DE2430249B2 - HIGH TEMPERATURE LUBRICANT FOR THE HOT FORMING OF METALS - Google Patents

Description

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6! ο The present invention relates to novel lubricant for the hot forming of metals. The products described here allow universal use in pressing, rolling, forging, drawing, punching and slotting and have an excellent lubricating effect in deformation processes in which high pressures and temperatures occur.

Lubricants that are suitable for the areas of application specified above are intended to reduce frictional resistance lower between the hot metal to be deformed and the tools so that the tool life becomes economically viable. This problem of economy can for hard and difficult to deform steels e.g. B. go so far that the matrices used already have to be replaced after a few pressings. Matrices have to be exchanged e.g. B. when the dimensional accuracy of pressed pipes or profiles is impaired by wear and tear is no longer guaranteed.

There has been no lack of attempts to develop lubricants for the hot forming of metals. It is common practice to use such lubricants on tools, but in certain cases also on the to be deformed workpieces to apply.

The use of graphite-based lubricants is generally known today are. In combination with mineral oils and inorganic salts, graphite's own Lubricating properties can still be improved. Unfortunately, with the use of essentially Graphite-based lubricants always cause difficulties when due to the type of Forming process parts of these lubricants can get into the material to be formed. Carburizations then lead to defective end products, which can only be manufactured with great difficulty

stellers are processed or even know thrown discarded. The weather can high-alloy workpieces such. B. on extrusion with these lubricants are practically not processed.

Have the difficulties of this Graptütschmierung therefore led to many considerations to solve pending lubrication problems by using more suitable lubricants.

One has z. B. tries to use raw materials from the mineral sector that are either in their original form Form used after mere crushing or after sintering or melting processes became. Other substances that were checked were sodium carbonate, calcium fluoride, calcium oxide, Magnetite, sodium chloride, iron oxide. Aluminum oxide, copper oxide, sodium borate, etc.

It is also known that attempts have been made to solve the problem indicated by using certain Melt products and. or to dissolve salt mixtures based on phosphate. The state of the art includes ζ. B. based on water-soluble lubricants Alkali phosphate'Alkaliborat in the form of mechanical Mixtures. Other high temperature lubricants consist of mixtures of mono- and or condensed Phosphates of alkali metals, to which certain metal oxides, e.g. B. Zinc oxide and iron oxide are added. The use of sodium.'potassium phosphate mixtures is also known, which to support the lubricating effect certain amounts of one or more Z or trivalent metals, especially magnesium. Zinc or manganese or aluminum in the form their phosphate salts are added. For hot drawing lubricants are also known from rivets, which consist of A'.kahphosphatglasern, which also May contain boron or aluminum. The incorporation of oxides of trivalent chromium and / or of trivalent iron in such sodium potassium phosphate glasses. which can also contain lithium is known. In particular In cases it is also known to reduce the lubricating effect of phosphate glasses through the incorporation of lead and ' or to improve barium compounds

It has also been described the properties of high temperature lubricants by addition of metal fluorides or sulfides and / or by adding graphite.

Known and widely used also lubricants based on Silikatgläiera, to which the aforementioned additives are added to improve their lubricating properties can, or in the course of their melting technology Production the aforementioned additives can be melted down.

Regarding the application? of the various high temperature lubricants have proven themselves in practice different variations enforced. For example, the high temperature lubricant can be in the form of a aqueous dispersion can be sprayed or brushed onto the tool and / or workpiece. Another There is then the possibility of applying the Lubricant dispersion by dipping or pouring to bring on the workpiece.

Wi.ii or you cannot erbe th with dispersions. So there is the possibility of introducing the Hoduemper.-rv ¹ -schmierstort in powdered form into the Urnfc.nsvsiera. This can be done, for example, in that the forming workpiece is powdered with the lubricant or that this workpiece is routed above a level occupied by the lubricant.

