Umbrella-Stiffened Rotary Tool for Large-Bore Internal Machining
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Solution Overview
Problem
Machining tools for cutting large inside diameters, such as those in electric motor stator housings, face challenges in maintaining dimensional stability and mechanical load capacity while being economically viable and manageable by automatic tool changers, especially with high-speed interactions requiring precise geometric compliance.
Innovation Solution
A rotary tool with an umbrella-type or jaw-type support structure radially stiffened by a tension-compression strut frame, which reduces weight and material usage while enhancing torsion resistance and machining accuracy, using materials like Ti6Al4V and Invar for additive manufacturing to ensure low thermal expansion and high mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the support structure is made heavier to increase torsion resistance and radial stiffness, then the mechanical load capacity and dimensional stability improve, but the weight increases leading to worse handling and increased dynamic unbalance
Solution Approach 1:
The support structure is divided into multiple radial segments or struts that extend from the chucking portion outward. These segmented elements provide torsion resistance and radial stiffness through their distributed arrangement, eliminating the need for a solid heavy structure while maintaining mechanical strength.
Solution Approach 2:
The support structure utilizes the radial dimension extensively, with stiffening elements arranged radially outward from the chucking portion. This radial arrangement creates a large distance from the axis of rotation, maximizing the torsion resistance moment without increasing axial or circumferential dimensions, thereby achieving high stiffness with minimal weight.
2Strength
If more material is used to increase radial stiffness and mechanical strength, then the structural integrity improves, but the manufacturing cost increases
Solution Approach 1:
Instead of using a solid structure, the support is segmented into discrete radial elements or struts. This segmentation reduces material consumption while maintaining structural integrity through the distributed arrangement of load-bearing elements, lowering manufacturing costs.
Solution Approach 2:
Material is concentrated only where structurally necessary - in the radial support elements that carry the cutting edges and transmit loads. Areas that do not require structural support are left empty or minimally reinforced, optimizing material usage and reducing manufacturing costs while maintaining required radial stiffness.
3Strength
If the support structure is designed with large radial extension to increase torsion resistance moment, then the mechanical strength improves, but the tool volume increases affecting dimensional stability
Solution Approach 1:
The design exploits the radial dimension to maximize the torsion resistance moment arm. By arranging support elements radially outward from the axis of rotation, the structure achieves high torsional strength without increasing axial length or circumferential width, thus minimizing overall tool volume while maintaining mechanical strength.
Data Source
AI summary
The invention relates to a rotary tool (1; 101; 201) for cutting large inside diameters at the outer circumference (2) of which at least one cutting edge (4) is arranged, comprising a support structure (10; 110; 210) which indirectly or directly supports the at least one cutting edge (4), and comprising a chucking portion (24) for coupling to a tool holder, wherein the support structure (10; 110; 210) widens in an umbrella-type manner starting from a coupling portion (11) adjacent to the chucking portion (24) and is radially stiffened by a stiffening structure (12).