Ball Screw Seal Lip Elastic Deformation Friction Reduction
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Solution Overview
Problem
The existing ball screw devices face challenges in maintaining seal properties while reducing friction resistance, as the stiffness of the seal member's lip portion needs to be decreased to allow for elastic deformation and prevent gaps between the screw shaft and seal member, but this compromises the seal's effectiveness.
Innovation Solution
A ball screw device design featuring a screw shaft with helical rolling grooves, a nut with opposing grooves, and a seal member with an easily deformable lip portion that matches the screw shaft's shape, including a protrusion in a U-shape for enhanced elasticity and a grinding clearance groove with a depth less than the seal member's interference, ensuring improved dust resistance and lubricant sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stiffness of the lip portion is decreased to allow elastic deformation and prevent gaps between the screw shaft and seal member, then the friction resistance is reduced, but the seal properties are compromised
Solution Approach 1:
The patent applies local quality by creating a dual-structure lip portion where only a specific region (the tip portion) is made easily deformable while the root portion maintains high stiffness. This is achieved by forming the tip portion with a smaller cross-sectional area than the root portion, allowing the tip to elastically deform and conform to the screw shaft surface for reduced friction, while the rigid root portion preserves the seal's structural integrity and sealing capability.
2Manufacturing precision
If interference of the seal member with respect to the screw shaft is increased to reduce shape accuracy errors, then the gap occurrence is suppressed, but the contact pressure and friction resistance are increased
Solution Approach 1:
The patent applies dynamics by making the lip portion's tip portion elastically deformable rather than rigid. This allows the seal member to dynamically adapt to variations in screw shaft shape and mounting errors through elastic deformation, maintaining effective sealing contact without requiring high interference. The dynamic flexibility compensates for manufacturing tolerances while avoiding the excessive contact pressure and friction that would result from a rigid, high-interference design.
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 design allows for easy elastic deformation of the seal member, reducing friction resistance without compromising seal properties, thus enhancing the ball screw device's operational performance and durability.
Implementation Method 1
the easily deformable portion which is elastically deformed so that a shape of the inner circumferential edge portion is matched to a shape of the outer circumferential surface of the screw shaft
Implementation Method 2
due to a decrease in a contact area between the lip portion and the screw shaft and a friction reduction effect by the lubricant exuding from the lubricant-containing polymer
Data Source
AI summary
There is provided a ball screw device capable of allowing interference to be easily elastically deformable and decreasing friction resistance of a seal member with respect to a screw shaft without damaging seal properties of the seal member. A predetermined section of a land sliding-contact portion (46) of a sliding-contact portion (40) and a section of a seal piece (37) of a lip portion (31) corresponding to the predetermined section are bent to protrude in one side in the axial direction of a nut (7) so that a protrusion (55) is formed, the bent section of the land sliding-contact portion (46) and the bent section of the seal piece (37) configure a pair of side surface portions (58, 58) of the protrusion (55) and a bottom portion (61) connecting the one side ends of the pair of side surface portions (58, 58).