Hollow Workpiece Positioning Using Core-Based Reference Points
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Solution Overview
Problem
Existing methods for positioning hollow workpieces with complex shapes, such as those in aviation, face challenges due to uncertainties in the placement of sacrificial cores during casting, leading to inaccuracies in machining internal structures.
Innovation Solution
A positioning method utilizing a frame of reference comprising at least three reference points from the surfaces defined by the sacrificial core, which directly associates with the shape and internal structures of the workpiece, allowing for accurate orientation and machining without randomness in core placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional positioning references on raw cast surfaces are used, then positioning is simple, but machining precision deteriorates due to core placement variability
Solution Approach 1:
The patent applies preliminary action by creating positioning references on the core before casting. The core is equipped with reference elements (such as pins, holes, or surfaces) that define the position of internal walls beforehand. This ensures that even though the core may shift during casting, the relationship between the reference elements and the internal walls remains known and controllable, allowing precise positioning during subsequent machining operations.
2Ease of operation
If reference points are placed on mold surfaces, then positioning is straightforward, but accuracy deteriorates due to dispersion in raw casting dimensions
Solution Approach 1:
The patent uses the sacrificial core as an intermediary to establish positioning references. Instead of relying directly on the mold surfaces which have dimensional dispersion, the core serves as a mediator that carries reference elements. These reference elements are positioned relative to the core geometry, which then defines the internal wall positions. This intermediary approach decouples the positioning system from the variable mold surfaces.
3Ease of manufacture
If cores are positioned with small margins of error during casting, then casting is easier, but machining accuracy deteriorates due to offset between reference frame and internal structures
Solution Approach 1:
The patent applies preliminary action by equipping the core with reference elements before casting. These reference elements (pins, holes, surfaces) are precisely positioned on the core to define the location of internal walls. Even if the core shifts during casting, the relationship between the reference elements and the internal walls remains known, allowing the machining system to compensate for the shift and maintain accuracy.
Data Source
AI summary
A method is for positioning a hollow workpiece obtained by casting and that enables the workpiece obtained in this way to be machined in accurate manner. The workpiece is obtained by a casting method involving a mold and a sacrificial core inserted inside the mold and serving to form at least one cavity in the workpiece. The workpiece includes surfaces of a first type defined during casting by the surfaces of the mold, and surfaces of a second type defined during casting by the surfaces of the core. A frame of reference for positioning the workpiece is constructed that includes at least three reference points (P1-P3) belonging to surfaces of the second type of the workpiece.