Deep-Drawn Composite Sheet Molding with Dynamic Holding Forces
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Solution Overview
Problem
Existing methods for molding composite plastic sheet materials to form deep-drawn articles often result in wrinkling, tearing, or ripping, especially when exposed to high temperatures, and lack desirable acoustic properties and appearance.
Innovation Solution
A method involving compression molding of composite plastic sheet material using a heated blank positioned over a female die with controlled holding forces to prevent wrinkling, tearing, and ripping, allowing for a single stamping step and the production of lightweight articles with excellent appearance and acoustical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If composite plastic sheet material is forced into the female die without controlled holding forces, then the deep-drawn article can be formed, but wrinkling, tearing, or ripping occurs due to uncontrolled material flow
Solution Approach 1:
The patent applies dynamic holding forces that vary during the deep-drawing process. The holding force is applied initially to prevent wrinkling during material flow, then reduced or removed to allow controlled stretching without tearing. This dynamic adjustment of constraints resolves the contradiction between preventing surface defects and maintaining structural integrity.
Solution Approach 2:
The patent applies holding forces preliminarily during the material flow stage to prevent wrinkling and tearing before the deep-drawing is complete. This preliminary control of material flow ensures that when the material is subsequently stretched, it does so uniformly without developing defects, thus resolving the contradiction between surface quality and structural integrity.
2Manufacturing precision
If multiple stamping steps are used to form deep-drawn articles, then manufacturing precision can be improved, but productivity decreases and production cost increases
Solution Approach 1:
The patent combines multiple stamping operations into a single stamping step by applying controlled holding forces during the material flow and stretching phases. This merging of operations achieves the precision that would otherwise require multiple steps while maintaining high productivity, thus resolving the contradiction between manufacturing precision and production volume.
Solution Approach 2:
The patent changes the parameters of the deep-drawing process by applying controlled holding forces during material flow, which enables a single stamping step to achieve the quality previously requiring multiple steps. This parameter change allows high-volume production without sacrificing precision, resolving the contradiction between production speed and article quality.
3Ease of manufacture
If composite plastic sheet material is heated to high temperatures during molding, then material flow and forming are improved, but wrinkling and tearing occur due to reduced material strength
Solution Approach 1:
The patent applies holding forces preliminarily during the heated material flow stage to prevent wrinkling and tearing before the material strength is compromised by high temperature. This preliminary constraint ensures that when the material is subsequently stretched at high temperature, it does so without developing defects, thus resolving the contradiction between formability and strength.
Solution Approach 2:
The patent applies dynamic holding forces during the high-temperature deep-drawing process. The holding force is applied initially to prevent defects during material flow at high temperature, then reduced to allow controlled stretching. This dynamic adjustment enables high formability while preventing strength loss from causing wrinkles or tears.
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 method enables the production of deep-drawn articles that controllably stretch without wrinkling or tearing, achieving high volume production at low cost with improved appearance and acoustic properties, suitable for automotive applications.
Implementation Method 1
forcing an inner portion of the heated blank into the article-defining cavity along a substantially vertical axis and against the inner surfaces of the female die to obtain deep-drawn material
Implementation Method 2
controllably holding outer peripheral portions of the blank adjacent the article-defining cavity with corresponding holding forces to guide material flow into the cavity
Implementation Method 3
the deep-drawn material controllably stretches during the step of forcing without wrinkling, tearing or ripping
Data Source
AI summary
A method of molding composite plastic sheet material to form a compression molded, deep-drawn article is provided. The method includes placing a heated blank of moldable, composite plastic sheet material over a female die having an article-defining cavity defined by inner surfaces of the die so that the heated blank has a predetermined position and orientation over the cavity. Then an inner portion of the heated blank is forced into the cavity along a substantially vertical axis and against the inner surfaces of the die to obtain deep-drawn material. Outer peripheral portions of the heated blank adjacent the cavity are controllably held with corresponding predetermined holding forces based on the size and shape of the article to resist movement of the outer peripheral portions towards the cavity during the step of forcing wherein the deep-drawn material controllably stretches during the step of forcing without wrinkling, tearing or ripping.