Conical Thread Milling in Wood for Fast Furniture Assembly
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Solution Overview
Problem
Traditional methods for forming threads in wood materials, such as screw taps, are not optimal for high-speed production of furniture, as they are inefficient and do not provide a strong mechanical connection.
Innovation Solution
A milling cutter with a tapered lower end and circumferential cutting edges is used to form conical threads within openings, allowing for high-speed production and easy assembly by creating a mechanically strong connection between furniture parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a screw tap is used to form threads in wood material, then threads can be formed, but the production speed is slow and the mechanical strength is insufficient
Solution Approach 1:
The patent changes the geometric parameters of the thread form from traditional cylindrical to conical shape, and modifies the threading process parameters by using a milling cutter instead of a screw tap. The conical thread geometry with specific angle ranges (30-60 degrees) provides better load distribution and higher mechanical strength while the milling process enables faster production compared to traditional tapping methods
Solution Approach 2:
The patent replaces the screw tap mechanical system with a milling cutter system. Instead of using a tapping operation that requires reverse rotation and is time-consuming, the invention uses a milling cutter that rotates in one direction to form threads, eliminating the need for direction reversal and significantly improving production speed
2Ease of operation
If a screw tap is used to form threads, then threads can be formed, but the assembly process is complex and time-consuming
Solution Approach 1:
The conical thread geometry provides self-aligning and self-centering properties during assembly. The tapered shape guides the mating parts into proper alignment automatically, eliminating the need for precise pre-positioning and reducing assembly complexity. The stop formed by the conicity ensures automatic positioning depth
Solution Approach 2:
Instead of using traditional cylindrical threads that require precise alignment and threading operations, the patent inverts to conical threads that naturally guide alignment during insertion. The inverted cone geometry works in favor of easy assembly rather than against it, allowing parts to self-align as they are brought together
3Reliability
If traditional threading methods are used, then threads can be formed, but the connection is not forgiving to tolerance deviations
Solution Approach 1:
The patent changes the thread geometry from cylindrical to conical with specific angle parameters (30-60 degrees). This geometric parameter change creates a tolerance-forgiving connection where the tapered shape accommodates variations in hole position, size, and angle. The conical geometry provides a larger effective engagement area that compensates for manufacturing tolerances
Solution Approach 2:
The conical thread design inherently provides a cushioning effect against tolerance deviations. The tapered geometry gradually engages the mating parts, allowing for gradual self-correction of misalignments before full engagement. This prevents sudden binding or failure that would occur with rigid cylindrical threads when tolerances are exceeded
Data Source
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AI summary
A method of forming conical threads (15) in a wooden part (8) is shown. The threads (15) are formed in that a milling cutter (1) is given a helical movement. The invention also comprises a milling cutter (1) having a lower part (5) with a number of cutting edges (3). The lower end (5) of the milling cutter (1) tapers towards a free end (6) of the milling cutter.