Linear Motion Guide Unit Shoulder Rigidity via Inclined Padding
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Solution Overview
Problem
Conventional linear motion guide units face challenges in reducing section height without compromising rigidity, particularly in the shoulder portions of the carriage, leading to potential stress concentration and deformation under load.
Innovation Solution
The implementation of slightly inclined surfaces on the inner corner portions of the carriage and corresponding inclined surfaces on the guide rail, along with larger contact surfaces for rollers, to increase the volume of the shoulder portions and reduce the overall height while maintaining rigidity and preventing skew of the rollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the section height of the carriage is reduced, then the overall height of the linear motion guide unit is decreased, but the rigidity of the shoulder portions decreases leading to deformation under load
Solution Approach 1:
The patent applies local quality by providing padding portions specifically at the shoulder portions of the carriage, which are the critical stress concentration areas. These padding portions increase the volume and rigidity of the shoulder portions without requiring an increase in the overall section height of the carriage. The inclined surfaces are also localized to the shoulder portions, allowing targeted reinforcement where needed.
Solution Approach 2:
The patent introduces inclined surfaces at the shoulder portions that extend in the width direction, creating a three-dimensional volume increase rather than simply increasing height. This dimensional approach allows the padding portions to provide structural reinforcement while maintaining a compact overall profile, effectively distributing the reinforcement across multiple spatial dimensions.
2Length of stationary object
If the section height of the carriage is reduced, then the overall height of the linear motion guide unit is decreased, but stress concentration occurs at the shoulder portions
Solution Approach 1:
The padding portions are specifically positioned at the shoulder portions where stress concentration occurs during operation. By locally increasing the volume at these critical stress points through the inclined surfaces, the patent distributes stress more evenly and prevents concentration at the boundary regions between the central and wing portions.
Solution Approach 2:
The padding portions act as preemptive stress-distributing elements that are built into the carriage structure before operation. These inclined surfaces create a cushioning effect that prevents stress concentration from occurring in the first place, rather than attempting to mitigate it after the fact.
3Strength
If 45° inclined surfaces are used to increase volume of corner portions, then rigidity is improved, but the overall height of the device becomes large
Solution Approach 1:
The patent modifies the geometric parameters of the inclined surfaces, using inclination angles between 0° and 30° instead of the conventional 45°. This parameter change allows the inclined surfaces to provide sufficient volume increase and rigidity enhancement while occupying less vertical space, thereby reducing the overall height of the device.
Solution Approach 2:
Instead of relying solely on vertical height to create volume (as with 45° inclined surfaces), the patent extends the inclined surfaces in the width direction and creates three-dimensional padding portions. This dimensional redistribution achieves the required volume increase without proportionally increasing the overall height.
Data Source
AI summary
A linear motion guide unit includes a guide rail and a slider. A carriage of the slider has a central portion located above the guide rail, and wing portions which extend downward from widthwise opposite ends of the central portion. Shoulder portions of the carriage located in inner boundary regions between the central portion and the wing portions of the carriage have first inclined surface so that the shoulder portions have padding portions. Corner portions of the guide rail located between an upper surface and longitudinal sides of the guide rail have second inclined surfaces which face the first inclined surfaces of the carriage and extend in the longitudinal direction parallel to the first inclined surfaces. The first inclined surfaces have an inclination angle substantially the same as an inclination angle of the nose surfaces of threaded holes formed in the carriage for attachment of a counterpart member.