Hygienic Robot Joint Sealing With Dynamic and Static Seals
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Solution Overview
Problem
Existing sealing solutions in industrial robots are inadequate for maintaining hygiene in food and pharmaceutical processing environments, as they can lead to bacterial contamination and require costly surface treatments and narrow tolerances, which are not satisfactory from a hygienic perspective and increase the risk of corrosion.
Innovation Solution
A joint design featuring a dynamic seal and a static seal, where the static seal is exposed to the external region and pushes the dynamic seal against a second surface, eliminating bacterial pockets and allowing for relaxed surface treatments and reduced tolerances, with the dynamic seal being made of food-grade materials and the static seal being elastic to enhance sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tight fit seal design is used between the first and second enclosures, then sealing performance is improved, but manufacturing cost increases due to narrow tolerances and surface treatments
Solution Approach 1:
The sealing system is divided into two separate seals: a first seal for the first enclosure and a second seal for the second enclosure. This segmentation allows each seal to be optimized independently, with the second seal providing the primary sealing function against the rotating shaft, thereby reducing the need for tight tolerances and expensive surface treatments on both interfaces simultaneously
Solution Approach 2:
The second seal acts as an intermediary element between the rotating shaft and the second enclosure, providing a dedicated sealing interface that protects against corrosion and contamination. This intermediary seal absorbs the sealing requirements, allowing the first seal interface to have more relaxed tolerances and reducing overall manufacturing complexity
2Reliability
If a tight fit seal design is used between the first and second enclosures, then sealing performance is improved, but device complexity increases due to multiple interfaces creating bacterial pockets
Solution Approach 1:
The second seal and its associated second enclosure are extracted as a separate sealing system from the first enclosure assembly. This extraction creates a dedicated sealing zone that can be independently designed for hygienic purposes, with the second seal positioned to prevent bacterial pocket formation at the interface between rotating and stationary parts
Solution Approach 2:
The second seal serves as an intermediary barrier that eliminates direct contact interfaces between the first and second enclosures that could create bacterial pockets. By positioning the second seal to abut the second enclosure and seal against the rotating shaft, it creates a simplified, easier-to-clean interface that reduces device complexity from a hygienic design perspective
3Reliability
If narrow tolerances and surface treatments are applied to the first and second enclosures, then sealing performance is improved, but manufacturing cost increases
Solution Approach 1:
The sealing design applies local quality by concentrating the high-performance sealing requirements specifically at the second seal interface with the rotating shaft, while allowing the first seal interface to have more relaxed tolerances. The second seal is positioned where precise sealing is most critical, enabling cost-effective manufacturing overall while maintaining high sealing performance where needed
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
The joint provides a high-performance, liquid and dust-proof sealing solution that improves hygiene by eliminating bacterial growth risks and reducing the need for complex surface treatments, while maintaining effective sealing even as the static seal ages, thus suitable for harsh washdown processes.
Implementation Method 1
The static seal may be elastic. In this way, the static seal can be axially compressed (with respect to the rotation axis) in use of the joint. The axial compression of the static seal causes the static seal to radially expand and increase the sealing against the first part.
Data Source
AI summary
A joint including a first part and a second part rotatable relative to each other about a rotation axis, the second part having a second surface; a dynamic seal arranged to dynamically seal against the second surface; and a static seal arranged to seal a gap between the first part and the dynamic seal, and arranged to push the dynamic seal against the second surface; wherein the static seal in the gap is exposed to an external region outside the joint. An industrial device including a joint is also provided.