly inserted into these holes, or ice can be placed inside the holes for cooling. This effectively reduces the temperature of the broken end of the rotor spindle, causing it to contract inwards. Alternatively, in some embodiments, the diameter of the inner ring of the rotor core can be changed by heating it, causing it to expand outwards, thereby improving the pressing efficiency.

[0093] The present invention provides a method for removing a broken rotor shaft from a large motor. Through measurement steps, this method effectively understands the specific deformation and length of the rotor shaft near the cross-section, facilitating the drilling of deformation holes. Specifically, this application drills several deformation holes on the cross-section to break the internal stress of the rotor shaft at that end. This effectively prevents this stress from damaging the inner ring of the rotor core during subsequent ejection. Simultaneously, all deformation holes reduce the strength of the rotor shaft at the cross-section end to a certain extent. During ejection, the inner ring of the rotor core compresses and forces the rotor shaft at that end to deform inwards, preventing damage to the inner ring or jamming within the rotor core during the ejection process. Furthermore, the finishing step effectively grinds the edges of the cross-section, preventing burrs or protrusions from scratching or damaging the inner ring of the rotor core, ensuring smooth installation of the rotor core later.

[0094] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for removing a broken rotor shaft from a large motor, characterized in that, Includes the following steps: Preparation steps: Fix the rotor; Finishing steps: Grind the periphery of the cross section of the rotor spindle and remove any protruding burrs. Measurement steps: On-site measurement of the actual size and shape of the cross-section, as well as the distance from the cross-section to the point where the rotor spindle begins to deform, and recording the measured data; Drilling steps: Based on the survey results, drill several deformation holes on the cross section. The depth of all deformation holes is greater than or equal to the distance from the cross section to the point where the rotor main shaft begins to deform. Pressing step: Use pressing equipment to press the cross section and push the rotor main shaft out of the rotor core to complete the removal of the broken shaft; The total diameter d of all deformation holes n for: Where D is the diameter of the rotor spindle, in meters (m); τ u σ is the ultimate shear stress of the rotor spindle, in Pa; α is the coefficient of thermal expansion of the material used in the rotor spindle; t is the temperature of the rotor spindle, in °C; T is room temperature (23 °C); σ maxc This represents the ultimate compressive stress on the rotor spindle, expressed in Pa.

2. The method for removing a broken shaft from a large motor rotor according to claim 1, characterized in that: The measurement steps specifically include: Measure the actual distance between the periphery of the cross section of the rotor spindle and the center line of the rotor spindle rotation, and record the measurement data; Based on the above measurement data, the actual horizontal plane projection of the cross section is drawn, thus obtaining the first projection diagram of the cross section; Draw a diagram showing the positional relationship between the projection graphic and the cross-sectional graphic of the rotor spindle; Divide the cross section into at least four equal parts, and measure the average projected distance of each divided region on the cross section from the horizontal plane where the rotor main shaft begins to deform, and record the measurement data.

3. The method for removing a broken shaft from a large motor rotor according to claim 2, characterized in that: The drilling process specifically includes: Based on the positional relationship diagram, project the point markings onto the cross-section of the rotor main shaft; Smooth out the marked area; Using a small-diameter drilling machine, drilling positioning holes are made on the point markings on the cross-section; Replace with a larger diameter drilling device and drill the deformation hole based on the positioning hole; The distance between the outer peripheries of any two adjacent deformation holes shall be less than one-third of the diameter of any one of the deformation holes.

4. The method for removing a broken shaft from a large motor rotor according to claim 3, characterized in that: The specific steps for projecting and marking the position marks on the cross-section of the rotor main shaft according to the position relationship diagram include the following steps: Draw equally divided regions on the first projection pattern, and mark the drilling points within the equally divided regions on the first projection pattern. The more points are marked in the equally divided regions with larger average projection distances. The point markers on the primary projection pattern are transferred onto the cross-section of the rotor spindle using a stamping method.

5. A method for removing a broken shaft from a large motor rotor according to claim 4, characterized in that: In the above steps of marking the drilling points, the more points are in the equally divided areas where the deviation between the primary projection pattern and the rotor spindle cross-sectional pattern is greater.

6. A method for removing a broken shaft from a large motor rotor according to claim 4, characterized in that: In the above-mentioned step of marking the drilling points, the drilling points are not marked in the areas where the projected image deviates from the cross-sectional image of the rotor spindle.

7. A method for removing a broken shaft from a large motor rotor according to claim 3, characterized in that: The diameter of the deformation hole is smaller the closer it is to the edge of the cross section, and the distance between the deformation hole and the edge of the cross section is greater than the diameter of the corresponding deformation hole.

8. A method for removing a broken shaft from a large motor rotor according to claim 2, characterized in that: The pressing step specifically includes the following steps: The gap between the outer wall of the rotor spindle and the inner ring of the rotor core is filled with lubricating oil, and lubricating oil is also applied to the outer wall of the rotor spindle near the cross section. The cross section of the rotor spindle is pressed forward by the pressing equipment, causing the rotor spindle to slide relative to the rotor core until the part of the rotor spindle that begins to deform contacts the end face of the rotor core. The pressing speed is 3-10 mm / min. Re-map the cross-section of the rotor spindle on the horizontal plane as a secondary projection. Compare the secondary projection with the primary projection. If the overlap ratio between the secondary and primary projections is less than 95%, increase the number of deformation holes or use tools to break the connection between two adjacent deformation holes in the area with the largest relative deviation. If the overlap ratio between the secondary and primary projections is greater than or equal to 95%, continue pressing at a speed of 2-6 mm / min, with each pressing session lasting no more than 4 minutes. Repeat the measurement and projection comparison operations multiple times until the cross-section of the rotor spindle does not protrude from the end face of the inner ring of the rotor core. The pressing device continuously presses the cross section of the rotor main shaft in the forward direction at a pressing speed of 3-10 mm / min until the rotor main shaft is completely pushed out of the rotor core.

9. A method for removing a broken shaft from a large motor rotor according to claim 8, characterized in that: When the pressing equipment presses the cross section of the rotor spindle, the cooling equipment is used to cool the rotor spindle, and the cooling temperature is below zero degrees Celsius.

10. A method for removing a broken shaft from a large motor rotor according to claim 1, characterized in that: The location where the rotor spindle begins to deform in the measurement step specifically refers to the area where the circular runout of one end of the rotor spindle in the cross-section begins to exceed the specified standard value.

Images