Co-Molded Inner Ring Bearing for Corrosion-Resistant Food Processing
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Solution Overview
Problem
Bearing units in the food and beverage industry face rapid corrosion of metal surfaces, particularly the radially inner ring, despite using stainless steel, which compromises corrosion resistance and mechanical strength due to high carbon content, and alternative materials like galvanized steel are not acceptable.
Innovation Solution
A bearing unit with a radially inner ring composed of a stainless steel collar and polymeric sleeves co-molded on opposite sides, replacing exposed metal surfaces with reinforced polymeric material to enhance corrosion resistance without compromising mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stainless steel with high carbon content is used for the radially inner ring to increase surface hardness, then the surface hardness is improved, but the corrosion resistance deteriorates
Solution Approach 1:
The radially inner ring is constructed as a composite structure combining stainless steel collar (for surface hardness and load-bearing) with polymeric material sleeves (for corrosion resistance). This composite approach allows each material to contribute its superior properties, resolving the contradiction between hardness and corrosion resistance.
Solution Approach 2:
Different parts of the radially inner ring have different material compositions optimized for their specific functions: the collar region uses high-carbon stainless steel for hardness where it contacts rolling elements, while the sleeve regions use polymeric material for corrosion resistance where they contact the corrosive environment, achieving local optimization of properties.
2Reliability
If stainless steel is used for the radially inner ring to improve corrosion resistance, then the corrosion resistance is improved, but the surface hardness deteriorates
Solution Approach 1:
The composite structure of stainless steel collar with polymeric sleeves allows the system to achieve both corrosion resistance (from the polymeric material) and surface hardness (from the stainless steel collar), eliminating the need to sacrifice one property for the other.
3Reliability
If galvanized steel is used for the radially inner ring to improve corrosion resistance, then the corrosion resistance is improved, but the material acceptance in food and beverage industry deteriorates
Solution Approach 1:
By using polymeric material sleeves instead of galvanized coating, the invention achieves corrosion resistance through an inherently corrosion-proof material that is also acceptable for food contact applications, thereby maintaining both corrosion resistance and industry acceptance.
Data Source
Figure 1
Figure 2a~3b
AI summary
Bearing unit (30) having: - a radially outer ring (31), stationary, - a radially inner ring (33), rotatable, - a row of rolling bodies (32) interposed between the radially outer ring (31) and the radially inner ring (33), - two sealing devices (35) arranged on axially opposite sides with respect to the row of rolling bodies (32), wherein the radially inner ring (33) is provided with three portions co-molded together: - a stainless steel collar (332) provided with a raceway (332a), and - a first sleeve (331) and a second sleeve (333) both of reinforced polymeric material and co-molded to the collar (332) on axially opposite sides.