OUTSIDE PART OF A COOKTOP OR AN OVEN

Abstract: Outside parts of cooktops and ovens, such as tops or fronts are traditionally manufactured in enamelled steel. There is a need to manufacture such parts in stainless steel. This has hitherto required special tools and special pressing operations and hence intermediate storage of stainless outside parts of cooktops and ovens. According to the invention precisely the same functionality of outside parts of cooktops and ovens as for stainless steel is obtained by manufacturing the parts in ordinary steel plate which is subsequently subjected to a complex electrolytic treatment which is finalised by a tin-nickel electroplating.

Description: Outside part of a cooktop or an oven . The invention relates to a drawn outside part for a cooktop or an oven with a metallic stainless suface. Modern outside parts for cooktops and ovens, such as the front or the top, have a profiled construction which emphasises rounded shapes, not the least in order to simplify cleaning. Enamelling has been a very much used surface treatment, but partly dependent on taste, and partly for technical reasons, such as resistance to impact, it is desirable with a metallic surface. Techniques have been transferred from steel sinks and kitchen work surfaces, because it has been found to be desirable to obtain the surface finish provided by a stainless plate after grinding or brushing. However, it turns out that an industrial production of a particular profiling which must be available both in an enamelled version (e.g. due to a choice of colours) and in a stainless version, cannot be performed using the same tools or dies. Work in stainless steel alloys requires a completely different type of tool and another composition of part processes than work in steel alloys which are suitable for enamelling. This means that while all dimensions on finished cooker parts of enamelable steel alloys and stainless alloys will be the same, such that cookers may be assembled from parts in storage in assembly plants, in practice one needs two positions in the raw materials store, one for raw steel parts and another for stainless parts which have been manufactured in other production plants. In the store for semimanufactured parts enamelled steel parts are added which have been through an enamelling station. Thus revisions are more difficult to perform, because it is necessary to use up a remiander of e.g. stainless parts, before a rationalisation and adaptation of a model can be performed, even though the normal, drawn steel parts have been used up. Quite some capital is hence tied up in the semi-manufactured parts constituted by the stainless steel parts. It is the purpose of the invention to provide parts for cooktops and ovens which display the same functionality as existing stainless parts for cooktops and ovens but which have a considerably improved ability to perform in the ordinary manner of production and of storage control. This is obtained in a construction which is 2 particular in that it is manufactured in an alloy suitable for drawing of the type used for enammelled parts, which is subsequently subjected to electrolytic treatment in a series of baths which in sequence provides at least one corrosion protective nickel layer and a tin-nickel combination layer with a tin content of 60-70 percent by weight and a thickness of at least 5 micrometer. In this manner a surface appears which in all respects acts as stainless steel. It is thus obtained that the raw parts store only needs to contain parts for cooktops and ovens in the form of uniform steel raw parts which are distributed to enamelling and electrolytic treatment respectively The invention will be described in greater detail with reference to two embodiments Example 1 An outer part for a cooktop is manufactured in Steel Alloy 37 which after drawing to the final shape is pre-treated in the following steps steel shot blast to remove scratches anodic degreasing rinse in demineralised water pickling in a dry acid bath containing sodium-hydrogen-fluroride rinse These steps are followed by electrolytic treatments in further steps bright nickel electroplating in Blasberg electrolyte with Topstar M bright additive, current density 6 A/dm 2 , plating time 10 minutes, creates 12 micrometer layer thickness pearly bright (satin) nickel electroplating in Blasberg electrolyte type SATINIK2, current density 6 A/dm 2 , plating time 10 minutes, creates 12 micrometer layer thickness tin-nickel electroplating in Blasberg electrolyte type STA NILOY, current density 2J A/dm 2 , creates 8 micrometer layer thickness 3 In this manner a total plating thickness of 32 micrometer is obtained, which in all respects appears as if it were a surface of stainless steel, i e visually, to the touch, and as to cleanability The liberation of nickel which may be allergenic, is less than in the case of ordinary stainless chromium-nickel steel In practice it turns out that the surface has an improved cleanability and is more scratch resistant than the stainless steel surface it is intended to simulate The surface may have an oil-water emulsion applied without spoiling the appearance Example 2 The same procedure as in Example 1 is used on a front part for an oven made in the same type of steel sheet, with a further matte deposit of nickel as the first layer, and the current density is reduced in order to obtain good plating on protruding edges, whereby the following electroplating times are used Matte nickel 20 minutes Bright nickel 20 minutes Satin nickel" 20 minutes Tin-nickel 12 minutes Dependent on adjustment of the baths, a total thickness of between 30 and 50 micrometers are obtained, in that the edges created by the drawing process differ in plating thickness from from the plane surfaces Technically the electroplating performed may be described as a first corrosion protective coat, a second structure-creating coat, and a third coat which counteracts contact allergy towards nickel However, it is the interaction between the coats which creates the advantageous effect when applied to a steel plate

Claims: 4 PATENT CLAIMS 1 A drawn outer part for a cooktop or a stove with a metallic stainless surface, characterised in that it is manufactured in a drawable steel alloy of the type used for enamelled parts, whereupon it is subjected to an electrolytic treatment in a series of baths which in sequence provides at least one corrosion protective nickel layer and a tin-nickel combination layer with a tin content of 55-70 percent by weight and a thickness of at least 5 micrometer 2 An outer part according to claim 1, characterised in that the corrosion protective nickel layer is prepared as a duplex nickel system 3 An outer part according to claim 2, characterised in that the corrosion protective nickel layers are a matte nickel layer, followed by a bright nickel layer with a thickness of 10-15 micrometer, said corrosion protective layer being covered by a pearly bright (satin) nickel layer with a thickness of 10- 15 micrometer 4 A process for the manufacture of an outer part for a cooktop or an oven according to claim 1 , characterised in that a steel sheet of steel No 37 is drawn in a press to the final form, including perforations for cooperation with interlocking elements, that it is subjected to a combined electrolytic treatment in a series of baths, which in sequence provide at least one corrosion protective nickel layer and a tin-nickel combination layer having a tin content of 55-70 percent by weight and thickness of at least 5 micrometer

Inventors: FEDDERSEN JAN, MADSEN MARTIN KIRSTEIN, FEDDERSEN, JAN, MADSEN, MARTIN, KIRSTEIN
Applicants: FEDDERSEN JAN, MADSEN MARTIN KIRSTEIN, VOSS FABRIK A S, FEDDERSEN, JAN, MADSEN, MARTIN, KIRSTEIN, VOSS FABRIK A/S
Application year: 1999
Main classification: C25D5
IPC codes: C25D5, C25D7, F24C15