Gas Guide Assembly for Uniform Non-Metal Permeation in Metal Workpieces
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Solution Overview
Problem
Existing methods for introducing non-metallic elements into metal workpieces with complex structures and deep holes result in uneven distribution of elements, leading to inconsistent properties and increased medical risks, particularly in vascular stents, due to temperature and flow rate inconsistencies in gas streams.
Innovation Solution
A method involving preheating the gas stream to a near-modification temperature and controlling its temperature and flow rate to ensure uniform distribution of non-metallic elements across the workpiece, using a gas guide assembly with a specific relational expression between length and inner radius to stabilize the gas temperature and flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional non-metal introduction method is used, then processing time is reduced, but uniformity of non-metallic element content is poor
Solution Approach 1:
The gas stream is preheated to near-modification temperature before contacting the workpiece surface. This preliminary heating action ensures that the gas reaches the workpiece at an optimal temperature for uniform element introduction, preventing temperature gradients that would cause uneven permeation while maintaining efficient processing time.
Solution Approach 2:
The patent controls and optimizes the temperature and flow rate parameters of the gas stream. By adjusting these parameters to specific ranges, the process achieves uniform distribution of non-metallic elements throughout the workpiece while maintaining acceptable processing times, resolving the contradiction between precision and time loss.
2Manufacturing precision
If gas stream temperature is not controlled, then processing simplicity is maintained, but element distribution uniformity deteriorates
Solution Approach 1:
The gas stream undergoes preliminary heating to near-modification temperature in a dedicated heating zone before reaching the workpiece. This separated preliminary action allows temperature control to be implemented at the gas source rather than requiring complex control at the workpiece interface, achieving uniform element distribution with moderate system complexity.
3Productivity
If gas flow rate is high, then processing efficiency is improved, but element distribution uniformity deteriorates
Solution Approach 1:
The patent optimizes the gas flow rate parameter to a specific range that balances processing efficiency with uniform element distribution. By controlling the flow rate rather than allowing it to be arbitrarily high, the system maintains sufficient productivity while ensuring adequate contact time between gas and workpiece surfaces for uniform permeation.
4Strength
If conventional nitriding process is used, then surface hardness is improved, but inner wall element content is insufficient
Solution Approach 1:
The patent employs a gas stream (ammonia or nitrogen) that penetrates through the workpiece structure. The gas flows along the inner wall surface and provides atomic nitrogen for permeation, ensuring that the inner wall receives sufficient element content while the outer surface achieves the required hardness through controlled atmospheric exposure.
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
Ensures uniform distribution of non-metallic elements, improving mechanical properties and reducing medical risks by maintaining consistent element content and temperature across the workpiece, suitable for large-batch processing.
Implementation Method 1
the gas stream is preheated to a near-modification temperature
Implementation Method 2
the introduction of nitrogen elements on the surface of the metal or metal alloy is often used to improve certain aspects of the properties
Implementation Method 3
the atomic element content in the gas stream of the upper half section of the metal workpiece is relatively high
Data Source
AI summary
The present invention belongs to the technical field of medical instruments and particularly relates to a method for integrally modifying a metal workpiece, and a gas guide assembly and an apparatus for modification. The method includes the steps of placing the metal workpiece in a gas stream for modification, and cooling a modified metal workpiece, wherein in the modification step, the gas stream is preheated to a near-modification temperature, and then flows onto a surface of the metal workpiece. The gas guide assembly includes a gas guide pipe, and the relational expression of the length L and the inner radius R of the gas guide pipe is E=LR2+A, 0≤A≤5 cm3 and 0.3 cm3≤E≤400 cm3. Through the above-mentioned relational expression, the values of the length and the inner radius of the gas guide pipe may be set, a non-metallic gas can be preheated to a reaction temperature by the gas guide pipe and then discharged, and the discharged gas may maintain a stable temperature and decomposition rate and a suitable flow rate to improve the uniformity of the non-metal permeating treatment of the metal workpiece. The apparatus of the present invention can perform large-batch metal workpiece modification treatment for prefabricated members, and a good metal workpiece modification treatment effect is achieved.