Horizontally supported planar surfaces – Miscellaneous
Reexamination Certificate
2001-05-07
2004-07-20
Chen, Jose V. (Department: 3637)
Horizontally supported planar surfaces
Miscellaneous
Reexamination Certificate
active
06763771
ABSTRACT:
The invention relates to a method for producing one-piece, three-dimensional shaped bodies, shaped bodies produced according to the method, a device for carrying out said method, as well as display furniture.
Industrially or manually prefabricated one-piece shaped bodies of the most varied materials have always been used in almost all technological fields. Such shaped bodies may either be functional individual objects ready for use, or constructional or component parts for more or less complexly structured devices or equipment. Especially in recent times, engineers have again directed their efforts increasingly towards developing modular systems for which complex devices or equipment are assembled from individual shaped bodies which should be as universally usable as possible, and for which the number of shaped bodies or modules of different design should be kept as small as possible. Primarily, this is intended to reduce both the number of specific, labor-intensive and thus costly shaping processes as well as the work and expenses required for storing and parts supply.
Finished shaped bodies may be the result of various original shaping processes in which—by definition—a solid body is formed from a shapeless material by creating a coherence. Another way of attaining a certain shaped body is to use various methods for re-forming or deforming semi-finished parts created by way of deformation. These latter methods include, amongst others, the deformation, by bending, of flat, plate-shaped work-pieces. Depending on the type and cross-section of the starting material used, and as a function of the bending radius to be achieved, cold or hot forming processes will be used. Shaped parts of a thermoplastic material formed by bending, for example, are generally produced by way of hot forming in a die, owing to their bending resistance once cooled down.
Finished shaped bodies in demand on the market are in particular display furniture items for the sales-promoting presentation of goods, covers or covering caps for covering display surfaces of a display furniture item as well as legs for supporting a post of a display furniture item.
From practice, various designs or shapes of display furniture items are known, the production of which, however, generally comprises various separating, deforming and joining steps. This makes the production of the prior art display furniture material- and time-intensive.
It is further disclosed in GB 1 603 489 to make a collapsible boat or other three-dimensional objects from a thermoplastic material blank by heating region by region of said material and bending it along edges predetermined by templates. This method is identically disclosed in DE 28 22 218 A1. It is furthermore known from the teaching of EP 0 022 884 A1 to create a three-dimensional body by deforming a metal sheet. However, it is neither disclosed in EP 0 022 884 A1 nor in GB 1 603 489 how to form or produce a display furniture item for the sales-promoting presentation of goods. What is set out in the following concerning the prior art is intended to relate to shaped bodies made of thermoplastic plastics as well as to methods for producing such shaped bodies. However, the problems and shortcomings to be set out hereinafter are in principle also encountered with any shaped parts formed by bending and made of materials which can be deformed under the influence of heat as well as the respective deformation methods used for this purpose.
Owing to their material properties, shaped bodies made of thermoplastic plastics are extremely versatile as regards their applications. With the traditional materials such as wood or metal being increasingly replaced with other materials, shaped bodies of both simple and complex designs are now commonly produced from thermoplastic plastics. Just like their application range, the variety of shapes of these bodies has increased to a vast extent. Nevertheless, the one-piece shaped bodies made of thermoplastic plastics hardly ever include any objects of excessive dimensions or objects of hollow or vessel-like shapes, except for, perhaps, long and hollow extruded sections such as pipeline parts. As will be illustrated in the following, a major reason for this is that the prior art methods are not suitable for the small-scale series production of shaped bodies of a certain geometrical design.
Depending on the three-dimensional shape to be attained and the semi-finished part or starting material that can be used for this purpose, different methods are employed for producing thermoplastic shaped bodies. Besides the original shaping methods of the prior art, which include the production of endless extruded sections, the widely used injection molding technique or also the further developed injection-blow molding technique, numerous forming methods are known. These latter methods may be differentiated according to the type of starting materials to be formed or deformed. However, what is set out hereinafter with respect to the prior art shall be restricted to the hot-forming methods of the prior art for processing thermoplastic plates.
A relatively simple method for producing likewise simple shaped parts of thermoplastic plastics formed by bending is the essentially manual hot forming method by means of a glow wire device or a so-called folding or bending device. In this case, a plate of thermoplastic plastic is rapidly and uniformly heated to the temperature of optimum thermoplastic behavior along a linearly extending heating region of a bending, buckling or folding line, and subsequently—under the influence of mechanical forces—bent, buckled or folded along the heated bending, buckling or folding line until a desired angle has been attained. A cooling step will ensure that the new shape is fixed automatically. The devices used for performing the method usually comprise a support device for the work-piece to be deformed, said device reflecting the bending line, as well as a linearly extending heating wire or heating rail mounted underneath said device. An elbow part produced from a thermoplastic plate may for example be subjected to further processing steps on said folding or bending device machine for obtaining a finite U-shaped or stepped beam. While this method does require a folding or bending device, its advantage is that it can do without shaping tools reflecting the exact shape and that the work-piece to be deformed need merely be subjected to a linear partial heating step.
It is self-evident that the range of possible shapes of shaped bodies produced in this manner is limited. It is not possible, for example, to produce simple containers without gluing or welding together, in a subsequent working step and, if necessary, including intermediate machining steps, the semi-finished products produced by means of a glow-wire device. A device involving a glow wire and a method adapted thereto are disclosed in DE 1 038 749 A1. The disadvantages of this approach are last but not least that it produces seams with material properties that may be undesired or difficult to foresee. If shaped bodies of transparent plastic are joined e.g. by gluing or welding them together, this will furthermore have a detrimental effect on the esthetic appearance of the body obtained in this manner since light will be refracted irregularly and sometimes strongly in the area of said seams.
So far, it has only been possible to avoid such disadvantages if any complex three-dimensional shapes (e.g. containers or the like) are produced by means of by far more laborious methods. Such methods include the blowing or suction methods involving high or low pressure which allow the deformation of thermoplastic plates heated over their entire surface into bowl-like or dome-shaped parts in a mold. Since forming tools are costly in production, producing shaped bodies in this manner will only be worthwhile if large series are produced.
One disadvantage inherent to all methods used for deforming plates heated over their entire surface areas is that the entire surface area to be deformed must be heated to the pr
Chen José V.
Schmeiser Olsen & Watts
Wolf-Dietrich Hannecke Kunststofftechnik
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