NO131059B - - Google Patents

Description

Lubricant for heat forming of metals.

A process by heat forming

of metals, especially forging, is already known, where tools and possibly the treated piece of metal are coated with a mixture of a solid lubricant, e.g. in powdered form in a suspension in water, where the mixture has such a composition that it at least partially becomes gaseous at the forming temperature and forms gases that do not ignite on contact with the air, and which form a gaseous, lubricating layer between the metal and the outer surfaces of the tool. The lubricating mixture used in this method usually contains sawdust, graphite in flake form and possibly other ingredients which are agglomerated with the help of a binder usually consisting of fat or drying oil. However, at the temperature at which the heat forming takes place, the binder is destroyed already at the beginning of the forming, so that the lubricating mixture is used up before the maximum forming pressures are applied.

The invention relates to lubricants which are free from this disadvantage. The lubricant

according to the invention comprises a combustible and non-rubbable finely divided substance and graphite in flake form which is agglomerated with a binding agent consisting of an organic substance that can be coked at the molding temperature, whose shear resistance at this temperature is so great that the graphite flakes cannot slide against each other until the maximum molding pressure is reached.

Such a binder is preferably mixed with lubricant in powder form. The mixture can be used either in the form of an aqueous suspension in all heat forming processes of non-metals, in particular in forging, continuous casting, punching, drawing, rolling and all analogous working methods, or in the form of pellets or briquettes produced by compressing the mixture under suitable heat conditions . This powder-form lubricant is characterized by the following composition:

45% graphite black

45% graphite in flake form

4% wood flour

6% pyrolusite

Depending on the method of use and the particular applications of the lubricant, this lubricant powder is brought into suspension in different conditions and with a synthetic binder, e.g. polystyrene or dextrin.

When the lubricant in powder form is to be sprayed onto a tool using a spray gun, suspensions with the following composition are used: 1) At low temperatures in the range of 250-300° C, especially for forging, spinning or punching:

3 kg of lubricant powder

1 kg of water-soluble resin, e.g. resin known under the trade name "Lustrex"

15 liters of water.

2) At high temperatures of over

400° C for hot forming processes:

3 kg of lubricant powder

1 kg of water-soluble resin, e.g. resin known under the trade name "Lustrex"

0.45 kg dextrin

0.45 kg sodium silicate

15 liters of water.

In this case, the sodium silicate improves adhesion of the lubricant to the metal

at high temperatures.

The above-mentioned lubricant powder suspended in water can also

is used for metal pieces that are to be treated by hardening, brushing or painting, as the lubricating mixture adheres to the metal when drying during the preheating of the metal pieces. This method of working can be used for tools, especially for extrusion needles

of metal pipes. In this case, the suspension has the following composition:

1) at high temperatures:

1 kg lubricant powder

0.115 kg polystyrene

1.35 kg of trichlorethylene

2) at low temperatures:

2.5 kg of lubricant powder

1 kg of water-soluble resin, e.g.

"Lustrex"

1.30 liters of water.

Claims (10)

1. Lubricant for product shaping of metals, of the type comprising a combustible and non-rubbing finely divided substance and flake graphite, agglomerated with a binder, characterized in that the binder consists of an organic substance which can be coked at the molding temperature and whose shear resistance at this temperature is 'so great that the flake cannot slide against each other before the maximum mold pressure is reached. 2. Lubricant according to claim 1, characterized in that the binder is a synthetic binder. 3. Lubricant according to claim 1, characterized in that the binder consists of polystyrene. 4. Lubricant according to claim 1, characterized in that the binder consists of dextrin. 5. Lubricant according to claim 1, characterized in that the binder is mixed with an aqueous suspension of a mixture comprising 45% graphite black, 45% phoenix graphite, 4% wood flour and 6% pyrolusite. 6. Lubricant according to claims 1 and 5, characterized in that water is replaced by a solvent. 7. Lubricant according to claims 1 and 5, intended for use in a spray gun for forming at low temperatures, characterized in that it comprises 3 kg of a mixture consisting of 45 percent graphite black, 45 percent flake graphite, 4 percent wood flour and 6 percent pyrolusite, 1 kg of water-soluble resin and 15 liters of water. 8. Lubricant according to claims 1 and 5, intended for use in a spray gun for forming at high temperatures, characterized in that it comprises 3 kg of a mixture consisting of 45 percent graphite black, 45 percent flake graphite, 4 percent wood flour and 6 pst pyrolusite, 1 kg of water-soluble resin and 0.45 kg of dextrin, 0.45 kg of sodium silicate and 15 liters of water. 9. Lubricant according to claims 1 and 5, intended to be used during hardening, brushing and coating during forming at high temperatures, characterized in that it comprises 1 kg of a mixture consisting of 45 percent black graphite, 45 percent flake graphite, 4 percent wood flour and 6% pyrolusite, 0.115 kg polystyrene and 1.35 kg trichlorethylene. 10. Lubricant according to claims 1 and 5, intended to be used during hardening, brushing and coating during forming at low temperatures, characterized in that it comprises 2.5 kg of a mixture consisting of 45% black graphite, 45% flake graphite, 4 parts wood flour and 6 parts pyrolusite, 1 kg of water-soluble resin and 1.30 liters of water.