Heat-Insulating Cavity Mold for Thermoplastic Resin Molding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional heat-insulating molds for thermoplastic injection molding face issues with mechanical stability, thickness variation, internal stress, and sink marks on molded surfaces, particularly on rib and boss features, due to inadequate adhesion and cooling shrinkage compensation.
Innovation Solution
A heat-insulating cavity mold is produced using a method that involves forming heat-insulating layers on joined metallic surface and cavity body members, followed by milling or discharge machining to create a thin metallic surface layer, and using materials with specific heat conductivities to enhance adhesion and cooling control, thereby improving durability and preventing sink marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thin metallic layer is formed by electroforming on a heat-insulating layer, then the heat capacity of the mold surface is reduced and surface luster transfer is improved, but the adhesive strength between layers is insufficient and thickness variation occurs
Solution Approach 1:
The patent changes the formation method of the metallic layer from electroforming to a new process involving application of metallic powder or slurry followed by heating treatment. This parameter change in the manufacturing process achieves both thin layer formation (0.01-0.5mm) and strong adhesion to the heat-insulating layer, while maintaining uniform thickness and excellent surface luster transfer properties
Solution Approach 2:
The patent creates a composite structure with a heat-insulating layer (ceramic or heat-resistant resin) combined with a thin metallic layer (nickel, copper, aluminum, or their alloys). This composite material approach provides both the heat insulation needed for surface temperature control and the metallic surface properties for luster transfer, while the heating treatment ensures strong bonding between the composite layers
2Temperature
If a metallic layer is formed on the heat-insulating layer, then the surface temperature rise during resin filling is improved, but sink marks occur on rib and boss surfaces due to inadequate cooling shrinkage compensation
Solution Approach 1:
The patent applies different thermal properties to different regions by controlling the metallic layer thickness and composition locally. The thin metallic layer (0.01-0.5mm) allows rapid heat transfer to the heat-insulating layer, creating localized thermal zones that compensate for cooling shrinkage at critical areas like ribs and bosses, preventing sink marks while maintaining overall surface temperature control
Solution Approach 2:
The patent utilizes thermal expansion and contraction principles where the thin metallic layer and heat-insulating layer expand and contract at different rates during heating and cooling cycles. This differential thermal behavior compensates for resin cooling shrinkage, preventing sink marks on raised features while maintaining surface quality
3Ease of manufacture
If electroforming is used to form the metallic layer, then the manufacturing process is established, but the metallic layer has high internal stress and easy breakage
Solution Approach 1:
The patent fundamentally changes the manufacturing parameter from electroforming to a powder/suspension application method followed by heating treatment. This new process eliminates the high internal stress inherent in electroformed layers, produces uniform thickness without variation, and creates a metallic layer with superior mechanical strength and breakage resistance while maintaining ease of manufacture
Solution Approach 2:
The patent replaces the electrochemical deposition mechanism (electroforming) with a thermal processing mechanism involving powder application and heating treatment. This substitution eliminates the internal stress problems associated with electroforming and produces a more mechanically robust metallic layer
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
The new method achieves stable durability, increased adhesive strength, reduced sink marks, and improved surface transfer without external assisting means, resulting in high-performance molds with beautiful appearances and effective sink prevention.
Implementation Method 1
the cavity surface is instantaneously raised in temperature due to the quantity of heat of the resin
Implementation Method 2
thereafter, the heat is quickly released and the temperature is lowered
Data Source
AI summary
A process for producing a heat-insulating cavity mold, characterized by producing two members, i.e., a metallic surface layer member (1) for forming a metallic surface layer (5) of a cavity mold in a mold for thermoplastic resin molding and a cavity mold main body member (9) for forming the cavity mold, forming a heat-insulating layer (10′) on a bonding surface of the member (9), bonding the two members to each other, and subsequently eliminating an unnecessary part (3, 12) of the metallic surface layer member to form the metallic surface layer (5); a heat-insulating cavity mold; and a mold for thermoplastic resin molding which employs the cavity mold. The mold for thermoplastic resin molding is characterized by being a heat-insulating mold comprising: the heat-insulating cavity mold produced by the production technique from a metallic surface layer member made of a metal having low thermal conductivity and a cavity mold main body member made of a metal having high thermal conductivity; and a core mold produced from an SUS steel material for molds.