Fully Threaded Screw Rolling for Uniform Long Thread Geometry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing manufacturing methods struggle to produce long, slender fully threaded screws with uniform thread geometry efficiently, particularly for structural wood construction, due to limitations in rolling processes with flat dies and increased power requirements with heat treatment, leading to deformation and straightening issues.
Innovation Solution
A combined rolling process using flat dies and axial through-feed process to form a threaded tip, followed by continuous thread formation in two portions of the screw blank, allowing for uniform thread geometry over extended lengths without subsequent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the rolling process with flat dies is extended to thread lengths greater than 600 mm, then longer threaded screws can be produced, but machine costs and tool costs increase disproportionately
Solution Approach 1:
The manufacturing process is segmented into two distinct rolling processes: a first rolling process for producing the initial thread portion and a second rolling process for extending the thread to the final length. This segmentation allows each process to be optimized independently, avoiding the need for a single complex rolling machine capable of handling the entire thread length, thereby reducing machine and tool costs while enabling production of screws with threads greater than 600 mm long
Solution Approach 2:
The first rolling process performs preliminary thread formation on the screw blank before the second rolling process extends it to the final length. This preliminary action creates a foundation thread structure that can be built upon, allowing the use of simpler initial rolling tools and machines that don't need to handle the full thread length and complexity from the start
2Strength
If heat treatment is performed before rolling to increase strength, then screw strength increases, but power requirements in the rolling process increase by 30 to 50%
Solution Approach 1:
Heat treatment is performed as a preliminary action before the rolling processes to increase the strength of the screw material. By preparing the material with enhanced strength properties beforehand, the rolling processes can work with a stronger blank, and the two-stage rolling approach distributes the deformation work, ultimately reducing the peak power requirements during rolling compared to attempting to roll heat-treated material in a single pass
3Strength
If heat treatment is performed after rolling to increase strength, then screw strength increases, but the screw deforms and requires subsequent straightening
Solution Approach 1:
Heat treatment is performed as a preliminary action before the rolling processes rather than after. This timing ensures that the material has enhanced strength and stability during the rolling operations, preventing deformation during thread formation. By establishing the heat-treated state before mechanical deformation, the screw maintains its straightness throughout the rolling process, eliminating the need for subsequent straightening operations
4Length of moving object
If fully threaded screws with length greater than 600 mm are produced using conventional rolling, then long threaded screws are available, but uniform thread geometry cannot be maintained
Solution Approach 1:
The thread formation is segmented into two rolling processes that work sequentially on different portions of the screw blank. The first rolling process creates uniform thread geometry on the initial portion, and the second rolling process continues this uniform geometry along the remaining length. This segmentation allows each rolling operation to focus on a specific thread section, maintaining consistent thread dimensions and geometry throughout the entire thread length exceeding 600 mm
Solution Approach 2:
The rolling parameters such as roll speed, feed rate, and rolling force are optimized differently for the two rolling processes to maintain uniform thread geometry across the entire thread length. By adjusting these parameters appropriately for each stage of thread formation, consistent thread dimensions are achieved throughout the extended thread length
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
Enables the production of fully threaded screws up to 2000 mm in length with precise placement and high strength, avoiding deformation and straightening issues, suitable for structural wood construction.
Implementation Method 1
processing the blank in said first portion by rolling with flat dies to form a thread in the first portion and a threaded tip at the first end
Implementation Method 2
processing the blank in a second portion adjoining the first portion by rolling in an axial through-feed process to form a thread in the second portion which continuously continues the thread in the first portion
Data Source
AI summary
A method of manufacturing a screw having a predetermined thread geometry and a screw tip, comprising the steps of: providing a screw blank having a first diameter, the screw blank having a first end corresponding to the leading end of the screw to be manufactured from the screw blank and a second end corresponding to the trailing end of the screw to be manufactured from the screw blank; reducing the first diameter to a second diameter in a first portion adjacent to the first end of the screw blank; processing the blank in said first portion by rolling with flat dies to form a thread in the first portion and said tip as a threaded tip at the first end; and processing the blank in a second portion adjoining the first portion by rolling in an axial continuous process to form a thread in the second portion which continuously continues the thread in the first portion, wherein the first and second diameters of the screw blank are each selected such that during processing in steps C and D a uniform or at least approximately uniform thread having the predetermined thread geometry is formed which extends over the first and second portions.