Vehicular Resin Molded Article Gate Mark Design
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Solution Overview
Problem
High-temperature molten resin used in injection molding can lead to insufficient solidification of the vehicular resin molded article at the valve pin contact area, resulting in 'string drawing' or 'silver streak' defects, which lower moldability.
Innovation Solution
The vehicular resin molded article features a concave gate mark with a specific L/T ratio, a flat or curved outer opening edge, and a conical or spherical surface shape, increasing the contact area and reducing temperature of the valve pin tip end portion, thereby improving solidification and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-temperature molten resin is used to increase fluidity for thin vehicular resin molded articles, then the fluidity of molten resin is improved, but the tip end portion of the valve pin becomes high temperature causing insufficient solidification and defects such as string drawing or silver streak
Solution Approach 1:
The gate mark is designed with a specific depth-to-diameter ratio (20% or more) to create a localized deep concave structure at the valve pin contact area. This local geometric modification increases the contact area between the valve pin and molten resin, enhancing heat dissipation precisely where needed without changing the overall molding temperature settings.
Solution Approach 2:
The invention transitions from a shallow planar gate mark to a deep concave three-dimensional structure. By increasing the depth dimension (making the gate mark depth at least 20% of its diameter), the valve pin contact area is significantly enlarged, providing additional surface area for heat transfer and improved solidification control.
2Ease of manufacture
If the valve pin tip end surface is formed in a planar shape with slight penetration into molten resin, then the gating function is achieved, but a shallow recess gate mark remains on the vehicular resin molded article
Solution Approach 1:
The gate mark geometry is changed by modifying the depth parameter. The concave portion depth is set to be 20% or more of the gate mark diameter, transforming the appearance from a shallow surface imperfection to a controlled deep concave feature that can be designed to match aesthetic requirements or be positioned in non-visible areas.
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 increased contact area and optimized gate mark design enhance solidification, minimizing 'string drawing' and 'silver streak' occurrences, thus improving the moldability and strength of the vehicular resin molded article.
Implementation Method 1
a structure called a hot runner system which flows the molten resin toward the cavity while heating the molten resin by a heater
Implementation Method 2
the tip end portion of the valve pin may also become a high temperature due to transfer of heat from the molten resin
Implementation Method 3
formed by solidifying a molten resin filled in a cavity of an injection mold
Data Source
AI summary
A vehicular resin molded article is formed by solidifying a molten resin filled in a cavity of an injection mold and having a concave gate mark formed by a valve pin and remaining thereon in which L/T is 190 or more where L is a flow distance of the molten resin from the gate mark to a filling terminal and T is a maximum thickness. When the valve pin is moved to the cavity side and is pressed against the molten resin, since the contact area of a tip end portion with respect to the molten resin in the vehicular resin molded article increases and the temperature of the tip end portion in the valve pin tends to decrease, the portion of the vehicular resin molded article where the valve pin is pressed against is sufficiently solidified and string drawing or silver streak is less likely to occur.