Plastic Tub Forming With Nestable Frames for Uniform Thickness
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Solution Overview
Problem
Existing methods for producing tub-shaped sanitary articles like bathtubs and shower trays using deep-drawing processes result in inhomogeneous thickness and surface quality due to uneven stretching and friction, requiring manual polishing and limiting mold flexibility for varying designs.
Innovation Solution
A method using a forming device with two nestable frames having frame-shaped bending structures to deform plastic sheets, allowing homogeneous stretching and eliminating surface contact except at essential bending points, enabling flexible production of varying depths and designs without additional reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If deep-drawing process with flat mold is used, then tub-shaped sanitary articles can be produced, but inhomogeneous thickness and surface quality occur due to uneven stretching and friction
Solution Approach 1:
The forming process is segmented into two distinct stages: first forming the basic tub shape using a flat mold, then separately forming the bending areas using frame-shaped bending structures. This segmentation allows each stage to optimize for its specific function, preventing the thickness inhomogeneity that occurs when attempting to form both the tub shape and bends simultaneously in conventional deep-drawing.
Solution Approach 2:
The invention transitions from conventional 2D flat mold forming to 3D frame-shaped bending structures that envelop the plastic sheet. The frame structures extend into the forming space, creating bends by wrapping around the plastic sheet in three dimensions, which eliminates surface contact friction and achieves uniform thickness in bending areas.
2Adaptability or versatility
If conventional deep-drawing mold is used, then one type of object can be produced, but mold flexibility for varying designs is limited
Solution Approach 1:
The frame-shaped bending structures are designed to be adjustable and interchangeable rather than fixed. The frames can be repositioned, reconfigured, or replaced to accommodate different bending requirements for various tub designs, enabling a single mold to produce multiple product variants with different depths, shapes, and bend configurations.
Solution Approach 2:
The flat mold is designed to serve multiple functions: it forms the basic tub shape and also serves as a support structure during the subsequent bending operation. The frame-shaped bending structures can be used with different flat molds to create various bend patterns, making the overall forming system universally applicable to multiple product types.
3Shape
If plastic sheet is stretched in deep-drawing, then tub shape is formed, but inhomogeneous thickness results due to friction and adhesion
Solution Approach 1:
The harmful friction and adhesion effects are eliminated by extracting the plastic sheet from contact with the mold surface during the bending operation. The frame-shaped bending structures envelop the plastic sheet in air, creating bends without surface contact, which prevents the friction-induced thickness variations and adhesion problems that plague conventional deep-drawing.
Solution Approach 2:
The frame-shaped bending structures act as intermediaries that form the bends indirectly by enveloping and deforming the plastic sheet from the outside, rather than directly pressing against it. This intermediary approach allows bend formation without the plastic sheet contacting the forming surfaces, eliminating friction and adhesion effects.
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
Achieves uniformly thick and high-quality surfaces without manual polishing, allowing for adaptable production of different geometries and depths using the same mold, reducing the need for additional reinforcement and increasing mold flexibility.
Implementation Method 1
cooling the plastic sheet
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
A method for manufacturing a tub-shaped sanitary ware made of plastic, having a visible side and a bottom, comprising the following steps: - providing a plastic sheet (26) to be formed to create the sanitary ware, - providing a forming device (1) comprising a frame arrangement (2) with a first frame (3) having a first frame-shaped bending structure (5) and a second frame (4) having a second frame-shaped bending structure (12), wherein the plastic sheet (26) is to be formed over the bending structures (5, 12), - arranging and fastening the heated plastic sheet (26) to the first frame (3), - inserting the second frame (4) into the open first frame (3) into a forming position such that, upon insertion, the second frame (4) takes the plastic sheet (26) with it by its bending structure (12), wherein the plastic sheet (26) is formed into a tub shape over both the first and the second bending structures (5, 12).- Cooling of the formed plastic sheet (26).,