Ball Screw Bearing Assembly With Adjustable Load Capacity

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Solution Overview

Problem

The assembly of ball screw devices with rolling bearings is cumbersome, and the load capacity of these bearings cannot be easily modified without altering the inner ring raceway groove, leading to increased complexity and reduced flexibility in application.

Innovation Solution

A ball screw device design featuring a threaded shaft with an inner ring raceway groove, an outer ring with a rolling element insertion hole, and second balls arranged between the inner and outer ring raceway grooves, allowing for easier assembly and adjustable load capacity without modifying the inner ring raceway groove.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the outer rings embedded with balls are inserted into the one axial end of the threaded shaft, then the rolling bearing can be assembled, but the assembly process becomes troublesome and complex

Engineering Contradiction:
Improveease of assemblyVSAvoidassembly complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The rolling bearing is divided into separate components: the inner ring raceway groove is formed on the threaded shaft, while the outer ring and balls are provided as separate pieces that can be independently assembled. This segmentation allows the outer ring and balls to be assembled into the threaded shaft in a straightforward sequence, reducing assembly complexity while maintaining manufacturing ease.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If the inner ring raceway groove is modified to change load capacity, then the load capacity of the rolling bearing can be adjusted, but the modification process becomes troublesome and time-consuming

Engineering Contradiction:
Improveload capacity adjustabilityVSAvoidease of modification
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The load capacity of the rolling bearing is adjusted by changing parameters of the outer ring (such as its dimensions, material properties, or structural features) and the balls (such as their size, material, or arrangement), rather than modifying the inner ring raceway groove. This allows load capacity adaptation while keeping the inner ring raceway groove unchanged, thereby maintaining ease of manufacture and reducing modification complexity.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the inner ring raceway groove is kept unchanged for repeated use, then manufacturing efficiency is improved, but the ability to change load capacity is reduced

Engineering Contradiction:
Improvemanufacturing efficiencyVSAvoidload capacity flexibility
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The rolling bearing is designed with dynamic adaptability through the outer ring and balls, which can be modified or replaced to change load capacity. The inner ring raceway groove remains fixed and reusable, ensuring manufacturing efficiency, while the outer components provide the flexibility needed for load capacity adjustment. This creates a system where different parts serve different purposes: the inner ring ensures repeatability and efficiency, while the outer ring and balls provide adaptability.

Inventive Principle:
Principle #15Dynamics

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 simplifies the assembly process and enables flexible adjustment of load capacity, reducing assembly troubles and enhancing the versatility of the ball screw device.

Implementation Method 1

multiple first balls rollably arranged on a helical raceway configured by a helical groove of the threaded shaft and a helical groove of the nut

Methodology Applied
Scientific EffectHelical raceway mechanism: Screw

Implementation Method 2

multiple second balls rollably arranged between the inner ring raceway groove and the outer ring raceway groove

Methodology Applied
Scientific EffectRolling contact: Ball Bearing

Data Source

PatentEP3540264B1Ball screw device
Publication Date: 2021.08.11 NSK LTD
  • EP3540264B1 patent drawingFigure 1
  • EP3540264B1 patent drawingFigure 2~3
  • EP3540264B1 patent drawingFigure 4~5

AI summary

A ball screw device (10) includes: a threaded shaft (1); a nut (2); multiple first balls rollably arranged on a helical raceway composed of a helical groove (11) of the threaded shaft and a helical groove of the nut; an inner ring raceway groove formed on an outer circumferential surface of one axial end of the threaded shaft (12); an outer ring (41) having an outer ring raceway groove that faces the inner ring raceway groove; and multiple second balls rollably arranged between the inner ring raceway groove and the outer ring raceway groove. The ball screw device converts rotation of the threaded shaft into linear motion of the nut through the first balls rolling on the helical raceway while being subjected to a load. The outer ring has a rolling element insertion hole (44) penetrating from its outer circumferential surface to the outer ring raceway groove and a lid configured to cover the rolling element insertion hole. An inner surface of the lid (45) is formed into a concave shape to serve as part of the outer ring raceway groove.