EP0524710B1 - Metallic cutlery - Google Patents

Abstract

The invention relates to integral metallic cutlery manufactured by powder metallurgy. The cutlery concerned is primarily that for table use and can be produced in the conventional shape or in a hitherto unusual configuration and the composition of the alloy used for it can be adjusted to match its function since the cutlery is manufactured from sintered metal. The cutlery is manufactured by methods known from powder metallurgy. <IMAGE>

Description

The invention relates to one-piece cutlery parts made of metal, in particular table cutlery, such as knives, forks, spoons.

The high-quality cutlery parts made of steel or nickel silver, which have become known and are available on the market, in particular made of rust-free chrome-nickel steel or nickel silver, have to be produced by complex manufacturing processes. The manufacturing processes for the production of cutlery made of nickel silver, which are silvered, and for cutlery made of chrome-nickel steel are roughly the same.

Fork and spoon cutlery are cut out of sheet steel in one piece. These pre-cuts, called brandeln, have to be deburred and rolled. The burners for the production of spoon cutlery parts must be rolled down to a smaller material thickness in the area of the bowl to be formed later. Afterwards fork and spoon brandies have to be cut to size according to the model. Washing and glowing operations follow before the cutlery parts get their shape and decor through the embossing process.

The embossing process creates an inevitable burr on the "high edge" of the cutlery. This burr has to be sanded down, only then can the grinding and polishing operations for leveling the surface and for producing the gloss on the surface take place. On The washing process then completes the steps for the manufacture of cutlery items made of chrome-nickel steel. With silver-plated cutlery, silvering follows.

This list alone shows how complex it is to manufacture. The problems in the individual work steps largely prevent mechanization in the manufacture of cutlery, which is why high-quality cutlery is relatively expensive to manufacture. The many work steps also result in a long lead time in production.
In order to be able to decorate cutlery parts in the same way as the associated spoons and forks, they must be made in several parts. The knife booklet is welded together from two half-shells, which were previously formed from a sheet metal strip. The blade is fastened in the hollow knife handle part, preferably by welding or cementing. With this type of knife, the handle is made from a surface-finishable chrome-nickel steel. The blade is made of hardened, elastic, stainless steel.

In order to avoid this complex manufacturing process, the manufacture of monoblock knives is known. In this manufacturing process, a one-piece knife is produced from a hardenable chrome-nickel steel by rolling and / or forging.

The different requirements, for example with regard to mechanical strength and scratch resistance for the magazine and on the other hand the cutting ability and elasticity for the Blade blade, but can not be optimally fulfilled when using a single sheet quality.

The same or similar decors as with an embossing process cannot be achieved by the forging process. The forging process is also very complex, especially because the surface has to be polished afterwards. Fine decors cannot be achieved here. These introduced during forging would be ground down again during the grinding operation. Monoblock knives can therefore only be provided with very simple decors. The matching spoons and forks, derived from them, can only be given simple decors.

In the manufacture of knives, forks and spoons, the manufacturing process is therefore very limited when it comes to the selection of shapes and decors.

The usual cutlery for picking up and transporting food from the plate to the mouth has hardly changed in the last hundreds of years. This is due to the fact that the manufacturing processes did not allow other shapes to be manufactured inexpensively.

However, there is actually a need to design cutlery items in such a way that the dishes can be more easily taken from the plate and can be more safely fed to the mouth. There is also a need to adapt the bowl to the mouth better than before and to shape the handles of the cutlery so that they fit better in the hand.
In addition, there is a desire to be able to produce cutlery with rich decors and distinctive designs in industrial production.

It is known from JP-A-2057604 to produce sintered bodies with excellent corrosion properties from stainless steel by injection molding metal powder mixtures kneaded with temporary organic binder and subsequently removing the binder from the green compact and sintering the green compact.

The applicant has found that it is possible to use this known powder-metallurgical method to produce one-piece cutlery which, over its longitudinal extent, consists of at least two different alloy compositions, one of which has a higher hardness.

The object of the invention is to provide cutlery parts for cutlery which are new, comparatively simple and economical to produce and which, in addition to the usual simple design, permit practically unlimited variety of shapes and design possibilities.

The object of the invention is characterized in the characterizing part of the claim. The subclaims 2 to 11 have expedient refinements.

The cutlery parts according to the invention are comparatively less technically complex to manufacture, extremely variable in shape and - with unchanged good, partly improved usage properties - allow any new cutlery designs that are advantageous and expedient for increasingly internationalized eating habits. Cutlery parts according to the invention give every possibility for fashionable innovations and progressive designs.

