A grinding process for the outer diameter of an electric motor rotor

Abstract

This invention relates to the field of electric locomotive processing technology, and discloses a process for grinding the outer diameter of an electric motor rotor, comprising the following steps: Step 1, sequentially rough grinding the feedback position of the rotor shaft and then fine grinding the feedback position of the rotor shaft to the required dimensions; Step 2, sequentially rough grinding the iron core position of the rotor shaft and then fine grinding the iron core position of the rotor shaft to the required dimensions; Step 3, sequentially heating the cast aluminum rotor and then heat-fitting the rotor shaft into the cast aluminum rotor to meet the requirements for shaft fitting; Step 4, precision turning the cast aluminum rotor to the required dimensions; Step 5, sequentially rough grinding the second bearing position of the rotor shaft and then fine grinding the second bearing position of the rotor shaft to the required dimensions; Step 6, sequentially rough grinding the first bearing position of the rotor shaft and then fine grinding the first bearing position of the rotor shaft to the required dimensions; Step 7, sequentially rough grinding the shaft extension position of the rotor shaft and then fine grinding the shaft extension position to the required dimensions. This improved process of the invention is used to solve the technical problem that the existing rotor outer diameter grinding process leads to poor coaxiality of the bearing position and shaft extension position of the rotor shaft, scratches on the rotor shaft surface, and affects the overall quality of the rotor.

Description

Technical Field

[0001] This invention relates to the field of electric locomotive processing technology, specifically to a process for grinding the outer diameter of an electric motor rotor. Background Technology

[0002] Turning the outer diameter of the motor rotor, also known as grinding the outer diameter, is an essential machining process in the production of motor rotors. Specifically, the motor rotor consists of a cast aluminum rotor and a shaft. During production, the surfaces of the cast aluminum rotor and shaft are ground, i.e., the outer diameter is turned and ground, to make the surface smooth. This ensures that the concentricity of the outer diameter of the cast aluminum rotor and the shaft, as well as its own roundness, meet the standards. After the motor rotor is assembled with the stator after turning and grinding, the friction force on the rotor within the stator can be reduced, thereby improving the rotor's rotational efficiency, extending its service life, ensuring a more uniform air gap between the rotor and stator, and suppressing motor noise and vibration.

[0003] The traditional machining process for motor rotors is as follows: blanking → machining the shaft → grinding the shaft → heating the cast aluminum rotor → hot-fitting the shaft into the cast aluminum rotor → precision machining the cast aluminum rotor → dynamic balancing of the rotor → warehousing. In this process, the cast aluminum rotor expands due to heating, increasing its inner diameter. The ground shaft is then placed inside. After cooling, the shaft and cast aluminum rotor are firmly fitted together due to an interference fit. However, the entire ground shaft deforms when heated, leading to poor coaxiality of the bearing positions and shaft extensions. This fails to meet the process requirements for high-speed motors: shaft extension runout less than 0.008mm. The scrap rate for rotors machined using this process is approximately 40%.

[0004] In addition, iron filings will inevitably be generated during the turning and grinding of the outer diameter. After the cast aluminum rotor is heat-fitted and the shaft is inserted, since only the middle part of the shaft is placed in the inner cavity of the cast aluminum rotor and the rest is exposed, when the rotor is precision turned, the iron filings will fly onto the exposed part of the ground shaft. This will scratch the exposed surface, damage the smoothness, and affect the overall quality of the motor rotor. This will not only make the final assembly difficult, but also increase the noise of the motor. Summary of the Invention

[0005] The present invention aims to provide a machining process for grinding the outer diameter of an electric motor rotor, in order to solve the technical problem that the existing rotor grinding process leads to poor coaxiality of the bearing position and shaft extension position of the rotor shaft, scratches on the rotor shaft surface, and affects the overall quality of the rotor.

[0006] The basic solution provided by this invention is: a machining process for grinding the outer diameter of a motor rotor, which is carried out in the following order: grinding the outer diameter of the rotor shaft in the first stage, precision turning of the cast aluminum rotor, and grinding the outer diameter of the rotor shaft in the second stage; the grinding of the outer diameter of the rotor shaft in the first stage includes the following steps:

[0007] Step 1: Roughly grind the feedback position of the rotating shaft, then finely grind the feedback position of the rotating shaft to the required size.

