GB2095290A

GB2095290A - Solder coating metallised vitreous sheet margins

Info

Publication number: GB2095290A
Application number: GB8108430A
Authority: GB
Original assignee: Glaverbel Belgium SA
Current assignee: AGC Glass Europe SA
Priority date: 1981-03-18
Filing date: 1981-03-18
Publication date: 1982-09-29
Also published as: SE454270B; ES8303263A1; IT8267309A0; NL8201060A; AT387211B; ES511147A0; ATA100282A; JPH0455987B2; CA1185127A; SE8201685L; JPS57170848A; ES511148A0; ES8303264A1; DK114382A; DE3209545A1; GB2095290B; BE892493A; DK158093B; FR2502138A1; DK158093C

Abstract

To provide a uniform solder coating to a metallised margin of a vitreous sheet for example as a step in the manufacture of a hollow glazing panel, an excess of molten solder is supplied to the sheet margin and the thus supplied solder is treated while molten with a doctor knife so that excess quantities of molten solder are continuously directed towards and over the edge of the sheet. The doctor knife is preferably a gas knife. <IMAGE>

Description

SPECIFICATION Solder coating metallised vitreous sheet margins The present invention relates to a method of and apparatus for applying a coating of solder td a metallised 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 multiple 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 metallised and solder coated margins of the sheets. Such soldering may be effected using only solder pre-applied to 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 application was performed manually by in situ melting of solder. This was highly labour intensive and expensive and time consuming. And accordingly various efforts have been made to mechanise this operation.

One such proposal is set out in Glaverbel-Mecaniver's published British Patent specification No.

1,41 8,827. This specification particularly proposes applying solder in molten form (in drops) and then spreading the drops with a heated shoe to form a coating which is more or less uniform. That specification also discloses spraying molten solder onto a narrow strip of the margin and allowing the solder to spread out by surface tension effects, 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 metallised sheet margin which enables an even more uniform coating quality to be achieved According to the present invention, there is provided a method of applying a coating of solder to a metallised margin of a vitreous sheet, characterised in that an excess of molten solder is supplied to the sheet margin and in that the thus supplied solder is treated while molten with a doctor knife so as to direct excess quantities of molten solder towards and over the edge of the sheet.

The invention enables high quality uniform coatings of solder to be applied to metallised sheet 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 reaily 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 conveyor in such a position that one margin of the sheet is automatically coated with solder as the sheet travels along the conveyor.

Of course when solder coating the margins of rectangular sheets as is most usual, a second solder supplying device and doctor knife can be located for solder coating the opposed margin of the sheet at the same time.

It is of course within the scope of the invention merely to solder coat one metallised marginal region of a vitreous sheet, but it is a more usual practical 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 translation 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 appreciated that such a sheet could alternatively be conveyed twice 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 with the invention need not be co-extensive with the metallising layer on which it is deposited. Indeed such co-extensiveness is not preferred when working according to the aforesaid manufacturing 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 above 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 perpendicularly to the edge of the sheet in the region where the jet of solder impinges, since for a given solder jet velocity, the horizontal veiocity component of the just applied solder towards the edge of the sheet will be at a maximum.

In the most preferred embodiments of the invention, said sheet is substantially horizontal and said solder delivery nozzle is inclined to the horizontal at an angle between 300 and 600.

In some embodiments of the invention, a solid (e.g. ptfe) doctor knife is used, but preferably said doctor knife is a gas knife. By using a gas knife it is easier to control the thickness of the solder coating applied, and a gas knife is also found to given an improved surface finish and uniformity to the solder coating, especially 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 margin since there is less risk of damaging that margin.

Said gas-knife is preferably arranged to direct a stream of gas against the sheet margin over an elongate zone of impingement which makes an acute angle with the edge of the substrate, which angle includes the zone of supply of molten solder. The acute angle is preferably between 700 and 900.

