Segmented Gasket for Recirculating Ball Screw Thermal Expansion
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Solution Overview
Problem
Traditional gaskets for recirculating ball screw actuators face challenges with thermal expansion mismatches between steel screws and plastic materials, leading to interference issues, contamination, and reduced functionality and life due to high radial rigidity and thermal deformation differences, especially under extreme temperature conditions.
Innovation Solution
A gasket comprising an outer ring and an inner ring with a pin, where the outer ring is securely attached to the screw nut and the inner ring is axially inserted into the outer ring, allowing for thermal deformation freedom, and a pin inserted through aligned holes to provide a sealing separation within the screw's coil-shaped groove, reducing interference and maintaining an effective seal across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional ring-shaped gasket with consistent thickness is used to ensure sealing, then the sealing function is improved, but the radial rigidity increases causing high interference and torque resistance under thermal expansion mismatch
Solution Approach 1:
The gasket is divided into two separate rings: an inner ring that contacts the screw and an outer ring that contacts the screw nut. This segmentation allows each ring to have optimized thickness and flexibility characteristics, reducing the overall radial rigidity while maintaining sealing effectiveness. The inner ring can deform more easily to accommodate thermal expansion differences, reducing interference forces and torque resistance.
2Stability of the object's composition
If a gasket with high radial rigidity is used to maintain seal integrity, then the sealing stability is improved, but the thermal deformation mismatch with steel screw causes excessive interference and reduced actuator life
Solution Approach 1:
The gasket design applies local quality by making the inner ring (which contacts the steel screw) thinner and more flexible to accommodate thermal expansion, while the outer ring can be thicker for structural support. This localized variation in thickness allows the sealing surface to adapt to thermal deformation without excessive interference, maintaining seal integrity while reducing stress on components and extending actuator life.
3Reliability
If the gasket thickness in radial direction is increased to improve sealing, then the sealing capability is improved, but the radial rigidity increases causing high pressure on screw and increased wear
Solution Approach 1:
By segmenting the gasket into inner and outer rings, the design allows the inner ring to have minimal necessary thickness for sealing, reducing radial rigidity and contact pressure on the screw. The outer ring provides additional structural support without directly contacting the screw, thus maintaining sealing capability while minimizing wear and energy dissipation at the critical screw-gasket interface.
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
The solution ensures a robust seal with reduced mechanical power dissipation and increased life by minimizing axial and radial interference, maintaining effective sealing and reducing torque resistance across varying temperatures, outperforming traditional gaskets in terms of torque variation and contamination prevention.
Implementation Method 1
a pin inserted through aligned holes to provide a sealing separation within the screw's coil-shaped groove
Implementation Method 2
The difference in the thermal expansion coefficients between the steel of the screw and the plastic material used to make the gasket
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A gasket for actuators of recirculating ball screw type comprises a rigid outer support ring (3) extending about an axis (X) and which can be engaged with a support portion, and an inner ring (3) stably connected to the outer ring (2) and which can be engaged by interference with an outer threaded portion of a screw (130) of the actuator. The gasket (1) further comprises a pin (9) radially inserted into corresponding aligned holes (5, 6) of the two rings (2, 3), the pin (9) partially protruding toward said axis (X) to be engaged by interference with an outer coil-shaped groove (150) of the screw (130) such as to obtain, in cooperation with the screw (130), a sealing separation between the interior and the exterior of the actuator.