Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-01-29
2001-04-03
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S272800, C156S273700, C156S308200, C219S121640
Reexamination Certificate
active
06210507
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for the manufacture of a plastic window comprising a frame and at least one pane of transparent plastic, in which method the pane is joined with the frame at an abutment surface provided thereon, and a window manufactured by said method.
In particular in case of windows of the type, in which, in consideration of thermal insulation, several panes are positioned in several layers, such that an air-filled cavity is enclosed, it is desirable that the enclosed cavity is hermetically sealed. This is due to the fact that if the cavity is not hermetically closed, moisture may penetrate and condensate on the interior side of the pane facing the cavity, the result being lack of an aesthetic appearance and opacity.
To ensure this hermetic joining, traditional joining methods like gluing have been used for windows, in which both frame and panes are made from plastic.
It is within plastic technology known to use laser welding for joining smaller objects, like eg. lids to containers. Such methods are for instance known from DE-A-44 32 081, EP-A-472 850 or EP-B-751 865.
Gluing of larger pieces of work, like window panes, is, however, among others in consideration of the working environment, a complicated, clow and consequently costly process. For that reason it would therefore be desirable if laser welding could be used for this joining.
It has, however, turned out that problems arise in respect of tightness, when attempts are made to weld larger objects, like exactly window panes, by laser.
SUMMARY OF THE INVENTION
The invention resides in the realization that the case of the problems in respect of weldings, which are not tight, is due to micro irregularities, which will invariably be found in the surfaces of the individual parts, of which the window is composed. Such micro irregularities, which are typically in the area of a few hundredth mm, derive for instance from sink marks in the surface, ejector marks, variations in the extrusion speed, etc., all depending on the method, by which the part in question is manufactured. These irregularities cannot normally be avoided or can only be avoided by means of precautions which make these parts considerably more costly.
It is thus the object of the invention to provide a method for laser welding of windows of the type mentioned by way of introduction, which method surmounts the problems deriving from inevitable micro irregularities in the materials used.
This object is met by a method of the type mentioned by way of introduction, according to which method the joining is performed by welding with laser light, and in which, while the welding is being performed, an average abutment pressure is established between the pane and the frame of at least approx. 2 MPa (2×10
6
N/m
2
).
In an advantageous embodiment of the invention the pressure is obtained by clamping the pane between the frame and a frame-shaped pressing means.
The advantage is that the frame-shaped pressing means through its aperture gives access to the laser light for the exposure, and at the same time such a frame is easy to manufacture from a tool technical point of view.
In a another embodiment of the invention the pressure is obtained by pressing the frame and the pane between two pressing plates, of which at least one is of a transparent material, preferably glass.
The advantage is that plane-parallelism can be obtained, which makes a more homogenous abutment pressure possible, as the force is applied directly above the place, where the welding is to be performed.
In an advantageous embodiment of the invention, the laser light exposes a limited area of the abutment surface, and this area is moved along the part of the abutment surface, which is to be welded together with the pane.
The advantage is that only one laser head is required for the welding, which welding head then in a relatively uncomplicated manner may be moved along the welding seam by means of a robot.
In an advantageous variant of the above-mentioned embodiment, the exposure by laser light is performed in several steps during the pressing, and such that the intensity in a first step is sufficient for softening the plastic in the frame and such that the intensity in at least one of the subsequent steps provides the liquefaction necessary for the welding.
Hereby is obtained that it becomes possible for the abutment pressure to plastically deform the interface in such a way that the irregularities to a certain degree are smoothed before the actual welding takes place.
This stepwise exposure is advantageously obtained in that the limited area, which is exposed by the laser light, is elongate, and in that the intensity viewed over the longitudinal direction of the area is unevenly distributed with high intensity in a central area and lower intensity in the two end areas.
The advantage is that the light distribution also with a single laser is easily obtained by optic means.
In yet another embodiment of the invention the laser light exposes during the welding at one instant simultaneously the entire part of the abutment surface, which is to be welded together with the pane.
The advantage is that the welding may be performed at a high speed.
In yet another advantageous embodiment of the invention the frame is designed such that the abutment surface, viewed in a direction transversely to its longitudinal direction, establishes a substantially homogenous pressure between itself and the pane during the pressing.
This contributes to ensuring the required abutment pressure, a good and homogenous welding being thus obtained.
In an advantageous embodiment, the frame is designed such that the abutment surface before the pressing forms an acute angle of preferably between 5° and 30° with the pane.
Hereby an elastic deformation of the frame is obtained, which ensures the required homogenous pressure.
In yet another embodiment of the invention, two abutment surfaces for two panes are provided on the frame, which surfaces face away from each other, and the welding is carried out simultaneously at the two abutment surfaces.
The advantage is that a completely hermetic window may be welded in one single operation.
In yet another advantageous embodiment of the invention two abutment surfaces for two panes are provided on the frame, which surfaces face in the same direction, and the welding is first performed at one of the abutment surfaces and then at the second abutment surface.
The advantage is that welding only has to be performed from one side, which permits the use of simpler equipment for the pressing.
In an advantageous embodiment of the window according to the invention, the frame is moulded.
This is an easy and cheap way of manufacturing frames on a large scale.
In an advantageous embodiment of the window according to the invention, the window comprises one frame and two panes such that the frame and the two panes enclose a cavity, which is hermetically closed.
This provides in a simple manner a window with good thermal insulating properties.
In yet another embodiment of the window according to the invention, the frame is substantially symmetrical around a plane which is parallel with the two panes.
The advantage is that by pressing the pane and by welding the pane from both sides, part systems having the same properties may be used, which ensured a homogenous quality.
REFERENCES:
patent: 3560291 (1971-02-01), Foglia et al.
patent: 4237363 (1980-12-01), Lemelson
patent: 5581971 (1996-12-01), Peterson
patent: 5893959 (1999-04-01), Muellich
patent: 3304717 (1984-08-01), None
patent: 4432081 (1996-03-01), None
patent: 0126787 (1984-12-01), None
patent: 0159169 (1985-10-01), None
patent: 0472850 (1992-03-01), None
patent: 0751865 (1998-05-01), None
Hansen Helge
Putz Heidrun
Treusch Hans-Georg
Ball Michael W.
Ostrolenk Faber Gerb & Soffen, LLP
Thermoform A/S
Tolin Michael A.
LandOfFree
Method for the manufacture of a plastic window does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for the manufacture of a plastic window, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for the manufacture of a plastic window will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2473460