[0008] Step 2: Roughly grind the iron core area of ​​the rotating shaft, and then finely grind the iron core area of ​​the rotating shaft to the required size.

[0009] After the first stage of grinding the outer diameter of the rotating shaft is completed, the precision turning of the cast aluminum rotor is performed, including the following steps:

[0010] Step 3: Heat the cast aluminum rotor sequentially, and heat-fit the shaft into the cast aluminum rotor to meet the requirements for shaft fitting.

[0011] Step 4: Precision machine the cast aluminum rotor to the required dimensions;

[0012] After the precision machining of the cast aluminum rotor is completed, the second stage of grinding the outer diameter of the shaft is performed, including the following steps:

[0013] Step 5: Roughly grind the second bearing position of the shaft and then fine grind the second bearing position of the shaft to the required dimensions.

[0014] Step 6: Roughly grind the first bearing seat of the shaft and then fine grind the first bearing seat of the shaft to the required dimensions.

[0015] Step 7: Roughly grind the shaft extension area and then finely grind the shaft extension area to the required dimensions.

[0016] The working principle and advantages of this invention are as follows:

[0017] After the shaft is cut and machined, the traditional machining process of grinding the outer diameter of the motor rotor is improved as follows: grinding the iron core position and feedback position of the shaft → heating the cast aluminum rotor → hot-fitting the cast aluminum rotor with the shaft → precision machining of the cast aluminum rotor → grinding the bearing position and shaft extension position of the shaft. After the above grinding of the outer diameter, the motor rotor is then dynamically balanced and put into storage. Since the shaft is machined with a margin, the grinding of the bearing position and shaft extension position is no longer performed before hot fitting, but is performed after hot fitting. This improved machining process can avoid the shaft being ground first and then hot-fitted, which can cause coaxiality deviation due to thermal deformation. At the same time, it can avoid iron filings flying onto the exposed part of the ground shaft during precision machining of the rotor after hot fitting, scratching the exposed surface and damaging the smoothness, improving the coaxiality of the bearing position and shaft extension position, improving the overall quality of the motor rotor, reducing the rotor scrap rate, improving the ease of final assembly, and reducing motor noise.

[0018] Furthermore, the rotating shaft also includes positions a, b, c, d, e, and f, none of which have their outer diameters ground after machining.

[0019] Beneficial effects: After machining, the shaft needs to be assembled with the cast iron rotor to form the motor rotor, and then assembled with the motor stator as a whole. After a long period of assembly, it was found that there are no other structural parts to be assembled with at positions a, b, c, d, e, and f of the shaft during the assembly process. These positions are only for making way, and machining can meet the machining requirements. There is no need for finishing processes such as grinding the outer diameter. Therefore, reducing the grinding process at these positions does not affect the overall rotor assembly and quality, and can also effectively improve machining efficiency.

[0020] Furthermore, the feed rate for rough grinding is 0.3 mm / min, the grinding speed is 200 mm / min, and a finishing allowance of 0.05 mm is left. The feed rate for finish grinding is 0.15 mm / min, and the grinding speed is 200 mm / min. After finish grinding, the dimensions are checked with an outside micrometer, and the taper is checked with a taper ring gauge to determine whether it meets the required dimensions. If it does, proceed to the next step; if it does not, continue with finish grinding.

[0021] Beneficial effects: By taking into account the tooling and workpiece material, an appropriate speed can be set to ensure both processing efficiency and quality.

[0022] Furthermore, the precision-machined cast aluminum rotor has a precision machining allowance of 0.02mm after rough machining. The precision machining cutting speed is 70mm / min, the feed rate is 0.01mm, and the cutting is done unidirectionally from right to left. After precision machining, the runout is measured to be ≤0.005mm using a dial indicator.

[0023] Beneficial effects: By controlling the speed according to the machine tool performance, the material being processed, the allowance and the tool requirements, high speed and low feed improve surface quality.

[0024] Furthermore, before the first stage of grinding the outer diameter of the shaft, the process includes shaft turning, with a finishing allowance of 0.4mm, a cutting speed of 130mm / min, and one pass for finishing. After turning, the runout is measured with a dial indicator to be ≤0.02mm. Prior to shaft turning, the shaft material undergoes heat treatment. The mechanical properties of the heat-treated shaft material are: tensile strength σb≥900N / mm, yield strength σs≥650N / mm, elongation δ5≥15%, and reduction of area. Impact energy αk≥49J / cm.

