US1823938A - Process for the production of silver plated metal articles such as table requisites - Google Patents

Description

Patented Sept. 22, 1931 UNITED STATES PATENT OFFICE GUSTAVIHENKE, 0F BREMEN, GERMANY, ASSIGNOR 'ro M. H. WILKENS & soHNE A31.- IGES., OF HEMELINGEN, NEAR BBEMEN, GERMANY PROCESS FOR THE PRODUCTION OF SILVER PLATED METAL ARTICLES SUCH AS TABLE REQUISITES No Drawing. Application filed ianuary 27, 1930, Serial No. 423,888, and in Germany December 11, 1928.

This invention relates to a process for producing silver-plated articles such as table requisites, knives, forks and spoons and the like in which multiple silver layers are applied which are combined by heating.

It has already been proposed to weld together the electrolytic deposits on a base by application of a high pressure with simultaneous heating to incandescence. On the other hand an alloy has already been deposited on a base metal and the deposit heated at high temperature in reducing gas.

This invention consists in that one or a number of pure silver layers are applied consecutively by galvanic or spraying process on a blank or half finished product of German silver, these layers being subsequently Worked in known manner by rolling, pressing, hammering or the like and then heated to incandescence.

It is not intended with such process to obtain a pure silver surface but to refine the base with silver. The applied silver layers combine with the surface crystals of the base and therefore form a diffusion with the base. By this means a base is produced, which ensures'a particularly favourable combination with the final silver-plating layer.

By the invention it is also attained that at those points of the metal article where hitherto no thickening of the silver coating could be effected the edge, after theouter plating (galvanizing) has worn, gradually grades into the colour of the metal of the base so that undesirable conspicuous spots on the metal object are as far as possible prevented.

A further advantage is, that the applying of the pure silver layer is adapted to the progressive manufacturing process of the metal article so that a specialoperation for refining the base with silver is not necessary but the production of the metal article can be carried out in the usual manner.

The invention can be carried out in several ways. The following is an example:

According to the invention the blank, i. e. a base of non-ferrous metal, for example of German silver, is suitably stamped after which, if necessary, after the usual treating with pickles or the like, the first silver coating is applied by plating, galvanizing 0r spraying. The blank is then worked in cold condition for example rolled, pressed orhammered, so that the silver layer comes into intimate contact with the blank. The blank is then heated to incandescence thereby effecting a fusion of the silver layer with the surface crystals of the blank. A second silver coating is then applied in the same manner after which the article is again mechanically cold worked and then again annealed. Further silver coatings can be applied consecutively in the same manner according to the degree to which it is desired to refine the blank with silver. Only when this has been completed the cold stamping is carried out, the burr removed from the metal article, for example a spoon, and then heated.

It is advisable to adapt the application of the pure silver layers to the progressive working stages of the me'al article. For example the blank can, as mentioned above, be galvanized, pressed and heated. At each pressing the shape of the article can be suitably altered.

After the stamping a silver layer is applied without subsequent annealing and only then is the article subjected to a final stamping, cleaned and the burr removed. When the article has reached this stage, a final silver plating is effected in the usual manner by galvanizing or the like, after which a final stamping in the polished die is carried out. v

In order to more easily be able to carry out the process and to increase its efiect, it is advisable to employ as base a metal alloy containing a small percentage of silver. This favours the. refining of the base with silver.

The metal article made in this manner, particularly knives, forks and spoons, possesses a particularly thick and stable silver plating. A thickening of the silver-plating is also obtained on .all parts of the articles, whereas all subsequent processes hitherto employed for applying a thicker layer of silver plating especially on the resting points could only obtain a partial thickening of the silver coating.

Such an article therefore possesses an extremely long life owing to the strengthening of the whole upper surface. The outer silver layer gradually extends into the base metal which layer can, according to this process, be applied without difliculty to all articles such as forks, spoons etc.

An extremely favourable adhesion of the final silver plating layer with the base is obtained.

I claim 1. A process for producing silver plated metal articles such as knives, forks, spoons and the like, consisting in coating an article of non-ferrous metal, mechanically working the coated member, heating the said member to incandescence'effecting a fusion of the silver layer with the surface crystals of the blank, applying a second coating of silver to the member, cold working the second coat, and subjecting it to heat to produce incandescence.

2. A process for producing silver plated metal articles such as knives, forks, spoons and the like, consisting in coating an article of non-ferrous metal, mechanically working the coated member, heatingthe said member to inoandescence effecting a fusion of the silver layer with the surface crystals of the blank, applying a second coating of silver to the membe-r,:cold working the second coat and subjecting it to heat to produce incandescence, and finally applying a layer of silver without subsequent annealing.

In testimony whereof I aflix my signature.

GUSTAV HENKE.