Stock material or miscellaneous articles – Structurally defined web or sheet – Including variation in thickness
Reexamination Certificate
2003-03-07
2004-11-23
Loney, Donald J. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including variation in thickness
C428S137000, C428S155000, C428S184000, C428S596000, C428S613000, C181S290000
Reexamination Certificate
active
06821607
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method of manufacturing a stack of embossed foil webs for a vehicle heat shield, a stack manufactured by this process, and a device for the manufacture of a stack of this kind.
Foil stacks of this kind are used, for example, as heat or as sound insulation, and consist of several profiled foil sheets lying on top of one another, for instance made of non ferrous metals, in particular of aluminium. The stacks described in the following are used preferably in the motor vehicle industry, in particular as sound absorbing insulation packs or as heat shields for vehicles.
For the manufacture of stacks of this kind, flat or sheet material is passed through a pair of embossing rollers, of which in general one of the rollers has the desired structure, whilst the other either has an elastic surface or is provided with a complementary structure (negative structure). The structuring/embossing of the flat material is combined with local stretching or elongation of the flat material. Examples of structuring of flat or sheet materials done in such a way are sufficiently well known to the specialist. This structuring or embossing can be in the form of knobs, corrugations or diamond shapes.
Sound absorbing insulation packs or heat shields, which are used, in particular, in vehicle or motor vehicle construction, generally consist of several structured flat or sheet materials arranged on top of one another, especially in the form of embossed foils or metal sheets The structured flat materials for creating an insulating effect are designed in such a way that air or gas volumes can form between the individual layers and contact between the layers arranged on top of one another is avoided over a large area. The individual sheets should therefore be as far apart from one another as possible. In order to achieve considerable embossing depths, the distances between the individual deformations are increased, which, however, leads to a reduction in bending strength and compression resistance. This kind of deformation of flat materials leads, therefore, to the disadvantage that the structured flat material is easily pressed back together again even at low surface pressure, which can occur, for example, by unintentional or undesirable pressing actions, and hence the insulation effect is lost. The low compression resistance of these structure flat materials is due both to the low number of deformations per surface unit (in the following also referred to as structural density, or knob or corrugation density) and also to the low thickness of the structured flat materials caused by the extension or stretching during embossing. As a consequence of the reduced structural density and the locally reduced material thickness, these flat materials have an inadequate rigidity for their intended purpose in the area of individual deformations (knobs, corrugation crests and depressions). This leads to the fact that with known knobbed flat materials, for example, the individual knobs can be pressed flat again or deformed even under slight pressure. Furthermore, these structured flat materials have a low overall bending strength, as they have a low compression resistance and low rigidity in the area of the individual knobs.
DE-43'29'411 describes a heat and sound insulation material made of several profiled foils, the said foils having a corrugated profile formed from parallel corrugation crests and depressions, with gussets folded into the depressions. However, practice has shown that these foil packs only meet the expectations of the motor vehicle industry in part. In additions it has proved that the rigidity in the area of the individual corrugation crests and depressions is not adequate for the use referred to above.
With the process for manufacturing foil stacks known today, a foil web is passed through a pair of rollers and the foil web, thus embossed, is cut into sections, which are laid or stacked on top of one another. Processes are also known where several pairs of rollers are used at the same time, and the embossed foil webs are passed over one another and cut together. With all these processes it may happen that the embossed foils become interlocked in one another, i.e., the individual embossings come to lie exactly over one another and the individual foils therefore slot into one another (in a similar way to a stack of egg boxes). This means that the individual foils are not at a distance from one another in the intended way, but lie instead closely on top of one another
From the printed publication EP 0 439 046 A1, a process and a device for the manufacture of a foil stack is known, where several embossing rollers are used. This manufacturing process also proves to be exceedingly complex and is correspondingly cost intensive. In order to be able to change the structure of the foils or the flat or sheet material, with this device a large number of embossing rollers must be exchanged.
In the following the concept of “foil web” will be used to include all types of sheet metal, flat or sheet material. The concept “sheets” is to be used to all types of stacked sheet metal, flat or sheet material which is cut from the processed foil webs. It is a matter of course that this material in the form of a web may consist of processed paper, suitable plastics or metal, unperforated or perforated foils, thin metal leaf or metal sheets, for example. These materials can also be layered and/or have slight deformation patterns, perforations or fissures.
An essential task of this invention is to create a cost effective process and a device for the manufacture of an insulation pack for vehicle heat shields, which has a good heat insulation effect and good sound absorption. Furthermore, this insulation pack is to have a high bending strength and high compression resistance.
A further task of this invention is to create an embossed foil web which does not have the disadvantages of the known foil webs. In particular, it is the task of this invention to create a foil web which has increased rigidity and, in particular, increased bending strength and higher compression resistance.
It is also a task of this invention to create a stack made of embossed foil webs, the said stack being suitable for use as a sound absorbing vehicle heat shield, and where the individual sheets of the said stack are certain to remain lying at a distance from one another. In particular, the task is to create a stack which has increased bending strength and higher compression resistance.
SUMMARY OF THE INVENTION
The task is solved by a method of manufacturing a stack made of embossed foil webs for a vehicle heat shield, where at least two unembossed foil webs are conveyed from a feed device in a conveying direction and are embossed, in particular knobbed, between at least one pair of embossing rollers, and the embossed foil webs are then brought together to form a stack in a stacking device wherein the embossed foil webs arranged next to one another are conveyed along different conveying routes with the aid of a conveying device in such a way that at least two embossed foil webs arranged next to one another in the stack are in the conveying direction due to the differences in length of the various conveying routes.
Preferably (including advantageously) the unembossed foil webs lying over one another are embossed by a single pair of embossing rollers. Preferably the embossed foil webs lying on top of one another are embossed with at least two different embossing patterns, including a first embossing pattern and a second embossing pattern. Preferably the first and second embossing patterns in the conveying direction are essentially structured to be of the same length, and that the embossed foil webs are guided along different length conveying routes in such a way that two foil webs arranged next to one another in the stack have a different embossed pattern.
It is preferred that the unembossed foil webs lying on top of one another are overstretched in a predetermined way during embossing, so that th
Wildhaber Alexander
Zwick Evelyn
Berkowitz Marvin C.
Loney Donald J.
Nath & Associates
Richmond Derek
Rieter Automotive (International ) AG
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