Composite Tool Holder Sleeve for Lower Rotational Inertia
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Solution Overview
Problem
Conventional tool holders made of steel have high mass and mass moment of inertia, requiring oversized drives and increasing wear and energy consumption during tool changes and machining processes.
Innovation Solution
A tool holder with a sleeve made of fiber-reinforced plastic is shrunk onto a metal holder body, providing high rigidity and stability while reducing mass and mass moment of inertia, achieved through interference fit and optimized fiber orientation, allowing for up to 50% weight reduction and 60% reduction in mass moment of inertia compared to steel designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a steel body is used to achieve the required rigidity, then the rigidity is improved, but the mass and moment of inertia increase
Solution Approach 1:
The patent applies composite materials by combining a metal holder body with a sleeve made of fiber-reinforced plastic. The fiber-reinforced plastic sleeve provides the necessary rigidity and stability while having significantly lower density than steel, thereby reducing the overall mass and moment of inertia of the tool holder while maintaining the required mechanical properties.
2Strength
If a steel body is used to achieve the required rigidity, then the rigidity is improved, but the moment of inertia increases
Solution Approach 1:
The fiber-reinforced plastic sleeve provides the necessary rigidity through optimized fiber orientation aligned with the force flows, while the lower density of the composite material compared to steel results in a significant reduction of the moment of inertia, enabling faster acceleration and deceleration of the tool holder.
Solution Approach 2:
The patent applies local quality by optimizing the fiber orientation in different regions of the sleeve to match the local stress and force flow patterns. This ensures that rigidity is provided precisely where needed, allowing for material optimization and reduced mass while maintaining the required mechanical performance.
3Weight of moving object
If a fiber-reinforced plastic sleeve is used to reduce mass, then the mass is reduced, but the connection stability may worsen
Solution Approach 1:
The patent employs thermal expansion principles by cooling the holder body to a low temperature (e.g., -180°C) before fitting the fiber-reinforced plastic sleeve. The holder body is then allowed to warm up, causing thermal expansion that creates an interference fit, securely anchoring the sleeve to the holder body without requiring additional fastening elements.
Solution Approach 2:
The patent replaces traditional mechanical fastening systems (such as screws or adhesives) with a thermal interference fit mechanism. This substitution provides a more reliable and integrated connection between the sleeve and holder body, ensuring connection stability while maintaining the mass reduction benefits of the fiber-reinforced plastic material.
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 reduces inertia forces on the work spindle, lowers drive power requirements, increases productivity, and extends tool changing system lifespan by reducing wear and improving surface quality through reduced oscillating masses and enhanced damping properties.
Implementation Method 1
the holder body can be cooled down before the sleeve is fitted
Implementation Method 2
When the holder body then heats up again, the sleeve is held in place by an interference fit
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a tool holding fixture (1) for rotationally driven tools (2), said tool holding fixture comprising a rotationally symmetrical holding body (3) which has a front clamping portion (4) having a holding opening (5) for a tool shaft (6) of the tool (2), and a rear holding portion (7) to be held in a work spindle of a machine tool. To achieve a reduced mass, a lower mass moment of inertia and at the same time high stiffness, a sleeve (11) consisting of a fibre-reinforced plastic is arranged at least in the front clamping portion (4).