Polymeric Thread Insert for High-Load Leadscrew Wear Reduction
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Solution Overview
Problem
Conventional metal-to-metal leadscrew and nut actuators experience excessive wear and require additional features like lubrication, while polymer nuts with metallic leadscrews offer low wear but are limited to low load applications due to design challenges in tensile and fatigue strength, especially in high load scenarios.
Innovation Solution
Incorporating a polymeric insert between the metallic leadscrew and nut to prevent direct material contact, allowing for high load capabilities by transferring force and reducing wear, with the insert being fixedly attached to either component and designed to match the thread geometry, thereby enhancing the load-carrying capacity and longevity of the actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal-to-metal leadscrew and nut configuration is used, then load carrying capacity is high, but wear is excessive and lubrication is required
Solution Approach 1:
A polymeric insert is introduced as an intermediary component between the metallic leadscrew and nut. This insert transfers force between the metal components while preventing direct metal-to-metal contact, thereby reducing wear and eliminating the need for lubrication while maintaining load carrying capacity
Solution Approach 2:
The solution employs a composite configuration combining metallic components (leadscrew and nut) with a polymeric insert. This composite structure leverages the high strength and load-bearing capabilities of metals while utilizing the low wear and self-lubricating properties of the polymer material
2Reliability
If polymer nut with metallic leadscrew is used, then wear rate is low, but load carrying capacity is limited to low load applications
Solution Approach 1:
The nut is segmented into two functional parts: a metallic outer structure that provides high load carrying capacity and tensile strength, and a polymeric insert that provides low wear and self-lubricating properties. This segmentation allows each material to perform its optimal function
Solution Approach 2:
The solution creates a composite nut structure combining metallic and polymeric materials. The metal provides structural strength for high load applications while the polymer insert provides wear resistance and low friction, enabling the system to handle high loads with minimal wear
3Strength
If polymeric insert is added between leadscrew and nut, then wear is minimized and load capacity increases, but device complexity increases
Solution Approach 1:
The polymeric insert is integrated within the existing nut structure, merging the wear-resistant polymer functionality with the load-bearing metal structure. This integration approach combines multiple functions (load carrying, wear resistance, lubrication) into a single composite component rather than adding separate external mechanisms
Data Source
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Figure 3A
AI summary
Leadscrew and nut actuators are described. The leadscrew and nut actuators include a leadscrew (302) having an external thread and formed from a first material, a nut (304) configured to receive the leadscrew (302), the nut (304) having an internal thread and formed from a second material, and an insert arranged between the internal thread of the nut (304) and the external thread of the leadscrew (302), the insert configured to transfer force between the external thread and the internal thread and prevent material contact between the leadscrew (302) and the nut (304). The insert is formed of a third material different from the first material and the second material.