DE2439597A1 - Generating three-dimensionally curved surfaces having min. area - using heat-shrinkable plastics film stretched over suitably shaped frames - Google Patents

Abstract

Three-dimensionally curved, mathematically accurate, "minimal" surfaces are prepd. without the use of models, templates or patterns, by stretching thermoplastics heat-shrinkable film over three-dimensional frames, followed by heating the film so as to shrink it, whereby the desired "minimal" surface results automatically. The frames are rigid or hinged, but the angles they enclose are fixed. Used for determining the optimal shape of technical components, (durable) consumer articles or building and architectural parts, where the prodn. of "minimal" surface areas admits an aethetically pleasing, economical and mechanically stable soln. The method dispenses with costly models, patterns or templates.

Description

§ 3 DESCRIPTION Technical name of the invention: Model-free Production of three-dimensionally curved, almost mathematically exact minimum £ 1 surfaces in different materials.

a) Field of application: The three-dimensionally curved, approximately mathematical exact minimal areas - hereinafter referred to as "lvlinimalElächen" for short, are intended in the Area of design for the creation of technical molded parts and consumer goods as well as architectural components are used wherever the process of manufacture from "MinimalElächen" a good aesthetic, economical and static solution while saving modeled impression tools.

b) State of the art on which the invention is based: 1) Technical Basics: The general Common shrink-wrapping technology used when placing goods on pallets by means of a polyethylene shrink film bag using a hot air device or oven can be held together firmly on the pallet by shrinking the film.

Second, the § 3 i3ESS DESCRIPTION b) State of the art 1) Technical principles: generally known Technique of manufacturing fiberglass laminates using hand lay-up or fiber spraying processes, applied with synthetic resins and fiberglass mats.

As a modification of the deep-drawing process of stretched acrylic or similar Plastic sheets with shrink properties can have "minimal areas" of a simple type can be manufactured directly in stable Iqmaterial without tools.

2) Scientific basis: dealing with contemporary mathematics deal with the mathematical calculation of minimal areas. Serve as literature for this the textbooks of differential geometry. For the graphic representation of the Computers are used in minimal areas. Mathematically exact outlines are smallest three-dimensional surfaces that are conceivable within a given framework and where deviations are eliminated by the law of gravity. Nearly exact ilinimal surfaces deviating from gravity are in nature Known form of soap bubbles.

c) Presentation of the invention: The method for model-free production consists of three-dimensionally curved, almost mathematically exact iVlinimal surfaces - In the main claim - in the combination of already known techniques for obtaining a new technology: on rigid three-dimensional frames (made of wood, metal or other suitable materials) a thermoplastic shrink-wrap is applied and shrunk by heating with hot air blowers or in an oven. There the property of shrinking due to a previous stretching of the # 3 DESCRIPTION - c) Representation of the invention materials and the memory character the molecules11 can be formed, only previously stretched material can be used. During the shrinking process, it must be ensured that the foils are secure and as taut as possible be stretched on the three-dimensional frame. The training is from levels Areas in the rail construction for the creation of "minimal areas" uninteresting, because there are only no zo-dimensional ~ minimal surfaces "in the manner of a Eardrums could come about. Even with very large areas it forms after pulling the film onto a three-dimensionally curved frame - what only with innumerable folds is possible - after the roughing process an almost flawless one "Minimal area" without any fold, which is so strong that it is direct can be coated with synthetic resin-fiberglass laminates.

After the laminate has hardened, the ~ minimal surfaces "can be used with can be molded using all common techniques. depending on the type of plastics used the carrier film can be peeled off or left on the laminate. The laminates can also be used directly as prefabricated parts (such as crystal-clear viewing domes) If you use stretched acrylic sheets instead of foil to make them stable without a coating To obtain "minimal areas", the frames are fitted with hinges. One assembles the plates in the flat frame surface and folds the frame while heating slowly into the intended angle where they are locked.

With the double-walled design of the scraped foil laminates - for ßisp: iP # at a distance of a bar thickness of 100 mm inside § 3 DESCRIPTION - c) Representation of the invention and attached to the outside of the beam - creates a hermetic closed air space, similar to double glazing, which has good insulating properties having.

For the production of concrete walls as in-situ concrete, the laminated ~ minimal surface "as usual with rough boards, formwork panels and beams sprouts. The structure is two-shell, the "PlinimalBläche" is intended as an exterior and analog inner surface can be created with the same wall thickness. The cavities between Laminates and moldings are either foamed with synthetic foam or in In the course of the concrete pouring, it was filled meter by meter with sand.

You proceed in the same way with transportable precast concrete parts by produces several positive and negative casts of the original "minimal surface". The shrinking process is here because of even greater mathematical accuracy in a special shrink oven.

d) Explanation of the invention The invention is intended to be the technical prerequisite for the automatic production of three-dimensional curved shapes that previously had to be laboriously modeled by hand first. This can be done in all Environmental areas of ~ minimal areas "use. The invention is intended contribute through technical progress to make our technoid environment richer of aesthetic forms and thereby becomes more human in the sense of a "nature-related" one. A nostalgic recourse could be made in architecture through the ~ minimal surfaces to avoid earlier stylistic epochs through technical innovations.

In contrast to the well-known tent constructions (Behnisch) § 3 DESCRIPTION - EXPLANATION OF THE INVENTION which is also related to "MINIMAL AREAS" have, the "alinimalflächen" of this process can easily be used in today's Structural engineering of the rigid architecture can be integrated.

