An oscillating power tool with an electric motor is provided, including an armature shaft with an armature and a fan wheel, including an eccentric arranged on the armature shaft at one end thereof, a first balancing mass for balancing an unbalance of the eccentric and possibly an eccentric bearing, being arranged in the proximity of the eccentric or the eccentric bearing, respectively, however, at an axial distance, further including a second balancing mass for balancing a couple unbalance caused by the axial distance between the eccentric and the eccentric bearing, respectively, and the first balancing weight, wherein the second balancing mass is arranged on the armature shaft at the side facing away from the eccentric or the eccentric bearing. Also a method for balancing such an electric motor is provided.

A method for producing a rotor of an electric machine is disclosed. The method may include providing at least two individual parts and individually balancing the at least two individual parts. The method may also include, subsequently to balancing the at least two individual parts, connecting the at least two balanced individual parts to one another such that the rotor is at least unbalance-low.

A manufacturing method of a rotor having insertion holes arranged in a circumferential direction around an axis and a magnet and resin placed in each insertion hole includes: a first step of placing the magnet and resin in each first insertion hole, and identifying an unbalance position by rotating the rotor at a first rotation speed; a second step of placing the magnet and resin in each second insertion hole in which the magnet is not placed in the first step, and rotating the rotor at a second rotation speed; and a third step of placing the magnet and resin in each third insertion hole in which the magnet is not placed in the first step, and rotating the rotor at a third rotation speed smaller than the second rotation speed. The second and third insertion holes are relatively far from and close to the unbalance position respectively.

The invention relates to a method for determining a balancing removal process for a balancing device for balancing a rotationally symmetrical component, particularly a rotor component, particularly of a turbomachine, a combination of machining lengths and depths being calculated, taking into account a pre-defined maximum machining length and minimum machining depth, in such a way that, with reliable combinations for compensating the same unbalance, the machining length of the calculated combination is longer than the machining length of at least one other permissible combination and, at the same time, the machining depth of the calculated combination is shallower than the machining depth of said other combination.

A rotor has a rotor body having: a flange with a circumferential array of discontiguous apertures; and a surface spaced apart from the flange. One or more rotor balance weight assemblies each have a weight and a fastener. The weight has: a passageway having a first end and a second end; an internal thread along the passageway; and a boss at the first end of the passageway. The boss is in a respective one of the apertures. The fastener has: a shank having a first end and a second end and an external thread engaged to the passageway internal thread; an engagement feature at the shank first end for engagement by a tool to turn the fastener; and a head at the second end contacts the surface.

An excitation system (15) is disclosed for providing excitation to a main rotating electrical machine (2). The excitation system comprises an exciter (50) and an auxiliary generator (52). The exciter and the auxiliary generator have separate stator cores (14, 18) and share a common rotor core (16). The common rotor (16) core may be located between the two stator cores (14, 18). This may help to optimize space, improve material usage and reduce the total rotating mass. A mounting arrangement for the common rotor core is also disclosed.

A method of balancing a rotor and/or fixing rotor components includes arranging a plurality of generally like laminations side by side in a stack to form at least a part of a rotor. The rotor has a rotational center axis and each of the laminations having a plurality of apertures that cooperate to form passages that extend axially along a length of the stack. In accordance with an aspect of the method, a polymer based fixation material is filled in the passages in a manner to fix the laminations together in the stack. With the fixation material, a sprue is formed, projecting from an axial face of the stack. In accordance with another aspect of the method, a weight of the sprue is adjusted to rotationally balance the rotor about the rotor center axis.

An induction machine with localized voltage unbalance compensation is disclosed. The use of an induction machine with a voltage unbalance correction compensator (VUC) may be used to maintain proper working conditions of the machine during intervals of voltage unbalance.

A method of manufacturing a rotor core having a plurality of core members stacked together includes determining weight imbalances for the plurality of core members with respect to a central axis of the rotor core; combining the weight imbalances of the plurality of core members to determine a weight distribution of the rotor core; and displacing the weight imbalances of one or more of the plurality of core members to adjust a position of the weight distribution of the rotor core with respect to the central axis.

An oscillating power tool with an electric motor is provided, including an armature shaft with an armature and a fan wheel, including an eccentric arranged on the armature shaft at one end thereof, a first balancing mass for balancing an unbalance of the eccentric and possibly an eccentric bearing, being arranged in the proximity of the eccentric or the eccentric bearing, respectively, however, at an axial distance, further including a second balancing mass for balancing a couple unbalance caused by the axial distance between the eccentric and the eccentric bearing, respectively, and the first balancing weight, wherein the second balancing mass is arranged on the armature shaft at the side facing away from the eccentric or the eccentric bearing. Also a method for balancing such an electric motor is provided.