# US 2014/0360008 A1 · Method of forming a power tool

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- Number: US 2014/0360008 A1
- Document ID: US20140360008A1
- Status: Published application
- Kind: A1
- Application number: 14/469,044
- Filed: 2014-08-26
- Published: 2014-12-11
- Earliest claimed: 2001-01-09
- Assignees: Black & Decker Inc.
- Applicants: Black & Decker Inc.
- Inventors: Hung T. Du; Brandon L. Verbrugge; Joshua F. West; Michael R. Sell; Richard T. Walter; David J. Smith; Earl M. Ortt; John C. Stone; Howard T. White
- Web page: https://patentgrep.com/patent/US20140360008A1

## CPC

- H02K 3/30: Windings characterised by the insulating material
- H01R 43/10: Manufacture of slip-rings
- H02K 3/48: in slots
- H02K 7/04: Balancing means
- H02K 15/12: Impregnating, moulding insulation, heating or drying of windings, stators, rotors or machines
- H02K 15/165: Balancing the rotors
- H02K 15/02: of stator or rotor bodies
- H02K 15/30: Manufacture of winding connections
- Y10T 29/49009: Dynamoelectric machine
- Y10T 29/49011: Commutator or slip ring assembly
- Y10T 29/49012: Rotor
- Y10T 29/49071: by winding or coiling
- Y10T 29/49073: by assembling coil and core
- Y10T 29/49075: including permanent magnet or core
- Y10T 29/49995: Shaping one-piece blank by removing material
- Y10T 29/49996: Successive distinct removal operations
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- H01R: ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method of manufacturing an armature for an electric motor, includes: placing a commutator and a lamination stack on an armature shaft, winding magnet wire in slots in the lamination stacks to form coils, attaching ends of the magnet wire to the commutator, and molding plastic around the magnet wire and around the shaft of the armature at ends of the lamination stack. A spinning inertia of the armature is adjusted by adjusting at least one of a mass of the plastic molded and a distribution of the plastic molded. Alternatively and/or additionally, at least one of a resonant frequency and critical speed of the armature is adjusted by adjusting at least one of a geometry of the plastic molded, the physical properties of the plastic and the mechanical properties of the plastic.

## Claims

### Claim 1

A method of manufacturing an armature for an electric motor, comprising:
placing a commutator and a lamination stack on an armature shaft;
winding magnet wire in slots in the lamination stacks to form coils;
attaching ends of the magnet wire to the commutator;
molding plastic around the magnet wire and around the shaft of the armature at ends of the lamination stack; and
adjusting at least one of a resonant frequency and critical speed of the armature by adjusting at least one of a geometry of the plastic molded, the physical properties of the plastic and the mechanical properties of the plastic.

### Claim 2 (depends on 1)

The method of claim 1, wherein adjusting the geometry of the plastic includes molding a sufficient amount of the plastic around the armature shaft to reduce vibration and flexing of the armature shaft.

### Claim 3 (depends on 1)

The method of claim 1, wherein adjusting the mechanical properties of the plastic includes adjusting at least one of its tensile modulus and flexural modulus and adjusting the physical properties of the plastic includes adjusting at least one of its density and hardness.

### Claim 4 (depends on 1)

The method of claim 1, wherein molding the plastic increases vibration damping of the armature shaft.

### Claim 5 (depends on 1)

The method of claim 1, wherein the plastic is thermally conductive plastic.

### Claim 6

A method of manufacturing an armature for an electric motor, comprising:
placing a commutator and a lamination stack on an armature shaft;
winding magnet wire in slots in the lamination stacks to form coils;
attaching ends of the magnet wire to the commutator; and
molding plastic around the magnet wire and around the shaft of the armature to stiffen the armature and thereby increase the critical speed of the armature.

### Claim 7 (depends on 6)

The method of claim 6, wherein the plastic is thermally conductive plastic.