Extruded plastics material hollow profiled strip for window frames, window frames produced from this type of profiled strips and method for the production of a window frame of this type

The invention relates to a glass fibre-reinforced, extruded plastics material hollow profiled strip for the production of window frames, glass doors, or the like. In order to be able to butt-weld profiled strips of this type together when producing the frame and to ensure a reliable bonding between the glass fibres and the plastics material of the profiled strips a synthetic resin is used as the bonding agent which causes this bonding, which synthetic resin has thermoplastic or thermoelastic properties and thus enables the glass fibres to be deflected during butt-welding and pressing together of the ends of the frame pieces.

The invention relates to an extruded plastic material hollow profiled strip 
for window frames with a profile body which consists at least 
substantially of a thermoplastics material and at least one profile wall 
of which is provided with at least one reinforcement element which is 
integrally connected to the profile plastics material. 
Hollow profiled strips made purely from plastics material do not have 
sufficient strength and rigidity for the production of window frames, 
however they have a considerable temperature linear expansion, in 
particular during insolation. For this reason a wide variety of methods 
have been attempted with respect to the reinforcement of this type of 
plastics material hollow profiled strips: insertion of a wood core or a 
core made from a metal hollow profile into the plastics material hollow 
profiled strips or embedding resinoid-bonded glass fibre bars in the 
cavity of the profiled strips and subsequently filling the latter with a 
hardening plastics material (THERMASSIV-window profiles of Schock GmbH). 
Apart from the fact that inserted wood or metal cores are unsatisfactory 
owing to the lack of connection with the plastics material hollow profile 
and owing to the corrodibility of the metal profiles, the reinforcements 
described involve considerable difficulties if it is desired to butt weld 
the profiled strips with one another at the frame corners on modern 
plastics material precision welding machines when producing the window 
frames. 
The invention was based on the object of developing a relatively cheap 
plastics material hollow profiled strip for the production of window 
frames which is more suitable for the production of window frames, owing 
to its physical properties (temperature expansion coefficient, strength, 
rigidity, temperature stability and heat expansion), than the known 
profiled strips and which, nevertheless, may be simply butt-welded during 
manufacture of the frames. Taking as a starting point a profiled strip of 
the initially-mentioned type this object may be solved in accordance with 
the invention in that the reinforcement element consists of 
resinoid-bonded reinforcement fibres and its bonding agent is a 
thermoplastics material or a synthetic resin which has thermoelastic 
properties which bonding agent softens at the welding temperature of the 
profile plastics material such that the reinforcement fibres may be 
deflected. The term "reinforcement fibres" also includes mono- and 
multi-filaments, and glass fibre rovings are preferably used. The bonding 
agent used in accordance with the invention for the reinforcement 
element(s) enables the frame pieces, produced from hollow profiled strips 
according to the invention, to be butt-welded to one another without 
having to remove the reinforcement elements a short distance away from the 
front faces of the frame pieces, since the ends of the reinforcement 
fibres may be deflected during butt-welding and pressing together of the 
frame pieces. In this way the manufacturing expenditure is considerably 
reduced. The hollow profiled strips according to the invention moreover 
lead to frames with greater bending strength since the reinforcement 
fibres extend into the weld seams. Since the primary requirement of the 
bonding agent of the reinforcement fibres is therefore simply that it 
allows a deflection of the reinforcement fibres during heating of the 
profile body plastics material in the course of butt-welding, such that 
reinforcement fibres do not prevent the pressing together of the frame 
pieces which are to be bonded together and the necessary formation of weld 
beads, any low-molecular, duroplastic synthetic resin having thermoplastic 
or thermoelastic properties is in principle suitable for the bonding agent 
for the reinforcement fibres. A bonding agent from the group of the 
unsaturated polyesters, epoxy or acrylic resins is preferred since these 
bond well with the plastics materials, such as PVC, PE or ABS, which are 
preferred for the extruded hollow profiled strips. 
The profiled strips according to the invention may, however, also be 
manufactured relatively cheaply since the reinforcement fibres which have 
been impregnated with synthetic resin may be bonded to the profiled body 
during extrusion of the hollow profiled strips, by allowing the 
reinforcement element(s) to run into the extrusion tool for the 
manufacture of the profiled strips. 
