Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates to a method of and
an apparatus for applying a coating of solder to a metallis-
ed margin of a vitreous sheet, to sheets having thus-
coated margins and to panels incorporating such sheets.
The invention finds use in particular in the
field of multlple glazing panels in which vitreous sheets
may be soldered directly to one another at their margins
or in which vitreous sheets are held spaced apart by
intervening metallic spacer members soldered to the metal-
lised and soldex coated margins of the sheetsO Such sold~
ering may be effected using only solder pre-applied ~o the
sheet margins and/or to the spacer member(s) when present,
or further solder may be applied.
Various proposals for applying solder to such
metallised sheet margins have been made. Initially, such
solder coating was formed manually by in situ melting of
solder. This was highly labour intensive and expensive
and time consuming. According~y, various efforts have
been made to mechanise this operation.
One such proposal is set out in Glaverbel-
Mecaniver's published British Patent specification No.
1,~18,827. Thisspecification particularly proposes applying
solder in molten forrn (in drops) and then spreading the
drops ~ith a 'neated shoe to form a coating which is more
or less uniform. That specification also discloses spraying
molten solder onto a narro~ strip of the maryin and allow-
ing the solder to sprea~ out by surface tension ef-fec-ts,
again to provide a more or less uniform coating.
It is an object of the present invention to
provide an alternative process of applying solder to a
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metallised sheet margin which enables an even more uniform
coating quality to be achieved.
According to the present invention, there is
provided a method o~ applying a coating of solder to a
metallised margin of a vitreous sheet, characterised in
that an excess of molten solder is supplied alony the sheet
margin and in that the thus supplied solder is treated
while molten with a doctor knife so that excess ~uantities
of molten solder are continuously directed towards and over
the edge of the sheet.
The invention enables high quality uni~orrn
coatings of solder to be applied to metallised shee-t
margins. The invention also facilitates the application
of solder coatings of a desired thickness, particularly
for thick coatings, onto metallised sheet margins.
A method according to the invention readily
lends itself to mechanisation. Since it is in any event
necessary to convey the vitreous sheets from one work
station to the next when manufacturing multiple glazing
panels, it is especially convenient to mount a solder
supplying device and doctor knife above a conveyorin
such a position that one margin of a sheet is automati-
cally coated ~,Jith solder as the sh~et travels along the
conveyor.
Of course ~Jhen solder coating the margins of
rectangular sheets as is most usual, a second solder
supplying device and doctor knife can be located ~or
solder coating the opposed margin of the sheet at the
sarne time.
It is of course ~ithin the scope o~ the
.~ ~ & ~
invention merely to solder coat one me-tallised marginal
region of a vitreous sheet, but it is a more usual prac-
tical requirement that margins extending around the whole
periphery of the sheet be metallised and solder coated.
Different margins of a sheet may be metallised and solder
coated in different stages, and it is not necessary for
the whole of the metallising operation to be completed
before solder is supplied to the sheet. Indeed, in one
preferred manufacturing schedule for treating rectangular
vitreous sheets, the sheets are successively conveyed
through four work stations, at the first of which one
margin is metallised and then solder coated. After trans-
lation of the sheet, the opposed margin is metallised and
this margin is then solder coated at a second station.
The conveyor then changes direction through 90 to convey
the sheet through a third station where one of the two
remaining margins is metallised and solder coated and
thence on to a fourth station where the last sheet margin
is metallised and coated with solder. It will be appre-
ciated that such a sheet could alternatively be conveyedtwice through each of two stations for metallising and
solder coating its four margins.
It will also be appreciated that the coating of
solder formed in accordance ~lith the invention need not
be co-extensive with the metallising layer on which it
is deposited. Indeed such co-extensiveness is not pre-
ferred when working according to the aforesaid manufactur-
ing schedule, at least insofar as the coatings applied
at the first and second work stations are concerned. In
that case, it is preferred to leave a strip of each
metallising layer uncoated so that the subsequently
applied metallising strips can key directly to the first
applied strips at the corners of the panel.
The molten solder may be supplied drop-wise or
by spraying to the metallised sheet margin, but it is
preferably supplied as a jet from a nozzle since this
feature, coupled with relative movement of the nozzle and
margin will ensure the deposit of a continuous strip of
molten solder which needs only to be regulated in thickness
by the doctor knife, and also allows efficient use of the
solder consumed.
