Plastic article or earthenware shaping or treating: apparatus – With apparatus assembly or dismantling means or with idle part – Including support or guide means for disassembled element
Reexamination Certificate
1999-09-28
2001-08-28
Nguyen, Nam (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With apparatus assembly or dismantling means or with idle part
Including support or guide means for disassembled element
C425S188000, C425S19200R, C425S376100, C425S392000
Reexamination Certificate
active
06280172
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for the extrusion of plastic pipes or profiles.
DESCRIPTION OF THE PRIOR ART
Extrusion apparatuses consist of the actual extruder in which a plastic granulate (or powder) is heated and is conveyed with the help of endless screws. An extrusion die is attached to such an extruder which brings the viscous plastic mass into the desired cross-sectional shape. Since a separate extrusion die is required for each shape of profile, it must be easily and rapidly exchangeable. A conventional flanged joint which is fastened with a plurality of screws comes with the disadvantage that the loosening and fastening of an extrusion die is time-consuming. As a result, so-called quick-change systems have become known in which the extruder flange and the die flange are embraced by a fastening element which presses the two flanges together. Conical seats are arranged on the rear sides of the two flanges to which correspond associated seats on the fastening element. In this way, a respective pressure can be exerted upon the two halves of the fastening element by means of a single tensioning element such as a screw for example, so that the same presses against the seat of the two flanges and then presses the two together. The fastening of an extrusion die can thus be considerably simplified in this manner. This disassembly of the extrusion die, however, is only possible in many cases under adverse conditions. In order to allow achieving respective pressing pressures between the two flanges, the seats must have a relatively flat angle of pressure. It is usually between 10° and 15°. The consequence of this is that the two halves of the fastening element must be separated from the flange under action of force after the loosening of the tensioning element. In day-to-day practice a hammer is used to beat on the fastening elements. This leads to an undesirable introduction of forces into the extruder. Moreover, the handling of the relatively heavy halves of the fastening element requires a considerable amount of effort and is therefore strenuous.
U.S. Pat. No. 3,632,279 shows a fastening apparatus for an extrusion die having two clamping members which can be tensioned by way of a lever arrangement. Although the tensioning is possible in an advantageous manner in this apparatus because the clamping members are self-centering, the release of the fixed clamping members is not substantially facilitated. Particularly in cases where one of the clamping members is fixed while the other is released, the lever arrangement will not contribute to helping the fixed clamping member to be released because any movement of the actuating lever is translated directly onto the already released clamping member. Moreover, the mobility of the clamping members is limited in the known solution by the lever arrangement.
SUMMARY OF THE INVENTION
It is the object of the present invention to reduce the set-up times in the extrusion of profiles by an improvement of the die fastening system and both to accelerate and facilitate the required work.
For this purpose it is provided for in accordance with the invention that the two halves of the fastening element are fastened swivelably to the extruder and that they are mechanically coupled in order to perform a restrained swiveling movement in opposite directions. The relevant aspect in the present invention is that as a result of the mechanical coupling of the two halves of the fastening element it is possible to achieve that the opening of one half also causes the opening of the other half. This means that the two halves only need to be pressed apart so as to achieve that the two halves detach from the flanges.
A particularly simple embodiment is obtained when a toothed gearing is provided as a mechanical coupling. In this respect it is particularly favorable when each of the two halves of the fastening element is integrally connected with a toothed wheel, which two toothed wheels are directly in mutual engagement. In this manner one can make do constructionally without additional components.
A particularly favorable introduction of force can be achieved in such a way that a screw is provided which is arranged so as to optionally press the two halves against one another or apart from one another. This means further that a single tensioning element is provided both for producing as well as for releasing the connection of the two flanges. A further improvement of the work flow is obtained when the screw is held captively and swivelably on one half of the fastening element. As an alternative, however, it is also possible to provide a pneumatically operating opening and closing apparatus.
In a particularly preferable embodiment of the present invention it is provided that the jointing plane of the two halves of the fastening element is arranged substantially horizontally. It is particularly preferable if the lower half of the fastening element is provided with a greater weight than the upper half of the fastening element. In this way it is achieved that the weight of the upper and the lower half of the fastening element approximately balance one another out. During the swiveling movement it is therefore only necessary to overcome the relatively low frictional resistance. When the lower half is provided with a slightly heavier arrangement than the upper half it is possible to achieve that the two halves have a slight tendency to move in the opened state and that they remain in the same without any influence of force.
REFERENCES:
patent: 2821745 (1958-02-01), Patton
patent: 5776519 (1998-07-01), Flammer
patent: 5888557 (1999-03-01), Houk
patent: 6126430 (2000-10-01), Coyle et al.
Mayrhofer Franz
Schwaiger Meinhard
Dykema Gossett PLLC
Heckenberg Donald
Nguyen Nam
Technoplast Kunststofftechnik GmbH
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