Crushing Tool Hardness Gradient via Differential Heat Treatment
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Solution Overview
Problem
Existing crushing tools and components used in mining and extraction processes suffer from significant wear, leading to frequent replacements and high maintenance costs, despite the use of materials like tungsten carbide, which can be expensive and heavy.
Innovation Solution
The development of crushing tools with varying hardness levels, featuring Rockwell hardness of HRC 50-60 at the surface and HRC 20-35 at internal locations, made from tool-grade steel, such as AISI S7, with heat treatment processes to enhance wear resistance and toughness, allowing for gradual hardness decrease from the surface to the interior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tools are made of tungsten carbide and other hard materials, then wear resistance is improved, but cost and weight increase
Solution Approach 1:
The patent applies different hardness levels to different regions of the crushing tool. The surface layer is heat treated to achieve high hardness (HRC 50-60) for wear resistance, while the interior maintains lower hardness (HRC 20-35) for toughness. This local differentiation allows the tool to have enhanced wear resistance at the contact surface without requiring the entire tool to be made of heavy, expensive hard materials like tungsten carbide.
Solution Approach 2:
The patent changes the physical parameter of hardness through controlled heat treatment processes. By adjusting heating temperature, holding time, and cooling rates, the surface hardness is increased to HRC 50-60 while the interior remains at HRC 20-35. This parameter change enables the tool to achieve wear resistance comparable to tungsten carbide without the associated weight and cost penalties.
2Reliability
If tools are made of uniformly high hardness materials, then wear resistance is improved, but toughness and impact resistance decrease
Solution Approach 1:
The patent creates a hardness gradient within the tool structure. The surface layer is heat treated to high hardness (HRC 50-60) to resist wear during crushing operations, while the interior maintains lower hardness (HRC 20-35) to provide toughness and absorb impact energies. This local quality differentiation resolves the contradiction between wear resistance and toughness.
Solution Approach 2:
The patent creates a composite structure within a single steel component through differential heat treatment. The tool effectively becomes a composite of hard surface layer and softer interior core, similar to how composite materials combine different properties in different regions. This internal composite structure allows simultaneous achievement of wear resistance and toughness.
3Duration of action of stationary object
If surface hardness is increased to improve wear resistance, then tool life is extended, but brittleness increases
Solution Approach 1:
The patent applies selective heat treatment to create local quality differences. The surface layer is hardened to HRC 50-60 to extend service life through improved wear resistance, while the interior remains at HRC 20-35 to maintain ductility and reduce brittleness. This localized approach allows the tool to achieve extended service life without suffering from the brittleness that would result from uniform hardening.
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 increases the service life of crushing tools by up to four times compared to previous designs, offering improved wear resistance and toughness, while reducing material costs and weight.
Implementation Method 1
with heat treatment processes to enhance wear resistance and toughness
Implementation Method 2
The development of crushing tools with varying hardness levels, featuring Rockwell hardness of HRC 50-60 at the surface and HRC 20-35 at internal locations
Data Source
AI summary
An improved crushing tool for the processing of aggregates, and a heat treatment method for metals used in the fabrication of such tools, is provided. The crushing tool may comprise an attachment portion having a relatively low material hardness and a crushing portion having, in comparison to the attachment portion, a relatively high material hardness. For example, the hardness of the attachment portion may be in the range of 20-35 HRC, and that of the crushing portion may be in the range of 50-60 HRC. Use of tool-grade steel, such as AISI S7 steel, may thereby result in a tool offering a compromise between the hardness (wear-resistance) of the crushing portion and the toughness of the attachment portion. A heat treatment process for the tool-grade steel may involve distinct heating, quenching, and tempering cycles in order to achievable desirable material properties.