The invention includes apparatus for performing a method as above defined. Such apparatus comprises: a support defining a predetermined locus for a said sheet; means for supplying an excess of molten solder to a margin of a sheet carried by said support; means for effecting relative movement between a said sheet carried by the support and such solder supply means; and a doctor knife associated with said solder supply means and arranged so as to direct excess quantities of molten solder towards and over the edge of the sheet. This is a simple and convenient apparatus for performing the method of the invention.

Advantageously, said support is a conveyor for conveying a succession of said sheets along a predetermined path constituting said locus. It is found easier to move the sheets relative to the solder supply means rather than vice versa.

Apparatus according to the invention preferably has one or more of the following optional features: said solder supply means comprises a nozzle for delivering a jet of solder; said nozzle is located above said sheet locus for discharge of solder in a direction having a horizontal component towards the edge of the sheet locus; said support is arranged to support said sheet horizontally and said nozzle is inclined to the horizontal at an angle between 300 and 600; said doctor knife is a gas knife; said 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, which angle includes the orthogonal projection of the delivery end of the solder supply means in the plane of said locus; said acute angle is between 700 and 900, and; means for producing said gas knife comprises a block having a slot orifice and means for supplying gas under pressure to said block for egress through said slot.

The invention extends to a vitreous sheet to a metallised margin of 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 diagrammatic drawings in which: Figures 1, 2 and 3 are respectively end, plan and side views of solder supply means and an associated doctor knife.

In the drawings, solder supply means 1 comprises a cylindrical structure 2 having a bore 3 terminating 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 example a conventional roller conveyor. Edge guide means (also not shown) are preferably provided and may 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 moving 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 which 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 cylindrical 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 450 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.

The slot 10 of the gas knife 8 has an elongate opening arranged to direct a stream of gas verticaily downwards onto an elongate zone at the margin 5 of the sheet 6. As indicated in Figure 2, the long axis of the opening of the slot 10 is arranged at 60 to the perpendicular to the edge 7 of the sheet 6 and thus forms an acute angle of 840 with that edge. This acute angle includes the zone of supply of molten solder and the orthogonal projection in the plane of the sheet locus of the nozzle 4 at the delivery end of the 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 temperature, 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 overflow 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 reuse.

In a specific practical embodiment of the apparatus described, the bore 3 has a length of 12 to 1 5 cm and the nozzle 4 has a internal diameter of 3.5 mm. The lower edge of the mouth of the nozzle 4 is arranged 4 mm above the upper surface of the sheet 6 which has a metallised margin 5 which is 10 to 1 2 mm wide and 5 to 1 5 Mm thick. In order to coat the whole width of such a metallised margin with solder the nozzle 4 is located with the orthogonal projection of the centre of its orifice on the sheet about 13 mm inside the edge of the sheet, that is about 1 to 3 mm away from the inner boundary of the metallised margin 5. As herein-before explained, it is sometimes preferred not to coat the whole metallised margin with solder so as to provide a key for a subsequently deposited metallising coating, and in such cases the nozzle is located closer to the edge of the sheet to leave 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 8.2 cm3/s.

The optimum thickness of the solder coating applied will depend in large measure upon subsequent assembly operations. For example, considering a double glazing unit where a metal spacer is soldered between metallised and solder coated margins of a pair of vitreous sheets, the soldering of the spacer to the sheets may be accomplished with or without the application of 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 um thick. According to another manufacturing technique, a solder coated flanged spacer member is soldered with its flanges 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 ,um thick.

In a manufacturing plant, vitreous sheets may be conveyed along a production line at a speed of 22 m/min, this speed being dictated by for example metallising and washing operations to be performed. The application of a 200 jum thick, 1 2 mm wide solder coating will use up 0.88 cm3/s of molten solder, that is, about 1 1% 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 gas knife having a suitably sized 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.

gas knife I gas knife II slot opening 0.2 x 16 mm 1 x 20 mm gas over pressure 300 g/cm2 750 g/cm2 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 zbm 200 Mm 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 ,um thick, a gas overpressure of several kilograms per square centimetre would be required.

