Injection Mold with Segmented Steam Channels for Hollow EPS Elements
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Solution Overview
Problem
Existing injection molding molds for expanded polystyrene struggle to produce hollow elements with thin walls, resulting in non-homogeneous bead holding and surface quality issues due to steam flow circumventing cores, and current methods for producing hollow parts are either inefficient or costly.
Innovation Solution
A mold design with external and internal water vapor filters surrounding the molding volume and core, ensuring steam flows uniformly through the entire wall, combined with a method involving sequential steam passage directions and pressure control to ensure complete filling and welding of expanded polystyrene beads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a core is placed in the mold to create hollow elements, then hollow shapes can be formed, but steam flow encounters the core and bypasses it, resulting in non-homogeneous bead holding and uneven surface finishes
Solution Approach 1:
The steam supply system is segmented into two independent channels: one supplying steam to the external surface and another supplying steam to the internal surface through the core. This segmentation allows each channel to independently control steam flow to its respective surface, ensuring homogeneous bead holding on both external and internal surfaces without interference from the core structure.
Solution Approach 2:
Different regions of the mold are provided with different steam supply characteristics. The external surface receives steam through one distribution system while the internal surface (facing the core) receives steam through a separate distribution system. This local differentiation ensures that each surface receives optimized steam flow for uniform bead adhesion, resolving the non-homogeneity caused by the core presence.
2Shape
If separately molded elements are assembled to create hollow parts, then hollow shapes can be achieved, but the manufacturing process becomes more time-consuming and expensive
Solution Approach 1:
The mold design merges the capability to produce hollow elements directly into a single-mold process. By incorporating a core with internal steam supply channels within the same mold cavity, the system can produce complete hollow elements in one injection and steaming cycle, eliminating the need for separate molding and assembly operations for multiple elements.
Solution Approach 2:
The core serves multiple functions: it defines the internal geometry of the hollow element, provides a pathway for steam distribution to the internal surface, and acts as a structural support during the molding process. This multi-functionality allows single-mold production of hollow elements with complex internal geometries, significantly improving productivity compared to assembly methods.
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 approach allows for the rapid and cost-effective production of hollow elements with high homogeneity and smooth surfaces, enabling the creation of complex shapes with good geometric precision and dimensional stability.
Implementation Method 1
Polystyrene that has undergone initial expansion with steam is injected into a mold. A stream of steam is then delivered through the mold, passing through the formed element to complete the expansion of the beads, which then adhere to one another, uniformly filling the mold.
Implementation Method 2
by covering the exterior and interior surfaces of the molding volume with filters located on both sides of the wall of the hollow element, a flow of water vapor is obtained in one direction or the other, which is forced to pass through the entire wall.
Implementation Method 3
The metal is then poured through an exposed portion of the casting system into the channels. By melting the expanded polystyrene, the elements are completely filled, resulting in parts with complex shapes, good geometric accuracy, and a smooth surface finish that replicates that of the model.
Data Source
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AI summary
Injection mold for a hollow expanded polystyrene element (12), having sides (2, 4) that can be opened containing a molding volume forming the outer surface of the hollow element (12), this molding volume being equipped with external water vapor passage filters (24) distributed over this outer surface, which is connected to a first water vapor supply channel (20) passing through the sides (2, 4), and having a core (14) disposed in the molding volume, forming the inner surface of the hollow element (12), which is equipped with internal water vapor passage filters (34) distributed over this inner surface, connected to a second water vapor supply channel (30) passing through the core (14).