DE1444912B1 - Process for the extrusion of heavy metals, in particular steel - Google Patents

Description

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The invention relates to a method for extruding an aluminum oxide protective layer against the oxypressing of heavy metals, in particular steel, to produce dation of the tool in the furnace. This protective layer, which is used to protect the tools against wear, is dissolved in cryolite before pressing and to protect the strand against oxidation, which makes it thinner than glass. Block temperature is not yet viscous, but 5 This light liquid has the disadvantage that the layer formed as a thin layer between the strand during the forming process has gaps because the tools and the past to be pressed, the low-viscosity _{cryolite Na 3 [AlF 6} ] is already in the sliding material to be pressed and the forming tool washes off the metal oxide film. Density and freedom from pores of oxide-oxidation protection layer covering agent, which protective layers are, however, a prerequisite for their silicon oxides, metal oxides, possibly water effectiveness on the extruded strand. Contains copper and optionally binders, on the block nickel oxides in the layer even promote the oxidation and / or the tools are applied. of the iron below, they leave the iron

Many substances have already been diffused to oxygen for such processes.

proposed as a mixture former. In practice, the present invention is now, as has already been shown, but only glass powder so far. Its addition, from a method of extrusion molding, is chosen so that it is viscous in the case of ingots of heavy metals, in particular of steel, at temperature or pressing temperature. It which to protect the tools against wear and tear forms a layer on the tools and on the and the strand against oxidation in the case of block strand, which protects the strand against oxidation. But ao temperature is not yet viscous, but it seldom succeeds in forming a smooth, even layer to the forming process as a thin layer between the tools, so that the strand after removal of the layer tools and the one to be pressed by stretching and / or pickling processes, if the sliding material to be pressed, which is completely stirred from removal, is a material to be pressed with a tightly pressed-on oxy, a more or less rough, partly pitted agent which covers the surface. Silicon oxides, metal oxides, optionally water. The mechanical removal of the layer does not work and optionally contains binding agents, to which the block is applied without hitting or scratching the and / or tools.
Strand in front of you. For example, the machining is carried out. The invention consists in that as a means a blasting with steel sand, whereby also a mixture of oxides is used, which roughening of the strand surface tends to occur. In addition to the silicon oxides, the optionally available binders from German Patent 887 186 and from the water content and optionally the Austrian Patent 187 376 contains such metal oxides, use of mica whose metals are equally large and optionally

35 sometimes have a greater affinity for oxygen than

[K, NaAl ₂ (OH, F) ₂ ] [AlSi ₃ O ₁₀ ] the heavy metals to be pressed.

The mixture used in the process according to the invention, inter alia in the form of micro-mica, is due to the property of the in it known. This material is still present when the silicon oxide is pressed at the ingot temperature Steel and other heavy metals have not proven their worth, 40 not viscous or even liquid. However, it does form because the steel strand does not have a protective layer as a thin layer on the pressed material sliding past layer against oxidation. Behaved in a similar way and covered the exiting strand with a the following minerals: thin, tightly pressed anti-oxidation layer,

A special security for the uniform

45 The process is given when a mixture

[Mg ₃ (OH) ₂ ] [Si ₄ O ₁₀ ] is selected, all of its constituents during

_ of the extrusion does not melt.

^ax · In this case, however, the majority of the

Na ₂ B ₄ O ₇ · 10 H ₂ O (which ^{becomes liquid at 731 0} C) crystals are plastically deformable, similar to the

P _M. 50 metal to be pressed.

heldspat: · Metal oxides, which have a chemical reaction with

Na or K [AlSi ₃ O ₈ ] would enter the block to be pressed, ie

,. Metal oxides whose metals have a lower affinity

'to have oxygen than the metal to be pressed,

(also in the form of asbestos powder) 55 can within the scope of the method according to the invention

[Mg ₈ (OH) ₆ ] [Si ₄ O ₁₁ ] · H ₂ O cannot be used.

, _# Are still to be excluded from use

lonerde. those metal oxides which are to be pressed

(in the form of bentonite) metal would cause intergranular corrosion,

[Al _lj67 Mg _0i33 (OH) ₂ ] [Si ₄ O ₁₀ ] Na _{0> 33} (H ₂ O) ₄ 60 which occurs, for example, when pressing steel

Use of lead oxide may be the case.

With graphite there is a risk of edge carburization. Finally, such metal-

with steels. oxides and such other substances which the diffusion

None of these substances could get into the compressed metal during the

Put efforts into practice. 6g relatively short contact time in the course of the

It is also accelerated by the French patent specification Preßgutabkühlung or the itself in

1 286 145 known to diffuse on a steel press block in this, d. i.e., it should for example

Heating furnace made of an aluminum powder coating when pressing steel, no oxide of the metals

Nickel, copper, cobalt and molybdenum may be present. Likewise, substances that contain oxygen are said to be nitrogen or emit sulfur dioxide gases, are not used as components of the mixture. For pressing Avoid adding graphite to steels that cannot tolerate edge carburization.

