US 9,038,703 B2Granted

Production of die cast rotors with copper bars for electric motors

AssigneeTHT Presses Inc.

InventorsMichael W. Thieman, Richard J. Kamm

Life of this patent

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Abstract

A rotor core for an electric motor includes a stack of laminations having peripherally spaced openings receiving copper bars with opposite end portions projecting from the stack. The core is mounted on an arbor and is inserted into a mold on a vertical die cast press having a shot chamber. The mold has upper and lower mold members defining annular cavities receiving end portions of the bars. Molten copper or aluminum is poured into the shot chamber and forced upwardly by a shot piston through passages in the lower mold member and into the cavity around the lower end portions of the bars. The pressurized molten metal solidifies and shrinks around the bar end portions to form an endring for the rotor. The core, endring and arbor are inverted and confined in the mold, and the casting steps are repeated to form the opposite endring.

A method of forming an endring on each end of an electric motor rotor core having a stack of metal laminations with a plurality of copper bars extending through peripherally spaced aligned openings within the laminations and with the bars having opposite end portions projecting from opposite ends of the stack of laminations, the method comprising the steps of

positioning the stack of laminations and bars within a mold having an upper mold member and a lower mold member with each mold member having an annular cavity receiving end portions of the bars projecting from the stack of laminations,
forming circumferentially spaced sprue passages within the lower mold member and extending the sprue passages upwardly to the annular cavity within the lower mold member,
positioning the mold adjacent a vertical die cast press having a hydraulically actuated shot piston within a shot sleeve to define a shot chamber,
placing a first charge of molten metal into the shot chamber and positioning the mold above the shot sleeve and shot chamber,
moving the shot piston upwardly with a hydraulic cylinder to force the molten metal upwardly through the sprue passages and into the annular cavity within the lower mold member and around the projecting end portions of the bars within the cavity,
allowing the molten metal to solidify and shrink around the projecting end portions of the bars to form a first solid endring electrically connecting the bars,
inverting the assembly of the stack of laminations, copper bars and first endring, with the assembly confined within the mold,
placing a second charge of molten metal into the shot chamber and positioning the mold above the shot sleeve and shot chamber,
moving the shot piston upwardly with the hydraulic cylinder to force the molten metal upwardly through the sprue passages and into the annular cavity within the lower mold member and around the projecting end portions of the bars within the cavity,
allowing the molten metal to solidify and shrink around the projecting end portions of the bars to form a second solid endring electrically connecting the bars, and
removing the assembly of the stack of laminations, copper bars, first endring and second endring from the mold.

8 more elements

Facts

Application

13/573,858Filed 9 Oct 2012

Published

US 2014/0097720 A110 Apr 2014

Granted

26 May 2015

Term ends

Not estimatedThe source records don’t support an estimate.

Classification6 codes

H02K 15/023
Magnetic cores: cage rotors
B22D 19/0054
Casting in, on, or around objects which form part of the product: rotors, stators for electrical motors
H02K 15/02
Processes or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines: of stator or rotor…
H02K 17/168
Having rotors with internally short-circuited windings, e.g. cage rotors: having single-cage rotors

Abstract

Claims7