Column with adjustable length and method for producing the same, 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 mechanisms that can deform or detach under high torque, leading to jamming and loss of length adjustment functionality, and often require additional installation space or compromise on torque resistance due to material limitations.
Innovation Solution
A length-adjustable column design featuring a cylindrical standpipe and section with a coaxially arranged pneumatic or hydropneumatic piston-cylinder unit, incorporating an anti-rotation device with a materially bonded connection between a high-strength inner and outer element, where the inner element is made of steel and the outer element is a self-lubricating plastic, ensuring stability and preventing rotation throughout the entire stroke without additional space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-rotation element is used to prevent rotation of the housing relative to the standpipe, then rotation is prevented, but the anti-rotation element may be deformed and/or detached under high torque, leading to jamming and loss of length adjustment functionality
Solution Approach 1:
The anti-rotation device is divided into two separate elements: an inner element attached to the housing and an outer element attached to the standpipe. This segmentation allows each element to be optimized for its specific function - the inner element can be made of high-strength material to withstand torque, while the outer element provides the anti-rotation constraint. The separation prevents stress concentration that would occur in a single integrated element.
Solution Approach 2:
The invention uses different materials for the inner and outer elements of the anti-rotation device. The inner element is made of a material with at least as high strength as the housing (typically metal), while the outer element can be made of a different material. This composite approach allows optimization of each element's material properties for its specific mechanical requirements, particularly torque resistance for the inner element.
2Area of stationary object
If profile parts are arranged in series with the length adjustment element to prevent rotation, then rotation is prevented and radial space is available, but with a given axial installation space, only relatively short profile parts can be used, which withstand relatively low torques
Solution Approach 1:
The anti-rotation device extends in the axial dimension rather than being limited to radial space. By utilizing the axial direction for the anti-rotation elements, the design achieves both rotation prevention and high torque resistance without consuming additional radial space. The inner and outer elements can extend axially along the housing and standpipe respectively, providing long leverage arms for torque resistance.
3Ease of manufacture
If the standpipe and section are designed cylindrical for ease of manufacture and mechanical stability, then manufacturing is easier and force absorbing ability is isotropic, but additional measures are needed to prevent jamming from slight rotation
Solution Approach 1:
The anti-rotation device is installed preliminarily to prevent any rotation before jamming can occur. By providing the anti-rotation constraint through the inner and outer elements engaged with the cylindrical surfaces, slight rotations are prevented before they can cause jamming between the cylindrical standpipe and section. This preliminary prevention maintains the manufacturing simplicity of cylindrical components while ensuring reliability.
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 a reliable, durable, and torsion-proof column that withstands high torques without deformation, ensuring consistent length adjustment and increased longevity while maintaining a compact and cost-effective manufacturing process.
Implementation Method 1
the outer element is a self-lubricating plastic
Data Source
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AI summary
The invention relates, on the one hand, to a length-adjustable column (100) with a standpipe (110) having a longitudinal axis (LA), a length-adjustment device (120) arranged in the standpipe (110) with a section (121) slidably mounted relative to the standpipe (110) along the longitudinal axis (LA), and a rotation-locking device for securing the section (121) against rotation about the longitudinal axis (LA) relative to the standpipe (110). The rotation-locking device comprises an inner element (140) attached to an outer surface of the section (121) and an outer element (130) attached to an inner surface of the standpipe (110). The inner element (140) engages with the outer element (130) in a positive-locking manner to prevent rotation about the longitudinal axis (LA) and is slidably guided by the outer element (130) along the longitudinal axis (LA). The inner element (140) is connected to the section (121) by a material-bonded connecting layer (160).The invention further relates to a method (200) for manufacturing a length-adjustable column (100) comprising the steps of: providing (210) a length-adjusting device (120) with a section (121) and an inner element (140) of a rotation-locking device (160) with an inner base body (141), wherein an outer diameter of the section (121) is less than or equal to an inner diameter of the inner base body (141); arranging (230) the section (121) in the inner base body (141) and joining (240) the inner base body (141) with the section (121).