The reinforcement elements themselves may be manufactured in such a way 
that the reinforcement fibres, e.g. the glass fibre rovings, are firstly 
led through a bath consisting of a synthetic resin which adheres well to 
the reinforcement fibres and connects to, in particular bonds by welding 
with, the profile body plastics material during extrusion of the hollow 
profiled strips. In this connection the bonding agent may be of the type 
such that the hardening of the resin is only triggered during a subsequent 
heat treatment, whereupon the bonding agent becomes soft again during 
extrusion of the profiled strips and during welding of the frame corners. 
Suitably there are used as bonding agents synthetic resins whose hardening 
occurs as a result of normal cross-linking without a substantial 
transverse cross-linking. One example of a suitable bonding agent is a 
resinous solution of MMA and PMMA in a ratio such that a polymer content 
of approximately 20 to 30% results, with a hot setting agent for example 
benzoyl peroxide. 
In order to increase the rigidity of the plastic material hollow profiled 
strips in question it may be recommended that reinforcing bands or 
resinoid-bonded glass fibres, such as are already available on the market, 
are used as reinforcement elements, since glass fibre bands of this type 
are processed for example during the manufacture of plastic skis. The 
glass fibres may be in the form of rovings extending in the longitudinal 
direction of the band, or in the form of woven webs, non-woven fabric or 
the like. Glass fibre bands of this type may be cemented or welded onto 
the surface of the hollow profiled strips since in this way the greatest 
effect with respect to the increase in rigidity is obtained, owing to the 
great distance of the bands from the neutral axis; in a preferred 
embodiment the reinforcement elements or glass fibre bands are, however, 
embedded in the profile wall plastics material and are surrounded thereby 
on all sides. 
It is finally recommended that the cavity of the profile is filled at least 
partially with a plastics material light foam of low density, in 
particular PU-light foam, in order to further improve the heat transition 
value of the profiled strips. A filling of this type does not prevent 
butt-welding since the foam of the frame pieces may very easily be pressed 
back, with a correspondingly shaped punch, from the front faces of the 
profiled strips into the interior of the profile before welding. 
If the reinforcement elements are disposed in the hollow profiled strip at 
a transverse spacing from one another such that there are longitudinal 
regions formed between them by the profile plastics material, this leads 
to particularly rigid frames since the profile plastics material then 
forms plastics material bridges in the welding seam planes between the 
reinforcement members. 
In order to produce a window frame from the profiled strips according to 
the invention it is in principle possible to proceed as in the case of 
known operations with the butt-welding machines which are available on the 
market: The profiled strips are heated in the region of the front faces, 
for example, their mitre sectional areas, and are then pressed together 
with these front faces and, during welding of a frame corner, in each case 
two covers are pressed against those profile walls of each strip which 
form the outer side and the inner side of the frame, the covers of 
corresponding walls initially forming a gap between themselves, which 
releases the front faces, and are moved towards each other when the front 
faces are pressed against each other, these covers being moved towards 
each other in accordance with the invention in such a manner that, when 
the profile front faces are pressed against each other, the reinforcement 
fibres, together with the greatest part of the profile body plastics 
material which is thereby displaced, is urged towards the interior of the 
profiled strip. In this manner the appearance of the reinforcement fibres 
at the welding seams after the welding beads formed during welding at the 
surface of the frame have been cut off is vie. = 
A frame produced in this way in accordance with the invention from profiled 
strips according to the invention is therefore characterized in that the 
reinforcement fibres at the weld seams are essentially deflected in the 
direction towards the interior of the profiled strips. 
Of course the invention may not only be applied to the outer pieces of 
window frames but also to so-called impost profiles. 
As well as avoiding the above-mentioned disadvantages of the prior art, the 
construction of a plastics material hollow profiled strip according to the 
invention also leads to the following advantages: No preliminary 
operations at all are necessary for butt-welding; the profile has a very 
low thermal linear expansion and may be formed in such a way that when it 
is warmed on one side, for example, by insolation, it only distorts to a 
minimum extent; there is no danger of rusting; the manufacturing cost of 
window frames according to the invention is very favourable; no metal 
chips result when the profiled strips according to the invention are cut 
to length; the reinforcement elements to be processed, including the glass 
fibre bands already mentioned, are already available on the market and 
they do not have the disadvantage that they draw off heat from the welding 
point during butt-welding, owing to their low thermal conductivity.

FIG. 1 shows a plastics material hollow profile 100 with a plurality of 
hollow chambers 102, 104, 106 and 108, of which hollow chamber 102 is 
filled with a polyurethane light foam core 110. In the profile walls 112 
and 114, which will subsequently form the outer and inner side of a window 
frame, concealed reinforcement elements 116 are embedded which extend in 
the longitudinal direction of the strip and are glass fibre rovings 
impregnated with synthetic resin, acrylic resins being used as the bonding 
agent for the glass fibres. 
