EP0754256B1 - Electric iron - Google Patents

Abstract

In an electric iron manufacturing process, in which an aluminium-silicon alloy block is cast together with the heating element and the ironing surface is provided with an aluminium oxide layer, the low silicon-content aluminium sole is fixed in good thermal contact with the block and the aluminium oxide layer is formed on the outer face of the sole by anodising. Preferably, the aluminium oxide layer is 20-80 mu thick and the sole is fixed to the block by means of a temperature resistant silicone adhesive.

Description

The invention relates to an electric iron with a silicon-containing Cast iron block with an electric heater and with a surface forming the ironing surface of the iron, which is covered by an aluminum oxide layer is formed.

In the brochure "HART-COAT", edition AHC / 83, by A.H.C.-Oberflächentechnik München GmbH, 81369-Munich, Euckenstrasse 4 Application examples on surface protection using anodic oxidation for aluminum materials, in particular a "HART-COAT" coating. According to the brochure, the anodic oxidation results on the surface the aluminum material has a very hard aluminum oxide layer that is wear-resistant, is corrosion-resistant, hard, glides well and can withstand high temperatures. For the application Such oxide layers on aluminum parts should according to the brochure among other things also suitable "iron soles" (5th page of the brochure).

An electric iron of the type mentioned at the outset is already known from EP 217 014 known. This iron has an iron block made of cast aluminum, in which an electric heater is included. The iron sole is as a composite sole integrally formed with the iron block, whereby by means of a Plasma sprayed an aluminum oxide layer sprayed onto the iron block so as to form the soleplate of the iron.

According to the invention, it is now proposed according to the features of claim 1 to create this aluminum oxide layer by anodizing the soleplate of the iron, which converts the surface of the soleplate to an aluminum oxide layer becomes. For this purpose, a plate-shaped iron soleplate made of a low-silicon aluminum used, which is then attached to the iron block so that it is in good condition There is thermal contact with the iron block. The use of the iron soleplate Low-silicon aluminum enables an optically high-quality, flawless and flawless aluminum oxide layer, through which - after attachment to the iron block and completion to the iron - an electrically operated Iron arises, which many placed on it in terms of its ironing surface Requirements such as corrosion resistance, wear resistance, very good hardness, good gliding behavior, no adhesion problems on the ironing material, good Temperature resistance and high insulation effect etc. fulfilled. By choosing the Material aluminum is a particularly light sandwich construction from Iron block and soleplate.

With the iron according to the invention, not only those mentioned above can be used Achieve benefits, but there is also an ironing surface that is extremely Uniform color coding with a high degree of purity and good surface quality having. An iron soleplate with such a high-quality coating is inexpensive to produce in series and it is also relatively easy to Fasten the iron block. In particular, discoloration occurs on the Iron sole surface hardly at temperature effects and prolonged use on, so that the visual impression of the ironing surface is still after a long time is still positive.

According to the features of patent claim 2, preferably plated ones are suitable Rolled sheets made of a wrought aluminum alloy, in particular of the types aluminum-manganese-magnesium (AIMg 4.5 Mn) aluminum-magnesium (AIMg 3), aluminum-copper-magnesium (AlCuMg 1), etc. Such rolling sheets are practically silicon-free, so that an absolutely homogeneous aluminum oxide layer can be produced. The components refining the aluminum not more than 5%, preferably even less than 3% be.

Due to the features of claim 3, the Aluminum oxide layer smoothed the surface of the iron sole according to the invention, preferably to a roughness depth of less than or equal to 0.1 mm. This high Surface quality can be advantageous, for example, by a grinding or polishing process to reach. By pre-polishing or pre-grinding the not yet with a Alumina provided iron soleplate has the advantage that after the Manufacture of the soleplate with aluminum oxide to achieve the required Final roughness needs to be removed from the surface thus produced less than if it had not been pre-polished or pre-ground. By the lesser The thickness of the aluminum oxide layer can also be selected to be relatively thin be without this hard layer in the polishing process partially again up to Reason must be removed in order to achieve the desired roughness. You get So despite the desired roughness, it is still closed and therefore always corrosion-protected aluminum oxide layer. The removal of aluminum from the still Iron sole not coated with aluminum oxide layer up to a roughness depth less than 0.1 mymeter can be carried out extremely quickly in practice, since the still uncoated and therefore still very soft aluminum surface Iron sole can be easily smoothed or machined.