S The purpose of the present invention was to create lubricants for high-temperature forming of metals zn, which audit the economic forming of high-alloy steels in Extrusion presses, Locfa presses, push benches, free-film

to forge and enable drop forging.

It has surprisingly been found that high-temperature lubricants, which are aas a melt product of phosphates and borates of alkali metals, alkaline earths, heavy metals or miscfon

is gen of it and one which improves the Danian effect Additives such as zinc sulfide, caldum flaoride, Sodium chloride or sodium zinc poryphosphai or Mixtures thereof consist of a spontaneously decomposing or decomposing by a blowing effect

ao burning organic product based on Cellulose, starch, synthetic resins or oil or mixtures of which they differ significantly in their lubricating effect through the formation of an additional gas separation layer let improve.

The alkali phosphate borate melt product can be composed of 5 to 60 percent by weight P2OS, 10 to 35 percent by weight alkali oxide and 5 to 35 percent by weight BjOj, and 0 to 25 percent by weight ZnO, 0 to 25 percent by weight AbOa. 0 to 25 weight percent PbO. 0 to 25 percent by weight MnO, 0 to 25 percent by weight of alkaline earth oxide or mixtures thereof. The lubricating effect Improving additive can consist of 1 to 25 percent by weight ZnS, 1 to 25 percent by weight CaFi, 1 to 25 weight percent NaF. 1 to 70 percent by weight Graphite. 1 to 25 percent by weight NaCl or 1 to 25 percent by weight Na-Zn polyphosphate in the form of a component or mixtures thereof. The other component, which consists of a

* o practically residue-free with a driving effect decomposing organic product is characterized by 5 to 70 percent by weight cellulosic! Material, 5 to 70 percent by weight starchy material, 5 to 70 percent by weight of a plastic-based material, 5 to 70 percent by weight oil, 5 to 70 percent by weight resin soaps. 5 to 70 percent by weight aliphatic alcohols. 5 to 70 weight percent oxalates or 5 to "0 percent by weight of azo compounds, thej

Components added individually or as a mixture can be.

With the addition of the propellant, the orga, which decomposes practically without leaving any residue niche product to the starting point, consist of phosphate borate glass and a plastic improving additives such as zinc sulfide, calcium fluoride, sodium fluoride, graphite, sodium chloride and un Zinc polyphosphate, or mixtures thereof, will significantly improve lubricating properties z. B. when extruding high-alloy steels and when punching the same material educate The greasy properties of this combination | They cherish significantly better than those of the individual ko; components or as those of a phosphate borate glass and | f> j an additive which improves lubrication.

It is important that the melting range of the Schmie material is chosen so that optimal adhesion on the tool and lightly melting a

the workpiece at the most favorable viscosity curve is achieved. The decisive factor in the present case is it is that the organic product which triggers the blowing effect and which decomposes practically without leaving any residue the melt film of the base product that is formed does not tear, but on the contrary an additional one Bringing "gas lubrication" into the system

High-temperature lubricants for the hot forming of metals on the basis of a phosphate borate glass and an additive which improves the lubrication, as mentioned above, cannot prevent welding of workpiece and tool from occurring under certain operating conditions. Malfunctions caused by fretting of the workpiece under certain circumstances by tearing off the dome ¹ S and loss of quality of the formed products obtained e.g. B. Dimensional inaccuracy and a relatively rough workpiece surface cannot be avoided. What has been said also applies if a phosphate borate glass without an additive which improves the lubrication is only mixed with an organic product that causes a blowing effect and which decomposes practically without leaving any residue. The outstanding forming results achieved with the present lubricant combination are undoubtedly connected with the fact that the phosphate borate glass used creates a melt layer between the workpiece and the tool, the stability of which is further improved by the lubricant improving the lubricant and a permanent separating layer whereby the organic product that triggers the propellant effect, which decomposes with practically no residue, builds up a "gas film" between the workpiece and the tool, which does not destroy the layer of enamel that is being formed. This improves the lubricating effect in a way that could not have been foreseen.