[0025] Beneficial effects: The quality of raw materials directly affects the machining quality of the shaft. Therefore, the quality of the basic workpiece for grinding must be guaranteed from the blanking and turning processes in order to further improve the machining quality of grinding. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the rotating shaft provided in an embodiment of the present invention.

[0027] Figure 2This is a schematic diagram of the structure of the motor rotor provided in an embodiment of the present invention. Detailed Implementation

[0028] The following detailed explanation illustrates the specific implementation methods:

[0029] The markings in the accompanying drawings include: shaft extension position 1, position a 2, first bearing position 3, position b 4, position c 5, iron core position 6, position d 7, second bearing position 8, position e 9, position f 10, feedback position 11, rotating shaft 12, and cast aluminum rotor 13.

[0030] In this embodiment, the motor rotor includes a cast aluminum rotor 13 and a rotating shaft 12. The cast aluminum rotor is a rotating body supported by the rotating shaft. The cast aluminum rotor in the motor is generally composed of a rotor core and an aluminum cage. It is an important high-speed rotating component in power machinery such as electric motors, engines, and gas turbines.

[0031] Before grinding the outer diameter, the shaft material must first be prepared. The shaft material must undergo quenching and tempering treatment to obtain good comprehensive mechanical properties. The mechanical properties after quenching and tempering are tensile strength σb≥900N / mm, yield strength σs≥650N / mm, elongation δ5≥15%, and reduction of area. The impact energy αk≥49J / cm, after tempering, high-frequency surface hardening or nitriding is required to improve surface hardness and enhance wear resistance.

[0032] After preparing the required shaft material, fix the shaft material on the machine tool and perform turning to remove excess material. After rough turning, perform finish turning to ensure workpiece accuracy and achieve the specified dimensions to meet process requirements. In this embodiment, a CK6152A CNC lathe is used, and the tools used include: rough turning external turning tool, finish turning external turning tool, boring tool, chamfering tool, center drill, and twist drill. The tool path is unidirectional from right to left, with a finish turning allowance of 0.4mm. The cutting speed is 130mm / min, and one pass is made for finish turning. After turning, the runout is measured with a dial indicator and is ≤0.02mm. Based on the long straight structure of the shaft, this tool path direction is selected, which can quickly and easily meet the processing requirements and significantly improve the turning quality. In the case of multiple processes, in order to improve processing efficiency and ensure processing accuracy, after turning to meet the process requirements, a reference line is machined at the first bearing position of the shaft using a finish turning tool to provide a reference for subsequent processing processes.

[0033] After the shaft is machined, the outer diameter is ground. The grinding sequence of the entire motor rotor is as follows: first stage grinding of the outer diameter of the shaft, precision turning of the cast aluminum rotor, and second stage grinding of the outer diameter of the shaft.

[0034] The grinding of the outer diameter of the shaft is divided into two stages. The first stage is before the shaft is installed in the heat-shrink fitting of the cast aluminum rotor, and the second stage is after the rotor is precision turned. The grinding sequence of each part of the shaft is precisely distinguished and coordinated with the grinding sequence of the cast aluminum rotor to ensure that the grinding steps of the cast aluminum rotor and the shaft do not affect each other, thereby improving the machining accuracy and ensuring the quality of the rotor.

[0035] As attached Figure 1 As shown: From left to right, the rotating shaft is sequentially divided into shaft extension position 1, position a 2, first bearing position 3, position b 4, position c 5, iron core position 6, position d 7, second bearing position 8, position e 9, position f 10, and feedback position 11. In this embodiment, a Huadong CNC MGK1320 precision cylindrical grinding machine is used.

[0036] The first stage of grinding the outer diameter of the rotating shaft includes the following steps:

[0037] Step 1: Roughly grind the feedback position of the rotating shaft, then finely grind the feedback position of the rotating shaft to the required size.

[0038] Step 2: Roughly grind the iron core area of ​​the rotating shaft, and then finely grind the iron core area of ​​the rotating shaft to the required size.