Preferably, such solder delivery nozzle is
located a~ove the sheet for discharge of solder in a
direction having a horizontal component towards the edge
of the sheet. This facilitates the direction of excess
quantities of molten solder over the edge of the sheet
by the doctor knife. The best results are achieved when
the solder delivery nozzle is angled substantially per-
pendicularly to the edge of the sheet in the region where
the jet of solder impinges, since for a given solder jet
velocity, the horizontal velocity component of the just
applied solder towards the edge of the sheet will be at
a maximum.
In the most preferred embodiments of ~he in-
vention, the sheet is substantially horizontal and the
solder delivery nozzle is inclined to the horizontal at
an angle bet~een 30 and ~0~.
In some embodiments of the invention, a solid
(e.g. PtFe) doctor knife is used, but preferably such a
do~or knife is a gas knife. By using a gas knife it is
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easier to control the thickness of the solder coating
applied, and a gas-knife is also found to give an imprGved
surface finish and uniformity to the solder coating, espe-
cially to thick coatings. It has also been found that the
use of a gas-knife permits a better quality bond between
the vitreous sheet and a member soldered to its maryin
since there is less risk of damaging that margin.
~ he gas-knife is preferably arranged to direct
a stream o~ gas agains~ the sheet margin over an elongate
zone of impingement which makes an acute angle with the
edge of the sheet, which angle includes the zone of supply
of molten solder. The acute angle is preferably between
70 and 90.
The present invention also provides an apparatus
for performing a method as defined above. The apparatus
of the invention comprises a support defining a predetermined
locus for a vitreous sheet; means for supplying an excess of
molten solder along a margin of the sheet carried by the
support, means for effecting relative movement between
the sheet carried by the support and such solder supply
means, and a doctor knife associated with the soider supply
means and arranged so as to direct continuously excess
quantities of molten solder towards and over the edge of the
sheet, This is a simple and convenient apparatus for per
forming the method of the invention,
Advantageously, the support is a cGnveyor for
conveying a succession of said sheets along a predetermined
path cGnstituting the locus. It is found easier to move
the sheets relative to the solder supply means rather
than vice versa~
5~
The apparatus according to the invention pre-
ferably has one or more of the following optional features:
The solder supply m~ans comprises a noz71e for delivering
a jet of solder, the nozzle is located above the sheet
locus ~or discharge of solder in a direction having a
horizontal component towards the edge of the sheet locus,
the support is arranged to support the sheet horizontally
and the nozzle is inclined to the horizontal at an angle
between 30 and 60: the doctor knife is a gas knife,
the gas knife is arranged to deliver a stream of gas
against a margin of the sheet locus over an elongate zone
which makes an acute angle with the edge of the locus,
w~ich angle includes the orthogonal projection of the
delivery end of the solder supply means in the plane of
the locus, the acute angle is between 70 and 90, and the
means for producing the gas knife comprises a block having
a slot orifice and means for supplying gas under pressure
to the block for egress through the slot.
The invention further extends -to a vitreous
sheet to a metallised marginof which a solder coating has
been applied by a method as herein defined and to a
glazing panel incorporating at least one such vitreous
sheet.
A preferred embodiment of apparatus according
to the invention will now be described by way of diagram-
matic drawings in which:
Figures l, 2 and 3 are respectively end, plan
and ~ide views of solder supply means and an associated
doc~or knife.
In the drawings, a solder supply means l
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5~ 7
comprises a cylindrical structure 2 having a bore 3 ter-
minating in a nozzle 4 for delivering a jet of solder to
a metallised margin 5 of a vitreous sheet 6~ No support
is shown for the sheet 6. In practice, it is convenient
to support the sheet 6 on a conveyor, for exarnple a con-
ventional roller conveyorO ~dge guide means (also not
shown) are preferably provided and ~ay take the form of
guide rollers for defining a locus for the edge 7 of sheet.
If, on the other hand, the support is arranged to hold
the sheet 6 stationary, then means are provided for rnoving
the solder supply means 1 and an associated doctor knife
8 along the margin 5 of the sheet.
The doctor knife 8 is a gas knife and comprises
a block 9 in ~Jhich is formed a slot 10 in communication
with an air supply conduit 11 attached to the block 9 by
an end fitting 12.
The solder supplying bore 3 of the cylindrica7
structure 2 is arranged above the locus of the sheet 6
in a vertical plane normal to the locus of the edge 7 of
the sheet and at an angle of 45 to the horizontal sheet
locus so that a jet of solder delivered by the nozzle 4
will have a horizontal component of motion directed towards
the edge 7 of the sheet.
