Electric motors are special machines that work in conjunction with supporting equipment, therefore, electric motor products involve specific installation dimensions and geometric tolerances. The most direct installation dimensions of an electric motor include center height, base hole diameter, relative position of the base holes, shaft extension diameter, and directly related dimensions such as the shape, width, depth, and symmetry of the shaft extension keyway. Other dimensions include the shaft extension runout of the entire product and the flange cover stop runout of flanged motors.
For a standard B3 motor, the requirements are relatively fewer, while for a B35 motor, in addition to the items mentioned above, requirements also include the diameter and relative position of the mounting holes on the flange cover, and the runout of the flange cover end face.
To check the runout of the machine shaft extension, a dial indicator is generally used. The dial indicator is fixed to the end cover or machine base, and the motor shaft extension is rotated to measure the corresponding runout. For flange end covers, the test can be performed during the machining process or on the machine. When testing on the machine, the dial indicator can be fixed to the shaft extension, and the shaft extension can be rotated to check the flange cover stop diameter and the runout of the stop end face.
It should be noted that when checking the runout of the entire machine, the influence of the axial and radial movement of the bearings on the measured values should be fully considered.
How a dial indicator works
A dial indicator is a measuring instrument that uses a rack and pinion or lever gear to convert the linear displacement of the measuring rod into the angular displacement of the pointer on a dial, thus allowing the measurement to be read.
Precautions for using dial gauges
●Before use, check the flexibility of the measuring rod. That is, when you gently push the measuring rod, it should move freely in the sleeve without any jamming, and the pointer should return to its original scale position after you release your hand each time.
●When using the dial indicator, it must be secured to a reliable clamp. Never try to save time by clamping it in an unstable location, as this can easily lead to inaccurate measurement results or damage to the dial indicator.
● When measuring, do not allow the measuring rod to travel beyond its measuring range, do not allow the dial indicator to suddenly hit the workpiece, and do not use a dial indicator to measure surface roughness or workpieces with significant unevenness.
● When measuring a plane, the dial indicator's measuring rod must be perpendicular to the plane. When measuring a cylindrical workpiece, the measuring rod must be perpendicular to the workpiece's centerline. Otherwise, the measuring rod will become sluggish or the measurement results will be inaccurate.
● To facilitate reading, the large pointer is usually set to the zero position on the dial before measurement.
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