Tapped Insert with Movable Bottom Wall
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Solution Overview
Problem
Conventional one-piece metal inserts with internally threaded sections are lengthened by clearance sections for tapping, making it difficult to manufacture thin plastic parts and prone to screw seizure issues, and alternative designs with separate parts increase manufacturing costs.
Innovation Solution
A one-piece metal insert with a radially pushed bottom wall that closes the longitudinal passage after tapping, reducing the overall length and eliminating the need for a clearance section, and an internally smooth section for screw release, along with a manufacturing method that folds the cylindrical wall to form a bottom wall without additional parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional one-piece metal insert with internally threaded section is used, then the insert can retain screws effectively, but the total length increases by 40-80% due to the clearance section TD, making it impossible to manufacture thin injected parts
Solution Approach 1:
The bottom wall PF is designed to be movable rather than fixed, allowing it to be pushed radially inward during the tapping operation to make space for the tap, then return to its original position to close the longitudinal passage. This preliminary positioning of the bottom wall enables the tapping operation without requiring a permanent clearance section, thus reducing the total insert length while maintaining screw retention capability.
Solution Approach 2:
The bottom wall PF is designed with dynamic capability to change its position radially. During tapping, it moves inward to accommodate the tap tool, and after tapping, it returns to close the passage. This dynamic behavior eliminates the need for a static clearance section, resolving the contradiction between needing space for tapping and minimizing overall insert length.
2Ease of manufacture
If a clearance section TD is provided for tap relief, then the tap can operate without breaking, but the internally smooth release section TD with internal diameter DI less than thread root diameter DFF causes screw end to seize when screw travels too far
Solution Approach 1:
The bottom wall PF is pushed radially inward during tapping to create temporary clearance space, allowing the tap to complete its operation without breaking. After tapping, the bottom wall returns to its original position, creating an effective seal without leaving a problematic internally smooth release section that would cause screw seizure.
Solution Approach 2:
The harmful internally smooth release section TD that causes screw seizure is eliminated by using the movable bottom wall approach. The clearance space is created temporarily during manufacturing but removed after the operation, leaving only the necessary threaded section and bottom wall closure that prevent screw seizure while maintaining tapping feasibility.
3Length of moving object
If a through longitudinal passage insert with no release section is used, then the total length is reduced, but separate parts and assembly operations are required increasing manufacturing cost
Solution Approach 1:
The insert is designed as a true one-piece component with the bottom wall PF as an integral part of the body C. The movable bottom wall is formed from the same material and in the same manufacturing process, eliminating the need for separate parts and assembly operations while maintaining reduced length compared to conventional designs.
Solution Approach 2:
The bottom wall PF and the main body C are merged into a single integral structure. The bottom wall is not a separate component but rather a deformable extension of the body that provides both the closure function and the temporary clearance space during tapping, simplifying the manufacturing process to a single operation.
4Length of moving object
If the bottom wall PF is made of movable material pushed radially, then the clearance section length is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The bottom wall PF is pre-positioned in a movable state during the injection molding process, allowing it to be pushed radially inward during tapping. This preliminary configuration enables the tapping operation to proceed without requiring complex post-manufacturing adjustments or additional manufacturing steps.
Solution Approach 2:
The movable bottom wall PF serves multiple functions automatically: it creates clearance space during tapping by moving inward, provides the necessary seal after tapping by returning to position, and eliminates the need for separate clearance sections. The single manufacturing process accomplishes multiple functions that would otherwise require separate operations.
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 allows for a significantly shorter total length of the insert, reducing manufacturing costs and preventing screw seizure, while maintaining structural integrity and sealing effectiveness.
Implementation Method 1
the bottom wall is made of metal pushed radially in the direction of the longitudinal axis
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A one-piece metallic insert (1) comprising: - a body (2) extending along a longitudinal axis (II) between a first end (3) open with an inlet orifice (4) and a second end (5), - between the first (3) and second (5) ends, a longitudinal passage (6) having an internally threaded section (7), - a bottom wall (8) closing the second end (5). The bottom wall (8) is made of metal radially embossed in the direction of the longitudinal axis (II).