Ball Screw Return Fixing That Preserves Spindle Nut Contour
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Solution Overview
Problem
Existing ball screw drives face challenges in securing ball recirculation systems to the spindle nut, with current fixing methods being either costly or requiring precise manufacturing tolerances, and they often disrupt the outer contour of the ball screw.
Innovation Solution
The implementation of metal plates arranged in or adjacent to radial through-holes on the spindle nut, which secure the ball return system without protruding beyond the outer surface, using methods like spot welding, gluing, or clamping, and optionally incorporating a spring-loaded intermediate layer for damping and tolerance compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If locking tongues or snap devices are used to secure the ball return system, then the ball return function is ensured under force loads, but the manufacturing tolerances must be precise and the structure becomes complex
Solution Approach 1:
The patent introduces a spring element as an intermediary component between the ball return system and the spindle nut. This spring element absorbs force fluctuations and compensates for tolerance variations, allowing the ball return system to function reliably without requiring extremely precise manufacturing tolerances between the ball recirculation and the spindle nut.
Solution Approach 2:
The patent employs a spring element that can elastically deform, changing its physical state from rigid to flexible. This parameter change allows the system to adapt to force variations and tolerance deviations dynamically, ensuring reliable ball return function while reducing the stringency of manufacturing precision requirements.
2Ease of manufacture
If a cylindrical sleeve is used to secure the ball return system, then the structure is simple and inexpensive, but the ball screw cannot be secured in the area of the sleeve and the outer contour is disrupted
Solution Approach 1:
The patent embeds the ball return system within the spindle nut structure, nesting it in radial through-holes. The spring element is contained within the spindle nut, and the entire assembly maintains the cylindrical outer contour. This nesting approach eliminates the need for external sleeves while keeping the structure simple and inexpensive to manufacture.
3Strength
If robust locking devices are used to withstand ball forces, then the ball return system is secure, but the structure becomes complex and manufacturing costs increase
Solution Approach 1:
The spring element serves as a force-absorbing intermediary that protects the locking mechanism from direct exposure to high ball forces. By absorbing these forces elastically, the spring element allows the use of simpler, less robust locking devices while maintaining overall system security, thereby reducing structural complexity.
Solution Approach 2:
The spring element provides beforehand cushioning by being pre-installed in the force path between the ball return system and the spindle nut. It absorbs and dampens force peaks before they reach the locking mechanism, allowing the use of simpler locking devices that would otherwise need to be overly robust to withstand full ball forces.
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
This design secures the ball return system effectively while maintaining the outer contour of the ball screw, simplifying assembly and reducing noise transmission, and accommodating manufacturing tolerances.
Implementation Method 1
a spring element is arranged between the ball return system and the sleeve, which fixes the ball return system in the desired position
Implementation Method 2
The metal plates are fastened in or adjacent to the openings of the spindle nut by spot welding, gluing or clamping
Data Source
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AI summary
A ball screw drive generically comprises a threaded spindle and a spindle nut with a plurality of balls that circulate endlessly in the space between the spindle nut and the threaded spindle. This is achieved by a ball return system that guides the balls out of the helical ball channel at one point via a ball deflection and feeds them back in at another point via a transfer channel and a further ball deflection. The ball deflections are arranged in radial openings in the surface of the spindle nut. According to the invention, one or more metal plates are provided on the spindle nut, which are arranged in or adjacent to the radial openings, offset inwards from the surface, and span the ball return system over a surface area.This fixes the ball return with its ball deflections in a predetermined position within the surface of the spindle nut (120), whereby the surface of the spindle nut is not extended beyond the surface of the spindle nut by the metal plates (180, 180') installed at the end. The metal plates (180, 180') can preferably be spot-welded, bonded, or clamped in the through-holes (170, 170') of the spindle nut (120).