Due to the features of claim 4, an ironing surface is achieved, which also withstands larger loads without significant damage and the extreme is protected against corrosion. The smallest thickness (20 mm) of the aluminum oxide layer is sufficient for a pretreatment of the surface of the soleplate according to claim 3 also ensure that the surface is then reduced to a surface roughness of less 0.1 mymeter is removed without local polished areas appearing.

According to the features of claim 5 it is achieved that during the Polishing the surface of the aluminum oxide layer to the specified roughness this is not completely removed in the area of the steam outlet holes, because at the Edges during the polishing process have a significantly higher erosion than on a flat, relatively smooth surface. It is advantageous that the outer Edge area of the soleplate has a radius greater than or equal to 0.3 mm, preferably 0.5mm. Through the two measures, namely on the one hand before the production of the Aluminum oxide layer the surface of the bare iron soleplate to a predetermined To bring roughness, for example by grinding or polishing, and on the other hand the To design transitions on edges sufficiently round, according to the invention achieved that even with a small thickness of the aluminum oxide layer this is not in subsequent polishing process on the vulnerable zones, such as the edges, except for the Reason is removed. On the other hand, less material is removed from one very hard aluminum oxide layer also for shorter processing times.

By developing the invention according to the features of claim 6 ends the individual steam outlet holes in recessed opposite the iron surface arranged ring steps. But since the ring steps at the transition to the ironing surface unite larger diameter than the diameter of the now recessed Have steam outlet holes, a larger radius can also be selected there. The more rounded edge area prevents that during the polishing process with unchanged polishing speed locally a noteworthy higher removal of the aluminum oxide layer occurs than on the flat areas the ironing surface is the case. If, on the other hand, the edge areas were sharp-edged, it would the aluminum oxide layer can be completely removed.

According to the features of claim 7, several steam outlet holes open into a bead so that its edge opening into the surface of the soleplate is a whole group of steam outlet holes, preferably two to five, surrounds. The way formed outer edge of the bead leaves a significantly larger curvature and a rounded edge area too. This advantage in turn enables the choice of larger ones Radii at the edge area of the bead, so that here, too, during the polishing process Aluminum oxide layer treats them gently in this edge area, so not completely is removed.

A particularly scratch and wear-resistant iron soleplate results from the Features of claim 8. The features of claim 9 are Sliding properties of the iron soleplate are good enough if the adhesion is not too high.

Due to the features of claim 10, an electrical ground connection Iron sole guaranteed with the iron block or the mass. This On the one hand, clipping can be done by subsequently grinding the non-current-carrying ones Aluminum oxide layer or by covering individual areas of the soleplate Introducing them into an acid bath, i.e. before producing the aluminum oxide layer, can be achieved.

According to the method according to the features of claim 11, this cannot yet be done iron sole provided with an aluminum oxide layer by means of a grinding or Pretreat the polishing process particularly easily and inexpensively, since the bare Aluminum surface very soft and therefore on the required in no time Roughness can be brought. Through this first editing process Surface roughness is reduced before the aluminum oxide layer is applied, that after application of the aluminum oxide layer, the roughness of the resulting The ironing surface has to be reduced very little by post-processing. This results in significantly shorter polishing times before reaching the desired roughness on the very hard ironing surface of the aluminum oxide layer, what leads to a reduction in the price of the soleplate.

