GB2028070A

GB2028070A - An improved method of affixing an electrical heater element to a glass pane

Info

Publication number: GB2028070A
Application number: GB7927329A
Authority: GB
Original assignee: CRYSTAL GLASS IND Ltd
Current assignee: CRYSTAL GLASS IND Ltd
Priority date: 1978-08-08
Filing date: 1979-08-06
Publication date: 1980-02-27
Also published as: AU528976B2; AU4959379A

Abstract

A method or apparatus for affixing a wire heater element to a glass pane. An electrical heating element is made by winding wire 5, Fig. 1, onto a frame 6, tensioning the wire, laying the tensioned wire (whilst supported on the frame) onto a glass pane, sticking the wire to the glass, and removing the frame once the adhesive is set. <IMAGE>

Description

SPECIFICATION An improved method of affixing an electrical heater element to a glass pane This invention relates to an improved method of affixing an electrical heater element, in particular an unsheathed wire, to a face of a glass pane.

This invention is primarily concerned with affixing an electrical heater wire to a face of a glass viewing pane of a refrigerated apparatus, in particular, a glass door of a retail outlet display freezer. It is known to affix an electrical heater element to a glass pane by incorporating the element into a plastics or similar transparent film which is adhered to the glass panes. Such is not particularly suitable where goods for retail sale are displayed beyond the pane as the film is noticeable. Additionally, in deep freeze applications a viewing panel needs to comprise at least two spaced glass panes with an intermediate sealed air chamber to provide thermal insulation. With a film heater element positioned within such an air space it has been found that the resultant drying of the air within the chamber can lead to the unpeeling of the film.

The intention of this invention is to provide a method of adhering an unsheathed electrical resistant heater wire to a face of a glass pane with the resultant product being suitable for incorporation in a multi-glazed viewing panel with the heater element positioned in an intermediate air chamber between the panes of the panel.

According to one aspect of this invention there is provided a method of affixing an unsheathed electrical heater wire to a face of a glass pane comprising the steps of mounting a length of the wire between and about upstands formed on opposing frame end members at least one of which is longitudinally adjustable of a parent frame thereof, the upstands being a limited relief to the surrounding surface of the frame end member such that the wire stands proud of the upstands, outwardly displacing the adjustable end frame member as to tension the run(s) of wire extending between the frame end members either prior or subsequent to applying an adhesive along the surface of the wire standing proud of the upstands, placing the wire and frame assembly to a face of a horizontally disposed glass pane such that the wire is in contact with the glass pane, applying a weight to the portion of wire between the frame end members as to impinge the wire to the glass pane, detensioning the wire and removing the frame and then allowing the adhesive to harden sufficiently to affix the wire to the glass pane before removing the weight.

According to a second aspect of this invention there is provided an apparatus to facilitate affixing an unsheathed electrical heater wire to a face of a glass pane comprising a frame element having lateral and end members with at least one end member being adjustable longitudinally of the frame and with corresponding faces of the end members incorporating upstands at transversely spaced apart intervals whereby a length of the wire can be mounted to extend back and forth of and about the upstands and be tensioned by outward displacement of the adjustable end frame member, the thickness of the upstands being less than the diameter of the wire.

In further describing the invention by way of a preferred embodiment reference is made to the accompanying drawings wherein; Figure 7 is a plan view of a frame loaded with a wire, and Figure 2 is a side elevation of Figure 1, and Figure 3 is a cross-sectional view on line A-A on Figure 1, and Figure 4 is a composition perspective view depicting various steps of the method.

A rectangular glass pane 3 suitable for incorporating as the outer sheet of a triple glazed vertical deep freezer door is fitted with a wire heater element 5. A wire 5 support jig is fabricated in the form of a rectangular shaped frame 6 preferably of adjustable width and length enabling use with differently sized glass panes. The jig frame 5 is preferably formed from lengths of box-section or cross-sectionally right angled aluminium.

One end frame member7 is mounted to its parent frame by way of detachable pins or clamps 8 enabling the longitudinal adjustment of end frame member 7 for size alteration purposes as aforesaid and to also enable tensioning of a wire element 5 mounted thereto as described hereinafter.

On corresponding faces of the end frame members 7, 9 upstands 10 are formed at spaced apart intervals with preferably the upstands 10 on one end frame element 7 being laterally off-set to those on end frame element 9. The upstands 10 are preferably in the form of thin rectangular shaped nibs. The upstands 10 can be formed from short lengths of aluminium strip welded face down to the face of the end frame members 7, 9. The thickness, that is, the degree of relief of the upstand 10 relative to the surrounding surface is less than the diameter of a wire 5 to be loaded to the frame. Thus, when the wire is so mounted about the upstands 10 the wire stands proud thereof.