To demonstrate the technical progress of the invention Lubricants versus lubricants that correspond to the state of the art, 4 " a number of comparative tests were carried out.

In the Auslegeschrift 20 46 727 a high temperature • lubricant described, which consists of a salt mixture of

Alkali sulfate
borax

Potassium chloride

Sodium acetate so

Ammonium sulfate and besides
Graphite consists and in addition
Magnesium hydroxide and
Thiatriazole derivatives as well

Dispersants and

May contain stabilizers and in addition
10 to 98% water.

So this is not a phosphate-borate glass, but about a mixture of seeds, which does not contain phosphates at all, and graphite. For certain uses may still contain additives that are at relatively low temperatures have a propellant effect and also gaseous and vaporous substances in a second stage set free.

In contrast, the claimed high-temperature material consists of a phosphate-borate glass and a The lubricating effect-improving substance, whereby the excellent lubricating effect of this 2-component system nor by a third component, which exerts a driving effect, this Propelling effect is triggered by spontaneous decomposition or combustion of an organic product, is still being improved. This third component causes So not only a separating effect but also improves the lubricating properties, with the trained Melt film of the base product must not be torn by the blowing effect, so that a additional "gas lubrication" occurs.

Comparative tests on a hydraulic extrusion press resulted in the use of a high-temperature lubricant as described in the German Auslegeschrift 20 46 727, the mixture on the die was applied, an average service life of 20 tubes. At the bottom of the driver could can be clearly observed that a large part of this lubricant during the pressing process by the Die fell.

When using a lubricant according to the invention, a Service life of 34 tubes achieved. When the lubricant was used in the form of a ring, none occurred Loss of lubricant.

The German Offenlegungsschrift 21 54 232 describes 2-component lubricants made from phosphate-borate glasses and additional components such as

ZnS

CaF ₂

NaF or

graphite

When using this lubricant, which does not contain any component that exerts a driving effect, it comes z. B. when spraying the block on the relatively cold transducer wall for recrystallization of glass, which interferes with the retraction of the ram and leads to the tearing of the die caps.

The glass residues are caused by the strong propellant effect of the lubricant according to the invention upwards and thrown outwards along the lowering punch head.

In comparative tests, as a result of the blowing effect of the lubricant according to the invention, the Lubricating effect improved to the effect that the workpiece on a gas cushion over the tool slipped, resulting in a significantly increased die life of 58 tubes compared to 40 tubes the known lubricant was achieved.

The German Auslegesdirift 14 52 449 describes a high-temperature lubricant made from a mixture of crystalline substances with a large Part of the mixture changes into a liquid, viscous or sticky state at block temperature and is forced to spontaneous crystallization by the admixture of the metal oxide powder. The decomposition of the metal oxide crystal powder component releases small amounts of oxygen forms a wafer-thin oxide skin on the extruded strand and also immediately after the pressing Strand, within the plastic anti-oxidation film, expands and its surface tension increased by bloating.

The dissociation products of the lubricant create a vfillip annprcr Pff »l ·» '"" ^ ¹

than occurred due to the additional "glue" exerting a driving effect and a trouble-free operating component of the lubricant according to the invention. sequence was not possible.
Phosphate glasses are not used. In the German Auslegeschrift 14 44 797 a

Glass-like product with a lubricating effect as a slide on a vertical hydraulic extrusion press, the die support disk was coated with the lubricant for drawing metals and metal alloy material, as described in German Auslegeschrift 14 52 449, which is described with a low melting point. There were tubes of the quality consisting of a glass with the following composition 10 Cr Mo 910 with a medium pressure:
pressed by 1145 t.

