DE279534C - Process for drawing very hard metal wires, especially those for the manufacture of incandescent lamps - Google Patents

Description

IMPERIAL

PATENT OFFICE.

It is known that when drawing wire from very hard metal, e.g. B. tungsten wire, the drawing holes are exposed to very heavy wear. The diamond drawing dies, which are preferably used, also wear out so quickly that a piece of wire of the usual length when drawing remains significantly thicker at the rear end than at the front end. The difference in diameter becomes extremely large if the wire is drawn very thinly, e.g. B. in filaments for electric lamps. A tungsten wire, which ^{has a diameter of 0.015 mm} at the front end, with a length of 1000 m, if it is drawn in the manner customary up to now, will already be 0.03 or more millimeters thick at the rear end. There are also sharp edges on the wall of the drawing hole, which cause damage and consequently breakage of the wire.

In order to avoid these disadvantages, a very hard wire has been proposed to clad with a layer of a softer metal (ζ. B. copper), which is a gentle Has an effect on the draw hole. A major disadvantage here, however, is the inconvenience the copper plating, which has to be renewed after the wire has been pulled through some holes, which is especially true for very thin wires is cumbersome. Also, this process is and will be very time consuming In addition, when drawing copper-plated wire with a small diameter, the risk of breakage is very high great.

It has also been proposed to protect the drawing hole by using a drawing die, Keeps the wire and lubricant at such a low temperature that the lubricant (oil, grease or wax) becomes more or less solid and a protective layer enveloping the wire forms. However, this procedure is costly and the implementation in practice, if you really want to achieve sufficiently low temperatures, very cumbersome.

It has now been found that the wear and tear can be achieved in a very simple and inexpensive manner of the draw hole can be reduced if the hard metal wire is covered with a solid layer an organic adhesive such as resinous and rubbery substances or the like., Coated. These Adhesive layer forms a very useful protection of the draw hole. Tungsten wire, which is covered with it can be pulled very well without the use of a lubricant; but you can also use a lubricant or the adhesive

give a lubricant as an additive. The gentle effect of the adhesive layer however, this reduces it.

The solid layer of adhesive around the wire can be e.g. B. obtained as follows:

The wire is passed through molten resin, the resin layer is allowed to solidify and passed the wire through the drawing hole, or the wire is passed through a resin solution, which leaves the The resin layer will dry and pull the wire through the drawing hole. In both cases it can to add a lubricant to the resin, e.g. B. beeswax. It's expedient, especially when pulling thicker wires quickly, cool the hole while pulling, to prevent the protective layer from becoming liquid.

In this way it is possible to e.g. B. to pull thin tungsten wires of 100 m length, in which the two ends have almost the same diameter; also use the Draw holes are much less peeled off than is usually the case. Furthermore, the wire is through the Cover protected and goes undamaged through the draw hole.

Claims (1)

Patent claim: Process for drawing very hard metal wires, especially those for incandescent lamp manufacture, characterized in that the wire is covered by a solid layer of an organic adhesive, such as resinous and rubbery substances or the like, with or without the addition of a lubricant surrounded and is drawn in this state through the drawing profile.