Annular Workpiece Quenching with Inner Die Restraint
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Solution Overview
Problem
During the quenching process of annular workpieces made of high-carbon steel, dimensional changes cause distortion and potential scratching when the workpiece is inserted into an outer die due to delayed timing of restraint state change, leading to increased grinding requirements and cycle times.
Innovation Solution
The method involves cooling the workpiece with an inner die and then inserting it into an outer die at a temperature below 500°C but before martensitic transformation, while applying low pressure to prevent scratching, and subsequently increasing pressure to restrain the workpiece during volume expansion, using a quenching apparatus with controlled movement and pressure adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the workpiece is inserted into the outer die after delayed timing (when outer diameter exceeds predetermined value), then the workpiece can be restrained during quenching, but the outer peripheral surface of the workpiece is scratched due to contact with the outer die
Solution Approach 1:
The workpiece is inserted into the outer die before the outer diameter exceeds the predetermined value, i.e., before martensitic transformation begins. This preliminary action prevents the workpiece from expanding beyond the die's inner peripheral surface, thereby avoiding scratches while ensuring proper restraint during subsequent quenching
Solution Approach 2:
The patent replaces purely mechanical timing-based insertion with temperature-based control. By monitoring workpiece temperature and inserting it into the outer die at a specific temperature range (before Ms point), the system achieves precise timing control that prevents scratching while ensuring reliable restraint
2Manufacturing precision
If the workpiece is inserted into the outer die while outer diameter exceeds predetermined value, then the workpiece can be restrained, but the amount of grinding increases and cycle time is prolonged
Solution Approach 1:
The workpiece is inserted into the outer die in advance, before martensitic transformation causes excessive expansion. This preliminary restraint prevents dimensional deviations that would require extensive grinding, thereby maintaining manufacturing precision while reducing cycle time
Solution Approach 2:
The patent changes the timing parameter from being based on dimensional measurement (outer diameter) to being based on temperature. By controlling insertion timing according to temperature (before Ms point), the system achieves optimal restraint that minimizes both dimensional deviation and subsequent grinding requirements
3Manufacturing precision
If the workpiece is cooled and inner peripheral surface contacts inner die, then the inner peripheral surface is restrained, but delayed insertion into outer die causes volume expansion and scratching
Solution Approach 1:
The workpiece is inserted into the outer die as a preliminary action before martensitic transformation begins. This ensures that when volume expansion occurs during transformation, the workpiece is already restrained by the outer die, preventing scratches while maintaining the restraint of the inner peripheral surface by the inner die
Solution Approach 2:
The patent implements a dynamic two-stage restraint system where the inner die restrains the inner peripheral surface during cooling, and the outer die is engaged before transformation to restrain the outer peripheral surface. This dynamic adjustment of restraint stages prevents scratching while maintaining dimensional accuracy
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 prevents scratching of the workpiece's outer surface, reduces grinding needs, and shortens the grinding cycle time by ensuring controlled thermal contraction and expansion, maintaining dimensional accuracy.
Implementation Method 1
an inner peripheral surface of the workpiece undergoes thermal contraction to make contact with an outer peripheral surface of the inner die
Implementation Method 2
the workpiece undergoes volume expansion due to the martensitic transformation
Data Source
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AI summary
An annular workpiece quenching method includes: cooling an annular workpiece (W) with an inner die (23) arranged radially inward of the workpiece heated at a quenching temperature; pressing the workpiece in a width direction at a low pressure and inserting the workpiece in an outer die (22) with restraint of an inner peripheral surface of the workpiece continued, when the restraint is started by contact with the inner die, after a temperature of the workpiece is decreased to 500°C or lower but before the temperature is decreased to a martensitic transformation start temperature (Ms point); and restraining the workpiece in the width direction by pressing the workpiece in the width direction at a high pressure, and restraining an outer peripheral surface of the workpiece that undergoes volume expansion due to martensitic transformation, using the outer die, after the temperature of the workpiece is decreased to the Ms point or lower.