Crankshaft Center Hole Determination via Mold Misalignment Compensation
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Solution Overview
Problem
Existing methods for determining the center hole of a crankshaft, such as those described in Japan Laid-open Patent Applications JP-A-H09-174382 and JP-A-S51-076682, are either time-consuming and costly due to the need for extensive sampling and statistical processing or require expensive dynamic balance tests, and often result in imbalance issues due to uneven thickness and misalignment in crankshaft counterweights.
Innovation Solution
A method that measures and compares shape data from portions of the crankshaft molded by top and bottom molds to compute misalignment, allowing for the accurate reproduction of the actual shape and determination of the center hole position to achieve rotational balance within a predetermined range, without the need for expensive balance meters or extensive sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extensive sampling and statistical processing are performed to determine center hole position, then the determination accuracy is improved, but the processing time and cost increase significantly
Solution Approach 1:
The invention extracts only the essential measurement data needed for center hole determination - specifically measuring the actual positions of counterweights and journals directly on the crankshaft, rather than performing extensive sampling. This extraction of critical information allows accurate determination without time-consuming statistical processing
Solution Approach 2:
The invention creates a simplified digital model (copy) of the crankshaft geometry based on direct measurements of key features. This digital replica contains only the necessary information for center hole calculation, eliminating the need for extensive physical sampling and statistical analysis while maintaining determination accuracy
2Measurement precision
If dynamic balance tests are conducted to determine center hole position, then the rotational balance accuracy is improved, but the equipment cost and measurement complexity increase
Solution Approach 1:
The invention replaces complex mechanical balance testing equipment with a simplified measurement system that directly measures the positions of counterweights and journals. By using basic dimensional measurements and computational geometry instead of sophisticated balance meters, the system achieves rotational balance accuracy without requiring expensive or complex equipment
Solution Approach 2:
The invention creates a computational model that simulates the balance characteristics of the crankshaft based on measured geometry. This digital copy allows balance analysis to be performed through calculation rather than physical testing, eliminating the need for complex balance testing equipment
3Ease of manufacture
If misalignment between top and bottom molds is not compensated, then the manufacturing process is simpler, but the crankshaft exhibits rotational imbalance due to uneven counterweight thickness
Solution Approach 1:
The invention performs preliminary measurement of the actual counterweight and journal positions after molding but before final machining. By detecting mold misalignment effects early in the process, the system can calculate and compensate for the imbalance by adjusting center hole positions, thereby maintaining rotational balance without requiring complex real-time control during molding
Solution Approach 2:
The invention implements a feedback mechanism where the actual measured positions of counterweights and journals are used to calculate the optimal center hole location. This feedback loop compensates for mold misalignment effects by adjusting the center hole position based on actual geometry, ensuring rotational balance is achieved despite variations in the molding process
Data Source
AI summary
A method of determining a center hole of a material crankshaft, which is obtained through molding with first and second molds, includes: obtaining first shape data of a first portion of the material crankshaft molded by the first mold and second shape data of a second portion of the material crankshaft molded by the second mold; comparing the first and second shape data respectively with first and second designed data corresponding to the first and second molds, respectively, for computing a misalignment amount of each of the first and second portions due to misalignment between the first and second molds; adjusting, based on the misalignment amount, data corresponding to the misalignment amount to reproduce actual shape data; and determining, based on the actual shape data, a position of the center hole in the material crankshaft such that a rotation balance of the material crankshaft is within a predetermined range.