Among motor components, the holes in end caps and bases are relatively concentrated, including both through holes and screw holes. The base feet are crucial for customer installation, and their size and relative position are very important. The holes on the end face of the base are related to the installation of the end caps.
Regarding motor end covers, at least two types of holes are involved. One type is the through-hole for fixing to the motor base. These holes must ensure that their indexing meets requirements and that they align with the motor base to ensure a neat and aesthetically pleasing assembly. The other type of hole on the end cover is the through-hole for fixing to the bearing cover. These holes must not only ensure their circumferential distribution but also their radial position and relative positional distribution with other holes. This involves the issue of drilling position control. If multi-hole drills or composite drill jigs are used, everything is fine as long as the drill jig design and manufacturing are done properly. However, for large end covers, using composite drill jigs and multi-hole drills is not very practical. When selecting a split drill jig, it is essential to consider the reference relationships between the parts to ensure that the positional relationships of all holes meet the requirements. Okay, after this video, Ms. will briefly discuss the machining technology requirements for motor parts.
Basic requirements for machined parts of electric motors
●Basic requirements for machining motor parts: (1) Dimensional accuracy, i.e., tolerances and fits of parts. (2) Accuracy of shape and position of parts, i.e., form and position tolerances of parts. (3) Surface roughness, i.e., the flatness and smoothness of the machined surface. (4) Installation dimensions should meet the requirements of relevant product standards for installation dimension tolerances, or the special requirements of customers, etc.
●Key points for shaft and rotor machining: (1) The core diameter, bearing diameter and roughness of the shaft, the outer diameter and roughness of the rotor core, the distance between the bearings at both ends, and the coaxiality of the outer circle of the core and the shaft are all key machining requirements. (2) The shaft, core, and fan blades should have appropriate tightness to ensure that the rotor core and fan blades do not loosen or move during motor operation. In addition, the dimensional tolerances of the shaft extension and keyway should meet the requirements of the relevant product standards for installation dimensional tolerances.
●End cover machining control: (1) Dimensional tolerances, cylindricity, and roughness of the bearing housing; because it involves the fit with the bearing, this dimensional control is very critical. (2) Dimensional tolerances, cylindricity, and roughness of the stop. The height and diameter of the stop are key dimensions for the fit with the machine base. A small stop diameter may cause stator rubbing, and a shallow stop may cause misalignment due to insufficient fit length. (3) Coaxiality of the bearing housing and the stop. The direct consequence of misalignment is stator rubbing of the motor, or even failure to complete the assembly. (4) Runout of the end face to the centerline of the stop. (5) Depth of the end face of the stop to the bearing housing.
●Key control points for machine base machining: (1) Meet the size, position and shape requirements marked on the drawing. Among them, the coaxiality of the two end stops and the inner circle, and the runout of the two end faces of the stop axis are the key to machine base machining. The inner circle and the iron core should have appropriate tightness to ensure that the stator iron core does not loosen or move during the operation of the motor, and can dissipate heat well. In addition, the base plane should be parallel to the axis. (2) The distance between the base hole and the center line of the machine base should be symmetrical from left to right and meet the specified tolerance. That is, the A, B, C dimensions and the center height.
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