In comparison with this, the compression pressure at Ver io was 50 to 66 percent by weight P2O5

application of the lubricant according to the invention in the 0 to 16 percent by weight AhO ^

Average only 945 t. 9 to 13 weight percent PbO and BaO

The German patent specification 12 78 663 describes 24 to 35 percent by weight of Na2O and

Boron-phosphorus-alkali metal oxides as solid lubricants, if necessary

medium, which may contain phosphates of 15 K2O and LbO

valuable metals are added. It's about ZnO

solid lubricants with similar intrinsic B2O3

shafts such as molybdenum sulfide and graphite. The Her- lime or Magnesia

these substances are produced by sintering and de- manganese, iron,

hydrate and not by melting as with the "copper or."

lubricants according to the invention. Molybdenum oxides.

It was a lubricant according to German patent specification 12 78 663 for forging. It is a phosphate glass with Flanging in deep dies by sprinkling in the single and higher quality metals; Boric acid is not Lubricant used in the dies. Already included after 35. Only in column 2, line 45 A few work processes resulted in the typical up to 50 is the admixture of other components of »adhesives«, since the lubricant mentions components. The other components will has no propelling effect. but not explained in more detail, and it does not work

When using the lubricant according to the invention, whether these additives increase a lubricating performance

"Glue" did not appear, rather the 3 ° had an effect. With the stressed lubricating

Dies excellent durability. these well-known products cannot be conveyed

When using the known and the inven- tive.

Appropriate lubricants when forging in fla- When extruding profiles of quality Chen dies were made with the known lubricating ST 35 was the known in comparative tests a die life of 3873 pieces 35 lubricant in the form of a ring on the die opposite given a service life of 4284 forged pieces. This was a throughbci Incorporation of the dimensions according to the invention, the additional service life of the die of 32 tubes was obtained. A technical advance is clearly enough. If on the other hand with the claimed given. Lubricant was worked, the mean stand-

According to German patent specification 12 79 875, the grain time of the die for 58 tubes.

Men as a lubricant a mixture melted at the temperature of also the German Auslegeschrift 14 44 885 be-Lager- or Gleitstellen containing a lubricant for the drawing of metals Meta-, Ortho- or Pyrophosphat an alkali and metal alloys with a low melting point tails with a so that a eutectoid melt is formed in the form of an alkali-phosphoric acid-alumina glass, the sulfate or chloride of an alkali metal or of a certain composition. The addition of andesMagnesium. A lubricant corresponding to its substances is mentioned in column 2, lines 53 υ> * 59 of the German patent specification 1279 875 for Schmiewähnt without further details being given. eng entered into the dies by crankshafts. For extrusion, a corresponding lubricant was formed after just a few blows, and the so-called "glue" was applied. The forging blank and the die support plate of a hydraulic strand engraving could only be separated by force. On arrival press brought were pipes of the quality ST 45 application of the inventive lubricant education pressed Here erga b a durchsdmittlidiie end to the CeDuloseanteö, the third component service life of the die of 28 tubes, was contained on blowing effect, a gas cushion ans, In In comparison, the erSndungsgewekhes was strong enough to prevent these seizures on the lubricant from an average service life. A trouble-free operational sequence was achieved by 58 pipes, and a tabular compulsory delivery of the tests was guaranteed

The German Anslegeschrift 12 76 268 asked a result of the following Bfld: The subject of lubricants is largely the

corresponds to German patent specification 12 79875, with 60 Vendekfasversnche

the difference is that the mixture aas Mete-, Or- ^eiCiVUS

tfa- or pyrophosphate nnt sulfate or oiloride of a, ._ *., «" *, -,

AftaBmetaDs or magnesium also 1- German interpretation Z) 46 727 Alkali tetraborate contains ^. . _. . . The experiments with this sdmnernnttel znm «s Extrusion: through- Extrusion: through- Dissatisfactions proceeded in the same way as those with a poor service life and the poor service life

34 corresponds tubes <: the Sdranenoittem according to the German patent specification die: 20 tubes Matriz e

12 79875, so that andi speaking with this Schnnenaitiel Example 1)