For the manufacture of cutlery parts according to the invention, use is made of powder metallurgical injection molding known for other purposes. This known working method involves the injection molding of metal powder mixtures pasted with temporary binders and the subsequent removal of the binder from the shaped body and sintering of the shaped body. With this so-called MIM method (metal injection molding), cutlery parts according to the invention can also be produced with a complicated shape, for example a special decorative design of the cutlery handles or particularly “exotic” cutlery shapes.

The starting materials for cutlery items according to the invention are commercially available. Metal powders of various compositions are available on the market in different particle sizes and shapes, in particular in spherical and spattery particle shapes with a relatively small particle size. In particular, such metal powders of up to 60 μm can be used well for cutlery items according to the invention. Metal powders down to 20 µm are especially recommended for the manufacture of cutlery items according to the invention. The special composition of the starting metal powder for the production of cutlery items according to the invention depends on the properties specifically desired for the finished cutlery items. In contrast to conventional sheet metal material, it is possible with metal powder mixtures as the starting material to achieve alloys not to be produced by melt metallurgy and thus to achieve material properties of the cutlery parts according to the invention which are adapted to the intended uses.

The cutlery part properties for cutlery parts according to the invention can be influenced in a comparatively wide range by the composition of the metal powder mixtures used for the production. The metal composition is no longer restricted to alloy phases. Largely variable chemical compositions can be formed by powder metallurgy, and the shape, size and mixing ratio of differently shaped powder particles can influence the properties in the finished cutlery during its manufacture.
One-piece cutlery parts according to the invention can have two or more different alloy compositions over their longitudinal extent. One-piece knife-cutlery parts according to the invention are particularly advantageous, the blade parts of which have a higher hardness than their shaft part.

Depending on the composition of the metal powder starting mixtures and the specially selected production conditions, cutlery parts according to the invention can also have a partially desired porosity and have a decorative coating, at least partially, for example on the handle part. Cutlery parts according to the invention can have plastic functional and / or decorative elements that cannot be produced by sheet metal technology using industrial production methods at any desired location on the cutlery part surface. And they can be surface-treated in a manner known per se, for example provided with a detector by painting or enamelling.
The surfaces of cutlery items according to the invention can advantageously be partially decorated according to the process described in DE-PS 12 98 384 by the applicant. You can silver in a manner known per se.

Cutlery parts according to the invention require a small amount of material in their production because, in contrast to sheet metal production, there is practically no waste in the course of processing.

example

18 Teile Ferrochrom

Korngröße 10 - 30 µm
6% Cr, 0,2% C, 0,05% Si, Rest Fe

9 Teile Carbonyl-Nickel

Korngröße 0,5 - 10 µm

73 Teile Carbonyl-Eisen

Korngröße 0,5 - 10 µm.

A metal powder mixture of the following composition and particle size distribution was used to produce a spoon:

18 parts of ferrochrome

Grain size 10 - 30 µm
6% Cr, 0.2% C, 0.05% Si, balance Fe

9 parts of carbonyl nickel

Grain size 0.5 - 10 µm

73 parts of carbonyl iron

Grain size 0.5 - 10 µm.

2.5% by volume of polyethylene oxide as dispersion aid and 50% by volume of xylene as suspending agent were incorporated into the powder in a ball mill. A well-pasted, viscous powder metal mass was obtained. Polyethylene in granular form was used as the binder. A tandem extruder system was used, as is known for the production of foam webs and is described, for example, in the trade magazine "Plastververarbeitung" 32, 1981, No. 8, page 948. The homogenizing extruder of the tandem system was designed with two feed openings arranged at a distance of 20 D (screw diameter). Binder granulate was continuously fed into the first feed opening and melted in the screw. Powder metal suspension was fed continuously into the second feed opening and mixed into the binder melt. The melting and homogenization process is controlled by the speed of the screw. The mixing length, ie the screw length of the homogenizing extruder, calculated from the powder metal mass feed opening, was 12 D.
The homogenized powder-binder melt then goes into the cooling extruder, which has a degassing device by means of which the solvent present in the melt has been removed. In the snail's head was solvent released molding compound is compressed and extruded through the nozzle into a spoon shape. The binder was then heated from the demolded spoon body (green body), which consisted of 63 vol% powder metal and 37 vol% binder and was practically non-porous. For this, the green body was placed in a continuous furnace with a heating rate of 15 ° C / min. heated to a temperature of 350 ° C and kept at this temperature for 5 hours. The resulting breakdown products (essentially water, CO ₂ and small amounts of cracked products) were continuously removed from the furnace space by diffusion.
The binder-free spoon body was then sintered in a sintering furnace for 10 hours under a pressure of 0.01 mb at 1260 ° C. and then slowly cooled to room temperature.
The spoon obtained in this way could be finished with conventional mechanical finishing and had an excellent appearance and very good usage properties.

