WELDING METHOD AND DEVICE

METHODE DE SOUDAGE ET APPAREIL

English Abstract

The invention relates to a method for welding two hollow profile members of plastic material, to form a window frame, wherein the two profile members which are to be joined are heated to a prescribed temperature by inserting a welding mirror between their joining surfaces, and pressing said surfaces against the welding mirror, whereby a weld bead is formed; then, after the welding mirror is removed, said profile members are joined together under pressure. In order to avoid at least part of the expense of removing the visible and thereby undesirable weld beads (or remnants of weld beads), further to reduce the time required for fabricating a window frame, and to eliminate formation of a "shadow groove", after the welding mirror is removed the outer parts of the weld beads which form on the eventual visible surfaces of the window frame in the region of the joining surfaces of the two profile members are pressed inward, following which the welding mirror is re-inserted between the joining surfaces of the profile members, and the joining surfaces are reheated, accompanied by simultaneous deformation of the inwardly pressed weld beads, and finally, after removal of the welding mirror, the joining surfaces of the two profile members are joined together.

French Abstract

Linvention concerne un procédé de soudage de deux profilés creux en matière plastique, pour former un cadre de fenêtre, dans lequel les deux profilés à assembler sont chauffés à une température prescrite en insérant un miroir de soudage entre leurs surfaces de jonction, et en plaçant lesdites surfaces contre le miroir de soudage, ce qui forme un cordon de soudure. Puis, après enlèvement du miroir de soudage, lesdits profilés sont réunis sous pression. Afin déviter au moins une partie des frais denlèvement des cordons de soudure visibles et donc indésirables (ou des restes de cordons de soudure), pour réduire davantage le temps nécessaire à la fabrication dun cadre de fenêtre, et pour éliminer la formation dun « rainure dombre », après enlèvement du miroir de soudure, les parties extérieures des cordons de soudure qui se forment sur les surfaces visibles éventuelles du cadre de fenêtre au niveau des surfaces de jonction des deux profilés sont pressées vers lintérieur, après quoi le miroir de soudage est réintroduit entre les surfaces de jonction des profilés, et les surfaces de jonction sont réchauffées, accompagnées de déformations simultanées des cordons de soudure pressés vers lintérieur, et enfin, après enlèvement du miroir de soudage, les surfaces de jonction des deux profilés sont réunies.

Claims

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Patent Claims:
1. A method for welding two hollow profile members of plastic material, to
form a
window frame, wherein the two profile members which are to be joined are
heated to a prescribed temperature by inserting a welding mirror between their
joining surfaces, and pressing said surfaces against the welding mirror,
whereby a weld bead is formed; then, after the welding mirror is removed, said
profile members are joined together under pressure, with the weld bead being
simultaneously enlarged;
wherein after the welding mirror is removed, outer parts of the weld beads
which form on eventual visible surfaces of the window frame in a region of the
joining surfaces of the two profile members are pressed inward, following
which
the welding mirror is re-inserted between the joining surfaces of the profile
members, and the joining surfaces are re-heated, accompanied by
simultaneous deformation of the inwardly pressed weld beads, and finally,
after
removal of the welding mirror, the joining surfaces of the two profile members
are joined together.
2. A device for carrying out the method according to claim 1, comprising
a welding head having a welding mirror and two forcing units, each of which
forcing units has an upper and a lower limiting ramp, which forcing units
accommodate the two profile members and act to press said profile members
against the welding mirror;
wherein at least one slider is guidable in the region of two mutually facing
end faces of the limiting ramps, the at least one slider being associated with
a
drive means for briefly pressing against and deforming the outer part of the
weld bead formed in the region of the visible surface of the eventual window
frame.
Date Recue/Date Received 2023-06-28

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3. The device according to claim 2;
wherein the end face of each limiting ramp extends at an angle to a base
surface of said limiting ramp.
4. The device according to claim 3;
wherein the angle between the end face and the base surface of the limiting
ramp is ca. 45 to 70 degrees.
5. The device according to claim 2 or 3;
wherein the at least one slider has a wedge-shaped cross section.
6. The device according to claim 3 or 4;
wherein the free end face of the at least one slider extends at a right angle
or approximately a right angle to the base surface of the limiting ramp.
7. The device according to any one of claims 2 to 6;
wherein a pointed edge of the at least one slider has a rounded cross
section.
8. The device according to any one of claims 2 to 7;
wherein the at least one slider comprises a first slider and at least one
additional slider, the at least one additional slider being guidable, at an
angle to
the first slider.
Date Recue/Date Received 2023-06-28