But in addition to this advantage, there is also the advantage that in particular not in the specifically higher-loaded edge areas up to the aluminum oxide layer is removed to the bottom. Because straight edges are flat and smooth Surfaces during the polishing process a higher specific contact pressure of the grinding or Exposed to polishing discs or brushes, causing abrasion in these areas Aluminum oxide layer is always higher anyway at constant polishing speed. Around To counteract this disadvantageous phenomenon, one could either use the Reduce the polishing pressure when reaching the corners, which is only very good in practice is difficult to carry out, or you can, as a further development according to the invention shows, rounding the transitions or edges so much that the polishing process specific surface load decreases in these marginal areas.

The features of claim 12 specify a method in which the Iron sole is particularly firmly connected to the iron block. In doing so at the same time the steam outlet holes opposite the edge of those in the iron block trained steam channels sealed so that the steam only on the Steam outlet holes emerges. Furthermore, the adhesive layer of the silicone adhesive is only so thin that as much heat as possible from the iron block into the soleplate is initiated. A two-component adhesive is used as the adhesive Alumina is added (approx. 70% share). This creates an intimate Connection and good heat conduction between the iron block and the Soleplate.

According to the features of claim 13, areas that are not associated with a Alumina layer should be provided by masking agent during the Anodizing process are covered. This can lead to the formation of current-carrying Freeing up subsequent processing operations can be avoided.

An embodiment of the invention is shown in the drawing and is in following described in more detail.

Fig. 1

Teilquerschnitt durch den Schichtaufbau eines mit einer Bügeleisensohle versehenen Bügeleisenblocks in vergrößertem Maßstab,

Fig.2

Teillängsschnitt durch die Oberfläche der Bügeleisensohle nach dem ersten Oberflächenbearbeitungsvorgang,

Fig. 3

Teillängsschnitt durch die Oberfläche der Bügeleisensohle nach Aufbringen der Eloxalschicht,

Fig. 4

Teillängsschnitt durch die Oberfläche der Bügeleisensohle nach dem Poliervorgang der Oberfläche der Eloxalschicht.

Show it:

Fig. 1

Partial cross section through the layer structure of an iron block provided with an iron soleplate on an enlarged scale,

Fig. 2

Partial longitudinal section through the surface of the iron soleplate after the first surface processing operation,

Fig. 3

Partial longitudinal section through the surface of the soleplate after applying the anodized layer,

Fig. 4

Partial longitudinal section through the surface of the soleplate after polishing the surface of the anodized layer.

According to FIG. 1, the iron block 1 cast from die-cast aluminum is in the vicinity its peripheral edge distributed steam outlet holes 11, which connect the Steam to the opening 19 formed on the iron block 1 up to Create the evaporation chamber (not shown). As from Figures 1 to 4 emerges, the ironing surface 6 points upwards, as if the iron is upside down, would be rotated by 180 °. The iron block 1 is made of cast aluminum, which so that the material flows better into the mold or other mold when pouring, Silicon is added.

In the iron block 1 of FIG. 1, an electric heater 4 for heating the Iron blocks 1 cast in. On the surface 5 of the iron block 1 is by means of a heat-resistant and good heat-conducting silicone adhesive 7, one made of rolled sheet die-cut iron sole 3 glued on. In addition to the adhesive 7 can still further mechanical fasteners can be provided, such as on the soleplate 3 trained sheet metal tabs, which for the purpose of attaching the Iron sole 3 are bent during assembly so that they Grip iron block 1 in a form-fitting manner, but not in the drawing is shown. The adhesive 7 also serves to seal the Iron sole 3 opposite the iron block 1 in the area of Steam outlet holes 11 with each other.

The outer surface 15 of the soleplate 3 is shown in FIG. 1 with a Provided aluminum oxide layer 2, which, with the exception of cutouts 14, preferably is formed on the entire outer surface 15. The exemptions 14 represent after Fastening the soleplate 3 on the iron block 1 a metallic connection to the surface 5 of the iron block 1 ago.