Fig. 1

eine Draufsicht auf eine Ausführungsform eines Löffel-Besteckteils,

Fig. 2

eine Seitenansicht des Löffel-Besteckteils der Fig. 1,

Fig. 3

einen Schnitt nach I-I der Fig. 1,

Fig. 4

einen Schnitt nach II-II der Fig. 1,

Fig. 5

eine Draufsicht auf eine andere Ausführungsform eines Löffel-Besteckteils,

Fig. 6

eine Draufsicht auf eine weitere Ausführungsform eines Löffel-Besteckteils,

Fig. 7

im Querschnitt eine Laffe-Gestaltung eines Löffel-Besteckteils,

Fig. 8

im Längsschnitt eine andere Laffe-Gestaltung eines Löffel-Besteckteils,

Fig. 9

im Querschnitt eine weitere Laffe-Gestaltung eines Löffel-Besteckteils, und

Fig. 10

im Längsschnitt eine Laffe-Stiel-Gestaltung an einem Löffel-Besteckteil.

Cutlery parts according to the invention are illustrated, for example, in the accompanying drawing. Show it:

Fig. 1

a plan view of an embodiment of a spoon cutlery part,

Fig. 2

2 shows a side view of the spoon cutlery part of FIG. 1,

Fig. 3

2 shows a section according to II of FIG. 1,

Fig. 4

2 shows a section according to II-II of FIG. 1,

Fig. 5

a plan view of another embodiment of a spoon cutlery part,

Fig. 6

a plan view of a further embodiment of a spoon cutlery part,

Fig. 7

in cross-section a spoon cutlery part,

Fig. 8

in longitudinal section another bowl design of a piece of spoon cutlery,

Fig. 9

in cross-section another bowl design of a spoon cutlery part, and

Fig. 10

longitudinal section of a spoon-shaped handle on a piece of cutlery.

1 to 4 illustrate an inventive spoon 1 made of sintered metal and consisting of a cup 2 and a stem 3 made of stainless steel. The spoon is made using powder metallurgy. The bowl 2 is - as can be seen from FIGS. 1 and 2 - asymmetrical to the longitudinal and transverse axes. The contour edge 4 of the bowl 2 forms a curve which has cracks. This curve consists of a total of three individual curves that do not continuously adjoin each other. The bowl 2 has depressions 5 on its front side.
As can be seen from FIG. 3, the dimensions of one depression 5a are larger than the other depression 5b. In addition, as can be clearly seen in FIG. 3, the thickness distribution of the bowl is discontinuous. In the recess 5b, the bowl near the contour edge 4 is thicker than in the recess part running towards the center of the bowl, and in the recess 5a, the material thickness at the contour edge 4 is weaker than in the center of the bowl. As shown in FIG. 1, the bowl 2 also has an engraving 6 on its front side, which serves for decorative design, but at the same time also contributes to the identification of the different recesses 5 of the bowl 2.
The different thickness of the spoon improves the usage properties of the spoon. The different recesses 5a and 5b, which are delimited from one another, make it possible to separate dishes on this spoon, so that dishes received in the spoon can be wiped off separately from the lips, for example liquids and solids.

In the area of the transition from cup 2 to stem 3, a three-leaf opening 7 is provided in the spoon 1. This breakthrough is for decorative purposes. However, it can also be used to drain liquid from the bowl 2 in the particular handling position of the spoon. This breakthrough 7 is harmoniously followed on the one hand by the engraving 8 and on the other hand by the curved lines of the stem neck 9. The stem 3 offers an all-round view. It is designed on all sides with merging structured elements. From the stem neck 9, the stem 3 extends in a tapered profile 10 to the handle part 11. The profile 10, as illustrated in FIG. 4, has a shape in its cut surface which is irregularly formed by various curves and undercuts. Both the cross-section and the shape of the profile 10 change over the length of the profile. Approximately in the middle of the handle 3, this thickens in several jumps to the handle part 11. The handle part 11 increases discontinuously in its cross-section up to the handle end 13. The profile 12 of the handle part 11 results up to the handle end 13, beveled by a cut running at an angle to the longitudinal axis of the handle. As illustrated in FIG. 2, oval openings 14 are provided in the handle part 11.