Varied development of ~ minimal surface "facades in the Changes with right-angled straight surfaces can be produced without any problems.

All utensils and technical devices can point to it be investigated whether their redesign taking advantage of the method of manufacture of "minimal areas" would not make sense.

Prototypes, small and test series can be made profitable and technical perform perfectly.

Some application examples: facade parts, roofs, supporting structures in architecture, ship hulls, bodies, spoons, forks, armchairs, tables, etc.

e) Achievable advantages over the prior art: The main advantage the invention is that all three-dimensionally curved surfaces so far could only be produced by means of expensive molding tools. As large architectural elements in rigid form, three-dimensional curved surfaces were as good as impossible to use, you can see tent constructions (Behnisch, olympiazeltdach) and domes (Buckminster Fuller), as there is currently no process for their automatic production. Mathematical minimal surfaces were previously only due to their coordinates, but not can be produced as closed surfaces.

The term (= title of the patent application) is approximately mathematical Exact, three-dimensional minimal surface already means that it is about the smallest possible areas under 3 3 DESCRIPTION e) Achievable benefits compared to the state of the art: respectively given edge constructions.

They therefore have favorable conditions similar to those of the spherical surface on. That means: 1.) all three-dimensional surfaces can with the invention the smallest surface and with the lowest material consumption.

2.) From the special nature of the minimal areas "- see also ancillary claim 1 - which refers to the exploitation of the natural law of the soap bubbles decreases, it follows that the ~ 1minimal surfaces "are particularly favorable static Must have properties.

3.) Even if one considers the "minimal areas" as shrunk foils without Coating, they have an amazing stability without any reinforcement, so that technology has a certain importance in the creation of emergency shelters should come.

f) Limitations of the procedure: Each time ~ ninimal surfaces are executed " the force of gravity acts and leads to a slight falsification of the pure mathematical exact minimum area. Only a part of the infinitely many ninimal surfaces can be using the method of the main claim.

"Minimal areas" are conceivable that reduce the shrinkability of the film overwhelm.

§ 3 DESCRIPTION g) References to the drawings: The drawings 1-4 show a selection of the simplest applications of the "minimal areas" on rectangular Base area, so that an easy connection to conventional architecture is possible.

to 1) the simplest form of a right-angled, bent surface. In the kink there are 2 hinges (S), which makes it possible to create a Minimal area with stretched acrylic sheets is possible.

to 2) The rectangular area was divided into two equal, right-angled triangles divided, on the shortest side of which an angle is welded in the third dimension will. By covering with two foils one gets strongly plastic facade elements, carried out in a large-scale test 9 m x 3 m.

to 3) A staggered shet roof construction was built over a rectangular base built. After shrinking on a large film, you get a very interesting one Roof area with a watershed.

to 4) Two-part facade element with a rectangular base. By attaching an equilateral tetrahedron to both cut surfaces a strongly plastic minimal surface.

to 5) Equilateral tetrahedron with four edges. This gives a special simple, stable ~ minimal surfaces = element. Large-scale experiment with an edge length of 2 meters executed.

Similar elements put together result in a load-bearing dome structure (Buckminster Fuller) § 3 DESCRIPTION g) References to the drawings to 6) Cube to 4), dependent claim, characterized in that it has 8 corners, 9 edges and has 3 faces.

The three surfaces of the cube are ~ ninimal surfaces and form automatically the diagonal D-D1 between the two three-dimensional frame nodes. The cube has, although it cannot be closed by further minimal areas, none Volume. I call it ~ minimal area cube "

Claims (4)

§ 3a PATENT CLAIMS: in the main claim as patentable under protection should be provided: 1.) the method for model-free production three-dimensional curved, approximately mathematically exact minimal surfaces, characterized by that by stretching thermoplastic shrink films or - plates on three-dimensional Frame (rigid frame, or movable with hinges; but firmly clicks into place in the end bracket) and then heating the film surface to cause it to shrink and thereby the ~ minimal area "adjusts itself. The further processing takes place with the usual techniques. 2.) in the ancillary claim should be placed under protection as patentable following procedure, based on the utilization of the natural law of the origin of soap bubbles, which always have approximately exact mathematical iqinimal surfaces Represent deviations due to gravity. The method is characterized in that three-dimensionally curved Space (made of aluminum, copper or bronze wire, etc.) in a container with glue can be dipped (Styrofoam - contact adhesive from Fischer & Fischer, Bühl / Baden) which takes the place of the soap solution. You pull the frame out of the glue and you get sturdy skins that hold the frame in the form of ~ 1minimal areas ". After dipping into one again other glue (e.g. diluted dispersion wood glue) which is thermally constant the object can be dipped in liquid wax after drying and then in metal § 3 a PATENT CLAIMS: 2.) Ancillary claim: (e.g. bronze, silver, gold) using the centrifugal casting process or the full-mold casting process (e.g. aluminum, iron) can be cast. So you get it directly from nature Shaped castings that can be used to represent even the most complex "minimal surfaces" Are location where the technology of the main claim would fail. This technique but can only be used for relatively small pieces. 3.) Ancillary claim: Used for the production of architectural models one the method of independent claim 2.) whereby the resulting glue membranes through Immersion in hardening one- or two-component synthetic resins can be solidified. 4.) Subclaims: here should be different, deductive with the procedure of secondary claim 2.) found simple, new geometric bodies under protection first: Minimal area cube # Cube, characterized by that it has 8 corners, 9 edges and 3 surfaces in the form of "minimal surfaces". (Drawing) Supplements will follow. L e r s e i t e