[0039] The first stage involves grinding the feedback position and the core position. Generally, the feedback position is ground first, followed by the core position. The core position is where the shaft and the cast aluminum rotor are fitted, so it must meet the process requirements and have good smoothness. Since grinding the outer circle will produce iron filings, if the core position is ground first and then the feedback position, the iron filings generated during the grinding of the feedback position will splash onto the ground core position, affecting the processing quality of the core position and requiring reprocessing, which is time-consuming, labor-intensive, and affects processing efficiency.

[0040] Using the baseline reserved during precision machining as a reference, the shaft is ground by clamping the shaft extension position with two top clamps and using a chuck, and then the first stage of grinding the outer diameter of the shaft is carried out.

[0041] Specifically, in step one, the feedback position of the rotating shaft is coarsely ground and then finely ground to the required dimensions. In this embodiment, the required dimensions of the feedback position are 15mm in length and 7.5mm in diameter. The rotating shaft is ground using a grinding wheel with a coarse grinding feed rate of 0.3mm / min and a coarse grinding speed of 200mm / min. A fine grinding allowance of 0.05mm is left, and the fine grinding feed rate is 0.15mm / min and the fine grinding speed is 200mm / min. After fine grinding, the dimensions are checked with an outside micrometer and the taper is checked with a taper ring gauge. If the dimensions meet the requirements of the drawing, proceed to the next step. If the dimensions do not meet the requirements of the drawing, the product is modified to another product or scrapped. The same method applies to other steps.

[0042] Specifically, in step two, the shaft core area is coarsely ground and then finely ground to the required dimensions. In this embodiment, the required dimensions for the 9101 model shaft core area are a length of 85±0.5mm and a diameter of 47mm. In other embodiments, L2 for different shaft models can also be 115, 160, or 225±0.5mm. The coarse and fine grinding methods are the same as in step one and will not be repeated here.

[0043] After the first stage of grinding the outer diameter of the shaft is completed, the cast aluminum rotor is precision machined, including the following steps:

[0044] Step 3: Heat the cast aluminum rotor sequentially, and heat-fit the shaft into the cast aluminum rotor to meet the requirements for shaft fitting.

[0045] Step 4: Precision machine the cast aluminum rotor to the required dimensions;

[0046] Specifically, such as Figure 2 As shown, in step three, the cast aluminum rotor 13 is heated sequentially, and the cast aluminum rotor 13 is heat-fitted with the shaft 12. Since the pressure-cast aluminum rotor has not been preheated, its temperature is low after casting, and it must be heated again before the shaft can be fitted. In this embodiment, the inner diameter of the cast aluminum rotor is 47mm-0.02 / 0.04mm, and the diameter of the iron core position on the shaft is 47mm+0.12 / 0.1mm. An interference fit is made, and the cast aluminum rotor is heated to 300°C for 3 hours, so that the inner diameter of the cast aluminum rotor expands due to heat. Hot-fitting the shaft is a simple but crucial step; failure directly impacts rotor quality. Therefore, it must be performed according to process requirements. First, check if the shaft hole size is sufficient for the shaft to pass through. The time between rotor heating stopping and shaft insertion should be minimized, generally not exceeding 15 minutes. Insert the shaft vertically into the shaft hole, with the shaft's feedback position facing down into the cast aluminum rotor. After confirming the axial dimensions are correct, do not touch the rotor or shaft before the rotor cools to prevent dimensional changes. After hot-fitting the shaft, proceed to the next step. After cooling, no inspection is needed; directly precision machine the rotor's outer diameter.

[0047] Step 4: Finish-machine the cast aluminum rotor to the required dimensions. In this embodiment, the diameter of the cast aluminum rotor is 119 + 0.03 mm. Clamp the rotor at position d7 using a chuck and perform finish machining using two cutting tools: a roughing cutter and a finishing cutter. After rough machining, leave a finishing allowance of 0.02 mm. The cutting speed for finish machining is 70 mm / min, and the feed rate is 0.01 mm. Cut unidirectionally from right to left. After finish machining, check whether the outer diameter of the rotor meets the dimensional requirements of the drawing using an outside micrometer. If the runout is ≤0.005 mm, proceed to the next step.

