Lead-Free Steel Hose Fitting for Low-Waste Cold Forming
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Solution Overview
Problem
Existing hose fittings made from solid semi-finished products containing lead are environmentally harmful, health hazardous, and inefficient due to high CO2 emissions, complex machining, and require costly heat treatment, leading to quality risks and extended lead times.
Innovation Solution
Hose fittings manufactured from a lead-free, low-CO2 steel alloy with a specific composition, produced via cold-drawing and seamless tubes, eliminating the need for heat treatment and reducing machining, featuring toothed connection areas for secure attachment and smooth surfaces for reduced machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solid semi-finished product containing lead is used for manufacturing hose fittings, then the material can be processed and formed, but it causes environmental harm and health hazards during production, processing, and use
Solution Approach 1:
The patent changes the chemical composition parameters of the semi-finished product by specifying a lead-free steel alloy with controlled content of alloying elements (Mn: 1.0-3.0%, Si: 0.10-0.60%, Cr: 0.10-1.80%, Mo: 0.05-0.50%, B: 0.0005-0.0100%). This parameter change eliminates harmful lead while maintaining cold formability and mechanical properties through the optimized alloy composition
Solution Approach 2:
The patent uses a composite steel alloy composition combining multiple elements (Fe-C-Mn-Si-Cr-Mo-B) to achieve the desired properties. This composite material approach replaces harmful lead with a synergistic combination of alloying elements that provide both processability and environmental safety
2Quantity of substance
If conventional steel production process is used, then steel can be produced, but it results in very high CO2 emissions
Solution Approach 1:
The patent specifies precise compositional parameters including low carbon content (0.01-0.60%) and controlled alloying element ranges, which are optimized for cold-forming processes. These parameter changes enable a more efficient production process that reduces energy consumption and CO2 emissions compared to conventional high-carbon steel production
3Reliability
If heat treatment is performed before bending to withstand cold forming stress, then material failure is prevented, but additional costs, logistical effort, and extended lead time occur
Solution Approach 1:
The patent applies preliminary action by incorporating all necessary microstructural optimizations and alloying during the initial steel production and tube manufacturing stages. The controlled rolling and drawing processes create the required grain structure and dislocation density beforehand, eliminating the need for subsequent heat treatment before bending operations
Solution Approach 2:
The patent extracts the heat treatment step from the manufacturing process sequence by designing the material composition and initial processing to inherently provide the necessary cold-forming resistance. This removes the heat treatment operation entirely, reducing lead time and associated costs
4Ease of manufacture
If solid semi-finished product is used requiring creation of bore and subsequent machining of internal and external surfaces, then the finished part can be manufactured, but more than 50% of the semi-finished product is machined away
Solution Approach 1:
The patent applies inversion by starting with a hollow tube structure instead of solid material. This reverses the conventional approach of drilling a bore through solid stock, eliminating the need to remove more than 50% of the material. The tube is then cold-formed and sized to final dimensions with minimal machining
Solution Approach 2:
The patent changes the fundamental geometric parameter of the semi-finished product from solid to hollow tube structure. This parameter change fundamentally alters the material utilization, reducing waste from over 50% to minimal amounts required for finishing operations
5Strength
If heat treatment is performed on finished parts, then they can withstand cold forming process, but quality risks are posed by corrosion and surface deposits due to temperature stress
Solution Approach 1:
The patent extracts the heat treatment operation from the process sequence by designing the material composition and initial microstructure to provide inherent cold-forming resistance. The controlled alloying and cold-working processes create a material that can be cold-formed without heat treatment, eliminating the source of surface quality problems
Solution Approach 2:
The patent applies preliminary action by optimizing the alloy composition and initial processing to create the necessary mechanical properties before cold forming. The controlled rolling and drawing processes establish the required grain structure and work hardening characteristics in advance, eliminating the need for subsequent heat treatment that would compromise surface quality
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 reduces environmental impact, health risks, machining time, and costs while enhancing cold formability and quality, ensuring secure connections without heat treatment-related issues.
Implementation Method 1
The hose connector and/or the press fitting are each manufactured from a seamless, cold-drawn tube as a semi-finished product
Implementation Method 2
The press fitting has an annular contact zone that is designed to be contacted with a contact zone of the hose connector by plastic deformation
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The invention relates to a hose fitting 1 with a hose nozzle 2 and a press fitting 3 for connection to the hose nozzle 2, wherein the press fitting 3 on the inside and the hose nozzle 2 on the outside each have a toothed connection area for fixing the hose and wherein the press fitting 3 has an annular contact zone which is designed to be contacted with a contact zone of the hose nozzle 2 by plastic deformation, wherein the hose nozzle 2 and/or the press fitting 3 consist of a steel alloy which, in addition to iron and impurities caused by the melting, has the following elements in percent by mass: C 0.01 - 0.60; Si max. 0.60; Mn 0.20 - 3.0; S 0.06 - 0.40; Cr max 1.8; Ca max. 0.02; Al max. 0.06; O max. 80 ppm; V max. 0.5; N max. 0.15, Pb max. 0.1; P max. 0.1, B max. 0.01; N+P max. 0.2; Bi max. 0.1; Te max. 0.07; Se max. 0.2; Ni max. 2.0; Cu max. 0.8; Nb max. 0.3; Ti max.0.5, wherein the microstructure is grain size 8 according to ASTM E112-13(2021) or finer and the elongation at break A5 is min. 15%, wherein the press fitting 3 and the hose nozzle 2 are each smooth-drawn on the outside in at least one length section with a roughness Ra 0.1 µm to 4 µm and on the inside up to a depth of 5 to 200 µm in at least one length section has a C content reduced by at least 10% compared to a core of the hose nozzle 2 and/or the press fitting 3.