Replaceable Cutting Head Coupling for Longer Tool Body Life
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Solution Overview
Problem
Rotary cutting tools with replaceable cutting heads face issues due to the deformation of internal clamping surfaces on the coupling legs, leading to a loss of clamping force and requiring premature replacement of the tool body.
Innovation Solution
The rotary cutting tool design features a coupling portion with convex cylindrical external clamping surfaces on the cutting head and concave internal clamping surfaces on the tool body, including a conical second sub-surface that allows for increased elastic deflection and reduced tolerance requirements, thereby extending the tool body's useful life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the internal clamping surfaces on the coupling legs are made conical and widen towards the rear end, then the clamping force is improved, but the manufacturing precision and tolerance requirements increase significantly
Solution Approach 1:
The patent replaces the conical clamping surfaces with cylindrical clamping surfaces that have a radius of curvature. This curvature allows the coupling legs to deflect elastically while maintaining contact, reducing the sensitivity to tolerance variations and simplifying manufacturing while preserving clamping force.
Solution Approach 2:
The patent changes the geometric parameters of the clamping surfaces from conical (widening) to cylindrical (curved), and introduces specific radius of curvature values (0.5-5mm) to optimize the balance between clamping force and manufacturing feasibility.
2Duration of action of stationary object
If the coupling legs are made more flexible to allow greater elastic deflection, then the tool body lifespan is extended, but the structural strength may be compromised
Solution Approach 1:
The patent applies different material properties or structural characteristics to different parts of the coupling leg. The coupling leg is designed with specific local features (such as reduced thickness in certain areas or material gradient) that enable elastic deflection in the clamping region while maintaining overall structural strength.
Solution Approach 2:
The cylindrical clamping surfaces with radius of curvature allow the coupling legs to deflect elastically during operation. This curvature design enables the legs to absorb wear and embossing through controlled deflection, extending tool life without requiring excessive flexibility that would compromise strength.
3Ease of manufacture
If the cylindrical clamping surfaces are used instead of conical surfaces, then the manufacturing complexity is reduced, but the elastic deflection capability is limited
Solution Approach 1:
The patent employs cylindrical clamping surfaces with a specified radius of curvature (0.5-5mm) rather than perfectly straight cylindrical surfaces. This curvature provides the necessary elastic deflection capability while remaining much simpler to manufacture than conical surfaces with precise taper angles.
Solution Approach 2:
The patent optimizes the radius of curvature parameter within a specific range (0.5-5mm) to achieve the right balance between elastic deflection capability and manufacturing ease, avoiding both excessive complexity and insufficient flexibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the elastic deflection of the coupling legs, allowing for more wear and embossing before losing clamping force, thus increasing the tool body's lifespan and reducing the complexity of achieving precise clamping surfaces.
Implementation Method 1
During the rotation of the cutting head from the disengagement position to the engagement position, the coupling legs are subjected to a slight elastic deflection radially outwards, i.e. a slight elastic bending in relation to the centre axis of the tool body, which in its turn implies that the coupling legs will exert a resilient clamping force on the coupling portion of the cutting head
Data Source
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Figure 6
AI summary
A rotary cutting tool comprising a tool body (2) and a cutting head (30) with a coupling portion (31) receivable between two axially projecting coupling legs (12) on the tool body. Internal clamping surfaces (14) on the coupling legs are designed for press fit engagement with cylindrical external clamping surfaces (34) on the cutting head. Each internal clamping surface is conical and inclined at a small angle outwards away from the centre axis of the tool body as seen in a direction from an upper edge to a lower edge of the internal clamping surface, or divided into a cylindrical first sub surface (14a) and a conical second sub surface (14b) that is located axially rearward of the first sub surface and inclined at a small angle outwards away from the centre axis of the tool body as seen in a direction from an upper edge towards a lower edge of the conical second sub surface.