Each steam outlet hole 11 opens into openings formed in the iron block 1 19, which may have a common longitudinal axis 20. But it is also conceivable that the opening 19 is formed by an upwardly open channel in which the Open the steam outlet holes 11. This saves individual, with the steam outlet holes 11 steam holes to be connected in the iron block 1, which the Manufacturing simplified during the casting process of the iron block 1 or the mold less expensive. The steam outlet hole 11 closes via a Edge area 13 on a bead 12 surrounding the steam outlet hole 11, which over the Edge area 9 with the radius R in the horizontally extending surface 8 of the Iron sole 3 runs in. Instead of the surrounding bead 12, this can also be done Steam outlet hole 11 directly over the radius R in the surface 8 of the soleplate 3 open, which is indicated in Fig. 1 by the dashed lines 16 is shown.

In Fig. 2 is a partial longitudinal section on an enlarged scale through the cross section of the Iron sole 3 shown in the area of its outer surface 8, but already after the first grinding or polishing process of the surface 8, but before the anodizing of the surface 8. In FIG. 3, the surface 6 of the aluminum oxide layer 2 is on the Iron sole 3 shown in cross section, which after the diving process Iron sole 3 according to FIG. 2 by an anodizing bath (not shown) on the surface 8 the soleplate 3 adjusts. The resulting surface roughness Ra is included already smaller than if the surface 8 of the soleplate 3 is not as shown in FIG. 2 was pre-ground or pre-polished. 4 is the surface 6 of the aluminum oxide layer 2 shown in cross section, which after the polishing of the surface of the 3 results in aluminum oxide layer 2.

The procedure for making the soleplate is as follows:

First, the surface 5 of the iron block 1 is calibrated or pressed, washed alkaline and degreased, the better adhesion of the adhesive 7 Surface roughness 5 for this purpose is greater than 1 mymeter. Regardless, the Iron sole 3 punched out of low-silicon rolled sheet and in the area of Steam outlet holes 11 depending on the formation of the annular groove or bead, embossed or deep-drawn or otherwise deformed, at the same time the transitions through the radii R and r are formed in their size of about 0.5 to 1 mm.

Regardless of this, the outer surface 8, which will later serve as the base for the The ironing surface 6 serves, as shown in FIG. 2, to be ground or polished until the after Rauhtiehe Ra given by the invention of not greater than 1 Mymeter results. Subsequently the soleplate 3 is immersed in an anodizing bath (not shown) that there is an aluminum oxide layer 2 on the outer surface 8 of the iron soleplate 3 results, the thickness of which is preferably 35 to 45 mm and the hardness is preferably 0.5 HV 480. Certain areas on the outer surface 15 should not be Aluminum oxide 2, as is the case for example with the free space 14, coated be so, for example by means of wax, lacquer, silicone or other Covering agent covered. As a result, these locations 14 remain free of aluminum oxide 2. Degreasing or cleaning processes are carried out after or before, depending on the requirements applied to every operation.

After the anodizing bath, which takes about as long until the one shown in FIG Roughness Ra of 0.5 mm on the surface 6 of the aluminum oxide layer 2, then the surface 6 of the aluminum oxide layer in a further polishing process 2 by polishing to the roughness depth Ra of less than 0.1 shown in FIG. 4 Brought my meter. Then the one to be glued to the iron block 1 Top 17 with a temperature-resistant and good heat-conducting silicone adhesive 7 provided and pressed onto the surface 5 of the iron block 1. At the same time 3 tabs formed on the soleplate of the iron (not shown) are bent over until they grip the iron block 1 in a form-fitting manner. As a result, the soleplate 3 forms a mechanical one in addition to the adhesive 7 Connection to the iron block 1.

The finished soleplate 3 including the iron block 1 can now be used with the still necessary parts (not shown) to form an iron be assembled together. The electric heater 4, which is already when pouring the Iron block 1 was cast in these, generated during operation of the iron Heat generated by the adhesive 7 and the aluminum oxide layer adjacent to the adhesive 7 2 penetrates into the soleplate 3, from where the heat then again through the outer Aluminum oxide layer 2 is passed to the ironing surface 6. There it will be during the Ironing on the ironing not shown in the drawing, such as Items of clothing. The fact that the adhesive 7 is a good heat conductor and in is intimate contact with the soleplate 3, the heat is good on the Transfer soleplate 3.

