Vehicle Outer Trim Molding for Flow-Line-Free Luminous Regions
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Solution Overview
Problem
Existing methods for producing exterior trim parts with transparent and translucent regions in injection molding result in visible flow lines due to differences in material properties, which are exacerbated by subsequent paint coatings.
Innovation Solution
The method involves feeding two plastic materials into a common multi-material sprue or channel, allowing them to combine before entering the cavity, and using a heating device to optimize bonding, reducing flow lines and enhancing material adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate single-material sprues are used to inject different plastic materials into the cavity, then the injection molding process can be performed, but flow lines form on the trim element due to differences in material properties
Solution Approach 1:
The patent merges separate single-material sprues into a single common multi-material sprue that feeds both plastic materials into the cavity simultaneously. This consolidation allows the materials to be injected through the same pathway, ensuring they meet and bond properly at the flow fronts without forming visible flow lines, thus resolving the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The patent applies preliminary heating to the common multi-material sprue before injection, ensuring both plastic materials are at optimal temperatures for bonding before they meet in the cavity. This preliminary thermal preparation prevents flow line formation by ensuring proper material compatibility and adhesion, thereby improving manufacturing precision while maintaining ease of manufacture.
2Ease of manufacture
If a paint coating is applied to the trim part, then aesthetic appearance is improved, but flow lines become more visible and pronounced
Solution Approach 1:
The patent performs preliminary heating of the common multi-material sprue and optimization of injection parameters before the paint coating is applied. This ensures that flow lines are minimized or eliminated at the source, so that subsequent paint application enhances aesthetic appearance without accentuating flow line defects.
3Ease of manufacture
If the two plastic materials meet in the cavity during injection, then the trim element can be formed, but the bond strength between materials is reduced due to cooling and gas reaction
Solution Approach 1:
The patent applies preliminary heating to the common multi-material sprue, ensuring both plastic materials maintain optimal bonding temperatures as they travel through the sprue and meet in the cavity. This preliminary thermal preparation prevents premature cooling and gas reaction, thereby maximizing bond strength while maintaining ease of manufacture.
Solution Approach 2:
The patent changes the thermal parameters of the injection molding process by heating the common multi-material sprue, thereby altering the temperature at which materials meet and bond in the cavity. This parameter change ensures materials bond at higher temperatures for stronger adhesion, resolving the contradiction between ease of manufacture and bond strength.
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 minimizes disruptive flow lines and increases the bond strength between plastic materials, resulting in a more uniform transition and improved aesthetic appearance.
Implementation Method 1
using a heating device to optimize bonding
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The invention relates to a method for producing an exterior trim part from plastic materials for a vehicle (V), wherein the exterior trim part comprises a thin-walled trim element (1) with a designated visible side (A) and an inner side opposite the visible side (A), wherein the trim element (1) is produced in an injection molding process in an injection molding tool (2) in a cavity (5). The trim element (1) has at least one first region (10) consisting of a first plastic material (6), and the trim element (1) further has at least one second transparent or translucent region (11) consisting of a second plastic material (7), wherein the method comprises the following steps.A step of molding the cladding element (1), which consists in injecting the first plastic material (6) to form the first region (10) and the second plastic material (7) to form the second region (11) into the cavity, at least one step of partially or completely arranging a cover layer (13) on the first (10) and the second region (11) of the molded cladding element (1), and at least one step of removing part of the cover layer (13) or the entire cover layer (13) in the at least one luminous region (12), wherein the luminous region (12) lies at least partially, preferably completely, within the transparent or translucent region (11) of the injection-molded cladding element (1).Wherein the first plastic material (6) and the second plastic material (7) are guided into the cavity (5) via at least one common multi-material sprue (8) or a common multi-material sprue channel (8), wherein the two plasticized and/or flowable plastic materials (6, 7) already meet in the common multi-material sprue (8) or in the common multi-material sprue channel (8) and are subsequently guided together into the cavity (5) and injected.