Multi-part Core with Movable Mandrel for Draft-Free Demolding
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Solution Overview
Problem
Conventional casting molds require draft angles for demolding, leading to material waste, increased machining complexity, and a higher risk of defects like shrinkage cavities and gas pockets due to uneven wall thicknesses.
Innovation Solution
A multi-part core with longitudinally movable mandrel and transversely moving core segments that assume different positions to form and demold without draft angles, using a wedge slide mechanism and springs for operation, allowing for precise casting and reduced post-processing needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If draft angles are used on cores or slides to enable demolding, then the casting can be removed from the mold, but excess material is created that requires time-consuming machining and increases material consumption
Solution Approach 1:
The core is divided into multiple core segments that can move independently relative to each other. This segmentation allows the core to change its shape during the demolding process, enabling the casting to be removed without requiring draft angles on the core surfaces, thus eliminating excess material generation.
Solution Approach 2:
The core transitions from a static structure to a dynamic one where core segments can change position. By making the core dynamic, it can adapt its geometry during different stages of the casting process - maintaining a compact shape during injection and expanding or reconfiguring during demolding to avoid contact with the casting surface.
2Ease of operation
If draft angles are used on cores or slides to enable demolding, then the casting can be removed from the mold, but the wall thickness becomes non-uniform which increases the risk of defects such as shrinkage cavities and gas inclusions
Solution Approach 1:
Dividing the core into multiple segments allows precise control over the demolding process. Each segment can be positioned to maintain uniform clearance from the casting, ensuring even cooling and solidification that prevents defects while still enabling successful demolding.
Solution Approach 2:
The invention changes the geometric parameters of the core during the demolding process. By adjusting the position and configuration of core segments, the core maintains optimal dimensions that ensure uniform wall thickness in the casting, preventing defects while enabling demolding.
3Manufacturing precision
If multi-part slides with opposing inclined directions are used to form internal contours, then draft angles are not required, but the device complexity increases with multiple slides and inclined surfaces
Solution Approach 1:
The core is segmented into multiple movable segments that work together to form the internal contour. This segmentation replaces the need for multiple complex slides with inclined surfaces, achieving the same precision in internal contour formation with a simpler overall structure.
Solution Approach 2:
Instead of using inclined surfaces to move core segments (as in conventional slides), this invention inverts the approach by having core segments move on surfaces that are perpendicular to the injection direction. This inversion simplifies the mechanical structure while maintaining the ability to form complex internal contours without draft angles.
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 design minimizes machining allowances, reduces material consumption, and lowers the risk of defects by enabling demolding without draft angles, resulting in more uniform wall thickness and improved casting quality.
Implementation Method 1
the core segments are moved or displaced transversely to the direction of movement of the mandrel when the mandrel is moved longitudinally
Implementation Method 2
using a wedge slide mechanism and springs for operation
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a mold (100) for producing a casting (200) which has at least one internal contour, comprising: - a mold cavity corresponding to the dimensions of the casting (200); and - at least one core (140) arranged in the mold cavity for forming the internal contour, wherein this core (140) is a component of the mold (100). According to the invention, the core (140) is multi-part and has several movable core segments (146) as well as a mandrel (141) arranged longitudinally displaceable between the core segments (146), wherein the core segments (146) are displaced transversely to the direction of movement of the mandrel (141) when the mandrel (141) is moved longitudinally and can be moved into a casting position by extending the mandrel (141) and into a demolding position by retracting the mandrel (141).