Function
The motor pole shoe press plate, sometimes simply referred to as "pole body press plate" or "magnetic pole press plate", is a sturdy metal plate installed at both ends (axially) of the magnetic pole core. Its core function is to tightly press the stacked magnetic pole laminations into a solid unit axially.
You can imagine it as a thick book:
Magnetic pole laminations = sheets of paper one by one.
The magnetic pole pressure plate = the front and back covers of a book, and they are tightly pressed together through the binding line (equivalent to the through-bolt or rivet).
II. Main Functions
Maintaining the integrity of the magnetic poles: This is the most fundamental and crucial function. When the motor rotates at high speed, the magnetic poles are subjected to tremendous centrifugal force. The pressure plate, through its powerful pressure, prevents the magnetic pole laminations from loosening, deforming, or scattering under the influence of the centrifugal force, ensuring the mechanical stability of the magnetic poles.
Provide a foundation for fastener installation: The excitation coils (windings) of the magnetic poles need to be fixed on the magnetic poles. The pressure plates are usually designed with special structures, such as dovetail slots, T-shaped tail slots or screw holes, for installation.
Extreme body insulation and coil support components.
The pressure plate or clamping piece of the fixed coil.
As part of the magnetic circuit: The pressure plate (usually made of low-carbon steel) serves as a component of the magnetic pole and is also a link in the magnetic circuit, helping to guide the magnetic flux.
III. Common Structural Types
According to the fixation method of the motor's magnetic poles, the magnetic pole pressure plate is often used in conjunction with the following typical structures:
Pigeon tail groove structure:
This is the most common type. The back of the magnetic pole pressure plate is machined with a dovetail-shaped tenon.
Corresponding dovetail grooves are machined on the magnetic yoke of the rotor.
When installing, slide the dovetail tenon of the magnetic pole into the groove of the yoke, and then fix all the magnetic poles of the entire rotor in the axial direction with end plates and tension bolts.
Features: Strong load-bearing capacity, accurate positioning, widely used in medium and large-sized DC motors and synchronous motors.
T-shaped tail structure:
Similar to the dove-tail groove, but the tenon section on the back of the pressure plate is in the shape of a "T".
It is also installed and fixed in coordination with the T-shaped groove on the magnetic yoke.
Features: It is relatively easy to process and is also a commonly used structure.
IV. Manufacturing Materials
Material: Generally, low-carbon steel or cast steel is used. This is because they not only have sufficient mechanical strength to withstand centrifugal force but also have good magnetic conductivity, which does not affect the magnetic circuit.
The manufacturing process: For the magnetic pole pressure plates of large motors, casting or forging is often adopted, followed by mechanical processing to ensure their dimensional accuracy and strength.Forging process flow quality control: Raw material steel ingot into warehouse(test the chemical content) → Cutting→ Heating(Furnace temperture test) → Heat treatment after forging(Furnace temperture test) Discharge the furnace(blank inspection)→ Machining→ Inspection(UT,MT,Visal diamention, hardness)→ QT→ Inspection(UT, mechanical properties, hardness, grain size)→ Finish machining→ Inspection (dimension)→ Packing and Marking(steel stamp, mark)→ Storage Shipment