Speed Reducer Bearing Alignment for Low-Runout Output Shafts

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Solution Overview

Problem

Existing speed reducers for industrial robots require high precision in runout of the output rotating shaft end, leading to high manufacturing costs due to the need for precise part fabrication and assembly, which is complex and costly.

Innovation Solution

A speed reducer design with specific parallelism adjustments between key surfaces and bearings, allowing for high-precision manufacturing with simplified adjustment work, minimizing runout and reducing manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high dimension accuracy and high assembling accuracy are used to fabricate parts, then runout precision of output rotating shaft end is improved, but manufacturing cost increases

Engineering Contradiction:
Improverunout precision of output rotating shaft endVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent divides the bearing support structure into two distinct locations: one bearing supports the input shaft while another bearing supports the output shaft. This segmentation allows each bearing location to be machined independently with appropriate precision levels, rather than requiring all components to meet the highest precision standards uniformly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different machining precision requirements to different locations based on their functional importance. The bearing surfaces are machined with high precision (within 10μm) to ensure proper bearing fit and minimize runout, while other non-critical surfaces can be machined with lower precision, thereby reducing overall manufacturing cost while maintaining runout precision.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If high assembling accuracy is used to assemble parts, then runout precision of output rotating shaft end is improved, but device complexity and adjustment work increase

Engineering Contradiction:
Improverunout precision of output rotating shaft endVSAvoidassembly adjustment complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent performs preliminary high-precision machining of bearing surfaces and shafts during the manufacturing process, ensuring that components arrive at assembly with pre-established precision. This preliminary action eliminates the need for complex adjustment procedures during final assembly, as the high precision is built into the components themselves rather than achieved through assembly adjustments.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The precision bearing surfaces and shafts are designed to self-align and self-adjust through their precise geometric relationships. The high-precision machining of bearing races and shafts ensures proper fit and alignment without requiring external adjustment mechanisms or complex assembly procedures, allowing the system to achieve high precision through its inherent design rather than through active adjustment.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4265937B1Method of manufacturing speed reducer, speed reducer, and rotating device
Publication Date: 2026.02.25 NABTESCO CORP
  • EP4265937B1 patent drawingFigure 1
  • EP4265937B1 patent drawingFigure 2
  • EP4265937B1 patent drawingFigure 3

AI summary

The present disclosure relates to a manufacturing method of a speed reducer. The speed reducer includes an outer tube, a shaft portion, an input shaft, a first bearing, a speed reducing portion, and an attachment member. The shaft portion has a first receiving surface and a shaft end surface. The outer tube has a second receiving surface. The first bearing has a first inner ring and a first outer ring. The first receiving surface contacts the first inner ring. The second receiving surface contacts the first outer ring. A first machining accuracy is obtained based on a first parallelism between the first receiving surface and the shaft end surface. A second machining accuracy is obtained based on a second parallelism between the second receiving surface and the flange mounting surface. The manufacturing method includes performing machining such that the first machining accuracy becomes higher than the second machining accuracy.