EP0200647B2 - Iron sole plate covered by an enamel coating - Google Patents

Abstract

The iron baseplate (1) has an enamel coating (8) on its surface (7) intended to be applied to the articles for ironing. This enamel coating (8) provides inter alia an improved coefficient of friction between the baseplate and the textile articles for ironing. Use inter alia in steam irons.

Description

The present invention relates to an iron soleplate, in particular a steam sole. The invention also relates to irons, comprising such a sole.

The soles of iron, dry or steam, are currently made of aluminum alloy molded in particular by pressure injection (see for example FR-E-57 460 and US-A-3 333 955).

These aluminum alloys have a relatively low hardness, so that the surface of the iron soles is easily scratched when ironing textile articles comprising hard objects such as buttons, zippers, staples, etc.

These scratches cause wear of the sole which has the effect of increasing the sliding coefficient thereof with respect to the textile articles to be ironed, thus making ironing more and more difficult for the user. Furthermore, these aluminum alloy soles become, depending on the use, more and more sensitive to staining due to the oxidation caused in particular by water vapor and carbonized organic matter originating from textile articles.

These stains dirty textile articles if the iron soleplate is not cleaned frequently.

Of course, the presence of scratches on the surface of the soleplate promotes the adhesion of these spots and these become very difficult to clean when the soleplate is heavily scratched.

• les fers à repasser sont livrés aux utilisateurs avec une protection provisoire qui met la semelle à l'abri des chocs mécaniques engendrés lors de la manutention et du transport; cette mesure grève le prix de revient des fers,
• les semelles sont réalisées en alliage d'aluminium renfermant du magnésium, qui est plus dur mais plus onéreux que les alliages d'aluminium plus courants renfermant du silicium,
• la surface de la semelle subit un polissage soigné pour réduire le plus possible son coefficient de glissement par rapport aux articles à repasser; cette opération est également coûteuse.

Currently, the following measures are adopted to limit the formation of scratches on the soles of irons:

• irons are delivered to users with a temporary protection which protects the soleplate from mechanical shocks generated during handling and transport; this measure strikes the cost price of irons,
• the soles are made of aluminum alloy containing magnesium, which is harder but more expensive than the more common aluminum alloys containing silicon,
• the surface of the sole undergoes a careful polishing to reduce as much as possible its coefficient of sliding compared to the articles to be ironed; this operation is also expensive.

The aforementioned embodiment of a conventional sole made of aluminum alloy molded in one piece constitutes a good solution of the problem of fixing the tubular heating resistance to the soleplate of the iron, and it makes it possible to obtain good heat exchange between the heating resistance and the aluminum alloy, without any deformation of the sole.

Furthermore, it is known to deposit a layer of enamel on an iron. This idea was described in 1924 in FR-575 630, which is however silent on the nature of the sole.

Fixing a tubular electrical resistance to a laminated sheet of aluminum alloy presents difficulties. Indeed, the Applicant has found that if one fixes, for example by welding, a tubular heating resistance on an aluminum metal sheet, the latter deforms under the effect of the thermal gradient which is imposed on it.

Thus, a metal sheet is compatible with a thin planar heating resistance, but not with a tubular resistance.

Furthermore, the most important drawback presented by cast aluminum alloys is that, in practice, an enamel coating cannot be applied to their outer surface.

GB-A-1 380 415 describes an iron according to the characteristics of the preamble of claim 1.

The object of the present invention is to remedy all the aforementioned drawbacks.

The invention thus relates to an iron soleplate, according to the subject of claim 1.

Thanks to this enamel coating, the hardness of the sole is considerably increased, so that it resists remarkably well the abrasion caused by the metallic parts of textile articles.

In addition, this enamel coating effectively protects the soleplate against oxidation caused by water vapor and other chemicals.

In addition, the stains caused by limescale caused by the evaporation of water or by the carbonization of organic matter from ironed articles, do not offer any grip on the enamel coating, so that the soleplate is easily cleaned .

On the other hand, it has been found that the enamel coating makes it possible to substantially reduce the sliding coefficient of the soleplate on the articles to be ironed, which allows users to iron effortlessly. This property is surprising since it does not result from the known properties of enamel coatings. This explains, moreover, the reason why enamel coatings have never been used to improve the slip coefficient. In addition, this enamel coating resists mechanical shock and therefore avoids the use of protection provisional. It also makes it possible to use less expensive alloys for the sole and to replace the costly polishing of the sole, by simple mechanical abrasion using an abrasive cloth.

Enamel coating thus not only prolongs the life of the iron, makes it easier to use and clean, but also reduces the cost of this iron.

The first part of the sole can be made of aluminum alloy, molded for example by pressure injection, vacuum or molded in a shell and containing silicon. This type of aluminum alloy is economical, but relatively soft. The enamel coating, however, gives the surface of the sole a largely sufficient hardness.

These molded aluminum alloys have the particularity that there remains within the alloy of air microbubbles. In conventional soles, not coated with enamel, the presence of these microbubbles of air is not harmful.