Description

CA 02945712 2016-10-17
WELDING METHOD AND DEVICE
Specification:
(0001) The invention relates to a method for welding two hollow profile
members of
plastic material, to form a window frame, wherein the two profile members
which are
to be joined are heated to a prescribed temperature by inserting a welding
mirror
between their joining surfaces, and pressing said surfaces against the welding
mirror, whereby a weld bead is formed, which bead extends exteriorly to some
extent; then, after the welding mirror is removed, said profile members are
joined
together under pressure, with the weld bead being simultaneously enlarged. The
invention further relates to a device for carrying out the method.
(0002) Welding devices are known for producing window frames from profile
members having continuous (throughgoing) chambers, which devices (depending on
the configuration of the fabricating device) are capable of simultaneously
welding
together one, two, or all four corners of a window frame. Each welding device
has a
welding head for each corner, which welding head has a heatable welding mirror
and
has a forcing unit for each profile member. Each forcing unit has an upper and
a
lower limiting ramp, between which pair of ramps a profile member is held.
(0003) For the actual welding and joining process, the two profile members,
which
at each end are approximately 3 mm longer than the dimensions of the finished
window frame, are aligned with each other and secured in a position in which
the two
connecting surfaces are held so far apart from one another that the welding
mirror,
heated to a predetermined temperature, can be introduced between said two
surfaces. The connecting surfaces of the two profile members are then pressed
against the welding mirror and melted to the extent that the length of the
profile bars
is reduced by ca. 2 mm. During this pressing, a first part of a so-called weld
bead is
produced in all regions of the profile members. Then, the profile members are
withdrawn briefly from the welding mirror, so that the welding mirror can be
returned
to its initial position. Subsequently, the heated joining surfaces of the two
profile
members are again pressed against each another, whereby the abovementioned
weld bead is enlarged, and at the same time the

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length of the profile members is further shortened by ca. 1 mm, so that the
welded
and joined ends of the profile members are now at the final lengths prescribed
for the
window frame.
(0004) The weld beads formed by the joining of the profile members in the
region
of the joining surfaces are not only comprised of exteriorly projecting parts
which
extend around the profile members, but they are also comprised of inwardly
projecting parts which extend inward into all of the web members of the
profile
members. These weld beads can be partially sharp-edged and do not give a
pleasant appearance to the visible surfaces of the eventual window frame.
Therefore, these weld beads are removed, at least at the visible surfaces of
the
welded (joined) window frame. This is done by means of special knives and/or
milling cutters on the top or front side and on the bottom or rear side of the
welded
window frame, in at least one subsequent additional method step, usually
resulting in
a so-called "shadow groove". These additional operations not only necessarily
increase the time for fabrication of the window frame, but also require an
additional
device. In addition, a shadow groove has a somewhat rougher surface compared
to
the other surfaces of the window frame, which is conducive to deposition of
particles
of soils.
(0005) Accordingly, the underlying problem of the present invention was to
devise
a method and a device for welding of two plastic profile members for serving
as
elements in fabricating a window frame, such that at least a part of the
expense of
removing the visible and undesirable weld bead is avoided, and such that the
time
for fabricating a window frame is reduced. No "shadow groove" should be
formed.
(0006) This problem is solved according to the invention with a method of the
type
described initially above, wherein, after the welding mirror is removed the

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outer parts of the weld beads which form on the eventual visible surfaces of
the
window frame in the region of the joining surfaces of the two profile members
are
pressed inward, following which the welding mirror is re-inserted between the
joining
surfaces of the profile members, and the joining surfaces are re-heated,
accompanied by simultaneous deformation of the inwardly pressed weld beads,
and
finally, after removal of the welding mirror, the joining surfaces of the two
profile
members are joined together.
(0007) By means of such a method, and the device which carries out the method,
any visible weld beads, at least on the upper or front side, and on the lower
or rear
side, of the joined profile members and of the finished window frame, are
eliminated.
The expenses for additional equipment to eliminate these beads are eliminated,
and
the expenses for the time involved are reduced. The "shadow groove" which
arose
under the prior art is no longer present, and thus particles of soils cannot
deposit at
these joining loci.
(0008) The invention will now be described with reference to an exemplary
embodiment which is illustrated in substantially simplified fashion in the
drawings.
(0009) The figures, Figs. 1-5, show partial views of the essential parts of
a device
for carrying out the invention, in successive method steps.
(0010) In Figs. 1 to 4, a so-called limited ramp 1, a slider 2, and a
welding mirror 3
may be seen, which are only some of the parts of which an inventive device is
comprised; in particular, they are components of a welding head (per se known
and
therefore not shown). The limiting ramp 1 is disposed on and rests against the
upper
side of a hollow profile member 4 comprised of plastic, the two end faces of
which
are cut in mitered fashion and the interior of which is (as is normal)
subdivided into a
plurality of differently sized and continuous (throughgoing) chambers by
suitably
disposed web members. On the