2. German Offenlegungsschrift 21 54 232 Die service life: Die service life:

40 tubes 58 tubes (corresponding to

Example i)

3. German Auslegeschrift 14 52 449 Extrusion: necessary extrusion: necessary press pressure: 1145 tons of pressure: 945 tons

4. German patent specification 12 78 663 Forging in deep dies Forging in deep dies: Occurrence of countersink no "glue" "glue"

Forging in flat Forging in flat

Lowering: Lowering: _X5

Service life of the dies: Service life of the dies:

3873 pieces 4284 pieces

5. German patent specification 12 79 875

Forging: Occurrence forging: no _ao

from "glue" to "glue"

6. German Auslegeschrift 12 76 268 Forging: Occurrence of forging: none from "glue" to "glue"

7. German Auslegeschrift 14 44 797 Extrusion: Die extrusion: Die service life: 32 tubes Service life: 58 tubes (according to example 2)

8. German Auslegeschrift 14 44 885 Extrusion: Die extrusion: Die service life: 28 tubes service life: 58 tubes (corresponding to Example 2)

The following examples are intended to clarify the invention without restricting it:

Example 1 A high temperature lubricant was made

a) 45 parts of a phosphate glass

composition

⁵⁵ ' ⁶ percent by weight P2O5

13.0 percent by weight Na2Ü

9.1 percent by weight K2O 15.6 percent by weight B2O3

6.7 weight percent AI2O3

^b ) ⁵ parts of graphite and

c) 30 parts containing cellulose! Material and 20 parts starch paste

manufactured.

35 35

This is the technical progress of the lubricant according to the invention over those of the prior art clearly presented.

The new lubricants are used in the case of extrusion, slotting or punching in the Production of seamless tubes or considerable increases in service life in the production of profiles achieved for the valuable tools.

The possibility of removing the lubricant residues from the formed workpieces is also of great economic importance. The workpieces formed with the above-mentioned new lubricants no longer need to be pickled with hydrofluoric acid, as is necessary when working with high-temperature lubricants based on silica glass. In many cases, it is no longer necessary to pickle formed workpieces that have been machined with the lubricants mentioned, or a simple sulfuric acid sparing pickle is sufficient.

The new lubricants can be applied to the workpieces by powdering them. You can but can also be used as a dispersion and irch brushing, spraying, pouring or applied to tool and workpiece 60

Another way of applying

consists in the lubricant used in extrusion in the form of a ring between the die and the block or the block and the ram. Another The possibility of applying the high temperature protective material described here is to use the To bring lubricant in powder form to the covered die or the workpiece.

The mixture was pressed into rings and on the metal support disk and on the 4fin _T .. ^Quality 10 Cr Mo 910 with the dimension oil r "! ^ ^{Length and 20 mm 0 to a} thin-walled aL α ^{d (} * ^dimension 89 · 4.5 mm pressed. When using these lubricant rings, this

st ^e _a ^r nH Τ ' ^Ver P ^reßbarcn steel quality achieved a die life of 34 tubes.

If, on the other hand, a high-temperature lubricant of the known type composed of 55 parts of graphite and
45 Expensive. NaCl

was used for the same pressing process, it was not possible to use a 10 Cr Mo 910 to be measured to a pipe bobbin, since the press

man ^ nH ^na * ^{initiation of} the pressing process broke off due to insufficient lubrication.

Example 2 A high temperature lubricant was selected

a) 50 parts of a phosphate borate glass

Composition 6.20 percent by weight Al2O3 1.32 percent by weight ZnO 8.24 percent by weight K2O 29.82 percent by weight NazO 42.00 percent by weight P2O5 12.42 percent by weight B2O3

b) 20 parts of ZnS and

c) 30 parts containing cellulose! Material and in the form of a powder to form a strand

τηΐ br 35 on the mattress pad

the one in the transducer

given a hydraulic extruder. Hblocks of 400 mm length and 200 mm 0 thin-walled tube blanks of the dimensions 4.5 mm pressed

i 58 tubes.

