Long Full-Thread Screw Rolling for Uniform Thread Geometry
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Solution Overview
Problem
Existing technologies face challenges in producing long, slim full-thread screws for structural timber construction due to limitations in thread length and strength requirements, particularly in rolling processes, which result in difficulties with exact placement and deformation during heat treatment.
Innovation Solution
A method combining flat die rolling and axial through-feed rolling processes to produce screws with uniform thread geometry over extended lengths, allowing for precise placement and avoiding deformation by pre-tempering the screw blank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flat die rolling process is used to produce threads, then high throughput and cost efficiency are achieved, but thread length is limited to maximum 600 mm
Solution Approach 1:
The thread production process is divided into two distinct segments: the first section (up to 600 mm) is produced using flat die rolling for high throughput, while the second section (exceeding 600 mm) is produced using axial through-feed rolling to extend the total thread length. This segmentation allows each process to operate within its optimal range.
Solution Approach 2:
Different rolling processes are applied to different sections of the screw blank based on local requirements. The first section uses flat die rolling optimized for efficiency, while the second section uses axial through-feed rolling optimized for extended length, creating a uniform thread geometry across the entire length despite using different processes.
2Strength
If heat treatment is performed before rolling to increase strength, then screw strength is improved, but power consumption increases by 30 to 50%
Solution Approach 1:
Heat treatment is performed as a preliminary action before the rolling process to increase the strength of the screw blank. This allows the material to be stronger prior to thread formation, enabling the production of high-strength screws with threads exceeding 600 mm length.
3Strength
If heat treatment is performed after thread rolling to increase strength, then screw strength is improved, but screw deformation occurs requiring subsequent straightening
Solution Approach 1:
Heat treatment is performed before rolling rather than after, which eliminates the deformation problem. By strengthening the material beforehand, the subsequent rolling process can be performed without causing screw deformation, thus maintaining manufacturing precision and eliminating the need for straightening operations.
4Ease of operation
If guide hole depth is limited to ten times the nominal diameter, then assembly is simplified, but exact placement of long screws becomes difficult
Solution Approach 1:
The patent replaces the mechanical guide hole system with a thread guide structure. Instead of relying on guide holes of limited depth, the thread itself acts as a guide, allowing long screws to be accurately positioned and inserted over extended lengths while maintaining exact placement precision.
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 screws with thread lengths exceeding 1000 mm, ensuring precise placement and high strength, suitable for structural timber construction applications.
Implementation Method 1
sufficient strength can be achieved by tempering the screw material, which typically involves heat treatment
Implementation Method 2
the thread is formed as the blank rolls. In this process, the forming process takes place primarily in the radial direction; axial deformation occurs only to a very small extent
Data Source
Figure 1a~2
Figure 3~4
AI summary
A method for producing a screw (10) with a predetermined thread geometry and a screw tip is shown, comprising the following steps: providing a screw blank (12) with a first diameter (Di), wherein the screw blank (12) has a first end (14) corresponding to the leading end of the screw (10) to be produced from the screw blank (12), and a second end (16) corresponding to the trailing end of the screw (10) to be produced from the screw blank (12); reducing the first diameter (D1) to a second diameter (D2) in a first section (20) adjacent to the first end (14) of the screw blank (12); machining the blank (12) in said first section by rolling with flat dies to form a thread (22) in the first section (20) and said tip as a thread tip (24) at the first end (14);Machining the blank (twelve) in a second section (26) adjoining the first section (20) by rolling in an axial through-feed process to form a thread (28) in the second section (26) which continuously continues the thread (22) in the first section (20), wherein the first and second diameters (D1, D2) of the screw blank (12) are each selected such that during machining in steps C and D a uniform or at least approximately uniform thread with the predetermined thread geometry is formed, which extends over the first and second sections (20, 26).