[0048] After precision machining the cast aluminum rotor, the second stage of shaft grinding is performed on the outer diameter, including grinding the second bearing position, the first bearing position, and the shaft extension position. Grinding is performed in this order because, starting with the center of the iron core, the second bearing position located on one side of the iron core is ground first, followed by the first bearing position and the shaft extension position located on the other side of the iron core. This allows for sequential grinding of the shaft's components, facilitating tool movement, avoiding the need for back-and-forth tool adjustments, and ensuring machining accuracy.

[0049] After the precision machining of the cast aluminum rotor is completed, the second stage of grinding the outer diameter of the shaft is performed, including the following steps:

[0050] Step 5: Roughly grind the second bearing position of the shaft and then fine grind the second bearing position of the shaft to the required dimensions.

[0051] Step 6: Roughly grind the first bearing seat of the shaft and then fine grind the first bearing seat of the shaft to the required dimensions.

[0052] Step 7: Roughly grind the shaft extension area and then finely grind the shaft extension area to the required dimensions.

[0053] Specifically, in step five, the second bearing seat of the shaft is coarsely ground and then finely ground to the required dimensions. In this embodiment, the required dimensions for the second bearing seat of the 9101 model shaft are 17mm in length and 40mm in diameter, with a chamfer of 1.5*45 degrees at the end facing position e. The chamfer is completed during the axle turning process. After the grinding process is completed in accordance with the above requirements for coarse and fine grinding, the dimensions are checked with an outside micrometer to see if they meet the drawing requirements. The runout is measured with a dial indicator and is ≤0.002mm before proceeding to the next step.

[0054] Step 6: Roughly grind the first bearing seat of the shaft and then finely grind the first bearing seat of the shaft to the required dimensions. In this embodiment, the required dimensions for the first bearing seat of the 9101 model shaft are 23mm in length and 40mm in diameter. After the grinding process is completed in accordance with the above rough and fine grinding requirements, proceed to the next step.

[0055] Step 7: Roughly grind the shaft extension area and then finely grind the shaft extension area to the required dimensions. In this embodiment, the required dimensions for the 9101 model shaft extension area are 80mm in length and 32mm in diameter, with a 2*45 degree chamfer at the end furthest from the first bearing position. The chamfer is completed during axle turning. After setting the grinding requirements as described above for rough and fine grinding, proceed to the next step.

[0056] It should be noted that the shaft also includes positions a, b, c, d, e, and f, none of which have their outer diameters ground. After machining, the shaft needs to be assembled with the cast iron rotor to form the motor rotor, and then assembled with the motor stator as a whole. After a long assembly process, it was found that there are no other structural components that need to be assembled with positions a, b, c, d, e, and f during the assembly process. These positions are only for clearance purposes, and machining can meet the machining requirements. There is no need for finishing processes such as grinding the outer diameter. Therefore, reducing the grinding process for these positions does not affect the overall rotor assembly and quality, and can also effectively improve machining efficiency.

[0057] After the motor was finally assembled, the shaft extension runout was measured, and the runout was less than 0.008mm, which meets the requirements.

[0058] After the outer diameter of the motor rotor is ground, a dynamic balancing test is performed. The purpose of dynamic balancing is to change the mass distribution of the rotor by removing or adding counterweights, so that the rotor vibration caused by centrifugal force due to eccentricity or the dynamic load on the bearing is reduced to within the allowable range, thereby achieving the purpose of smooth engine operation.

[0059] In the current motor rotor processing technology, the shaft is ground between the shaft turning and the heating of the cast aluminum rotor. The entire shaft is ground in one go to improve processing efficiency. However, in actual assembly, it has been found that grinding the entire shaft before heating the cast aluminum rotor causes the shaft to be heated after the cast aluminum rotor is installed, resulting in poor coaxiality of the bearing position and shaft extension position. To solve this problem, adjustments are usually made in other assembly processes. Since the coaxiality of the motor shaft is a critical factor for the overall assembly and operation of the motor, this invention addresses this issue by optimizing the processing sequence and dividing the shaft into parts that require grinding and those that do not, based on assembly requirements. The grinding of the shaft and rotor is then carried out in stages. Specifically, the grinding sequence of the shaft and rotor is rationally arranged according to the assembly requirements of the shaft and cast iron rotor and the assembly contact surfaces. The grinding sequence of the bearing positions and shaft extensions is adjusted, effectively solving the problems of poor coaxiality of the bearing positions and shaft extensions and the mutual influence of metal shavings on the smoothness of the outer diameter of various parts caused by previous processes. For parts that do not require grinding, the number of processing steps is reduced, improving processing efficiency. Simultaneously, the processes for rough grinding, fine grinding, and precision turning are improved to increase processing efficiency, ensuring rotor coaxiality from multiple aspects, improving the surface smoothness of the shaft after grinding, enhancing the quality of the motor rotor, further improving the motor's operational stability, and extending its service life.