'rhe slot 10 of the gas knife 8 has an elongate
opening arranged to direct a stream of gas vertically
downwards onto an elongate zone at the margin 5 of the
sheet 6. As indicated in Figure 2, the long axis o~ the
opening of the slot 10 is arranged at 6 to the perpendi-
cular to the edge 7 of the sheet 6 and thus fo~ns an acute
angle of 84 ~ith that edge. This acute angle includes
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the zone of supply of rnolten solder and the orthogonal
projec~ion in the plane of the sheet locus of the nozzle
4 at the delivery end of ~he solder supply means 1.
The cylindrical structure 2 of the solder
supply means may incorporate heating means to maintain
solder flowing through the bore 3 at a suitable tempe-
rature, and/or it may be thermally insulated. In use,
solder may be fed to the bore 3 by gravity from a heated
crucible (not shown), and excess solder which flows over
the edge of the sheet is preferably collected in an over-
flow pan (not shown). This overflow pan may also be
heated to keep the solder molten, and such excess molten
solder may be recirculated to the heated crucible for
reuseO
In a specific practical embodiment of the
apparatus described, the bore 3 has a length of 12 to 15 cm
and the nozzle 4 has an internal diarneter of 3.5 mm. The
lower edge of the mouth of the nozzle 4 i5 arranged 4 mm
above the upper surface of the sheet 6 which has a metal-
lised margin 5 which is 10 to 12 mm wide and 5 to 15 ~m
thick. In order to coat the whole width of such a metal-
lised margin with solder, the noz~le 4 is located with the
orthogonal projection of the centre of its orifice on the
sheet about 13 mrn inside the edge of the sheet, that is
about 1 to 3 rrlm away frorn the inner boundary of the
metallised margin 5. As herein-before explained, it is
sometimes preferred not to coat the ~Ihole metallised
margin with solder so as to provide a key for a subse-
quently deposited metallising coating, and in such cases
the nozzle is located closer to the edge of the sheet to
5~
le2v~ an uncoated metallised strip (e~g. 2 to 3 mm or
more wide). Solder may be supplied to the nozzle with a
head of about 40 cm to give a pressure of about 400 g/cm2,
so that the solder jet issues at the rate of ~2 cm3/s.
The optimurn thickness of the solder coating
applied will depend in larye measure upon subsequent
assembly operations., For example, considering a double
glazing unit ~here a metal spacer is soldered between
metallised and solder coated margins of a pair of vitreous
sheets, the soldering of the spacer to the s~eets may be
accomplished with or without the application o~ additional
solder. For example, a flat leaden spacer strip may be
soldered edgewise between a pair of sheets by beads of
solder applied at a stage subsequent to the coating stage.
In this case the solder coating applied according to the
present invention may be regarded merely as a tinning
coating and need be only 20 to 25 ~m thicko According
to another manufacturing technique, a solder coated
flanged spacer mer~er is soldered with its glanges in face
to face contact with the solder coated metallised margins
of a pair of sheets; this is done without the addition of
any further solder, by clamping and heating the assembly
to melt the pre~applied solder coatings~ In this case,
it is desirable for the solder coatings on the sheet
margins to be thicker, for example in the range 100 to
200 ~m thick.
fn a manufacturing plant, vitreous sheets may
be conveyed alony a production line at a speed of 22 m/min,
this speed being dictated by for example metallislng and
~ashing operations to be performed. The application of a
200 ~m thick, 12 mm wide solder coating will use up 0.88
cm3/s of molten solder, that is, a-bout 11% of the amount
supplied (at a rate of 8.2 cm3/s), the remainder of the
solder being directed over the edge of the sheet by the
gas doctor knife for recirculation.
Such a solder coating thickness can readily be
achieved by using a gàs kni~e having a suitably si~ed
slot opening, a suitable spacing from the sheet margin
and a suitable gas flow rate and pressure.
By way of example, various parameters relating
to two such gas knives are given below.
qas knife I qas knife II
slot opening 0.2 x 16 mm 1 x 20 mm
gas over pressure 300 g/cm 750 g/cm
gas output 0.696 Nm3/h 1.67 Nm3/h
gas exit speed 60.4 m/s 23.2 m/s
height above margin (approx) 4 to 5 mm 2 mm
mean coating thickness 200 ~m 200 ~m
In fact when using such gas knives, the thickness
of the solder coating can be adjusted merely by regulating
the gas supply pressure~ In order to achieve a coating
20 to 25 ~m thick, a gas overpressure of several kilograms
per square centimetre would be required.
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