Pull-Out Rail Guide With Mixed-Diameter Rollers for Quiet Operation
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Solution Overview
Problem
Existing pull-out guides for furniture parts, such as drawers, suffer from loud rolling noises due to the interaction of roller bodies with varying hardness and size, which are not effectively reduced by size differences of only one-tenth of a percent, and can lead to damage of softer roller bodies under high loading.
Innovation Solution
Specifying a greater difference in diameter between harder and softer roller bodies, considering production tolerances and the modulus of elasticity, to ensure quiet operation under low loading and prevent damage under high loading, with an upper limit preventing material failure and ensuring load transfer between roller bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a small difference in diameter (one-tenth of a percent) is used between roller bodies of different hardness, then the structure complexity is minimized, but the rolling noises are not effectively reduced
Solution Approach 1:
The patent changes the diameter parameter of roller bodies to resolve the noise issue. Specifically, it specifies that the diameter of softer roller bodies should be larger than that of harder roller bodies by at least the sum of their production tolerances. This parameter change ensures that softer rollers consistently engage with the rail under low loading conditions, effectively reducing rolling noises while accounting for manufacturing variations.
2Object-generated harmful factors
If a large difference in diameter is used between roller bodies, then rolling noises are reduced, but the softer roller bodies may be destroyed under high loading
Solution Approach 1:
The patent optimizes the diameter parameter within specific bounds to balance noise reduction and durability. The diameter difference is set to be at least the sum of production tolerances (to ensure noise reduction) but also limited to prevent the softer rollers from being overloaded and destroyed. This creates an optimal parameter range that satisfies both requirements.
Solution Approach 2:
The patent applies partial action by having different roller bodies engage under different loading conditions. Softer, larger-diameter rollers engage under low loading to reduce noise, while harder, smaller-diameter rollers engage under high loading to prevent destruction. This partial engagement strategy allows each roller type to operate in its optimal range.
3Strength
If only hard roller bodies are used, then the pull-out guide can handle high loading, but loud rolling noises occur especially under low loading
Solution Approach 1:
The patent applies local quality by using different roller body materials with different hardness levels in the same roller body cage. Softer roller bodies are positioned to engage under low loading conditions for quiet operation, while harder roller bodies are positioned to engage under high loading conditions for strength. This local differentiation of material properties resolves the contradiction between noise and load handling.
Solution Approach 2:
The patent uses a composite approach by combining roller bodies of different materials (different hardness levels) within the same cage assembly. This composite structure allows the system to exhibit different characteristics under different loading conditions, achieving both quiet operation under low load and high strength under heavy load.
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 solution effectively reduces rolling noises, especially under low loading, and extends the service life of the pull-out guide by ensuring the softer roller bodies handle light loads quietly and the harder roller bodies take over under heavier loads without damage.
Implementation Method 1
Cylindrical rollers or balls that are rotatably mounted are used as roller bodies in the roller body cage. 'Hard' steel balls or rollers with a high modulus of elasticity (MOE) are frequently used because they enable smooth guidance even under high mechanical loading by a heavy weight which is movably mounted by the pull-out guide. Loud rolling noises can be disadvantageous, which can be the stronger the less the pull-out guide is loaded.
Implementation Method 2
at least one of the roller bodies has a greater diameter and a lower modulus of elasticity than the remaining roller bodies of the at least one roller body cage
Data Source
AI summary
A pull-out guide for furniture parts which can move relative to one another includes at least two pull-out rails, between which at least one first roller body and at least one second roller body are disposed, which are held in a rotatable manner in at least one roller body cage, the at least one first roller body having a greater nominal diameter and a lower modulus of elasticity than the at least one second roller body of the roller body cage. The pull-out guide is characterized in that a difference in diameter (Δd) between a first nominal diameter of the first roller body and a second nominal diameter of the second roller body is greater than a lower limit which is at least as great as a manufacturing tolerance (Δd1) in the diameter of the first roller body.