[0060] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics of the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A process for cylindrical grinding of an electrical machine rotor, characterized in that, According to the sequence of the first stage grinding of the rotating shaft, the fine turning of the cast aluminum rotor and the second stage grinding of the rotating shaft, the first stage grinding of the rotating shaft is performed. The first stage grinding of the rotating shaft comprises the following steps: Step one, rough grinding the feedback position of the rotating shaft and fine grinding the feedback position of the rotating shaft in sequence to the required size; Step two, rough grinding the core position of the rotating shaft and fine grinding the core position of the rotating shaft in sequence to the required size; After the first stage grinding of the rotating shaft is completed, the fine turning of the cast aluminum rotor is performed, comprising the following steps: Step three, sequentially performing the heating of the cast aluminum rotor and the hot fitting of the cast aluminum rotor into the rotating shaft to meet the requirements of the shaft fitting; Step four, fine turning the cast aluminum rotor to the required size; After the fine turning of the cast aluminum rotor is completed, the second stage grinding of the rotating shaft is performed, with the center position and the core position, the second bearing position on one side of the core position is ground first, and then the first bearing position on the other side of the core position and the shaft extension position are ground; comprising the following steps: Step five, rough grinding the second bearing position of the rotating shaft and fine grinding the second bearing position of the rotating shaft in sequence to the required size; Step six, rough grinding the first bearing position of the rotating shaft and fine grinding the first bearing position of the rotating shaft in sequence to the required size; Step seven, rough grinding the shaft extension position of the rotating shaft and fine grinding the shaft extension position of the rotating shaft in sequence to the required size; Before the first stage grinding of the rotating shaft is performed, the rotating shaft turning is also included, and since there is a margin during the turning of the rotating shaft, the grinding of the bearing position and the shaft extension position is not performed before the cast aluminum rotor is hot fitted into the rotating shaft.

2. A process for grinding the outer diameter of an electrical machine rotor according to claim 1, characterized in that, The rotating shaft also includes a position a, a position b, a position c, a position d, a position e and a position f, which are not ground after turning.

3. A process for grinding the outer diameter of an electrical machine rotor according to claim 1, characterized in that, The feed speed of the rough grinding is 0.3 mm / min, the grinding speed is 200 mm / min, and the fine grinding margin is 0.05 mm.

4. A process for grinding the outer diameter of an electrical machine rotor according to claim 3, characterized in that, The feed speed of the fine grinding is 0.15 mm / min, the grinding speed is 200 mm / min; after fine grinding, the size is checked with an outside micrometer and the taper is checked with a taper ring gauge, which meets the required size and proceeds to the next step.

5. A process for grinding the outer diameter of an electrical machine rotor according to claim 1, characterized in that, The fine turning of the cast aluminum rotor leaves a fine turning margin of 0.02 mm after rough turning, the fine turning cutting speed is 70 mm / min, the feed amount is 0.01 mm, and the fine turning is performed from right to left in one direction, after which the runout is measured with a micrometer to be ≤0.005 mm.

6. A process for grinding the outer diameter of an electrical machine rotor according to claim 1, characterized in that, The rotating shaft turning leaves a fine turning margin of 0.4 mm, the cutting speed is 130 mm / min, and the turning is performed with one tool, after which the runout is measured with a micrometer to be ≤0.02 mm.

7. A process for grinding the outer diameter of an electrical machine rotor according to claim 6, characterized in that, Before the shaft is processed, the shaft material is quenched and tempered, and the mechanical properties of the quenched and tempered shaft material are: tensile strength σb≥900 N / mm, yield strength σs≥650 N / mm, elongation δ5≥15%, reduction of area ≥45%, impact energy αk≥49 J / cm.

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