Molded Part Edge Pair Alignment via Segmented Back-Injection
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Solution Overview
Problem
Existing methods for producing molded parts with visible surfaces featuring different materials often result in visible seams or deformation, particularly when using sensitive materials like textiles or plastics, which compromises the quality and appearance of the final product.
Innovation Solution
A method utilizing a molding device with a movable slide device that positions preformed shaped films with bent edges adjacent to each other, allowing for minimal contact and gentle fixation to prevent deformation, and introducing carrier materials in a way that encloses the edges to create a seamless transition between surface areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high pressure is applied by the slide to hold the edge pair together during back-injection, then the edge pair is firmly enclosed and fixed, but the masking materials with sensitive surfaces are deformed or damaged
Solution Approach 1:
The molding process is divided into two distinct phases: first, the edge pair is enclosed in a separate small partial mold cavity and back-injected at lower pressure; second, the slide is retracted and the remaining areas are back-injected over a large area. This segmentation allows different pressure levels to be applied to different regions, protecting sensitive masking materials while ensuring proper edge pair formation.
Solution Approach 2:
The edge pair is pre-fixed by back-injection into a separate small partial mold cavity before the main back-injection process. This preliminary action secures the edge pair alignment in advance, allowing the subsequent large-area back-injection to proceed without requiring high pressure on the masking materials, thus preventing deformation.
2Manufacturing precision
If a nose-like tapered projection is used to support the edges of the masking materials, then the masking materials are held in shape during back-injection, but a pronounced joint is created in the transition area of the finished molded part
Solution Approach 1:
The problematic nose-like tapered projection that caused pronounced joints is removed from the molding tool design. Instead, the edge pair is enclosed in a separate small partial mold cavity defined by the slide components, which eliminates the need for tapered projections and prevents the creation of visible joints in the finished product.
3Strength
If the slide components are driven against the masking materials with relatively high pressure, then the edge pair is held together during injection, but the masking materials with sensitive surfaces suffer damage
Solution Approach 1:
The bonding process is segmented into two stages with different pressure applications: first, lower pressure is used to enclose the edge pair in a separate small partial mold cavity; second, after the slide is retracted, the main back-injection occurs over a large area. This ensures adequate bonding strength while avoiding high-pressure damage to sensitive masking materials.
Solution Approach 2:
The edge pair is preliminarily bonded by back-injection into a separate small partial mold cavity before the main injection process. This preliminary bonding establishes sufficient strength without requiring high pressure on the masking materials during the subsequent large-area back-injection, thus preventing damage.
Data Source
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AI summary
A method for producing a molded part (17) with a visible surface (18) with different surface areas is described, wherein the method is carried out using a molding device (1) which comprises a die (2) and a core (3) with a movable slide device (4), characterized in that first an arrangement of a plurality of mold sheets (7, 8, 19) with at least one folded edge area each on the die (2) and/or on the core (3) is made such that after closing the molding device (1) at least two mold sheets (7, 8) are arranged next to each other, so that a first edge (9) of the folded edge area of a first mold sheet (7) and a first edge (10) of the folded edge area of a second mold sheet (8) lie at least partially directly next to each other, so that an edge pair (11) is formed.The forming device (1) is then closed by bringing the die (2) and the core (3) closer together, so that at the end of the closing process a plurality of cavities (12, 13) are formed, wherein a first cavity (12) encompasses the edge pair (11), and wherein, at the end of the closing process, in an end position of the slide device (4), a front part of the slide device (4) is in the immediate vicinity of the edge pair (11) and an end face (20) of the slide device (4) fixes the second forming film (8) onto the die (2). Subsequently, a first carrier material (14) is introduced into the first cavity (12). Following this, the slide device (4) is moved towards the core (3) into a retracted position, thus enlarging a second cavity (13). Subsequently, a second carrier material (15) is introduced into the second cavity (13).Following this, the molding device (1) is opened and the molded part (17) is subsequently removed from the molding device (1). A molded part (17), a control device (25), and a molding system (24) are further described.