A mixture of metal oxides and silicon oxides can be used to extrude a certain heavy metal with a significant proportion of oxides of the same heavy metal or one of this heavy metal related heavy metal can be used. For pressing out most metals including Steel can also be used as a mixture of oxides with a significant amount of aluminum oxide.

Particularly suitable for technical and economic reasons When pre-pressing steel, it is important to use a mixture with a significant number of reasons Share of oxides of iron. The use of the mineral amosite with a silicon dioxide content is preferred of about 50%> an iron oxide content of about 32%, iron oxide with about 8%> Magnesium oxide with about 4%, water with about 4% and a remainder of alkalis.

The use of Kapland blue asbestos with a silicon dioxide content of about 51%, ^with an iron oxide content of about 36%, with a magnesium oxide content of about 2%, with a water content of about 4% has also proven itself. and a residual content of alkalis.

In order to avoid excessive layer thicknesses and a smooth run-out of the wear and oxidation protective film To ensure through the die, the mixture should preferably not contain any particles with a grain size of more than 300 μ. To produce a thick film on the pressed one Strand mixtures are used here, the particles of which have a larger grain size than particles a mixture which is used to produce a thin film.

The protective layer that forms on the strand can thus be removed very easily from the strand, that the strand is stretched. For manufacturing reasons, this is generally necessary anyway. The protective film pops off the strand when it is stretched and leaves a completely smooth, scar-free one Strand surface. In the case of strands, which are of a rectilinear or Do not require the stretching process, a brief surface heating is sufficient to remove the film from the smooth Detach the strand surface (brush with a gas burner flame).

The mixtures used in the process according to the invention can be in the form of powder masses, Pastes or shaped pieces (discs) are introduced into the extrusion or pipe press. The only important thing is that they somehow get between the hot metal block and the pressing tools. So you can be introduced into the press at the same time as the block or before the block. It is also possible to them to be applied to the pressing tools, in particular the die, before they are heated or introduced. Various metal oxides can be used in admixture with silicon oxides. Heavy metal oxides of mineral or synthetic origin can be used.

The powder masses, pastes or shaped pieces (for example disks) can with the help of fine-grained, powdery metal oxide powders are produced. Binders can be added to them, such as water glass; Fixed fittings, especially discs, can also be used before insertion be made in the press by a special pressing process. The ones on the tools and / or powder masses, pastes or shaped pieces firmly pressed on or loosely applied to the metal block are so changed in their structure due to their fine grain during the hot pressing process that they are the constantly changing outer shape of the plastic metal as a resilient fine-grained compressed Fit the powder layer and the outflowing metal in the form of a firmly pressed, coherent powder film surrounded, naturally also between the metal and the shaping Tools lies. This powder film protects the tools against wear.

The wear protection value of the film can be influenced by the thickness of the powder film, whereby As already mentioned, the thickness of the powder film is determined by the grain size of the powder. The wear protection value consists of a thermal insulation value and a friction reduction value. The thermal insulation value is determined not only by the film thickness, but also by the thermal conductivity values the components of the mixture, for example the silicon oxide components certainly.

The pressed-on powder film never adheres firmly to the pressed metal and / or the Tools because none of its metal oxide parts melt. Herein the cause of the Ease of removal of the protective film and the economic viability of this process can be seen.

Claims (6)

Patent claims: 1. A method for the extrusion of heavy metals, especially steel, in which to Protect the tools against wear and tear and protect the strand against oxidation Block temperature is not yet viscous, but becomes a thin layer during the forming process and forming between the tools and the pressed material to be pressed past hereby covering the leaking pressed material with a tightly pressed-on anti-oxidation layer Agent, which silicon oxides, metal oxides, optionally water and optionally binders contains, is applied to the block and / or the tools, characterized in, that a mixture of oxides is used as an agent, which in addition to the silicon oxides and the proportion of water that may be present and the proportion of water that may be present Binding agents contains those metal oxides, the metals of which are just as large and, if appropriate, partly have a greater affinity for oxygen than the heavy metals to be compressed. 2. The method according to claim 1, characterized in that a mixture is used, its Components do not melt during extrusion. 3. The method according to claim 1, characterized in that for the extrusion of steel as Mixture or mixture fraction the mineral amosite, analytically consisting of 1. about 50 ° / o silica; 2. about 32% iron oxide, 3. about 8% iron oxide, 4. about 4% magnesium oxide, 5. about 4% water and 5 6. Alkalis in addition to 100% »is used. 4. The method according to claim 1, characterized in that for the extrusion of steel as Mixture or mixture portion of the mineral Kaplandio blue asbestos, analytically consisting of 1. about 51% silica, 2. about 36% iron oxide, 3. about 2% magnesium oxide, 4. about 4% water and 5. alkalis in addition to 100%, is used. 5. Process according to claims 1 to 4, characterized in that an oxide mixture is used, the grain size of which is about 300 μ or below this value.