Wire element 5 is unsheathed but may possibly incorporate an electrically insulating coating such as the wire used in the construction of small transformers or a nikron wire. Wire 5 is fed back and forth of an about the upstands 10 to thus form several parallel runs or strands disposed longitudinally of the frame 6 between the end members 7, 9 thereof. The ends of the wire elements 5 are left as tails 11 to enable in situ electrical coupling, the tails being temporarily anchored to the frame 6 such as by wrapping about a section thereof clear of the plane of the upstands 10.

An adhesive, preferably an epoxy resin, for example, Araldite (trademark) of suitable consistency to provide the required drying and curing time is then applied throughout the full length of the runs of the wire element 5. In essence only that surface of wire element 5 standing proud of upstands 10 needs to be coated with the adhesive. However, a thin layer or film of adhesive only is necessary and in practice if the complete surface of the wire is given such a thin coating this does not prove adverse. Preferably wire element 5 is coated by passing the wire element through a dip of adhesive or alternatively by running fingers or a cloth smeared with the adhesive along the wire once loaded to the frame 6.

With the subject glass pane 3 disposed horizon tally the jig frame 6 with wire element 5 loaded thereto is then placed on the upper face of the glass pane 3 such that the wire element 5 is disposed between the glass pane and the frame. Preferably the geometrical relationship between the wire and frame assembly and the glass pane 3 provides that the runs of wire are disposed longitudinally of the pane 3 at spaced apart parallel intervals across the width with the ends of the runs being disposed adjacent the ends of the glass pane 3.

The adjustable end frame member7 is then released from the lateral frame members and pulled outwardly to thus displace it from its original position and in so doing tensioning the runs of wire between the end frame members 7,9 to remove any undesirable wrinkles therein. End frame member 7 is then recoupled in its new position.

To facilitate contact of the full length of the wire with the face of the glass pane 3 a weight is placed on the runs of wire to thus impinge them into contact with the face of the glass pane 3. Preferably the weight is in the form of a sheet of glass with the wire contacting face thereof coated with an adhesive relief agent. The weight sheet is preferably of a size marginally less than the subject sheet as will enable the frame to be lifted clear thereabout.

If desired the step oftensioning the strands of wire element 5 can be carried out subsequent to placing the weight element 11 thereon.

With hardening of the adhesive as to affix the wire element 5 to the glass pane 3 the frame 6 and weight element 11 are removed. Preferably a quick drying adhesive solution is utilised as this enables the early removal of the frame with the weight element 11 being sufficient to retain the position of the wire element while full or at least further curing of the adhesive takes place.

Claims

1. A method of affixing an unsheathed electrical heating wire to a face of a glass pane comprising the steps of mounting a length of the wire between and about upstands formed on opposing frame end members at least one of which is longitudinally adjustable of a parent frame thereof, the upstands being in limited relief to the surrounding surface of the frame end member such that the wire stands proud of the upstands, outwardly displacing the adjustable end frame member as to tension the run(s) of wire extending between the frame end members either prior or subsequent to applying an adhesive along the surface of the wire standing proud of the upstands, placing the wire and frame assembly to a face of a horizontally disposed glass pane such that the proud face only of the wire is in contact with the glass pane, applying a weight to the portion of wire between the frame end members as to impinge the wire to the glass pane, detensioning the wire and then removing the frame and allowing the adhesive to harden sufficiently to affix the wire to the glass pane before removing the weight.

2. A method of affixing an unsheathed electrical heater wire to a face of a glass pane as claimed in Claim 1 wherein the wire contacting face of the weight is coated with an adhesive release agent and the adhesive is selected for its drying capabilities as will enable the frame to be moved from the wire shortly after application of the wire to the pane with reliance being placed upon the weight to maintain the set of the wire.

3. An apparatus to facilitate affixing an unsheathed electrical heater wire to a face of glass pane comprising a frame element having lateral and end members with at least one end member being adjustable longitudinally of the frame and with corresponding faces of the end members incorporating upstands at transversely spaced apart intervals whereby a length of the wire can be mounted to extend back and forth of and about the upstands and be tensioned by outward displacement of the adjustable end frame member, the thickness of the upstands being less than the diameter of the wire.

4. A method of affixing an unsheathed electrical heater wire to a face of a glass pane substantially as herein described with reference to the accompanying drawings.

5. An apparatus to facilitate affixing an unsheathed electrical heater wire to a face of a glass pane substantially as herein described with reference to the accompanying drawings.