DE1204767B - Use of salts or mixtures of salts to lubricate when extruding steel - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

ClOm

German KL: 23 c -1/04

Number: 1 204 767

File number: M 60373IV c / 23 c

Filing date: March 20, 1964

Opening day: November 11, 1965

It is known that when hot forming materials made of iron and steel, especially when Drawing or extrusion, the tools used for this are mechanically and thermally very strong claimed. They are therefore subject to high wear, which also leads to a poor surface of the deformed object leads. In order to eliminate the high level of tool wear as much as possible, numerous proposals have been made to improve lubrication.

The previously known lubricants can be divided into two groups. One group includes the homogeneous substances, of which glasses - in lumpy or powdery form - and glass-like ones Substances that do not have a specific melting point and are below in a certain melting range the influence of the deformation temperature remain viscous, has acquired great practical importance especially when extruding high-alloy steels. For processing ordinary However, they are too expensive for bulk steels. Another disadvantage is that the required removal the glass residues from the deformed workpieces, which, for example in the case of steels, only occurs after cooling by blasting or pickling is possible, causes considerable costs. In the case of extruded pipes, which have to be further processed in the press heat in order to be compared to the modern Welding manufactured pipes to remain competitive affect these costs particularly stressful.

The second group of lubricants includes inhomogeneous substances. This includes the well-known mixtures of oil with graphite, pitch, lime or borax. Since the oil volatilizes or decomposes at the high deformation temperatures, which are usually above 1000 ^° C., the additives are easily removed mechanically, whereby the workpiece and tool come into metallic contact and wear out. Other known mixtures consist of finely ground substances that have layer lattices such as graphite, molybdenum sulfide or mica, with inorganic salts, e.g. B. sodium or potassium hydroxide, sodium or potassium cyanide, alkali dichromates or silicates. These salts, which are thin at the deformation temperature, have the task of ensuring the transport and uniform distribution of the solid lubricant. However, not all of these lubricants can be heated to high temperatures. They are also relatively expensive.

Contrary to the previous view that salts such as the use of salts or salt mixtures for Lubricating when extruding steel

Applicant:

Mannesmann Aktiengesellschaft,
Düsseldorf, Mannesmannufer 1 b

Named as inventor:

Dr.-Ing. Gerhard Naeser,
Dipl.-Ing. Otto Wessel, Duisburg

Sodium and / or potassium carbonate are suitable for use because of their viscosity in the liquid state not suitable for extrusion, it has now surprisingly been found that such salts or salt mixtures, which have a transition point and which, prior to their use, to an at or above the temperature lying at the transition point have been heated for lubrication during extrusion of steel can be used. The transformation point for soda is 356 ° C and for potash at 400 ° C.

These lubricants are very thin at the deformation temperature and have a vis- viscosity, which corresponds approximately to that of water at room temperature. They wet the material very quickly and thus meet an important requirement for the training of a closed Lubricating film. The improvement of the lubricating effect of these salts through the heat treatment described is probably due to the fact that complete drying is prevented and that after the heat treatment due to the slow conversion rate, the high-temperature modification preserved. However, this is easier to deform than normal salt; a crumbling of the Sintered disks or rings, which are widely used for lubrication, therefore occur at the beginning of the Not pressing process. Experience has shown that crumbling causes defects in the surface and increases the wear and tear of the dies.

The viscosity of the molten carbonates is only 0.015 poise at 1000 ° C and at 1100 ° C only 0.005 poise, so it is about the size of ether. Compared to the previously known lubricants The lubricants according to the invention are considerably cheaper and the further processing of the

509 737/340

deformed workpieces does not cause any problems. The salt residue can be removed by simply washing it off can be removed with water or, if necessary, by hydraulic descaling. It recommends add small amounts of anti-corrosion salts to the lubricating salts, e.g. B. Phosphates or chromates, for example in amounts between 0.1 to 3 percent by weight, preferably 0.3 percent by weight, which prevents the workpieces from rusting after washing off the residual salt.

Claims (2)

Patent claims: 1. Use of salts or mixtures of salts which have a point of transition and which heated to a temperature at or above the transition point before use have been used for lubricating steel extrusion. 2. Use according to claim 1, characterized in that sodium and / or potassium carbonate, optionally with small amounts, e.g. B. between 0.1 and 3 percent by weight, anti-corrosive Salts, e.g. B. phosphates or chromates is used. Considered publications:
British Patent No. 903,957;
U.S. Patent No. 2751312. 509 737/340 11.65 © Bundesdruckerei Berlin