Forged Crankshaft Preforming for Precise Volume Distribution
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Solution Overview
Problem
Existing methods for producing forged crankshafts face challenges in achieving precise shape formation and improving material yield, particularly in distributing volume between weight and arm regions, leading to under-filling and reduced efficiency.
Innovation Solution
A method involving a first preforming process to reduce cross-sectional areas of pin and journal regions, followed by a second preforming process using separate dies to decenter pin regions, resulting in a final preform with appropriate volume distribution for efficient finish forging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single preforming process is used, then the process is simple, but the volume distribution between weight and arm regions is insufficient leading to under-filling
Solution Approach 1:
The preforming process is divided into two distinct stages: first preforming to create an intermediate preform with initial volume distribution, and second preforming to achieve final precise volume distribution. This segmentation allows each stage to focus on specific shaping requirements, resolving the contradiction between precision and complexity by breaking down the complex task into manageable steps.
Solution Approach 2:
The first preforming process performs preliminary volume distribution to create an intermediate preform that approximates the final shape. This preliminary action prepares the material for the second preforming stage, enabling better final shape precision while managing overall process complexity through staged preparation.
2Manufacturing precision
If excess volume is added to prevent under-filling, then fillability improves, but material yield decreases due to increased flash formation
Solution Approach 1:
Both first and second preforming processes perform preliminary volume distribution to accurately position material before finish forging. This ensures proper fillability of the crankshaft cavity without requiring excessive material, thereby preventing under-filling while minimizing flash formation and maintaining high material yield.
Solution Approach 2:
The preforming processes create local volume distribution variations tailored to specific regions of the crankshaft, particularly concentrating material in the weight regions that require it. This localized quality control ensures adequate fillability in critical areas without adding excess material overall, thus improving fillability while preserving material yield.
3Manufacturing precision
If multiple preforming processes are used, then volume distribution and shape precision improve, but the number of steps increases
Solution Approach 1:
The manufacturing process is segmented into first preforming, second preforming, and finish forging stages, with each stage optimized for specific objectives. This segmentation improves volume distribution precision and shape accuracy while managing production efficiency by ensuring each stage contributes meaningfully to the final product quality.
Solution Approach 2:
The first and second preforming processes are combined in sequence to achieve cumulative volume distribution improvements. This merging of preparatory steps creates a more accurate intermediate preform that reduces the complexity and material removal required in the subsequent finish forging stage, thereby maintaining production efficiency while improving precision.
4Manufacturing precision
If the cross-sectional area of pin and journal regions is reduced, then material distribution to arms improves, but the strength of critical regions may be compromised
Solution Approach 1:
The first preforming process performs preliminary reduction of cross-sectional area in pin and journal regions, creating an intermediate shape that redistributes material toward the arms. This preliminary action is followed by second preforming that refines the shape while maintaining adequate material in critical regions, ensuring both proper material distribution and sufficient strength through staged shaping.
Solution Approach 2:
The preforming processes apply local quality control by selectively reducing cross-sectional area in specific regions while maintaining or enhancing material concentration in critical load-bearing areas. This localized shaping ensures adequate material distribution to arms without compromising the strength of journals and pins, as each region is shaped according to its specific functional requirements.
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 enhances material yield and allows for the formation of a forged crankshaft with a precise shape by ensuring adequate material distribution and minimizing flash formation during the finish forging process.
Implementation Method 1
a billet is heated in a heating furnace
Implementation Method 2
a press performs pressing on the preform
Data Source
AI summary
Provided is a production method, including a first preforming process for obtaining a first preform from a billet, a second preforming process for obtaining a final preform from the first preform, and a finish forging process for forming the final preform into a finishing dimension of a forged crankshaft. In the first preforming process, a plurality of flat parts are formed by pressing pin-corresponding parts and journal-corresponding parts in a direction perpendicular to an axial direction of the billet. The second preforming process includes: a process of pressing regions to be a plurality of journals with a width direction of the flat part as a pressing direction by using a pair of first dies; and a process of, after starting pressing by the first dies, decentering regions to be a plurality of pins with the width direction of the flat part as a decentering direction by using second dies.