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underside of the profile member 4 (not shown) a second limiting ramp 1 is
disposed
which is advantageously identical and in mirror-image form with respect to the
first
limiting ramp 1, with the profile member 4 being held by forcible means
between the
two limiting ramps (1, 1), wherewith the end face of the profile member 4
extends
beyond the free end face 5 which is relatively low and which extends
perpendicularly
to the surface of the profile member 4, the distance of this extending beyond
being
prescribed and being typically ca. 3 mm. The end face 5, at its upper end,
undergoes a transition to a rearwardly directed incline 6. The angle of this
incline 6
may be, e.g., 45-70 degrees, advantageously below 60 degrees. The slide 2 has
a
wedge-shaped cross section with a free end face 7, which may extend, e.g.,
perpendicularly to the profile member 4; this slide 2 is guided on the incline
6 of the
limiting ramp 1. The lower limiting edge of the slide 2 advantageously has a
rounded
cross section.
(0011) The above-described welding head also accommodates a second profile
member 4, visible only in Fig. 5, which is also held by forcible means between
two
limiting ramps (1, 1), each of which ramps 1 is associated with a respective
slider (2,
2). In known fashion, this arrangement comprises a mirror image arrangement on
the other side of the welding mirror 3. Depending on the design of the welding
apparatus, the welding apparatus may have two, four, or six welding heads.
(0012) To initiate the welding and joining process, the welding mirror 3 which
is
(normally) disposed outside the region of the profile members (4, 4) [lit.,
"1"], and
which is heated, is now inserted between the end faces (joining faces) of the
two
profile members (4, 4), with the two limiting ramps (1, 1) each initially
being disposed
at a distance of ca. 3 mm from the welding mirror 3 (Fig. 1). Next, the
profile
members (4, 4) are pressed with a prescribed force against the welding mirror
3.
Thereby the end faces (joining faces) of the two profile members (4, 4) are
heated
and melted. Since in the process the magnitude of the pressing-together force
of the
profile members (4, 4) against the welding mirror 3 is maintained, the
distance
between the respective limiting ramps 1 and

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the welding mirror 3 is reduced, and a so-called weld bead (8a, 8b) (Fig. 2)
is formed
outside and inside the walls of each of the profile members 4; the shape of
these
beads will differ from the simplified shape which is illustrated. As soon as
the
distance between the limiting ramp 1 and the welding mirror 3 has been reduced
by
ca. 2/3, i.e. ca. 2 mm, the pressing force is reduced, and the profile members
(4, 4)
are withdrawn from the welding mirror 3. Then the welding mirror 3 is removed
from
the region of the profile members (4, 4). At this point, the slide 2 comes
into
operation. It is moved by a drive means along the end face 6 of the limiting
ramp 1,
from its position in Figs. 1 and 2 into the position according to Fig. 3. In
the process,
the outer weld bead 8a is forced to be moved inward (inverted), wherewith the
two
weld beads 8a and 8b melt together to form a larger weld bead 8c (the shape of
which also does not match the shape illustrated).
(0013) Immediately thereafter, the slide 2 is withdrawn into its initial
position
according to Figs. 1 and 2. Then the welding mirror 3 is re-introduced into
the region
of the two profile members (4, 4), and the profile members (4, 4) are once
again
pressed against the welding mirror 3. However, this pressing process is only
of short
duration, and the pressing force is very low, such that the lengths of the
profile
members (4, 4) are only slightly (insignificantly) reduced, but the end faces
of the
profile members (4, 4) come to be re-heated (Fig. 4).
(0014) As soon as the welding mirror exits its position between the two
profile
members (4, 4), the profile members are pressed together. This results in an
increase in the size of the previously inwardly inverted weld bead 8c
(according to
Figs. 3 and 4), wherewith the weld bead 8c acquires a size and shape 8d
according
to Fig. 5. In this instance as well, the simplified representation of the weld
bead 8d
[lit., "8c"] does not correspond to the actual configuration. The important
factor,
however, is that no weld seam is now present on the outer side of the walls of
the
profile members (4, 4), which later will comprise the exterior sides of the
window
frame (the upper and lower sides). Instead, a minor depression with a V-shaped
cross section may form, given that ordinarily no sharp-edged corners are
formed in
the upper region of the joining surfaces of the profile members (4, 4).

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(0015) It is well known that profile members for constructing window frames
are
rarely perfectly flat on their upper and front surfaces. Usually a chamfer or
rounded
edge is present on the inner and/or outer edge. In order to ensure that no
remnant
of an external weld bead survives in these regions, one may, e.g., configure
the slide
2 in a profiled configuration. It is advantageous to have at least two
separated slides
2, with the second slide 2 traveling at an angle with respect to the first
slide 2, which
angle is large enough that in its region it is incident approximately
perpendicularly on
the outer weld bead 8a.

Representative Drawing