_KA "-—— * was a lubricant of the conventional type, consisting of

SS parts graphite
28 parts NaQ and
17 parts mineral oil

used for the same pressing process. In this case the service life of the die was only 17 tubes.

Example 3

For forging crankshafts an aqueous dispersion, the solid content of which consists of

a) 50 parts of a phosphate borate glass of the composition

5.0 parts AhO ₃

1.5 parts ZnO 17.3 parts B2O3

6.3 parts Na ₂ O 80.0 parts K2O 59.9 parts PaOs

b) 25 parts of graphite

c) 25 parts of a synthetic resin

applied to the warm dies of a closed-die forging press.

The solids content in the dispersion was 20%, and 2% finely divided silica was used for stabilization admitted.

Compared to the previously used combination xo of graphite and water with additional use sawdust increased the service life of the dies.

Claims (8)

10 * 5 claims: 1. High temperature lubricant for the hot forming of metals on the basis of a Phosphate-borate glass and an additive which improves lubrication, characterized in that that he is out a) a melt product of phosphates and borates of the alkali metals, alkaline earth or Heavy metals or mixtures thereof, b) zinc sulfide, calcium fluoride, sodium fluoride, Graphite, sodium chloride or sodium zinc polyphosphate or mixtures thereof as an additive that improves the lubricating effect, c) an addition of a propellant that triggers a practically residue-free decomposing organize cn product based on cellulose, Stirl: e, synthetic resins or oils or Mixtures thereof, if appropriate d) a stabilizing agent and optionally e) consists of an inorganic or organic binder. 2. High temperature lubricant according to claim 1, characterized in that it consists of a) a melt product 5 to 60 percent by weight P2OS
10 to 35 weight percent alkali oxide
5 to 35 percent by weight BjO?
0 to 25 percent by weight ZnO
0 to 25 percent by weight AI2O3
0 to 25 percent by weight PbO
0 to 25 weight percent MnO
0 to 25 weight percent alkaline earth oxide b) an additive which improves the lubricating effect 1 to 25 percent by weight ZnS 1 to 25 percent by weight CaF2 1 to 25 weight percent NaF 1 to 70 percent by weight graphite 1 to 25 percent by weight NaCl 1 to 25 percent by weight Na-Zn polyphosphate or mixtures thereof c) an organic which triggers the propellant effect and decomposes practically without leaving any residue Product from 5 to 70 percent by weight of cellulose!
material 5 to 70 percent by weight starchy
material 5 to 70 percent by weight of resin-based material 5 to 70 percent by weight oils 5 to 70 percent by weight resin soaps 5 to 70 weight percent aliphatic
Alcohols 5 to 70 percent by weight oxalates 5 to 70 percent by weight of azo compounds or mixtures thereof. 3. The high-temperature lubricant according to the present Anprüchen 1 and 2 ^r in the form of a PUI the mixing of. 4. High-temperature lubricant according to claims 1 and 2 present in the form of an aqueous Dispersion. 5. High temperature lubricant according to claim 4, characterized in that the Lubricant in the form of an aqueous dispersion, which is used as a stabilizing agent for dispersed silica ^ Tylose, alginates, bentonites, sodium alkylnaphthalene sulfonates, Polysaccharides, proteins, montmorillonite, contains sulfonated aliphatic polyesters or sulfated alcohols. 6. High temperature lubricant according to claims 1 and 2, characterized in that the lubricant is in the form of a ring or disk 7. Hochteniperaturschmierstoff according to claim 6, characterized in that the lubricant in the form of a ring or a disk is also an inorganic or organic Contains binding agent. 8. Use of the high-temperature lubricant according to Claims 1 to 7 as a lubricant for hot forming of metals during extrusion, casting, forging or slotting.