There are known large varieties of jewellery of all kinds of configurations, shapes and sizes. The present invention relates to jewellery which is referred to as "hollow jewellery' or "back to back" made of two concave bowl like parts which are welded to each other along the rim thereof to form a spheric body, such jewellery is used as earrings, pendants and the like.

The hollow spheric bodies which could constitute the whole jewellery or part thereof are manufactured mostly of very thin gold sheets which are relieved according to a mould, two parts which have an identical contour are welded together and form the required body.

During the process of producing the two concave parts of the hollow body, the seam line after production is not smooth and has small particles or splinters of the material which the body is made of; thus the rim of each part is sanded and smoothed so that proper welding can be obtained.

Nowadays after each part of the hollow bowl like body is relieved by means of a mould, the relieved part is cut out of the gold sheet, the cutting line is sanded on a smooth flat surface which is provided with sanding material. After the two parts are smooth enough, the welding material is applied on both halves of the inner part of the body, both parts are placed one on top of the other along their rim and clamped or tightened temporarily with a clamp or the like, both parts are heated until the inner welding material welds the seam line, the clamp is removed to obtain the required hollow spheric body. The removal of the superfluous particles or splinters before the welding process is manually performed by applying a two- sided adhesive tape to two fingers which secures the holding of the body and attaching it to a revolving grinding surface.

Needless to say this manual method of removing the particles is a time consuming operation and is not always performed accurately.

It is the object of the present invention to provide a device which would sand and smooth the two parts of the hollow spheric body.

It is a further object of the present invention to provide a machine which will automatically perform the sanding and smoothing of the two parts of the hollow jewellery.

According to the invention there is provided a machine which comprises a first endless sanding belt surface on to which the parts to be smoothed will travel and a second endless belt made of rubber or sponge material which will move parallel and in the same direction of the said first endless belt; the said second belt is provided with adjustable means which would enable the adjustment of the distance between the two parallel moving belts, each of said endless belt would be provided with independent propelling means.

The invention is now described with reference to the annexed drawings in which: Fig. 1 is a cross section of a relieved part of a jewellery according to the invention.

Fig. 2 illustrates the part as seen in Fig. 1 after being cut-out from the gold sheet.

Fig. 3 illustrates the part after the sanding thereof.

Fig. 4 is a schematical illustration of the machine according to the invention.

As can be seen in Fig. 1 the relieved part 1 has a flange 2 which when cut off from a bowl like part (Fig. 2) having particles or splinters or protrusions 3.

Turning now to Fig. 4 illustrating schematically the machine. The parts to be sanded will be held in a sorting and orientation feeding drum 11 provided with a hopper 12, the part to be sanded 13 will travel on the first endless belt 14 which is propelled by an electric motor 15. The part 13 will travel on belt 14 until the upper part of which will engage the second endless belt 16 made of rubber or the like and be propelled by an electric motor 17. Said second belt 16 could be adjusted by means of screw 18 which could lower or raise the belt 16. Due to the fact that both belts move in the same direction, however at different speeds, i.e., the upper one would travel slower thus when part 13 will engage with belt 16 then it will partly be stopped by it; consequently and due to the continuous movement of belt 14, the lower part of part 13 will be sanded by the surface of belt 14. Part 13 will move slowly along belt 14 and eventually will be ejected at the end of the belt.

It is quite obvious that the speed of the two belts is adjustable by conventional means. It would also be within the scope of the invention to shorten or lengthen the two moving belts in accordance with the requirements of the specific body to be sanded. Furthermore, by using screw 18 different sizes of bodies could be sanded with the machine as the distance between the two moving belts is controllable. By means of screw 18 the pressure on part 13 is also adjustable.

As each of the two endless belts is provided with independent propelling means the speed of each belt could be adjusted separately which enables the adjustment of the sanding of the part, and the time the sanding would last.

The feeding mechanism of the machine can be provided with a vibrating means to facilitate the feeding in of the parts.