Ball Screw Preload Structure for Easy Assembly and Smooth Movement
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Solution Overview
Problem
Conventional ball screw devices face difficulties in easily and quickly assembling and engaging ball bearing elements into the ball nut and ensuring smooth movement through the endless ball guiding passage.
Innovation Solution
A ball screw device with a preload structure featuring a nut member with a helical groove, a sleeve with an inner protrusion, and a tubular member with an outer depression, allowing for stable anchoring and smooth movement of bearing elements through the endless guiding passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional ball screw devices are used, then the structure is simple, but the ball bearing elements cannot be easily and quickly assembled and engaged into the ball nut
Solution Approach 1:
The device is divided into distinct segments: a ball nut with an open end for easy loading, a sleeve component with curved side surfaces, and a tubular member with bearing elements. This segmentation allows the bearing elements to be easily engaged into the ball nut through the open end, while the sleeve and tubular member are assembled separately and then combined, simplifying the overall assembly process despite adding structural components.
Solution Approach 2:
The sleeve is inserted into the tubular member, and the bearing elements are nested between the curved side surfaces of the sleeve and the outer peripheral depression of the tubular member. This nested arrangement allows compact packaging of multiple components while maintaining easy access for assembly and disassembly of the bearing elements through the open end of the ball nut.
2Ease of operation
If conventional ball screw devices are used, then the structure is simple, but the ball bearing elements cannot smoothly move through the endless ball guiding passage
Solution Approach 1:
The sleeve includes curved side surfaces (first and second curved side surfaces) that provide smooth, rounded surfaces for the bearing elements to move against. These curved surfaces reduce friction and guide the bearing elements smoothly through the endless ball guiding passage formed between the ball nut and ball screw, eliminating rough edges and sharp corners that would impede smooth movement.
3Reliability
If the ball nut is assembled without a preload structure, then the assembly is simple, but the ball bearing elements cannot be stably anchored and retained
Solution Approach 1:
The sleeve provides localized anchoring features with its curved side surfaces that contact and retain the bearing elements at specific locations within the endless ball guiding passage. The inner peripheral protrusion of the sleeve creates localized engagement points that stabilize the bearing elements, while the rest of the structure remains relatively simple, maintaining overall structural efficiency.
Solution Approach 2:
The sleeve acts as an intermediary component between the ball nut and the bearing elements. It mediates the interaction by providing the curved side surfaces that guide and retain the bearing elements, and by being inserted into the tubular member, it creates a stable anchoring system without requiring complex direct engagement features between the ball nut and bearing elements.
Data Source
AI summary
A ball screw device includes a screw engaged into a nut member for forming an endless ball guiding passage and for receiving bearing members, the nut member includes a thickness reduced barrel for forming a peripheral surface in the nut member, a tubular member is engaged onto the barrel of the nut member, a number of bearing elements are engaged onto the nut member and the tubular member, a sleeve is engaged onto the nut member and includes an inner peripheral protrusion having two curved side surfaces for engaging with the bearing elements and for solidly and stably anchoring and retaining the bearing elements between the sleeve and the tubular member and the nut member.