Cold-Worked Strip Steel Knife Edge for Wear-Resistant Cutting
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Solution Overview
Problem
Existing methods for hardening the cutting edge of strip steel knives through transformation hardening affect the base microstructure, leading to undesirable properties at the interface and reduced durability, requiring complex and energy-intensive processes.
Innovation Solution
Partial cold forming at the cutting edge creates a work-hardened microstructure with increased hardness, avoiding thermal treatment and maintaining ductility in the strip body, using processes like cold rolling to enhance dislocation density and strain-induced deformation martensite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If transformation hardening is applied to the cutting edge region, then hardness is improved, but the base microstructure is affected leading to reduced durability and stability
Solution Approach 1:
The patent applies local quality by differentiating the microstructure treatment between the cutting edge region and the base microstructure. The cutting edge region receives transformation hardening to achieve high hardness, while the base microstructure is preserved through controlled cooling to maintain its original properties, thus avoiding negative interface effects and ensuring both hardness and durability
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the heating and cooling parameters of the transformation hardening process. By adjusting the heating temperature to austenitic or partially austenitic range and controlling the cooling rate, the patent achieves martensite formation in the cutting edge region while preventing adverse effects on the base microstructure, thereby resolving the contradiction between hardness improvement and durability maintenance
2Reliability
If complex heat treatment processes are used to reduce adverse interface effects, then durability is improved, but process complexity and energy consumption increase
Solution Approach 1:
The patent applies partial action by limiting the transformation hardening treatment only to the cutting edge region rather than the entire strip body. This selective approach reduces the extent of thermal processing, thereby simplifying the overall process while maintaining durability through targeted hardening of only the critical cutting edge area
Solution Approach 2:
The patent extracts the harmful thermal effects from the base microstructure by using a cooling strategy that prevents the base material from undergoing transformation hardening. This separation allows the cutting edge region to be hardened while the base microstructure remains unaffected, reducing process complexity and energy consumption compared to treating the entire component
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 method achieves high hardness and wear resistance with reproducible properties, reducing manufacturing costs and cycle times, while preserving the strip body's ductility and avoiding the drawbacks of thermal treatment.
Implementation Method 1
cold forming can be pressure forming (according to DIN 8583). Cold rolling is also conceivable
Implementation Method 2
creating a distal cutting edge area with a work-hardened microstructure
Implementation Method 3
Cold forming can increase the dislocation density in the base structure and/or generate strain-induced deformation martensite in the base structure
Data Source
Figure 1~2
Figure 3a~3b
AI summary
A method for hardening a cutting edge (3) of a cutting edge (2) of a strip body (5) having a base structure (7), made of a cold-workable steel alloy, a strip steel knife (1), and this strip steel knife (1) is presented. In order to enable high cutting performance and wear resistance of the strip steel knife (1), it is proposed that the distal cutting edge region (4a) has a cold-worked, in particular cold-rolled, microstructure (6), the hardness (HV) of which, decreasing in the proximal direction (R) of the cutting edge (2), is always above the mean hardness (HV) of a base structure (7) of the strip body (5) adjoining this cold-worked microstructure (6) up to a hardening depth (t) of at least 0.2 mm, in particular 0.45 mm.