Two-Stage Multi-Layer Blanking for Complex Motor Laminations

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Solution Overview

Problem

The existing multi-layer blanking process is limited in terms of complexity of metal parts that can be manufactured and is inefficient due to the need to remove scrap material and metal parts sequentially, which slows down the production speed.

Innovation Solution

The process is divided into two stages: the first stage cuts holes in the layered basic material without a counter punch, allowing scrap to be discarded through the blanking die, and the second stage cuts the metal parts using a counter punch, enabling easier removal of both scrap and metal parts after opening the blanking device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a counter punch is applied in multi-layer blanking to ensure surface quality and shape accuracy, then manufacturing precision is improved, but device complexity and operation complexity increase due to the need to remove both scrap and metal parts sequentially

Engineering Contradiction:
Improvesurface quality and shape accuracyVSAvoidblanking device structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The blanking process is divided into two separate stages: a first blanking stage without a counter punch for simple parts, and a second blanking stage with a counter punch for complex parts requiring high precision. This segmentation allows each stage to be optimized independently, reducing overall device complexity while maintaining manufacturing precision when needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first blanking stage performs preliminary cutting of simple contours and holes without a counter punch, removing scrap material through the blanking die. This preliminary action simplifies the subsequent second stage, where only the final precision cutting with counter punch is needed, reducing the complexity of the complete blanking device.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If scrap material is held between blanking die and blank holder after blanking stroke, then manufacturing precision is maintained, but productivity decreases due to sequential removal of scrap and metal parts

Engineering Contradiction:
Improvecut side face qualityVSAvoidblanking stroke rate
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The scrap material is extracted and removed through the blanking die cavity during the first blanking stage, before the metal parts need to be removed. This extraction of scrap material during the punching action itself, rather than holding it for subsequent removal, eliminates the sequential removal step and maintains high productivity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The removal of scrap material is performed as a preliminary action during the first blanking stage, before the second blanking stage processes the metal parts. This preliminary removal of scrap eliminates the need for sequential removal operations, maintaining both manufacturing precision and productivity.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If minimum separation is required between two cutting lines to ensure adequate strength and rigidity of blanking die, then manufacturing precision is maintained, but adaptability decreases for complex metal part designs

Engineering Contradiction:
Improveshape accuracyVSAvoidcomplexity of metal parts
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The blanking process is segmented into two stages with different capabilities: the first stage handles simple cutting operations with greater design freedom, while the second stage handles precision operations. This segmentation allows complex metal parts to be manufactured without being constrained by minimum separation requirements between cutting lines, as the first stage can create initial features that the second stage then refines with precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The blanking device operates dynamically by switching between two modes: a first mode without counter punch for operations requiring close cutting lines, and a second mode with counter punch for precision operations. This dynamic operation allows the system to adapt to complex part designs that would be impossible with a single fixed mode, maintaining shape accuracy while increasing versatility.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3883704B1Multi-layer blanking process for the manufacture of metal parts such as rotor and stator lamination sheets for an electric motor
Publication Date: 2025.04.23 ROBERT BOSCH GMBH
  • EP3883704B1 patent drawingFigure 1A~1F
  • EP3883704B1 patent drawingFigure 2~5
  • EP3883704B1 patent drawingFigure 6~8

AI summary

The present disclosure concerns a process for the blanking of metal parts (1 ) from a - layered basic material (51 ) composed of a number of mutually stacked individual layers (50) placed and clamped between a blanking die (80) and a blank holder (70) of a blanking device (100), wherein a blanking punch (31; 32) of the blanking device (100) is moved relative to the blanking die (80) to cut and separate the metal parts (1) from the basic material (51). According to the present disclosure, such multi-layer blanking process is carried out in two successive stages (I, II), whereof a first stage (I) entails the punching of holes (3) by a first blanking punch (31) without applying a counter punch and whereof a second stage (II) entails the blanking of the metal parts (1) by a second blanking punch (32) while being supported by a counter punch (40).