FIG. 2 shows a plastics material hollow profile 10 with hollow chambers 12 
and 14 in whose profile walls 16 and 18 forming the outer and inner sides 
of the frame glass fibre bands 20 and 22 are subsequently embedded. These 
consist, for example, of glass fibre rovings 24 and an acrylic resin 
bonding agent 26. In the embodiment according to FIG. 2 the glass fibre 
bands 20, 22 are embedded in the plastics material of the profile walls, 
the layer of plastics material inside the glass fibre bands preferably 
being thinner than the layer of plastics material forming the outer side. 
The embodiment according to FIG. 3 differs from the embodiment according to 
FIG. 2 only in that the glass fibre bands 20' and 22' are located in the 
inner side of the profile walls 16' and 18' and that there is a 
polyurethane light foam core 30' in the hollow chamber 14'. 
As can be seen from the embodiment according to FIG. 4 glass fibre bands 
20" and 22" used in accordance with the invention may also be bent during 
the extrusion of the plastics material hollow profile. 
Finally the embodiment according to FIG. 5 is to show that the glass fibre 
bands 20a and 22a to be used according to the invention may also be placed 
on the outer surfaces of the profile walls 16a and 18a and it is even 
possible to stick on the glass fibre bands after extrusion. 
FIGS. 6 and 7 show the butt-welding according to the invention and the 
construction of a welding point according to the invention. 
FIG. 6 shows profile walls 16b and 16b' of two plastics material hollow 
profiled strips according to the invention, the front faces 40b of which 
strips are to be butt-welded together. In these profile walls there are 
glass fibre bands 20b and 20b' according to the invention. 
As is usual in the known type of plastics material butt-welding machines, 
for example in the automatic butt-welding machines HASSOMAT ZLN 2 of 
Hassomat Maschinenbau GmbH & Co., Helbingstrasse 63, D-2000 Hamburg 70, 
firstly for welding a so-called welding reflector 50 (a heated metal blade 
with polished surfaces) is inserted between the front faces 40b, which are 
to be joined together, in order to heat the plastics material of the 
actual plastics material hollow profile so strongly that it becomes at 
least a pasty consistency; at these temperatures the synthetic resin 
bonding agent of the glass fibre bands according to the invention should 
likewise become flexible in a plastic or elastic manner. The 
above-mentioned butt-welding machines have on both sides of the welding 
point blades which also act as covers and are designated 52: The cutting 
edges of these blades are firstly at a distance from the front faces 40b 
of the profiles. 
After the plastics material has been heated to a sufficient degree the 
welding reflector 50 is pulled out from the gap between the ends of the 
profiled strips whereupon the front faces of the profiled strips which are 
to be bonded together are pressed against each other. Simultaneously the 
blades 52 are moved together, which results in the following: 
In order to obtain a qualitatively high-grade welding joint the ends of the 
profiled strips should be urged together is such a way that the plastics 
material is displaced laterally. However, the blades 52 prevent the 
plastics material being displaced outwardly to the same extent as into the 
interior of the profile, on the contrary they cause the predominant part 
of the plastics material, which is displaced during the butt-welding 
process, to be displaced into the interior of the profiled strips together 
with the glass fibre bands 20b and 20b' which extend as far as the front 
faces 40b, whereas only a small plastics material bead 54 is formed 
between the cutting edges of the blades 52 which have been moved together 
at least approximately, which bead 54 may readily be cut off subsequently. 
Thus the glass fibres of the glass fibre bands are prevented from appearing 
at the surface of the frame during the butt-welding. 
If the blades 52 which act as covers are dispensed with the glass fibres of 
the reinforcement elements 116 or the glass fibre rovings 24 fan out 
essentially in all directions in the welding seam plane formed by the 
front faces 40b, as is the case with a paintbrush which is pushed flush 
onto a surface. 
Finally, FIG. 8 shows a plastics material hollow profile 200 with glass 
fibres or glass fibre rovings which are impregnated with synthetic resin, 
are combined to form reinforcement elements 202 and are delivered to the 
extrusion tool during extrusion of the hollow profile, namely with a 
synthetic resin bonding agent which either has already hardened or is to 
be hardened. According to a further feature of the invention the 
reinforcement elements 202 are disposed in the four corners of the profile 
200 and have cross-section dimensions which are preferably approximately 
8.times.3 mm.