Twisted Surface Cutting Insert for Corner Milling Squareness
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Solution Overview
Problem
Existing corner milling cutters with replaceable cutting edges face challenges in achieving squareness and flatness of cut corners due to negative radial rake and inferior cutting quality, which are not adequately addressed by previous technologies.
Innovation Solution
A replaceable-blade cutting insert with a height offset on the first surface, positive lands on the outer perimeter, and a twisted surface forming a hump when viewed from the front, allowing for a positive axial rake and negative radial rake, improving cutting quality and corner squareness and flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a parallelogram or trapezoid insert is used to provide a positive axial rake, then the axial rake angle is improved, but the radial rake angle becomes negative which reduces cutting quality
Solution Approach 1:
The insert design transitions from a simple 2D parallelogram/trapezoid shape to a 3D structure with a twisted surface that includes a hump. This three-dimensional configuration allows the ridge line to maintain a positive axial rake angle while eliminating the negative radial rake angle problem through the twisted geometry, thereby resolving the contradiction between axial rake improvement and cutting quality degradation.
2Ease of operation
If the insert is sloped to position the end point of the ridge line on the path circle, then the approach angle is improved, but the ridge line departs from the path circle toward the center which reduces corner squareness
Solution Approach 1:
The twisted surface of the insert includes a hump that creates a curved ridge line geometry. This curvature allows the ridge line to follow the circular path more accurately, with the hump compensating for the departure that would otherwise occur toward the center. The curved geometry maintains both the improved approach angle and the corner squareness by keeping the cutting edge trajectory aligned with the path circle.
3Ease of manufacture
If a height offset is formed at the ceiling surface or base surface to provide a positive radial rake angle, then the radial rake angle is improved, but the flatness of the wall surface and squareness of the cut corner deteriorate
Solution Approach 1:
The twisted surface includes a hump that creates an asymmetric geometry on the insert. This asymmetric configuration allows the ridge line to maintain a positive radial rake angle through the twisted geometry while the hump compensates for any height variations that would otherwise cause wall surface irregularities. The asymmetric design enables simultaneous achievement of positive radial rake and improved surface flatness with corner squareness.
Data Source
Figure 1A~1F
Figure 2
Figure 3A~3D
AI summary
A replaceable-blade cutting insert 20 for corner milling cutters includes: a first surface 1 and a second surface 2; a third surface 3 and a fourth surface 4 connected to a first side edge and a second side edge thereof respectively; and a fifth surface 5 and a sixth surface 6 connected to a first edge and a second edge of the first surface and the second surface respectively. The first surface 1 is used as rake face, the third surface is used as an outer perimeter flank face, and the fifth surface is used as a forward flank face. A twisted surface 10 is disposed on a section of the third surface 3 to form a ridge line 7 that acts as a main cutting edge intersecting with the first surface 1 and interposed between the third surface 3 and the first surface. It would be preferable for the first surface 1 and the second surface 2 to be positioned with a height offset relative to each other so that at least one set of diagonal corners are projected.