Curved-Edge Milling Tool With Flat Inserts for Wood Cutting

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Solution Overview

Problem

Existing milling tools with monolithic or separate cutting inserts face challenges in producing curved cutting edges and chip surfaces efficiently, leading to high costs, material wastage, and thermal limitations, especially when processing wood-like materials.

Innovation Solution

A multi-part milling tool design with flat cutting inserts manufactured to have curved cutting edges and chip faces, where the curvature is achieved during production from a composite material blank, allowing for efficient use of hard materials and easier base body manufacturing, reducing material consumption and thermal stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If a monolithic milling tool with hard metal is used to achieve long service life and good cutting qualities, then the cutting edge durability is improved, but the shank becomes sensitive to breakage and loses damping properties

Engineering Contradiction:
Improveservice lifeVSAvoidshank strength
Core Design Contradiction:
Duration of action of stationary objectVSStrength

Solution Approach 1:

The milling tool is divided into two separate parts: a steel shank and a hard metal cutting head, which are joined together. This segmentation allows each component to be made from material optimized for its specific function - the steel shank provides strength and damping, while the hard metal cutting head provides durability and cutting performance.

Inventive Principle:
Principle #1Segmentation

2Shape

If concave cutting edges are produced with a rotating production tool, then the cutting edge geometry is achieved, but the production complexity increases and the rake face curvature is limited by the smallest possible diameter of the production tool

Engineering Contradiction:
Improvecutting edge geometryVSAvoidproduction complexity
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The concave geometry of the cutting edge and rake face is pre-formed in the cutting head during the casting or sintering process, before the final tool is assembled. This preliminary action eliminates the need for complex subsequent machining operations and allows for greater design freedom in the rake face curvature.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If hard metal is used in areas other than cutting edges where its material properties are not needed, then the cutting edge performance is maintained, but the cost increases and the shank becomes more sensitive to breakage

Engineering Contradiction:
Improvecutting edge performanceVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Hard metal material is applied only to the cutting head where cutting edge performance is required, while the shank is made from steel where strength and damping properties are more important. This local differentiation of material quality optimizes both performance and cost by avoiding unnecessary use of expensive hard metal in non-critical areas.

Inventive Principle:
Principle #3Local quality

4Adaptability or versatility

If separate cutting plates with flat inserts are used, then material selection flexibility is improved, but the manufacturing of curved cutting edges becomes complex and requires large volume removal of expensive PCD material

Engineering Contradiction:
Improvematerial selection flexibilityVSAvoidmanufacturing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The curved geometry of the cutting edge and rake face is pre-formed in the cutting head during the casting or sintering process, before the final tool is assembled. This preliminary action eliminates the need for complex subsequent machining operations and allows for greater design freedom in the rake face curvature.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3974087A1Milling tool and method for manufacturing such a milling tool
Publication Date: 2022.03.30 LEDERMANN GMBH & CO KG
  • EP3974087A1 patent drawingFigure 1~2
  • EP3974087A1 patent drawingFigure 3~4
  • EP3974087A1 patent drawingFigure 5~9

AI summary

The invention relates to a milling tool (1) for wood or wood-like materials, and to a method for manufacturing such a milling tool (1). A longitudinal direction (3), a radial direction (4), and a direction of rotation (5) are defined by a rotational axis (2) of the milling tool (1). The milling tool (1) comprises a base body (6) and at least one cutting edge (7), which adjoins a rake face (8) extending forward in the direction of rotation (5) and a clearance face (9) extending outward in the radial direction (4). The cutting edge (7) and the rake face (8) are curved in the longitudinal direction (3). The curved cutting edge (7) and the curved rake face (8) are formed on a cutting insert (10) that is separate from the base body (6). The cutting insert (10) is attached with its flat inner surface (20) to a flat bearing surface (21) of the base body (6), and in particular is soldered on.