Length-adjustable column and manufacturing method thereof, piece of furniture
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Solution Overview
Problem
Existing length-adjustable columns for furniture, such as chairs and tables, face issues with anti-rotation locking mechanisms that fail under high torque, leading to jamming and loss of length adjustment functionality, and require additional construction space or use of weaker materials for anti-rotation profiles.
Innovation Solution
A length-adjustable and rotationally-secured column design featuring a cylindrical standpipe and portion with an anti-rotation locking device, where the inner element is connected to the portion through a substance-to-substance layer, using high-strength materials for the inner element and a self-lubricating plastic outer element, ensuring stability and preventing rotation over the entire travel path without additional space or material weakness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-rotation locking element is used in existing length-adjustable columns, then rotation is prevented, but the locking element deforms or detaches under high torque, causing jamming and loss of length adjustment functionality
Solution Approach 1:
The invention uses a composite structure where a plastic outer element (e.g., polyoxymethylene) is combined with a metal inner element. The plastic provides self-lubrication and corrosion resistance, while the metal inner element provides high strength to withstand torque without deformation. This composite approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The anti-rotation locking device is segmented into an outer element and an inner element that can be manufactured separately and then assembled. This allows optimization of each component's material properties - the outer element can use self-lubricating plastic while the inner element uses high-strength metal, resolving the strength-reliability contradiction.
2Shape
If profile parts are arranged in line with the length-adjustment element to be invisible, then aesthetic appearance is improved, but radial construction space is reduced, limiting the length of profile parts and their torque capacity
Solution Approach 1:
The invention moves the anti-rotation locking mechanism from a radial arrangement (profile parts extending outward) to an axial arrangement (inner element inside outer element along the axis). This dimensional change allows the locking mechanism to be hidden within the column's length rather than width, maintaining aesthetic appearance while providing sufficient space for long, high-strength profile parts.
Solution Approach 2:
The inner element is nested within the outer element, with the inner element having a smaller outer diameter than the outer element's inner diameter. This nested arrangement allows both elements to coexist in the same radial space, enabling the inner element to be sufficiently long for high torque capacity while remaining hidden within the overall column structure.
3Strength
If the inner element is made of high-strength material to withstand high torque, then strength is improved, but manufacturing complexity and cost increase
Solution Approach 1:
By segmenting the locking mechanism into separate outer and inner elements, the high-strength inner element can be manufactured using optimized processes (such as cold drawing or precision machining) while the outer element can be manufactured separately. This segmentation allows each component to be manufactured efficiently with specialized processes, reducing overall manufacturing complexity despite the high-strength material requirement.
Solution Approach 2:
The invention changes the material parameter of the inner element to high-strength material (such as hardened steel) to withstand torque, while keeping the outer element in standard plastic. This parameter change is localized only to the inner element where it is most needed, minimizing the impact on overall manufacturing complexity and cost.
4Stability of the object's composition
If the standpipe and portion are cylindrical with round cross-section, then mechanical stability and isotropy are improved, but the anti-rotation locking mechanism requires additional design complexity
Solution Approach 1:
The cylindrical standpipe and portion provide mechanical stability and isotropy, while the composite anti-rotation locking mechanism (outer element with inner element) adds rotational security. The simplicity of the cylindrical geometry is maintained while the composite locking mechanism provides the necessary anti-rotation function through the interaction between the outer element's inner surface and the inner element's outer surface.
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 provides enhanced reliability and durability by ensuring the anti-rotation locking device withstands high torque without deformation, maintaining smooth length adjustment and preventing rotation, while being cost-effective and simple to manufacture.
Implementation Method 1
a self-lubricating plastic outer element, ensuring stability and preventing rotation
Data Source
AI summary
Provided is a length-adjustable column with a standpipe having a longitudinal axis, a length-adjustment device arranged in the standpipe with a portion displaceably-mounted along the longitudinal axis with respect to the standpipe and an anti-rotation locking device for locking the portion against a rotation around the longitudinal axis relative to the standpipe. The anti-rotation locking device includes an inner element, which is fastened to an outer surface of the portion, and an outer element, which is fastened to an inner surface of the standpipe. The inner element cooperates with positive locking with the outer element against a rotation around the longitudinal axis, and is displaceably guided along the longitudinal axis by the outer element. The inner element is connected with the portion through a substance-to-substance connecting layer.