Non-rotating T-nut and screw catch for use in a chair panel and method for using the same
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Solution Overview
Problem
Traditional T-nuts in metal frame chair manufacturing often spin within their receivers when screws are driven, requiring stapling to prevent rotation, which adds material and manufacturing steps, and can lead to incomplete tightening if the plywood has soft spots.
Innovation Solution
An oval-shaped T-nut with a press-fit engagement in an oval receiver and a U-shaped screw catch with rib members to prevent rotation and secure upholstered chair panels, eliminating the need for stapling and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional plastic T-nut is used and stapled to the OSB panel, then the T-nut is prevented from spinning during screw installation, but additional materials and manufacturing steps are required
Solution Approach 1:
The T-nut is designed with an asymmetric D-shaped cross-section featuring a flat side and a curved side. The flat side engages with a corresponding flat surface in the oval receiver, creating a non-circular interface that prevents rotational movement. This asymmetric geometry inherently stops the T-nut from spinning during screw installation without requiring additional fastening methods like stapling.
Solution Approach 2:
An oval receiver is machined into the OSB panel to serve as an intermediary component. This receiver provides a precisely fitted housing for the D-shaped T-nut, creating a controlled interface between the T-nut and the panel. The receiver's internal geometry complements the T-nut's asymmetric shape, ensuring proper positioning and preventing rotation while simplifying the overall assembly process.
2Reliability
If a traditional plastic T-nut is stapled to the OSB panel, then the T-nut is secured in position, but additional materials and time are consumed in the manufacturing process
Solution Approach 1:
The D-shaped T-nut with its flat and curved sides provides inherent anti-rotation capability when engaged in the oval receiver. This asymmetric design ensures the T-nut remains securely positioned during screw installation without requiring stapling operations, thereby eliminating additional manufacturing steps and improving production efficiency.
Solution Approach 2:
The T-nut's asymmetric geometry and its engagement with the oval receiver create a self-securing mechanism. The non-circular interface automatically prevents rotation and secures the T-nut in the correct orientation during installation, eliminating the need for external fastening methods and reducing manufacturing complexity.
3Strength
If a plastic T-nut is used with high torque screw driving, then the screw cuts its own threads into the plastic, but the T-nut may spin if stapled to a soft spot in the plywood
Solution Approach 1:
The D-shaped T-nut engaged in the oval receiver provides inherent anti-rotation capability that is independent of the underlying panel conditions. This asymmetric interface ensures the T-nut cannot spin regardless of whether the OSB panel has soft spots or varying density, guaranteeing complete screw tightening and reliable thread engagement.
Data Source
AI summary
An oval-shaped T-nut that is received within an oval receiver machined into the upholstered panel to be secured to a chair frame is provided. The oval shape of the T-nut prevents the oval-shaped T-nut from rotating when a screw is driven into the T-nut. Further, this eliminates the necessity of stapling the traditional plastic T-nut to the chair panel, thus saving time and money associated with the manufacture of an upholstered metal frame chair. In addition to the oval-shaped T-nut described herein, a novel U-shaped screw catch is also provided which cooperates with a barbed nylon or plastic push rivet to secure the upholstered chair panels to one another. Further, a method for connecting upholstered seat back panels to the tabs positioned on the back frame of a chair, utilizing the T-nut and the screw catch is disclosed.