However, experience has shown that if a conventional sintered aluminum enamel is applied to these soles at a temperature of the order of 600 ° C., although the enamel coating has good adhesion, a refusal rate is obtained. very high, which the Applicant explains as follows: when the soleplate is heated to a temperature above 350 ° C., the aforementioned microbubbles of air escape from the alloy. From 500 ° C this phenomenon is sufficient to blister the enamel coating. In addition, beyond this temperature, there is a deformation of the soles.

According to an important characteristic of the present invention, the aforementioned drawback is eliminated by applying the enamel coating in the form of a sintered enamel frit at a temperature between 500 ° C and 600 ° C, not directly on the cast aluminum alloy, but on the second part, consisting of a laminated aluminum sheet attached to the aforementioned aluminum alloy.

Other features and advantages of the invention will appear in the description below.

• la figure 1 est une vue en coupe transversale d'une semelle de fer à repasser comportant un revêtement d'émail,
• la figure 2 est une coupe à grande échelle et partielle d'un revêtement d'émail composé de deux couches,
• la figure 3 est une vue analogue à la figure 1 concernant une réalisation conforme à l'invention.

In the appended drawings, given by way of nonlimiting examples:

• FIG. 1 is a cross-sectional view of an iron soleplate comprising an enamel coating,
• FIG. 2 is a large-scale and partial section of an enamel coating composed of two layers,
• Figure 3 is a view similar to Figure 1 relating to an embodiment according to the invention.

In the embodiment of FIG. 1, the soleplate 1 of the iron is made of aluminum alloy injection molded under pressure, under vacuum or in shell, such as AS9U3, AS9G, AU4G, AS12 or AG5 (A denotes aluminum, S denotes silicon, U denotes copper and G denotes magnesium). In the aluminum alloy of the sole 1, an armored tubular heating resistance 2 is embedded by overmolding.

The boss 3 surrounding the resistor 2 defines an interior vaporization chamber 4 and a peripheral chamber 5 for distributing the vapor. These two chambers 4, 5 are intended to be covered by a sealed cover, not shown. The peripheral steam distribution chamber 5 opens out to the outside via steam distribution channels 6 passing through the soleplate 1.

The surface 7 of the soleplate, which is intended to be applied to the articles to be ironed, is covered by an enamel coating 8.

This enamel coating 8 is produced by projecting onto the surface 7 of the sole, an enamel frit slip which is then dried and then fired to make the mineral particles (SiO2 and other metal oxides) contained in this slip vitrify.

To avoid the blistering phenomenon and the deformation of the sole mentioned above, due to the release of air from the air microbubbles trapped in the aluminum alloy, it is possible to use a sintered enamel frit at a temperature lower than 500 ° C such as the frit sold by the company FERRO under the name GL 43 - 48 which sintered at 480 - 490 ° C. The thickness of the enamel coating 8 is generally between 20 and 100 microns.

However, the adhesion of the enamel coating 8 remains insufficient.

The enamel coating can be formed from two layers of enamel 8a, 8b (see FIG. 2) fired simultaneously according to the process described in French patent application No. 8,306,178 of April 15, 1983 in the name of the applicant, in replacing the enamel frit described in this patent application by the one mentioned above which sintered at 480 - 490 ° C.

At least the outer layer 8b can contain colored pigments 9 (see FIG. 2) or can be applied by screen printing if a pattern or a decoration is to be formed on the surface of the sole 1.

It was also found that the enamel coating 8 had, taking into account its thinness, no harmful influence on the thermal conductivity of the sole. Thus, there is no need to load this enamel coating with conductive particles.

To remedy the difficulties posed by the micro-bubbling phenomenon mentioned above, it is possible to use, to make the soleplate, a sheet of laminated aluminum alloy.

FIG. 3 describes an example of an iron soleplate using a laminated aluminum alloy sheet.

In the embodiment of this FIG. 3, the laminated alloy sheet 1a is assembled with an upper part 1b produced by injection. as in the case of the realization according to the Figure 1. This assembly can be done for example by hot stamping.

The enamel coating 8c applied to the surface of the aluminum alloy sheet 1a can be obtained from a conventional enamel composition for aluminum, which can be sintered at a temperature of between 500 and 600 ° C. of course the assembly supports this temperature.

Claims (4)

1. A baseplate for an iron, more particularly a steam iron, the outer surface of which has a coating of enamel, and comprising a first part (3), made of cast aluminium alloy in which a tubular heating resistance (2) is embedded, characterised in that it also comprises a second part (1a) formed by a rolled aluminium sheet fixed directly to the surface of the first part (3) adjacent said sheet in such a way that the whole supports a temperature of between 500°C and 600°C, the outer surface of the rolled sheet being covered by an enamel coating produced from an enamel frit composition frittable at a temperature of between 500 and 600°C.
2. A baseplate according to claim 1, characterised in that the enamel coating comprises two layers (8a, 8b), at least the outer layer (8b) containing colouring pigments.
3. A baseplate according to claim 1 or 2, characterised in that the surface (7) of the baseplate (1) is abraded but not polished.
4. A baseplate according to any one of claims 1 to 3, characterised in that the surface of the baseplate has a keying undercoat for the enamel coating, said undercoat being made by chromatation.

Images