The spoon 15 shown in FIG. 5 is made in one piece from a bowl 16 and a handle 17 and, according to the material, from sintered metal made of stainless steel. It was manufactured using powder metallurgy. The bowl 16 is formed on one side with a straight edge 18. With such a spoon according to the invention, dishes, especially liquids, can advantageously be taken from a plate. The material distribution in the cross section of the bowl 16 is discontinuous. The thickness of the bowl is thinner on the straight edge 18 than on the opposite side. With this type of material distribution, the spoon is also suitable for being able to share food more easily.

FIG. 6 shows a spoon cutlery part 19 made of stainless sintered steel and made of a bowl 20 and a stem 21 in a conical shape of a bowl with roundings on the bowl tip 22. In this bowl 20 there are approximately straight side edges 23a and 23b on both sides, which bring about the same use effect as previously described in connection with the design according to FIG.

Further novel creative bowl shapes which could not be produced industrially with conventional spoon cutlery parts are shown in FIGS. 7 to 10.

The bowls 24, 26 and 29 shown in FIGS. 7, 8 and 9 have an advantageously thin bowl material, as a result of which very light cutlery parts are desirably created. The required stability in use is ensured according to the embodiments of FIGS. 7 and 8 by edge reinforcements 25 and 27, so that the cutlery parts according to the invention thus formed are stable in use despite the thin material thickness of the bowl due to the thickened and rounded rim of the bowl. In the embodiment of FIG. 8, the bowl 26 is designed to be pulled up laterally on one side. The rim 28 of the bowl does not run in one plane, which also has an advantageous effect on the properties of use. The light-weight cup 29 made of very thin material shown in FIG. 9 has an unreinforced, but angled cup edge 30 which ensures the required stability in use and is not unpleasant to handle and use.

FIG. 10 shows a spoon shape of a cutlery part according to the invention made of sintered metal, which is made in one piece from the bowl 31 and the handle 33, the handle 33 already beginning at the lateral bowl edge 32 and / or the bowl 34 increasing in thickness and continuously in its part 34 facing the handle turns into a thickened stem neck. Through this Measure increases the bending strength of the cutlery at the critical point of the stem neck, a particularly stable embodiment.

The design features illustrated in the drawing for spoon cutlery parts can of course be realized in a comparable manner to fork and knife cutlery parts according to the invention.

It is also possible and advantageous in terms of material and manufacture to provide cutlery parts, such as spoons, forks or knives in a conventional design, but consisting in one piece of sintered metal according to the invention.

Cutlery parts according to the invention, which are produced by powder metallurgy, can be finished by a polishing operation in such a way that they have the same surface quality as a previously common cutlery part, which was produced and polished from sheet metal material.

Claims (11)

1. Article of steel produced by injection-moulding of metallic powder mixtures, kneaded With a temporary organic bincer, and subsequent removal of the binder from the green part and sintering the green part, characterized in that said article means a one-piece eating utensil (1) consisting over its longitudinal extend of at least two differing alloy compositions with one of said alloy compositions exhibiting a higher hardness.
2. Eating utensil (1) according to claim 1 wherein one of the alloy compositions is hardenable.
3. Eating utensil (1) according to claim 1, charaterized in that the utensil surface, at any desired location, is provided with plastic fuctional elements (5a, 5b) and/or with decorative design elements (6, 7, 8).
4. Eating utensil (1) according to any of claims 1 through 3, which is conventially surface-treated and/or decorated, at least partially.
5. Eating utensil (1) according to claim 4, which is at least partially enameled.
6. Spoon eating utensil (15) according to any of claims 1 through 5, characterized in that the bowl (16) is designed on one side with a straight edge (18).
7. Spoon eating utensil (19) according to any of claims 1 through 5, charaterized in that said spoon has a conically extending bowl (20) with rounded portions on the bowl tip (22), and has on both sides partially linearly extending lateral edges (23a and 23b).
8. Spoon eating utensil (1) according to any of claims 1 through 7, charaterized in that the bowl rim is designed with a reinforcement (25, 27).
9. Spoon eating utensil (1) according to any of claims 1 through 8, charaterized in that the bowl rim (28) is fashioned, at least on one side of the bowl (26), to be drawn upward laterally curved.
10. Spoon-(1) and fork eating utensil according to any of claims 1 through 9, charaterized in that the bowl (31) continuously increases in thickness passing over into a thickened handle neck (33).
11. Spoon-(15) and fork eating utensil according to any of claims 1 through 10, charaterized in that the thickness of the bowl (16), as seen in cross section, is asymmetrical, decreasing from one side towards an opposite side of the bowl.

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