Crankshaft Shape Inspection Using Multi-Axis Optical Measurement
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Solution Overview
Problem
Existing crankshaft inspection methods are time-consuming and inaccurate due to the need for manual operation and limited ability to measure entire lengths, particularly failing to accurately assess vertical surfaces and distinguish between underfill and bend flaws.
Innovation Solution
A crankshaft shape inspection apparatus with multiple shape measuring devices positioned around the crankshaft to acquire partial shape information, allowing for relative movement and combination of data to generate a three-dimensional shape, enabling accurate estimation of pin, journal, and counterweight positions, and correction for inclination and position errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual inspection using plate gages is used, then inspection can be performed with simple equipment, but inspection accuracy varies due to individual differences and inspection time is excessive
Solution Approach 1:
The patent replaces manual mechanical inspection using plate gages and scales with an automated optical measurement system. The shape measuring device uses light projection and reception to automatically capture crankshaft geometry, eliminating human operators and manual tools. This substitution achieves consistent high-precision measurements while dramatically reducing inspection time, as the automated system can process multiple measurement points simultaneously without fatigue or individual skill variations.
Solution Approach 2:
The patent creates a digital three-dimensional copy of the crankshaft by combining partial shape information from multiple measurement positions. Instead of physically comparing the crankshaft against master gages, the system generates a virtual model that can be precisely analyzed against design specifications. This digital copying enables automated, repeatable measurements with sub-millimeter precision while eliminating the time-consuming manual comparison process.
2Measurement precision
If laser light is projected only in orthogonal direction to rotation center axis, then measurement setup is simple, but vertical surfaces of counterweights cannot be accurately measured
Solution Approach 1:
The patent transitions from one-dimensional light projection (orthogonal to rotation axis only) to multi-dimensional measurement by adding light projection in the axial direction of the rotation center axis. This dual-directional approach enables the shape measuring device to capture both the cylindrical surfaces and the vertical side surfaces of counterweights, achieving complete three-dimensional geometry acquisition without requiring complex mechanical positioning systems.
Solution Approach 2:
The patent designs the shape measuring device with multi-functional capability to measure different crankshaft features using the same device. By incorporating light projection in multiple directions and using image processing algorithms, the single measurement system can accurately capture journals, pins, and counterweight geometries without requiring separate specialized measurement equipment for each feature type.
3Productivity
If sampling inspection or limited inspection is performed, then inspection time is reduced, but inspection accuracy and completeness deteriorate
Solution Approach 1:
The patent implements continuous measurement action by rotating the crankshaft and continuously acquiring shape data at multiple positions around the entire crankshaft length. Rather than performing discrete sampling inspections, the system maintains continuous light projection and data acquisition throughout the measurement process, ensuring complete coverage of all crankshaft features including journals, pins, and counterweights without missing any potential defects.
Solution Approach 2:
The patent divides the crankshaft measurement into multiple segments or positions around the rotation axis. The shape measuring device acquires partial shape information at each angular position, then combines these segmented measurements into a complete three-dimensional model. This segmentation approach enables comprehensive inspection of the entire crankshaft while maintaining high productivity, as multiple measurement points are captured simultaneously at each position.
4Measurement precision
If multiple shape measuring devices are positioned around the crankshaft to measure entire length, then measurement completeness is improved, but device complexity and data processing requirements increase
Solution Approach 1:
The patent merges partial shape information from multiple measurement positions and devices into a single integrated three-dimensional model of the crankshaft. By combining the partial measurements through coordinate transformation and data fusion algorithms, the system achieves complete crankshaft geometry acquisition without requiring each individual device to measure the entire crankshaft independently, thus reducing the effective complexity of the measurement system.
Solution Approach 2:
The patent introduces an image processing unit as an intermediary that processes and integrates data from multiple shape measuring devices. This intermediary component performs coordinate system transformations, aligns measurements from different positions, and combines partial shape information into a unified three-dimensional model, thereby managing the complexity of multiple measurement devices through automated data fusion rather than manual integration.
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
Enables rapid and accurate inspection of crankshaft shapes, effectively distinguishing between underfill and bend flaws, and ensuring dimensional accuracy and weight balance.
Implementation Method 1
a projection unit which projects light and a light-receiving unit which receives light projected by the projection unit
Data Source
AI summary
Around a crankshaft (S) supported by a support device (10), a first shape measuring device (31) to a fourth shape measuring device (34) are disposed, and the crankshaft (S) and the first shape measuring device (31) to the fourth shape measuring device (34) are relatively movable in an axial direction (X direction) of the crankshaft (S). The first shape measuring device (31) and the third shape measuring device (33) are disposed so as to face to one X direction and acquire partial shape information (including the other side surfaces in the X direction of counterweights (S2)) of the crankshaft S, and further, the second shape measuring device (32) and the fourth shape measuring device (34) are disposed so as to face to the other X direction and acquire partial shape information (including one side surfaces in the X direction of the counterweights (S2)) of the crankshaft S. This makes it possible to accurately inspect a shape of the crankshaft (S) in a short time.