Composite End Mill Helix Layout to Prevent Delamination
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Solution Overview
Problem
Existing shaft milling cutters struggle to achieve high surface quality and prevent delamination or fiber overhangs when milling composite materials like fiber composite plastics (FVK).
Innovation Solution
A shaft milling cutter with a defined cutting direction, featuring a cutting part with first and second circumferential cutting edges of alternating positive and negative twist angles. The cutting part is designed to produce an almost exclusively pulling cut in the front length area and an almost exclusively pressing cut in the rear length area, generating axial forces that compress the material and prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional end mills with uniform helix direction are used, then the structure is simple to manufacture, but delamination and fiber protrusions occur on the machined surfaces
Solution Approach 1:
The cutting part is divided into two distinct sections: a front longitudinal section with first circumferential cutting edges of first helix direction, and a rear longitudinal section with second circumferential cutting edges of second helix direction. This segmentation allows each section to perform different cutting functions (pulling vs. pushing), preventing delamination and fiber protrusions while maintaining manufacturability through systematic design.
Solution Approach 2:
Different regions of the cutting part are assigned different helix directions to optimize local cutting performance. The front section uses one helix direction for pulling cuts, while the rear section uses the opposite helix direction for pushing cuts. This local differentiation addresses the specific requirements of different cutting zones to achieve high surface quality.
2Reliability
If first and second circumferential cutting edges are ground into separate front and rear longitudinal sections, then opposing axial forces are generated to prevent delamination, but the formation of the cutting part becomes difficult and time-consuming
Solution Approach 1:
The cutting part is segmented into front and rear longitudinal sections with distinct helix directions. This segmentation enables the generation of opposing axial forces that compress fiber composite layers, reliably preventing delamination and fiber protrusions while allowing for a systematic manufacturing approach.
Solution Approach 2:
The cutting edges are arranged in a periodic pattern around the rotational axis, with alternating first and second circumferential cutting edges having opposite helix directions. This periodic arrangement ensures consistent opposing axial forces are generated during rotation, preventing delamination while enabling efficient tool formation through standardized grinding processes.
3Reliability
If cutting edges with alternating helix directions are implemented, then compression forces are generated to separate fiber layers, but the device complexity increases
Solution Approach 1:
The cutting part is divided into front and rear longitudinal sections with different helix directions, creating a structured approach to generating compression forces. This segmentation achieves reliable fiber layer separation while maintaining manageable device complexity through systematic design.
Solution Approach 2:
The cutting part structure serves multiple functions: the front section performs pulling cuts while the rear section performs pushing cuts, both contributing to fiber layer separation. This multi-functionality is achieved within a unified end mill structure, balancing device complexity with effective fiber layer separation.
Data Source
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AI summary
The invention relates to an end mill (10) for milling composite materials, e.g.Fiber-reinforced plastics, with a defined direction of rotation, a shank (200) and a cutting element (100), wherein the cutting element (100) extends from a shank-side end (130) to a face-side end (120) and has, in a front longitudinal region (121) adjacent to the face-side end (120) of the cutting element (100), a plurality of first cutting ribs (122) extending with a positive helix angle (α1) with first circumferential cutting edges (1221), each adjoining a first groove (1222) extending with a positive helix angle (α1), and in a rear longitudinal region (131) adjacent to the shank-side end (130) of the cutting element (100), a plurality of second cutting ribs (132) extending with a negative helix angle (α2) with second circumferential cutting edges (1321), each adjoining a adjacent to the second groove (1322) which runs with a negative helix angle (α2).According to the invention, each first cutting edge (122) has at least one third circumferential cutting edge (1223) downstream of the first circumferential cutting edge (1221), which adjoins a third groove (1224) which has a smaller groove cross-section than the first groove (1222), and each second cutting edge (132) has at least one fourth circumferential cutting edge (1323) downstream of the second circumferential cutting edge (1321), which adjoins a fourth groove (1324) which has a smaller groove cross-section than the second groove (1322).