Abrading – Machine – Sandblast
Reexamination Certificate
2000-08-02
2002-06-18
Hail, III, Joseph J. (Department: 3723)
Abrading
Machine
Sandblast
C451S092000, C451S102000, C451S310000
Reexamination Certificate
active
06406360
ABSTRACT:
INTRODUCTION AND BACKGROUND
The invention pertains to a device for cleaning, in particular for dry ice cleaning, the inner walls of vulcanization molds for tires, said molds being divided for opening into upper and lower partial molds, said cleaning being by means of a blasting material, with a movably provided blasting material device
ozzle, moved along at least four axes by means of a manipulation device, for application of blasting material to the inner walls, and with a device designed as an isolation hood for encapsulation of the blasting material application device and of the thereby cleaned inner walls with respect to the environment, where the isolation hood can be tightly joined at the outer perimeter to a partial mold and has openings and leads for supply elements for power, compressed air and blasting material.
For cleaning the inner surface or the inner walls, respectively, of molds and tools used in industry, essentially meaning those made of metal, different types of chemical and physical cleaning methods and means are known.
Whereas the chemical cleaning method places strict demands—specified by legal statutes—on the safety and disposal equipment due to the aggressive media often used, with regard to physical cleaning methods in which the impurities, as a rule, are removed from the surface to be cleaned by sandblasting or by directing blasting material composed of sand, metal or glass particles thereon, it is necessary that the cleaning itself be carried out in special cabinets, so that the component to be cleaned first has to be removed from the corresponding machine and has to be placed into such cabinet.
An additional alternative consists in that the components can be cleaned by exposure to high-velocity dry ice pellets, that is, small, dry ice particles about the size of a grain of rice. With dry ice we are delaying with carbon dioxide cooled to at least −78.5° C. and converted into the solid state, which has the advantage that under atmospheric pressure it passes directly from the solid phase into the gas phase, with no melt liquid being produced. Thus, in a particularly simple manner, namely with normal compressed air, both the exposure to high-velocity dry ice and also the removal and disposal of dirt particles takes place.
When using high-speed dry ice pellets, several favorable effects will occur. In addition to the initially occurring mechanical removal of dirt and impurities by means of abrasion, a powerful, point-wise cooling of the exposed region will occur, so that the impurities, and in particular the rubber residues in tire molds, will become embrittled and are easier to remove. In addition, upon impact of the dry ice pellet against the surface under atmospheric pressure, the already mentioned transition of the dry ice to the gaseous state occurs, so that a roughly 700-fold increase in volume of the dry ice will occur. The gas cloud produced in this manner is able to blow out the subcooled and embrittled impurities, without itself damaging the substrate or the surface itself.
However, with dry ice cleaning exceptionally large sound emissions occur, and it is therefore necessary to supply and then subsequently to eliminate a large quantity of compressed air mixed with dry ice, carbon dioxide or dirt. In this case as well, it is necessary either to treat the component being cleaned in special cabinets, or in the event that the component is to be cleaned in situ, to shield the environment in a very cost-intensive manner against the emissions of the dry ice cleaning method.
In addition, many cleaning methods, in particular the cleaning of vulcanization molds for tires, have to proceed rather quickly so that production stoppages will be avoided. In addition, vulcanization molds for tires are very hot, even for some time after removal of the vulcanization material, so that removal of the molds and their transport into a separate cabinet can occur only after cooling, and this takes a considerable amount of time. Thus, cleaning is very difficult and sometimes cannot even be carried out by manually operated blasting material systems within the vulcanization press (in situ) due to the aforementioned emissions and the heat.
DE 197 12 513 A1 discloses a method and a device for cleaning an inner wall of a mold by means of dry ice, where the cleaning can take place within the vulcanization press, without the vulcanization mold having to be dismantled.
The vulcanization molds for tires, as a rule, are designed as partial molds which can be opened after the vulcanization process. In this case, on the one hand there segmented molds, which usually have an upper mold which surrounds the vulcanized tire on one side and on the road strip or tread, and which feature laterally adjustable segments, in the tread region for closing the mold, and which comprise a lower mold (side dish) with which the mold is closed and the remaining tire side is shaped and vulcanized.
On the other hand, there are two-partial molds which are nearly identically designed without displaceable segments, and each forms one side wall and covers roughly half of the tread region.
With regard to the device disclosed in DE 197 12 513 A1, encapsulation of the region being cleaned is used, which takes place by means of the two partial molds and of a possibly telescoping or bellows-like mantle, so that the mantle or the encapsulation also contains the blasting material device.
The disadvantage of this kind of encapsulation consists in that a complete encapsulation can only take place when the mantle is stretched between two partial molds and is fixed to them and held in place, so that the movement of the encapsulation up to the still hot molds requires a considerable amount of manual effort and also can only be carried out after a longer cool-down time. In this case, the encapsulation or the mantle must be flexible enough so that different positions of the two partial molds relative to each other can be handled, and yet still a movable lateral opening for a robot arm is provided, which causes the overall structure to be very complex.
The heat radiation, with the heating of robot devices/controls to over 60°, makes the use of industrial robots problematic, and in addition, requires a spatial repositioning or new reading of the precise robot standpoint based on three reference points before each cleaning a mold, which requires a reprogramming before each new cleaning process, unless stationary or at least rail-based robot devices are used, but these, in turn, disrupt the normal production sequence.
Document DE 195 35 557 A1 discloses a device for cleaning an inner wall of a mold with dry ice pellets, with a cover hood matching the opening cross section of the mold, through which at least the supply lines extend, and which has in its edge region at least one elastic seal for placement against the mold. However, the disadvantage of this device is not only that all handling devices for adjusting the jet nozzle, but also for adjusting the cover hood are placed at a central carrier passing through the cover hood, with parts of the central carrier and several actuating devices, especially those for height adjustment of the nozzle, being located outside and beneath the cover hood. Thus, the design height of the entire device has to be increased to such an extent that in-situ cleaning, at least of tire molds for smaller tires, is not possible. In addition, a number of rotary transmission lead throughs equipped with bearings are required in the cover hood, so that the weight of the device is increased and its handling is made more difficult.
Thus one problem for the invention was to design a device for cleaning the inner walls of molds by means of blasting material, in particular for dry ice cleaning of the inner regions of vulcanization molds, which can be employed in situ—i.e.,in the vulcanization press after opening the molds and without waiting out the cooling time, which allows a dependable and complete encapsulation of the high-speed material or cleaning regions, which can be installed in a simple ma
Brandt Holger
Gonschior Martin
Köhler Heinz
Kuhr Wolfgang
Nguyen Nhu Vinh
Berry Jr. Willie
Continental Aktiengesellschaft
Hail III Joseph J.
Smith , Gambrell & Russell, LLP
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