Screw Anchor Thread Rolling Without Carburizing Heat Treatment
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Solution Overview
Problem
The existing manufacturing method for screw anchors is complex and cost-intensive, involving multiple steps and heat treatments, which complicates the production process and increases tool wear, especially for longer lengths and larger diameters.
Innovation Solution
A method that uses a blank with a high carbon content of at least 0.5% to form anchoring and metric threads by rolling, eliminating the need for carburizing and tempering heat treatments, and forming the force application through machining or hot forming, such as polygon turning, to simplify and accelerate the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-carbon steel is used for the blank to enable cold forming and reduce diameter, then the blank can be efficiently formed without excessive tool stress, but the manufacturing process becomes complex and cost-intensive due to multiple heat treatment steps required later
Solution Approach 1:
The patent changes the material parameter by using high-carbon steel (≥0.5% carbon content) instead of low-carbon steel, which fundamentally alters the manufacturing approach. This parameter change eliminates the need for carburizing heat treatment since the carbon content is already sufficient, thereby reducing process complexity while maintaining cold forming capability through appropriate process adjustments
Solution Approach 2:
The high carbon content is built into the blank material from the beginning, performing the carbon enrichment action in advance during material production rather than during the manufacturing process. This preliminary action eliminates the need for subsequent carburizing steps, simplifying the overall manufacturing process
2Strength
If multiple heat treatment steps (carburizing, hardening, tempering) are applied to achieve required hardness and strength, then the anchoring thread gains sufficient torque resistance, but production time and costs increase significantly
Solution Approach 1:
The patent changes the material composition parameter by using high-carbon steel (≥0.5% carbon), which inherently provides the necessary hardness and strength after simple heat treatment. This eliminates the need for multiple complex heat treatment steps (carburizing, hardening, tempering) while maintaining or improving torque resistance, thereby significantly reducing production time
Solution Approach 2:
The patent extracts and eliminates unnecessary heat treatment steps (carburizing and tempering) from the manufacturing process. By using high-carbon steel, only a single hardening step is required, removing redundant processes that consume time and resources while still achieving the required mechanical properties
3Manufacturing precision
If the first section is reduced in diameter before rolling the anchoring thread, then suitable rolled diameter is achieved for the anchoring thread, but an additional cold forming step is required increasing process complexity
Solution Approach 1:
The patent changes the material parameter by using high-carbon steel, which allows the blank to maintain its diameter without reduction. The higher carbon content provides sufficient strength to enable direct rolling of the anchoring thread on the full-diameter blank, eliminating the need for preliminary diameter reduction and associated cold forming steps
4Ease of manufacture
If low-carbon steel is used to minimize tool stress during cold forming, then the blank can be formed without excessive stress on tools, but the material requires subsequent carburizing to achieve sufficient hardness
Solution Approach 1:
The patent changes the carbon content parameter from low (<0.45%) to high (≥0.5%), which fundamentally alters the material's response to forming and heat treatment. The high-carbon steel requires less severe forming conditions but eliminates the need for carburizing, achieving a different balance between forming ease and heat treatment requirements that ultimately simplifies the overall process
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
This approach significantly reduces production costs and time, minimizes tool wear, and allows for efficient production of screw anchors with larger lengths and diameters, while maintaining or improving torque resistance and insertion performance.
Implementation Method 1
The blank 18 is then reduced in diameter, forming a stepped blank 18... This diameter difference is achieved by reducing in one or more steps on a press or multi-stage press, i.e. by cold forming.
Implementation Method 2
the force application point 16 is also formed by cold forming, typically by extrusion
Implementation Method 3
the metric thread 14 and the anchoring thread 12 by rolling
Implementation Method 4
the screw anchor 10 is typically carburized during a heat treatment to achieve a carbon content of more than 0.65%, hardened, and tempered.
Implementation Method 5
hardened, and tempered
Implementation Method 6
hardened, and tempered
Implementation Method 7
the leading end of the anchoring thread 12 is typically additionally hardened, for example, by induction hardening
Data Source
Figure 1a~1e
Figure 2a~2c
Figure 3a~3c
AI summary
Disclosed is a method for producing a screw anchor comprising an anchoring thread, a metric fine connection thread and a driving feature. The method comprises the following steps: - providing a blank having a first section, on which the metric fine connection thread is to be formed and a second section, on which the anchoring thread is to be formed, the blank having a carbon content of at least 0.5 %, preferably at least 0.6 %, - forming the driving feature by a metal-removing process, a joining process or hot forming process, - forming the metric fine thread by rolling and - forming the anchoring thread by rolling.