Overview of Machining Process for Motor Products
Mechanical processing is an important component of the motor manufacturing process. The precision, dimensional accuracy, and roughness of motor components are mainly achieved through mechanical processing methods. The quality level of mechanical processing directly affects the overall quality grade of the motor and its compliance with design goals, greatly affecting the performance and lifespan of the motor. Mechanical processing equipment accounts for about 40-50% of all machine tools and equipment used in batch production of small asynchronous motor manufacturing plants. Mechanical processing accounts for about 25-30% of the total labor required to manufacture motors.
At present, the percentage of mechanical processing labor in the motor manufacturing industry is gradually decreasing. This is due to the continuous improvement of the structural processability of components and the increasing accuracy of blank manufacturing, which reduces the workload of mechanical processing. With the continuous improvement of the performance of metal cutting machine tools and cutting tools, as well as the adoption of combination machine tools, assembly lines or automatic production lines, the productivity of mechanical processing has been significantly improved. However, this does not mean that the role of mechanical processing technology research in motor manufacturing tends to be marginalized, and the importance of process schemes and routes is more prominent.
The components that require mechanical processing in motors include the seat, end cover, shaft, rotor bracket, rotor, stator, bearing cover, commutator, slip ring, as well as the base plate, bearing seat, and bearing shell of large motors. How to choose machining benchmarks and machining schemes to meet technical requirements is a fundamental issue in mechanical machining. Here, we will discuss in detail the characteristics of machining several large motor components, clarify key elements and their control measures.
Interchangeability of motor components
In batch production and mass production of components, without selection and repair, any part or component of the same specification can be easily assembled onto the product and the quality of the product can be guaranteed. The property that parts or components of the same specifications can be interchanged and used is called interchangeability of parts or components.
Components with interchangeability can be professionally produced by specialized workshops or factories using advanced manufacturing methods, greatly improving labor productivity and reducing product costs. At the same time, it can shorten assembly time and improve assembly quality in terms of assembly. In terms of repair, when a part or component is damaged, it can be quickly replaced with a new part or component. The larger the production scale, the more important the interchangeability of components becomes.
In terms of usage units, the motor itself is often used as a component or part. Firstly, it is required that motors of the same specifications can be installed interchangeably, and secondly, detachable components can be used interchangeably.
Dimensions related to installation, use, and post maintenance
Center height H, which is the height from the axis center to the base plane;
Axis extension diameter D and length E, keyway width P and axis groove depth G;
The horizontal center distance A of the foot hole and its distance from the centerline A/2
The axial center distance B of the foot hole and the distance C from the shoulder to the first foot hole;
Bottom hole diameter K;
Inner diameter of stator and outer diameter of rotor;
The fitting size between the end cap and the machine base stopper;
The fitting dimensions of bearings, bearing gears, and bearing chambers,
The fitting dimensions of the external fan, external slip ring, and shaft extension.
Among them, A, B, C, D, and H are the main installation dimensions to ensure the interchangeability of motors; Interchangeability is generally achieved through mechanical processing.
Characteristics of mechanical processing of motor components
The machine tools and cutting tools used in the mechanical processing of motor components are not much different from those used in general machine manufacturing plants. However, due to the influence of motor structure and electromagnetic performance, the following characteristics must also be noted when machining motor components:
The air gap has a significant impact on the performance of the motor. When formulating the machining plan for motor components, full attention should be paid to the coaxiality of the components and the reliability of the mating surfaces in order to ensure the size and uniformity of the air gap.
Compared with ordinary machine parts, the structural rigidity of the motor base and end cover is poor, which can easily cause deformation or vibration during clamping and processing, affecting machining accuracy and roughness.
For components with insulating materials, such as stators, rotors, commutators, and slip rings, cooling agents such as engine oil and soap solution should not be used during mechanical processing to prevent metal shavings from falling into the insulation parts and to avoid deterioration of insulation performance; It is even more important to prevent chips from entering the insulation material and causing insulation damage accidents.
For magnetic parts, cutting stress should not be too high to avoid reducing magnetic permeability and increasing iron loss.