Claims

1. A method of applying a coating of solder to a metallised margin of a vitreous sheet, characterised in that an excess of molten solder is supplied to the sheet margin and in that the thus supplied solder is treated while molten with a doctor knife so as to direct excess quantities of molten solder towards and over the edge of the sheet.

2. A method according to Claim 1, characterised in that said solder is supplied as a jet from a nozzle.

3. A method according to Claim 1 or 2, characterised in that such solder delivery nozzle is located above the sheet for discharge of solder in a direction having a horizontal component towards the edge of the sheet.

4. A method according to Claim 3, characterised in that said solder delivery nozzle is angled substantially perpendicularly to the edge of the sheet in the region where the jet of solder impinges.

5. A method according to Claim 3 or 4, characterised in that said sheet is substantially horizontal and said solder delivery nozzle is inclined to the horizontal at an angle between 30" and 600.

6. A method according to any preceding claims, characterised in that said doctor knife is a gas knife.

7. A method according to Claim 6, characterised in that said gas knife is arranged to direct a stream of gas against the sheet margin over an elongate zone of impingement which makes an acute angle with the edge of the substrate, which angle includes the zone of supply of molten solder.

8. A method according to Claim 7, characterised in that said acute angle is between 70" and 900.

9. Apparatus for applying a coating of solder to a metallised margin of a vitreous sheet, characterised in that such apparatus comprises; a support defining a predetermined locus for a said sheet; means for supplying an excess of molten solder to a margin of a sheet carried by said support; means for effecting relative movement between a said sheet carried by the support and such solder supply means; and a doctor knife associated with said solder supply means and arranged so as to direct excess quantities of molten solder towards and over the edge of the sheet.

10. Apparatus according to Claim 9, characterised in that said support is a conveyor for conveying a succession of said sheets along a predetermined path constituting said locus.

1 Apparatus according to Claim 9 or 10, characterised in that said solder supply means comprises a nozzle for delivering a jet of solder.

12. Apparatus according to Claim 11 , characterised in that said nozzle is located above said sheet locus for discharge of solder in a direction having a horizontal component towards the edge of the sheet locus.

1 3. Apparatus according to Claim 12, characterised in that said solder delivery nozzle is angled substantially perpendicularly to the edge of the sheet in the region where the jet of solder impinges.

14. Apparatus according to any of Claims 11 to 13, characterised in that said support is arranged to support said sheet horizontally and in that said nozzle is inclined to the horizontal at an angle between 30 and 600.

1 5. Apparatus according to any of Claims 9 to 14, characterised in that said doctor knife is a gas knife.

1 6. Apparatus according to Claim 1 5, characterised in that said gas-knife is arranged to direct 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, which angle includes the orthogonal projection in the plane of said locus of the delivery end of the solder supply means.

1 8. Apparatus according to any of Claims 1 5 to 1 7, characterised in that means for producing said gas-knife comprises a block having a slot orifice and means for supplying gas under pressure to said block for egress through such slot.

19. Apparatus for applying a coating of solder to a metallised margin of a vitreous sheet substantially as herein described with reference to the accompanying drawings.

20. A method of applying a coating of solder to a metallised margin of a vitreous sheet according to Claim 1 and substantially as herein described.

21. A vitreous sheet to a metallised margin of which a solder coating has been applied by a method according to any of Claims 1 to 8 and 20.

22. A glazing panel incorporating at least one vitreous sheet according to Claim 21.

New claims or amendments to claims filed on 2/10/81.

Superseded claims 1.

New or amended claims:

1. A method of applying a coating of solder to a metallised margin of a vitreous sheet, characterised in that an excess of molten solder is supplied to the sheet margin and in that the thus supplied solder is treated while molten with a doctor knife so that excess quantities of molten solder are continuously directed towards and over the edge of the sheet.