Molded Foam Ejector Pin Design to Reduce Inclined-Face Recess Depth

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Solution Overview

Problem

Molded foams with inclined pressed portions relative to the mold opening direction experience strength degradation and releasability issues due to the formation of deep recesses for ejector pin extrusion, leading to scratches and increased perpendicular pressing forces.

Innovation Solution

The method involves manufacturing molded foams with an inclined face that includes a recess configured for ejector pin extrusion, where the ejector pin's tip surface has a first extruding surface perpendicular to the mold opening direction and a second extruding surface inclined relative to the first, reducing the depth and size of the recess.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the entire tip surface of the ejector pin is formed perpendicular to the mold opening direction to press the molded foam, then the molded foam can be extruded effectively, but a deep recess must be formed on the inclined outer surface which degrades the strength around the recess

Engineering Contradiction:

Improvereleasability from moldVSAvoidstrength around recess

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The tip surface of the ejector pin is segmented into two distinct surfaces: a first extruding surface perpendicular to the mold opening direction, and a second extruding surface inclined relative to the first. This segmentation allows the pressing action to be distributed across different orientations, reducing the need for deep recesses while maintaining effective extrusion capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the tip surface are given different orientations and functions: the first extruding surface (perpendicular) provides primary extrusion force, while the second extruding surface (inclined) accommodates the inclined face of the molded foam. This local differentiation optimizes the pressing action for each specific region, reducing overall recess depth and preserving structural strength.

Inventive Principle:

Principle #3Local quality

2Force

If the tip surface of the ejector pin is formed parallel to the outer surface of the molded foam without forming a recess, then the pressing force increases in the direction perpendicular to the extrusion direction, but the tip surface slips on the outer surface causing scratches and degrading releasability

Engineering Contradiction:

Improvepressing forceVSAvoidscratches on outer surface

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The tip surface employs an asymmetric configuration with two surfaces at different angles rather than a single symmetric surface. The first extruding surface is perpendicular to the mold opening direction while the second is inclined, creating an asymmetric pressing pattern that directs force appropriately along the extrusion direction while minimizing perpendicular force that would cause slipping and scratches.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Instead of making the entire tip surface parallel to the inclined outer surface (which would increase perpendicular force), the invention inverts the approach by using a perpendicular first surface combined with an inclined second surface. This inversion of the conventional single-surface design allows force to be applied more effectively in the extrusion direction while reducing harmful perpendicular components.

Inventive Principle:

Principle #13The other way round (Inversion)

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 configuration maintains sufficient pressing force in the mold opening direction while minimizing perpendicular forces, preventing scratches and strength degradation, ensuring smooth release and improved releasability.

Implementation Method 1

The ejector pin has a tip surface that pushes the molded foam out of the one of the pieces of the mold

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

The tip surface has: a first extruding surface that is perpendicular to the mold opening direction and forms a bottom face of the recess; and a second extruding surface that is inclined relative to the first extruding surface

Methodology Applied

Scientific EffectForce Vector Decomposition: Mechanical Force

Data Source

PatentUS12358191B2Method for manufacturing molded foam, and molded foam

Publication Date: 2025.07.15 SEKISUI PLASTICS CO LTD

AI summary

Provided are a method for manufacturing a molded foam, and a molded foam. A method for manufacturing a molded foam includes: a molding step of molding the molded foam; and a releasing step of opening a fixed mold and a mobile mold and extruding the molded foam from the fixed mold by an ejector pin. The molded foam has an inclined face that is inclined relative to a direction of opening the mold. The inclined face has a recess for extruding of the molded foam by the ejector pin. The tip surface of the ejector pin has a first extruding surface that is perpendicular to the mold opening direction and forms a bottom face of the recess, and a second extruding surface that is inclined relative to the first extruding surface.