Concrete Screw Coating With Embedded PTFE for Lower Driving Torque
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Solution Overview
Problem
Existing concrete screws experience rapid wear of dry lubricants on their thread flanks, leading to a loss of friction-reducing effect during screwing, resulting in increased torque requirements.
Innovation Solution
A concrete screw design featuring a base body made of hardenable carbon steel with a hardened external thread and a two-layer corrosion protection system, including a zinc-nickel coating and an organic epoxy resin matrix with embedded PTFE lubricant, enhances abrasion resistance and maintains lubrication efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a dry lubricant is applied directly to the steel or galvanic corrosion protection layer, then the friction-reducing effect is present at the beginning of the screwing process, but the lubricant is rapidly and completely worn away, resulting in loss of friction-reducing effect
Solution Approach 1:
The patent applies a composite coating system consisting of a primer layer (first corrosion protection layer) and a topcoat layer (second corrosion protection layer) containing the dry lubricant. This composite structure protects the lubricant from rapid wear while maintaining its friction-reducing function throughout the screwing process.
Solution Approach 2:
The primer layer acts as an intermediary between the steel base body and the topcoat layer containing the lubricant. It provides adhesion and corrosion protection, while the topcoat layer protects the lubricant from mechanical wear, ensuring prolonged lubrication effectiveness.
2Strength
If the external thread is hardened to at least 50 HRC to enable thread cutting into concrete, then thread penetration capability is improved, but the base body material must be hardenable carbon steel requiring additional hardening processes
Solution Approach 1:
The patent applies hardening locally to the external thread region rather than the entire base body. The thread area is hardened to at least 50 HRC to enable concrete penetration, while the rest of the base body maintains its original properties, optimizing both performance and manufacturing efficiency.
Solution Approach 2:
The patent changes the material parameter of the base body to hardenable carbon steel, which allows achieving the required thread hardness of at least 50 HRC through controlled hardening processes, enabling effective thread cutting into concrete.
3Reliability
If a two-layer corrosion protection system with embedded lubricant is applied, then abrasion resistance and lubrication efficacy are maintained, but the manufacturing process becomes more complex
Solution Approach 1:
The patent uses a composite coating system where the topcoat layer (second corrosion protection layer) contains embedded dry lubricant particles. This composite structure provides both corrosion protection and sustained lubrication, maintaining abrasion resistance while reducing friction throughout the screwing process.
Solution Approach 2:
The lubricant is pre-embedded in the topcoat layer during the coating process, so it is already in position to provide friction reduction from the beginning of the screwing process. This preliminary placement ensures consistent lubrication performance without requiring additional lubrication steps.
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 design ensures a durable friction-reducing effect by embedding PTFE in an epoxy resin matrix, bonded to a zinc-nickel layer, reducing torque requirements and maintaining thread penetration efficiency.
Implementation Method 1
a friction-reducing lubricant is applied to the body of the concrete screw, particularly in the area of the external thread
Implementation Method 2
the lubricant is arranged in a matrix of a second, organic corrosion protection layer applied to the first, metallic corrosion protection layer
Implementation Method 3
at least a portion of the external thread must have a hardness sufficient to allow the thread to penetrate the concrete and cause localized removal of concrete
Implementation Method 4
a first metallic corrosion protection layer is applied to this steel to protect the base body against corrosion. This corrosion protection layer is preferably a zinc-nickel (ZnNi) coating, which is applied electroplated
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a concrete screw (1) for screwing into a drilled hole (2) in a component (3) made of concrete. On a main body (5) of the concrete screw (1) there is a first, metallic anti-corrosion layer, and on this anti-corrosion layer there is a second, organic anti-corrosion layer. According to the invention, a matrix of the second, organic anti-corrosion layer contains a friction-reducing lubricant.