Co-mouldable tube

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Solution Overview

Problem

Existing co-mouldable tubes for washing machine tubs face maintenance challenges due to integrated rolling bearings, which require replacement of the entire tub upon malfunction, and incur additional production costs from machining circumferential grooves on steel bearings.

Innovation Solution

A co-mouldable tube design featuring metal bushes interposed between rolling bearings and a cylindrical sleeve, allowing separate extraction and replacement of bearings, and utilizing glass-fibre reinforced plastic for the spacer and sleeve, reducing production costs and enabling easy maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If rolling bearings are directly embedded in the cylindrical containment sleeve through co-moulding, then the tube structure is simplified and production efficiency is improved, but maintenance becomes impossible and replacement requires replacing the entire tub

Engineering Contradiction:

Improveproduction efficiencyVSAvoidmaintenance capability

Core Design Contradiction:

ProductivityVSEase of repair

Solution Approach 1:

The invention divides the bearing support structure into separate functional components: a spacer element and a cylindrical containment sleeve. The spacer houses the rolling bearings and is inserted into the sleeve, creating distinct replaceable units. This segmentation allows the bearings to be maintained independently while preserving the integrated co-moulded structure of the overall tube assembly.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rolling bearings are extracted from direct embedding in the cylindrical sleeve and placed within a separate spacer element. This extraction enables the bearings to be removed and replaced without affecting the sleeve structure, while the sleeve still provides the necessary containment and integration with the co-moulded tub.

Inventive Principle:

Principle #2Taking out (Extraction)

2Stability of the object's composition

If circumferential outer grooves are machined on the rolling bearings to ensure angular stability, then bearing stability is improved, but production costs increase due to additional machining operations

Engineering Contradiction:

Improveangular stabilityVSAvoidproduction cost

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The invention introduces a spacer element as an intermediary component between the rolling bearings and the cylindrical containment sleeve. This spacer provides the necessary angular stability and positioning through its structural design and material properties, eliminating the need for costly circumferential grooves to be machined directly on the bearing races.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The spacer element serves as a sacrificial or replaceable component that provides stable bearing mounting without requiring expensive machining operations. If stability issues arise, the spacer can be replaced rather than machining the bearings, reducing overall production costs while maintaining angular stability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS12553474B2Co-mouldable tube

Publication Date: 2026.02.17 AB SKF SKF PATENT DEPARTMENT

AI summary

A co-mouldable tube (10) includes with two rolling bearings (20) arranged along a respective axis (A) of rotation. A spacer (40) is interposed between the two rolling bearings (20) so as to give the co-mouldable tube (10) structural rigidity. A cylindrical containment sleeve (5) is co-moulded around the two rolling bearings (29) and the spacer (40). Two metal bushes (60) are interposed between the cylindrical sleeve (50) and the two rolling bearings (20) so as to be co-moulded together with the said cylindrical sleeve (50).