Rotating Mass Balancing via CMT Welding

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Solution Overview

Problem

Existing methods for balancing rotating mass components, such as those in electric motors, face challenges like chip formation, component weakening, and material availability issues, particularly in achieving high balancing qualities efficiently and automatically.

Innovation Solution

The method employs cold metal transfer (CMT) welding to apply spot welds onto the mass component, allowing for flexible and precise addition of mass without chip formation or component weakening, enabling high balancing quality and automation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If negative balancing is used to achieve high balancing quality, then balancing precision is improved, but component strength deteriorates due to material removal and chip formation

Engineering Contradiction:
Improvebalancing qualityVSAvoidcomponent strength
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The patent inverts the conventional negative balancing approach by implementing positive balancing through CMT welding. Instead of removing mass to achieve balance, the method adds mass in the form of spot welds at specifically calculated positions. This inversion eliminates chip formation and component weakening while achieving the required balancing quality through controlled mass addition.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the fundamental parameter of mass adjustment from subtraction to addition. By using CMT welding to deposit precise amounts of material at calculated positions, the system transforms the balancing process from material removal to controlled material deposition, thereby improving both component strength and balancing precision simultaneously.

Inventive Principle:
Principle #35Parameter changes

2Strength

If positive balancing by conventional welding is used to add mass, then component strength is maintained, but manufacturing complexity increases due to material availability requirements and handling variants

Engineering Contradiction:
Improvecomponent strengthVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent changes the welding process parameters by implementing CMT welding with automated control. This allows precise regulation of weld mass, position, and distribution through digital parameters rather than manual handling of various balancing plates. The automated calculation and execution system simplifies the manufacturing process while maintaining component strength.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system performs automated calculation of required balancing mass and automatically executes the welding process without manual intervention. The self-service approach eliminates the need for complex material handling and selection of different balancing plate variants, reducing manufacturing complexity while maintaining strength.

Inventive Principle:
Principle #25Self-service

3Manufacturing precision

If negative balancing is used to achieve precise mass adjustment, then balancing precision is improved, but material availability requirements increase

Engineering Contradiction:
Improvebalancing precisionVSAvoidmaterial availability
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent inverts the material flow direction by adding mass through welding instead of removing it. This eliminates the requirement to pre-provision excess material for removal, as the balancing mass is created in-situ through controlled deposition. The system achieves precise mass adjustment by controlling the welding parameters rather than by selecting from pre-manufactured balancing components.

Inventive Principle:
Principle #13The other way round (Inversion)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach achieves high balancing quality with weight savings, low heat input, and reduced vibration, leading to a long service life and improved comfort in motor vehicle drives.

Implementation Method 1

cold metal transfer welding (CMT) is carried out, in which the welding wire is conveyed in the direction of the workpiece until it comes into contact with the workpiece. After the formation of a short circuit, the wire feed direction is then reversed during a short circuit phase and the welding wire is moved away from the workpiece until the short circuit is broken.

Methodology Applied
Scientific EffectCold metal transfer welding: Welding

Implementation Method 2

after which an arc is ignited, a cold metal transfer welding process (CMT) is carried out

Methodology Applied
Scientific EffectArc heating: Electric Arc

Implementation Method 3

the current flow for the welding current is regulated in such a way that during an arc phase the welding wire begins to melt, ie droplets form

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2501957B1Method for balancing a mass component by means of cmt welding
Publication Date: 2018.08.15 MERCEDES BENZ GROUP AG
  • EP2501957B1 patent drawingFigure 1~3

AI summary

The aim of the invention is to provide a rotating mass component with a high balancing quality, the balancing being carried out as automatically as possible and without the formation of chips. To achieve this, a method is provided for balancing a rotating mass component, in particular a rotor (1), by means of deposition welding welding points on the mass component, wherein the mass symmetry of said mass component with respect to the rotational axis is improved. The deposition welding is carried out by means of cold-metal-transfer welding, in particular of a plurality of individual mass points (4).