Shafts for rotating machines

Sorting of rotating el. machines According power –Small < 10 kW –middle-class up to 1 MW –big (not correctly specified) Ac. principle –DC –asynchronous –synchronous –Alternative, ECM etc. Ac. application - traction, - crane, slow/fast rotating - compressors, - explosion-proof, etc.)

Sorting of non-rotating machines Ac. power and voltage –low-power, up to 10 kW –middleclass, up to 1 MW –big Ac. design, assembly –air (transformers) –oil based –special (auto- transformers, regulating tr., etc.) Acc. application –power plants –traction –ovens/furnaces –electrochemical –Etc. (especially chokes, transformers, elmag. chucks) Modern trend – increase of operating temperature (class „F“) very popular (190°C)

Characterization of production flow Piece production –product = big machines or technology element –layout designed according technological requirements –special production machines and templates are used –exacting preparation of production and high requirements on the staff – qualifications! Mass-production –product = small machines –layout according production flow! –Often single-usage technology equipment (machines) –just for one operation –using of „lines“ layout –more automation –lower requirements of staff - qualification

Manufacturing of shaft Initial material: rolled- steel rod up to  150 mm steel rod calibrated up to  70 mm (for mass-production) forged ingot, heated and hammered Issue: strength, precision of mechanical turning, dimensions acc. standards Note: Quality of material is checked, some off-takes are done and analyzed

Hammered shaft – production procedure casting (founding) – ingots with double mass hammering – at circa 700 °C pre-heating (possible) annealing °C (also „tempering), changing of hardness and mechanical properties axis hole – off-taking of samples, analysis, also space for winding or cooling Tests of mechanical parameters.: visual, DC current, ultrasonic, etc.

Mechanical turning of shafts 1) Rolling – between two rollers, presses 2) Splitting – scissors, sawmill, flame-cutting 3) Clamping – centering by axis-hole 4) Mechanical turning: –Rough turning (big tolerance) –Finishing of surface (précising) – pads for bearings Issues: using of more tools, troubles with clamping and accuracy. Today popular clamping with magnetic chucks or induction heating. Cutting of grooves – sometimes by turning, more often by mill- tool.

Steps of mechanical turning

Finishing of surfaces (polishing)

smooth (plain) shafts – small machines graded shafts (terrace) profile shaft with flange – just for rolling-bench special design – shaft made from segments special surface – grooving – for small machines Sorting of shafts

Fixing rotor plates on shafts Plain shaft Plain shaft with grooves (fixing) Plain shaft with grooves and ruler Shaft made from segments – fixing with „locks“

Complete process of mass production of shafts for small drivers

Balancing of shaft vertical rotors – hydro („lens“ or lentils design) horizontal rotors – AC generators, synchronous rotors (rulers design) principle: –static balancing –dynamic balancing typical dimensions of rotors: –hydro generator: up to 6 meters height, diameter 6-10 meters, –synchronous generators: meters length, diameter up to 1 meter (limited with the solidity of used steel). Note: some parts of rotor have nearly supersonic velocity!