Claims (13)

1. An electric pressing iron, including an iron body (1) made of cast aluminum containing silicon and provided with an electric heating means (4), and a surface (6) formed by an aluminum oxide coating (2) and defining the ironing surface (6) of the pressing iron, characterized in that a plate-shaped soleplate (3) made of an aluminum material with a low silicon content is attached to the iron body (1) such as to be in good thermal contact with the latter, that the outer surface (8) of the soleplate (3) defines the ironing surface (6) provided with the aluminum oxide coating (2), and that the aluminum oxide coating (2) is produced by anodizing.
2. The electric pressing iron as claimed in claim 1,
   characterized in that the soleplate (3) is made of a rolled sheet material.
3. The electric pressing iron as claimed in claim 2,
   characterized in that the surface (8) of the soleplate (3) is machined to a roughness height Ra less than or equal to 0.1 µm, preferably higher than 0.06 µm, prior to the fabrication of the aluminum oxide coating (2).
4. The electric pressing iron as claimed in claim 3,
   characterized in that the aluminum oxide coating (2) has a thickness of between 20 and 80 µm, preferably between 35 and 45 µm.
5. The electric pressing iron as claimed in claim 4,
   characterized in that steam discharge ports (11) extend through the soleplate (3), the edge areas (9) thereof being rounded in the transition areas to the outer surface (8) of the soleplate (3), and that the rounding (9) has a radius R greater than or equal to 0.3 mm, preferably 0.5 mm.
6. The electric pressing iron as claimed in claim 5,
   characterized in that the steam discharge ports (11) are surrounded in the direction of the edge area (9) by an annular step (11) recessed relative to the ironing surface (6).
7. The electric pressing iron as claimed in claim 6,
   characterized in that several steam discharge ports (11) are encompassed by a bead (12) recessed relative to the ironing surface (6), that the transition area of the bead (12) is rounded in the direction of both the steam discharge ports (11) and the outer surface (8) of the soleplate (3), and that the edge area (13) of the bead (12) has a radius R greater than or equal to 0.3 mm, preferably 0.5 mm.
8. The electric pressing iron as claimed in claim 1,
   characterized in that the aluminum oxide coating (2) has a Vickers hardness of between 400 and 600 HV 0.5.
9. The electric pressing iron as claimed in claim 4,
   characterized in that the aluminum oxide coating (2) has a roughness height Ra less than or equal to 0.1 µm, preferably higher than 0.06 µm.
10. The electric pressing iron as claimed in claim 1,
    characterized in that the outer surface (8) of the soleplate (3), with the exception of one or several voids (14), is completely coated with aluminum oxide (2), and that at least one of the voids (14) is connected to the iron body (1) in an electrically conducting fashion.
11. A method of manufacturing an electric pressing iron as claimed in claim 9,
    characterized in that, prior to the fabrication of the aluminum oxide coating (2), the outer surface (8) of the rolled sheet (3) is machined by means of a surface treatment operation as, for example, grinding or polishing, such that a roughness height of Ra lower than or equal to 0.1 µm, preferably 0.06 µm, results, and that the surface (8) of the rolled sheet (3) is transformed by anodizing involving a chemical oxidation process into an aluminum oxide coating (2) of a thickness of between 20 and 80 µm, preferably between 35 and 45 µm, and that following fabrication of the aluminum oxide coating (2) its surface (6) is machined by a polishing operation such as to obtain a roughness height Ra lower than 0.12 µm, preferably 0.06 µm, and that the soleplate (3) thus produced is subsequently attached to the iron body (1) by joining means (7).
12. The method as claimed in claim 11,
    characterized in that the soleplate (3) is bonded to the surface (5) of the iron body (1) by means of a temperature-resistant silicone adhesive (7).
13. The method as claimed in claim 11,
    characterized in that at least a partial area of the outer surface (8) of the soleplate (3) is masked during the anodizing operation, such that this partial area defines an electrically conducting void (14) following anodizing.

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