Thread-Rolling Flat Die Geometry to Prevent Chipping
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Solution Overview
Problem
Conventional thread-rolling dies for producing high-hardness bolts are prone to chipping and deformation, leading to a shortened die life and increased production costs.
Innovation Solution
A thread-rolling flat die with a dual bite surface structure, where the first partial bite surface has a high inclination angle and large crest angles, and the second partial bite surface has a smaller inclination angle and longer length, reducing load application and preventing chipping by maximizing material displacement and controlling loads throughout the processing region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rolling dies are used to produce high-hardness bolts, then the initial bite is achieved, but chipping and deformation occur leading to shortened die life
Solution Approach 1:
The bite surface is divided into multiple distinct regions (first bite region, second bite region, and finishing region) with progressively different parameters. This segmentation allows each region to perform a specific function: the first region initiates biting with appropriate geometry, the second region continues material displacement with controlled loads, and the finishing region completes the thread formation, thereby preventing chipping and deformation throughout the process
Solution Approach 2:
Each region of the bite surface is assigned locally optimized parameters: the first bite region has specific inclination and crest angles suitable for initial engagement, the second bite region has different parameters for continued material flow, and the finishing region has final parameters for precise thread formation. This local quality optimization ensures that no single region imposes excessive localized stresses that would cause chipping
2Manufacturing precision
If processing teeth have large crest angles for initial bite, then material displacement is sufficient, but excessive loads are applied to the die
Solution Approach 1:
The bite surface is divided into multiple distinct regions (first bite region, second bite region, and finishing region) with progressively different parameters. This segmentation allows each region to perform a specific function: the first region initiates biting with appropriate geometry, the second region continues material displacement with controlled loads, and the finishing region completes the thread formation, thereby preventing chipping and deformation throughout the process
Solution Approach 2:
Each region of the bite surface is assigned locally optimized parameters: the first bite region has specific inclination and crest angles suitable for initial engagement, the second bite region has different parameters for continued material flow, and the finishing region has final parameters for precise thread formation. This local quality optimization ensures that no single region imposes excessive localized stresses that would cause chipping
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 effectively suppresses chipping and extends the die's lifespan, enabling high-volume, stable production of threaded fasteners with reduced production costs.
Implementation Method 1
a bite surface 12 having an inclination with respect to a finishing surface 13 in which thread rolling is completed; processing teeth 31 for forming a processed portion W1 of the workpiece W into a threaded shape
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
[Problem to be Solved] A thread-rolling flat die for a threaded fastener capable of long life and a thread-rolling method using the thread-rolling flat die for a threaded fastener are provided. [Means for Solving the Problem] A thread-rolling flat die 1 is provided with a first partial bite surface 15 having an inclination with an angle α with respect to a finishing surface 13, and a second partial bite surface 16 formed between the first partial bite surface 15 and the finishing surface 13 and having an inclination with an angle β with respect to the finishing surface 13. A crest angle θ1 of a processing tooth 31 at a thread-rolling starting point 17 in the first partial bite surface 15 is larger than a crest angle θ2 of a processing tooth 31 in the finishing surface 13. Therefore, loads applied to dies 10, 50 can be reduced, and this allows a longer life of the thread-rolling flat die 1.