Expansion Bushing Recess Layout for Small-Shank Torque Clamping
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Solution Overview
Problem
Existing expansion bushings face challenges in establishing a high-friction connection with tools having small shank diameters, leading to uncontrollable deformation and reduced service life due to increased clamping pressure, especially when transmitting high torques.
Innovation Solution
An expansion bushing with radially deformable annular material web and strategically placed recesses and coolant/lubricant slots, allowing uniform deformation and controlled pressure distribution, enhancing torque transmission without increasing clamping pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If clamping pressure is increased to establish sufficient frictional connection with small shank diameter tools, then frictional connection is improved, but expansion bushing service life deteriorates and uncontrollable deformation occurs
Solution Approach 1:
The patent introduces recesses at specific locations on the expansion bushing surface to create localized deformation zones. These recesses concentrate the deformation in specific areas, allowing the bulk of the bushing structure to remain intact and maintain its load-bearing capacity, thus preventing uncontrollable deformation while still achieving sufficient frictional connection with small shank diameter tools
Solution Approach 2:
The expansion bushing surface is segmented into multiple recesses distributed around the circumference. This segmentation allows the deformation to be distributed across multiple localized zones rather than concentrating stress in a single area, enabling better control over the deformation process and maintaining structural integrity during high-pressure clamping operations
2Power
If clamping pressure is increased to transmit high torques with small shank diameter tools, then torque transmission is improved, but concentricity control deteriorates due to uncontrollable deformation
Solution Approach 1:
By strategically positioning recesses on the expansion bushing surface, the patent creates predetermined zones where deformation is allowed and controlled. This localized approach ensures that the overall circular geometry and concentricity of the bushing are maintained even under high clamping pressure, enabling reliable torque transmission without sacrificing positioning accuracy
Solution Approach 2:
The recesses are pre-formed during manufacturing, creating predetermined deformation pathways before the actual clamping operation. This preliminary structuring of the bushing geometry ensures that when high pressure is applied, the deformation follows predictable patterns that preserve concentricity, rather than allowing random or uncontrollable deformation
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
Enables reliable clamping of tools with a wide range of shank diameters, including small ones, by uniformly distributing deformation and maintaining concentricity, even under high torque conditions.
Implementation Method 1
a radially elastically deformable, annular material web and which, together with an inner circumferential surface of the receiving opening, delimits a pressure chamber
Data Source
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AI summary
Described is an expansion bushing (30) for sealed insertion into an axial receiving opening of a base body of a hydraulic expansion chuck. The expansion bushing (30) has a bushing body extending along a longitudinal central axis (A30) and having a central clamping bore (40) for receiving and clamping a cylindrical shank of a cutting tool. On the outer circumference, the bushing body, in the region of the clamping bore (40), has a lateral surface (44) that forms a radially elastically deformable, annular material web (42) and, together with the inner circumferential surface of the receiving opening, delimits a pressure chamber.In order to be able to clamp tools in the wide range of shaft diameters, in particular also with very small shaft diameters with controllable pressures in the pressure chamber, a plurality of recesses (50) are formed in the bushing body radially inside the outer surface (44), extending along the longitudinal center axis (A30) and distributed, preferably at equal angles, around the clamping bore (40), which are closed with respect to the outer surface (44) and the clamping bore (40).