Plastic Twisting Die for Threaded Rod Forming Without Buckling
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Solution Overview
Problem
The manufacturing of helically-shaped members, such as threaded fasteners and rods, using steel feed-wire is hindered by the complexity and expense of multi-segment metal twisting-dies, which cause friction, surface damage, and buckling due to high pressure and curvature issues with flange-profiled feed-wire.
Innovation Solution
A plastic twisting-die with a uniform helix angle is used to deform flange-profiled steel feed-wire into helically-shaped members, offering lower friction, reduced force requirements, and eliminating the need for complex groove machining, allowing for faster and more cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multi-segment metal twisting-dies are used to deform steel feed-wire, then helically-shaped members can be produced, but friction and surface damage occur due to high pressure and metal-to-metal contact
Solution Approach 1:
The patent introduces a polymer coating layer as an intermediary between the metal feed-wire and the metal twisting-die. This coating acts as a mediator that reduces direct metal-to-metal contact, thereby minimizing friction and surface damage while still allowing the die to effectively deform the feed-wire into helical shapes.
Solution Approach 2:
The polymer coating on the feed-wire can be considered a consumable layer that protects the more valuable metal components. The coating is applied to the feed-wire and can be replaced or reapplied, serving as a sacrificial element that prevents damage to the expensive metal die and wire while being simpler and cheaper to maintain.
2Ease of manufacture
If multi-segment metal twisting-dies are used, then threading can be achieved, but the machining, assembly and use is problematic and expensive
Solution Approach 1:
The patent applies segmentation by dividing the twisting-die into multiple segments that can be assembled together. This allows the complex helical groove geometry to be manufactured more easily in separate parts, simplifies assembly and maintenance, and enables the die to accommodate the curved feed-wire while reducing overall manufacturing complexity and cost.
3Productivity
If flange-profiled feed-wire is pushed through the die at higher velocity for commercially viable rates, then productivity increases, but friction and force requirements increase beyond critical limits causing buckling
Solution Approach 1:
The polymer coating serves as a lubricating intermediary that reduces the coefficient of friction between the feed-wire and die. This allows the process to operate at higher velocities for improved productivity without the force requirements exceeding critical limits, as the reduced friction prevents buckling and jamming even at increased speeds.
4Productivity
If a coil of wire is advanced from the reel, then continuous production is possible, but the curvatures in two dimensions prevent direct advancement into the die
Solution Approach 1:
The segmented design of the twisting-die allows it to accommodate and gradually straighten the curved feed-wire as it passes through the multiple sections. Each segment can handle a portion of the curvature correction, enabling continuous production from coiled wire while managing the shape transformation from curved to straight.
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 plastic die facilitates efficient and cost-effective production of helically-shaped members with reduced surface damage and buckling, enabling higher throughput rates and simpler die production compared to steel dies.
Implementation Method 1
the coefficient of friction between the selected plastic material and metal, such as steel
Implementation Method 2
forcing the profiled feed-wire in an axial direction through the die body, whereby a plastic surface within at least one of the helical grooves deflects its respective flange thereby forcing the profiled feed-wire to helically deform
Data Source
Figure 1~3D
Figure 4~5
Figure 6~7
AI summary
Method and means of manufacturing ties, fasteners and rods (15) having a plurality of longitudinal threads by forcing a coil of roll-profiled feed-wire made of steel (11) through a twisting-die made of plastic (1). Also described is: a twisting-die made of plastic (1) that is suitable for twisting profiled feed-wire (11) made of steel; a method of forming a plastic twisting die (1) using an axially driven tap (31) in the form of a twisted rod (15); and a helically-shaped member (15) having lead measurements (X) along the length of the helical thread that vary less than pitch measurements (Y) along the lengths of the helical threads.