Sealing System for Tool Holder Reduces Sliding Speed
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Solution Overview
Problem
Machining processes involving rotating tools are limited by the need for large rotary joints, which restrict the maximum frequency of rotation due to high peripheral sliding speeds, prohibiting certain operations, especially when drilling small diameters.
Innovation Solution
A sealing system with two seals, one applied to the tool or adapter and the other to the tool holder, optimizing the diameter ratio to reduce sliding speed and allow higher rotational frequencies, enabling the use of tool holders with reduced size and extended operational ranges without rotary joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a large diameter commutator is used to transmit torque, then the torque transmission capability is improved, but the peripheral sliding speed increases which limits the maximum rotational frequency to around 5000 rpm
Solution Approach 1:
The sealing system is divided into two separate seals: a first seal applied to the tool or adapter and a second seal applied to the tool holder. This segmentation allows each seal to be optimized independently, with the second seal having a smaller diameter sliding surface that reduces peripheral sliding speed while the first seal handles torque transmission, thereby enabling higher rotational frequencies without compromising torque capability.
Solution Approach 2:
The invention transitions from a single large-diameter sealing surface to a two-seal configuration where the critical sliding surface diameter is reduced. By applying the first seal to the rotating tool/adapter and the second seal to the stationary tool holder with an optimized diameter ratio (0.3 ≤ Do/Djmax), the system achieves high-speed rotation while maintaining sealing effectiveness and torque transmission through the combined action of both seals.
2Speed
If the diameter of the sliding surface is reduced, then the peripheral sliding speed decreases allowing higher rotational frequencies, but the torque transmission capability may be compromised
Solution Approach 1:
The torque transmission function is segmented between the two seals. The first seal on the rotating tool/adapter and the second seal on the stationary tool holder work in combination to transmit torque, while the second seal's optimized smaller diameter (maintaining 0.3 ≤ Do/Djmax) reduces peripheral sliding speed. This segmentation allows the system to achieve both high rotational frequency and adequate torque transmission capability.
Solution Approach 2:
The invention optimizes the diameter ratio parameter (Do/Djmax) between the two seals to maintain an optimal balance between sliding speed and torque transmission. By controlling this parameter within the specified range (0.3 to 0.5 depending on tool diameter), the system achieves reduced peripheral sliding speed for higher rotational frequencies while maintaining sufficient torque transmission through the optimized sealing configuration.
3Reliability
If a conventional sealing system with large diameter sliding surface is used, then the sealing effectiveness is maintained, but the tool holder size increases and operational range is limited
Solution Approach 1:
The sealing system is segmented into two seals with different functions and optimization criteria. The first seal ensures sealing effectiveness at the tool/adapter interface, while the second seal with optimized smaller diameter (0.3 ≤ Do/Djmax) reduces the tool holder size. This segmentation maintains reliable sealing while enabling the tool holder to accommodate a broader range of tool diameters and operational conditions.
Solution Approach 2:
The invention changes the critical parameter of sliding surface diameter by implementing the two-seal configuration with optimized diameter ratio. This parameter change reduces the overall tool holder size while maintaining sealing effectiveness, thereby extending the operational range to include small diameter drilling operations and high-speed applications that were previously prohibited by conventional large-diameter sealing systems.
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3C
AI summary
The present invention concerns a sealing system for a tool holder (10) of a fluid-assisted axial machining or milling machine, comprising: -at least first (50) and second (60) seals contributing to define a space (41) for the flow of fluid to at least one inner channel (21) of the tool, one (60) of the seals being applied to the tool (20) or an optional adapter carrying the tool and the other seal (50) a) being applied to the tool or to the adapter carrying the tool or b) being applied to a surface spaced apart from the tool and rotating with same, with 0.3 ≤ Do/Djmax for Do in the interval [1; 3] in mm and 0.5 ≤ Do/Djmax for Do in the interval [3; 20] in mm, where Do is the diameter of the tool facing this other seal (50) and Djmax is the internal diameter of this seal (50).