Dielectric Surface Layer for Uniform Resin Heating
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Solution Overview
Problem
Existing electromagnetic wave irradiation methods for thermoplastic resins face challenges in effectively absorbing electromagnetic waves, leading to inconsistent heating and poor dimensional accuracy, especially for parts with varying thickness or complex shapes.
Innovation Solution
An electromagnetic wave irradiation molding apparatus with a surface layer on the mold's inner wall surface that absorbs specific electromagnetic waves, allowing heat conduction to the thermoplastic resin, which then absorbs and re-emits waves for uniform heating, combined with a vacuum system to reduce cavity volume and enhance resin flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If electromagnetic waves with wavelength of 0.01 m to 100 m are irradiated from the mold surface, then the thermoplastic resin is heated more strongly than the rubber mold due to difference in physical properties, but depending on the type of thermoplastic resin, the electromagnetic waves are not effectively absorbed
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the electromagnetic wave source and the thermoplastic resin. This dielectric layer has high electromagnetic wave absorption capability and converts the waves into heat, which is then transferred to the resin. This mediator ensures consistent and effective heating regardless of the resin type's inherent absorption properties.
Solution Approach 2:
The patent changes the physical parameters of the mold surface by coating it with a dielectric layer having specific electromagnetic properties. This layer has high dielectric constant and loss tangent, enabling it to absorb electromagnetic waves effectively and convert them to thermal energy, thereby improving heating reliability across different resin types.
2Temperature
If a surface layer with infrared absorption capability is formed on the mold inner wall, then the surface layer absorbs electromagnetic waves, but the inner part of the thermoplastic resin is likely to be unable to be sufficiently heated
Solution Approach 1:
The patent replaces conventional thermal conduction heating with electromagnetic wave-based dielectric heating. The dielectric layer absorbs electromagnetic waves and generates heat throughout its volume, which is then transferred to the resin. This substitution enables more uniform heat distribution that penetrates to the resin interior, not just the surface.
Solution Approach 2:
The mold structure is transformed into a composite system consisting of the rubber mold base and a dielectric functional layer. This composite structure combines the flexibility of rubber with the electromagnetic wave absorption and heat generation capabilities of the dielectric material, enabling both surface and internal heating of the resin.
3Productivity
If electromagnetic waves are irradiated to heat the thermoplastic resin, then heating speed is improved, but uniform heating of molded articles with varying thickness or complex shapes cannot be achieved
Solution Approach 1:
The dielectric layer is applied selectively on the mold surface areas that require enhanced heating. For molded articles with varying thickness or complex shapes, the layer can be concentrated on thin-walled or difficult-to-reach areas that need additional heat input to achieve uniform melting and filling, while thicker areas receive heat through conventional conduction.
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 method enables the stable formation of thermoplastic resin articles with varying thickness and complex shapes, achieving high dimensional accuracy and excellent surface appearance by ensuring uniform heating and efficient resin distribution.
Implementation Method 1
a surface layer having a capability to absorb specific electromagnetic waves is formed on at least part of the inner wall surface of the cavity
Implementation Method 2
the thermoplastic resin near the surface layer is heated by heat conduction from the surface layer
Implementation Method 3
the thermoplastic resin itself starts to effectively absorb the specific electromagnetic waves. As a result, the thermoplastic resin itself produces heat
Implementation Method 4
vacuum means for evacuating an inside of the cavity
Data Source
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AI summary
An electromagnetic wave irradiation molding apparatus 1 includes a mold 2 made of an insulating material and electromagnetic wave irradiation means 4 for irradiating specific electromagnetic waves X including a wavelength region of 0.01 m to 100 m. The mold 2 is separated into mold parts 2A and 2B, between which a cavity 20 to be filled with a thermoplastic resin 6 is provided to form a molded article. A surface layer 3 having a capability to absorb the specific electromagnetic waves X is formed on at least a part of an inner wall surface of the cavity 20.