Dual-Material Screw Anchor Threads for Tapping Concrete
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Solution Overview
Problem
Concrete screw anchors formed entirely of stainless steel struggle to tap out their own receiving thread in concrete due to stainless steel's lower hardness compared to concrete, making it difficult to manufacture within narrow tolerances.
Innovation Solution
A method involving a stainless steel anchor blank with a carbon steel leading screw thread section formed using metal deposition techniques, such as laser metal deposition, to create a harder thread capable of tapping into concrete, while the rest of the anchor remains stainless steel for corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire screw anchor is formed of stainless steel, then corrosion resistance is improved, but the ability to tap out a receiving thread in concrete deteriorates due to insufficient hardness
Solution Approach 1:
The screw anchor features a dual-material construction where the body is made of stainless steel for corrosion resistance, while the leading thread portion is made of a harder material (such as carbon steel or tool steel) capable of tapping concrete. This local differentiation of material properties resolves the contradiction by applying the appropriate material quality to each functional region of the anchor.
Solution Approach 2:
The invention uses composite construction by combining stainless steel with a harder material in a single screw anchor component. The harder material is applied as a coating, overlay, or bonded layer on the leading threads, creating a composite structure that simultaneously provides corrosion resistance from the stainless steel base and thread-tapping capability from the harder outer layer.
2Strength
If a coil of hard material and receiving channel are formed within narrow manufacturing tolerances, then thread tapping capability is improved, but manufacturing difficulty increases
Solution Approach 1:
The harder material is applied to the leading thread portion before the anchor is inserted into the concrete. This preliminary application of the hard coating or overlay eliminates the need for complex post-manufacturing adjustments and simplifies the manufacturing process while ensuring the thread has sufficient hardness for tapping concrete.
Solution Approach 2:
Instead of mechanically forming a coil of hard material and receiving channel within tight tolerances, the invention uses material deposition techniques (such as electroplating, thermal spraying, or bonding) to apply the harder material layer. This substitution of the manufacturing method reduces complexity and manufacturing difficulty while achieving the required hardness.
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 carbon steel thread effectively taps a female thread into concrete, allowing the stainless steel anchor to secure properly, maintaining corrosion resistance and reducing the risk of thread degradation and concrete cracking over time.
Implementation Method 1
a leading part of a screw thread on its exterior surface which is formed of another type of metallic material that is harder than the rest of the anchor and which is deposited thereon using a metal deposition manufacturing technique
Implementation Method 2
such as laser metal deposition
Data Source
AI summary
A screw anchor and method of forming such a screw anchor, the method comprising: forming a first male screw thread section on a metallic body and which is integral to the metallic body; and using a metal deposition technique to deposit a second male screw thread section on the metallic body; wherein the second male screw thread section is formed of metallic material having a greater hardness than the metallic body and is able to tap out a female thread in a hole in a support for receiving the first male screw thread section when the screw anchor is twisted into the hole.