Chemistry: electrical and wave energy – Processes and products – Electrophoresis or electro-osmosis processes and electrolyte...
Reexamination Certificate
2000-05-30
2002-04-16
Mayekar, Kishor (Department: 1741)
Chemistry: electrical and wave energy
Processes and products
Electrophoresis or electro-osmosis processes and electrolyte...
C204S512000, C204S623000, C204S625000
Reexamination Certificate
active
06372107
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a process for conveying vehicle bodies through a treatment tank for the surface treatment of the vehicle bodies.
Furthermore, the present invention relates to a conveyor device for conveying vehicle bodies through a treatment tank for the surface treatment of the vehicle bodies, comprising a conveyor which introduces the vehicle bodies into the treatment tank, conveys them through the treatment tank and brings them out of the treatment tank again.
Such a process and such a device are known, for example, from DE 36 12 128 A1. With the process known from this publication, the vehicle bodies mounted on support carriages (designated in the following as skid frames) are suspended on a conveyor line, with which the vehicle bodies are conveyed through a phosphating and painting plant, with the aid of oscillatingly suspended pairs of support elements which are each formed from two L-shaped arms located opposite one another.
The vehicle bodies are immersed in the phosphating and painting bath by the pairs of support elements with the vehicle bodies suspended therefrom being conveyed along an inclined conveyor section of the conveyor line into the relevant treatment tank. In this respect, a floor pan of the respective vehicle body is first immersed in the treatment tank. Since the floor pan of a vehicle body offers the liquid from the treatment tank only small entry cross sections for penetrating into the interior of the vehicle body, a high counterpressure (immersion resistance) must be overcome when the vehicle body is immersed in the treatment tank.
Furthermore, as the vehicle body is emerging from the treatment tank the floor pan of the vehicle body leaves the treatment tank last. In this respect, it is possible that the liquid of the treatment tank will run only incompletely out of the interior of the vehicle body or irritating markings will remain when the liquid runs out after leaving the treatment tank.
Furthermore, a process and a device are known from DE 196 41 048 A1, with which vehicle bodies are immersed in the treatment tank due to superposition of a translatory movement and a rotary movement at the beginning of a treatment tank and at the end of the treatment tank are moved out of the treatment tank by a like superposition of translatory and rotary movements. On account of the superposition of the translatory movement of the vehicle bodies with a rotary movement at the beginning and at the end of the treatment tank, the depth of the treatment tank must be selected to be larger than is required for the process according to DE 36 12 128 A1. Moreover, higher flow velocities of the liquid of the treatment tank result relative to the submerging or emerging vehicle body due to the superposition of the translatory and the rotary movements which leads to a greater mechanical load on the vehicle body and its holder. In particular, holding elements provided on the vehicle body, as a result of which doors, hood and trunk lid or tailgate of the vehicle body are kept in a slightly opened state during the surface treatment, have to be of a more stable design.
SUMMARY OR THE INVENTION
The object underlying the present invention is therefore to provide a process of the type specified at the outset, with which the liquid of the treatment tank offers only a slight immersion resistance to the vehicle bodies during immersion and the flow velocities of the liquid of the treatment tank relative to the submerging and emerging vehicle bodies are kept low.
This object is accomplished in accordance with the invention, in a process for conveying vehicle bodies through a treatment tank for the surface treatment of the vehicle bodies, in that prior to their introduction into the treatment tank the vehicle bodies are transferred from a standard position, in which window openings of the respective vehicle body are arranged above the floor pan of the vehicle body, into a headfirst position, in which the window openings of the respective vehicle body are arranged beneath the floor pan of the vehicle body, and that the vehicle bodies are subsequently introduced into the treatment tank, conveyed through the treatment tank and brought out of the treatment tank again in the headfirst position.
As a result of the inventive idea, the immersion resistance offered to the vehicle body during immersion is considerably reduced since the window openings of the vehicle body, which offer the liquid of the treatment tank large entry cross sections for penetrating into the interior of the vehicle body, are immersed in the treatment tank earlier than is the case when the vehicle bodies are introduced in the standard position.
Moreover, no increased flow velocities of the liquid of the treatment tank relative to a submerging or emerging vehicle body occur since the vehicle body is already transferred into the headfirst position before being introduced into the treatment tank. For the same reason the depth of the treatment tank need also not be increased.
When the vehicle bodies are brought out of the treatment tank in the headfirst position, the liquid which has penetrated the interior of the vehicle bodies can run off completely and free from markings through the window openings.
Furthermore, as a result of the fact that during its transport through the treatment tank the roof of the vehicle body hangs downwards no air bubbles or foam can collect underneath the roof, as is frequently the case when a vehicle body is conveyed through a treatment tank in a standard position. On the contrary, such air bubbles and foam can escape upwards out of the interior of the vehicle body through outlet openings in the floor area of the vehicle body when a vehicle body is conveyed through the treatment tank in a headfirst position. As a result, it is possible to avoid parts of the vehicle body not coming into contact with the liquid of the treatment tank on account of air bubbles or the formation of foam and thus not being subjected to the desired treatment, i.e., for example, cleaned, degreased or painted.
Furthermore, when the vehicle bodies are transported through the treatment tank in a headfirst position the roof and the hood hang downwards and so no dirt from the treatment tank can be deposited on these particularly critical, visible surfaces of the vehicle body. As a result, treatment errors, for example, paint errors on account of sedimented dirt particles are avoided, in particular, on the extended, horizontal visible surfaces of the vehicle body.
Finally, the immersion contour of a vehicle body introduced into the treatment tank in a headfirst position differs from the immersion contour of a vehicle body introduced in a standard position which can—as a function of the shape of the vehicle body and the predetermined minimum immersion time—result in the treatment tank of the inventive process being of a shorter design than with a process, with which the vehicle bodies are introduced into the treatment tank in the standard position.
Such a shortening of the treatment tank is possible, in particular, with short immersion times.
Once the vehicle bodies have been brought out of the treatment tank they can be returned to the standard position in order to carry out a further step in the production process of the vehicle, for example, the assembly of additional components on the vehicle body which is normally carried out in the standard position of the vehicle body.
It is, however, in no way necessary to return the vehicle body to the standard position after each passage through a treatment tank. On the contrary, it is possible to convey the vehicle bodies in the headfirst position through several treatment areas arranged one behind the other, for example, pretreatment areas, painting areas and drying areas and not return the vehicle bodies to the standard position until after the last of these treatment sections.
In principle, the orientation of the vehicle body relative to the direction of conveyance in the headfirst position is optional in the inventive process as long as
Besinger Hartwig
Lachenmaier Klaus
Mogck Gerhard
Duerr Systems GmbH
Lipstiz Barry R.
Mayekar Kishor
McAlliste Douglas M.
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