Round Milling Insert Mounting Geometry to Prevent Floating and Rattling
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Solution Overview
Problem
Conventional cutting tools with round milling inserts often experience floating or rattling due to machining accuracy or assembly errors, leading to unintended point or line contacts instead of surface contacts between the insert and the tool body.
Innovation Solution
The tool body features a mounting seat with a seating surface, a female screw hole, and a recessed portion with curved inner surfaces that guide and secure the protrusions of the round milling insert, ensuring contact at predetermined areas to prevent floating or rattling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat side faces are used for contact between protrusion and recessed portion, then manufacturing is simple, but contact instability occurs due to machining accuracy errors causing point or line contact instead of surface contact
Solution Approach 1:
The patent applies curvature by forming the inner surfaces of the recessed portion and the outer surfaces of the protrusion as curved surfaces instead of flat surfaces. This curvature design ensures that the contact area between the protrusion and recessed portion is a predetermined surface area rather than a point or line, thereby maintaining stable contact even when machining accuracy deviations occur during assembly.
2Reliability
If curved surfaces are used to ensure stable contact area, then contact stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent changes the geometric parameters of the contact surfaces by specifying that the inner surfaces of the recessed portion and the outer surfaces of the protrusion are formed as curved surfaces with specific radius of curvature (R1 and R2). This parameter change from flat to curved surfaces ensures stable contact area while the curvature radii are chosen to be practical for manufacturing, balancing reliability improvement with manufacturing feasibility.
3Strength
If multiple protrusions are used for fixation, then fixation strength is improved, but unintended contact points increase causing floating or rattling
Solution Approach 1:
The patent employs asymmetry by providing only one recessed portion among multiple protrusions formed on the round milling insert. This asymmetric configuration ensures that only one specific protrusion contacts the tool body at the predetermined contact area, while other protrusions remain non-contacting. This prevents unintended contact points that would cause floating or rattling, while still providing sufficient fixation strength through the single well-defined contact point.
Data Source
AI summary
A cutting tool body for indexable inserts, and a round milling insert, are configured not to cause floating or rattling upon mounting the milling insert. The tool body includes a recessed portion for fitting one of a plurality of protrusions thereto, the protrusions being formed in the milling insert to protrude in the radial direction. The recessed portion has two inner surfaces having curved portions disposed so the distance between them gradually decreases at the contact area between the recessed portion and the protrusion fitted thereto. The milling insert includes protrusions protruding radially, any of which fit into a recessed portion on a mounting seat of the tool body. The protrusions each have two curved outer surfaces arranged so the distance between them gradually decreases toward a tip of the protrusion, at the contact area between the protrusion and the recessed portion into which the protrusion is fitted.