Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
2000-08-21
2004-11-30
Eashoo, Mark (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S280000, C264S294000, C264S296000
Reexamination Certificate
active
06824722
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to the field of the manufacture of objects provided with profiled elements made of plastic, such as windows provided with ornamental or sealing strips. It relates more particularly to a process for fashioning a portion of a profiled bead extruded onto an object, and to articles resulting therefrom, as well as to a device especially designed to implement this process.
It is generally known to deposit profiled beads of polymer, for example along the edge of a pane, by continuous extrusion, and to use them directly as a sealing strip, especially for windows fitted into a frame by bonding. Suitable sections of strips help, on the one hand, to centre the window when fitting it into a frame or chassis, for example into a body opening, and guarantee, on the other hand, the position of the window while the adhesive usually employed is curing. Compared with the injection moulding of such strips, which is also known, extrusion has the advantage of greater flexibility since it is not necessary to keep a specific mould for each shape of pane, but all that is required is to guide an extrusion die of calibrated cross section along the edge of the pane, the extrusion die being controlled by a programmable robot, with a defined, generally continuous, flow of material.
Sometimes it is also required to cover corner parts in the window opening with the bead of the sealing strip. Compared with the main cross section of the profiled bead, which is fixedly predetermined by the calibrated shape of the extrusion die, more material is needed in such corner regions. According to Patent DE-C-196 04 397, there exists an extrusion die whose cross section can automatically increase in the corner regions of a pane. Furthermore, the die comprises two channels for supplying the polymer, in each of which the volume flow rate may be controlled independently of one another by valves. Overall, the additional material needed compared with the bead of normal profile is extruded in a continuous path with the desired cross section. However, such a die is very expensive to manufacture.
It is also known to subsequently touch up the extruded strip in such regions where modification of the profile is required, or in “critical” regions such as the join region between the start and end of the extrusion.
Certain existing solutions thus modify the cross section of the bead by cutting off a defined portion of the bead in a corner region or join region and by filling the gaps thus created by injecting an additional material which joins up with the profiled bead (EP-B 0,524,060), or add additional material for filling the corners by injection onto the continuous profiled bead of uniform cross section in a work phase after the extrusion (cf. DE-C-195 37 693).
In practice, the windows have hitherto been removed from the extrusion station before the profiled bead is touched up and are repositioned in a separate touch-up station. The extrusion station therefore has the best possible occupancy since, before injection of additional material or partial cutting and filling of the gap created, it is necessary to wait for a hold time until the extruded material has stabilized sufficiently.
It is also already known, from Patent DE 4,445,258 C2, to touch up the join region between the start and end of a profiled bead made of extruded polymer surrounding the edge of a pane by means of a multipart compression mould which executes a closure movement going from the centre of the pane towards the external edge so that the excess material in the join region is expelled to the outside and is detached therefrom by a cutting edge carried by the compression tool. However, the particular direction of operation of that known device leads to a bulky system for which there is not enough space in the immediate vicinity of an extrusion station. Thus, all the windows in that device must also be refitted and repositioned separately.
Another known postforming tool (DE-U-90 11 573) for profiled beads of extruded polyurethane is also designed in such a way that the panes must be positioned with respect to the device and cannot therefore be touched up directly in the extrusion station.
Touch-up processes with transfer of the window furthermore have the drawback that the solutions proposed do not always give exactly the expected result with, in particular, visible transition marks on the postformed region which are due to the addition of fresh material alongside the earlier extruded material which has already at least partially cured.
It is therefore desired to find improved processes, with a more reliable appearance result, preferably by reducing the cost compared with that currently borne, in the techniques using postforming or filling especially by injection moulding, by the succession of steps of transferring each window provided with the moulded profiled bead out of the extrusion station, of fitting and positioning the following touch-up station and finally of fashioning the critical portion.
Thus, the object of the invention is to present a process which markedly improves the touching-up, in particular by decreasing the hold time for the postforming of critical regions of a profiled bead, especially corner regions and/or join regions. A corresponding device, which is also advantageously as compact as possible, especially suitable for implementing this process, may also be proposed.
SUMMARY OF THE INVENTION
The subject of the invention is thus a process for the fashioning of a portion of a profiled bead extruded onto an object, in particular a pane, in which process an initially shapeless mass of material is produced in the portion in question and is given the desired final shape by contact with a shaped surface of a moving tool, any excess material being automatically expelled from the tool in order to be removed, characterized in that the mass of material is produced by the superposition of two segments of the extruded strip, with the following steps:
the extrusion die is guided along a first segment of the intended path of the profiled bead, including the portion to be fashioned;
the die is taken away from the object and is moved, relative to the object, to an adjacent position of the portion to be fashioned;
the die is guided again, along a second segment of the path of the profiled bead, also including the portion to be fashioned.
The process according to the invention is characterized by the fact that material needed for the final fashioning is supplied directly at the time of extrusion, so that after the die has left the region in question, the touch-up operation can be started at the same time as the extrusion stops.
The saving in production time represents a certain economical advantage.
Furthermore, since the touch-up operation is started immediately, any difference in appearance between the region which is extruded ir the usual manner and the region which has undergone the additional treatment is lessened, since the material of the extruded part has not yet been cured and/or crosslinked significantly by the time the fashioning of the adjacent part is started.
This process is particularly useful for the local production of particular shapes in limited regions of the strip, in particular for corner regions which are more difficult to produce the more acute-angled the corner.
According to one particular embodiment for fashioning a corner, especially an acute-angled corner, the die is moved relative to the object by changing the relative orientation of the die with respect to the object, especially by rotation through the desired angle, and the die is guided, in the new direction thus obtained, along the following side of the object.
In one particular case, the first and/or second segment extend/extends beyond the perimeter of the object so that the fashioned portion projects beyond the end face of the object.
In general, it is not necessary to interrupt the flow of material during intermediate movement of the die.
According to an advantageous variant, the accumulation of material is formed by moving
Cornils Gerd
Fischer Florian
Verbeek Stefan
Eashoo Mark
Saint-Gobain Vitrage
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