DE1794240B2 - PROCESS FOR MECHANICAL WORKING OF A HOT DEFORMABLE METAL - Google Patents

Description

The invention relates to a method for mechanically working a hot, deformable metal using a synthetic liquid organic lubricant in which the following Procedural measures are carried out:

1) heating said metal to a temperature at which it is in a deformable state, in particular to a temperature of 870 ° to 1315 ⁰ C,

2) Applying and evenly distributing a liquid consisting of fatty acid polyol ester Lubricant, the polyol component of which is 2 to

12 hydroxyl groups and the fatty acid component of which has 12 to 22 carbon atoms, on the Machining surface of a machining element before it is deformable with the heated one Metal under a certain processing pressure comes into contact to form a separation medium at the contact surfaces of this machining surface and the surface of this To create metal.

Modern lubricants often have to work at temperatures above about 204 ^° C., where the known mineral oils deteriorate rapidly, become corrosive, volatile and thus useless for the intended use. The available synthetic base oils, such as esters, ethers, silicones or hydrocarbon polymers, are often subject to thermal or oxidative degradation under these extreme conditions, which leads to the formation of sludges and deposits, changes in viscosity, discoloration, increased corrosion and other undesirable changes. Attempts to eliminate this deficiency with the help of the usual measures have been unsuccessful due to the extreme working conditions; z. B. the addition of an antioxidant can cause increased corrosion or the addition of an antiwear agent can reduce the stability. Attempts to eliminate the newly emerged defects often create new problems by causing increased sludge build-up, etc.

Metalworking lubricants are well known. In the OE-PS 2 60 403 the use of mixed esters of straight-chain saturated fatty acids with 6-14 carbon atoms and polyvalent ones Alcohols in mineral oil emulsions have been proposed as lubricants for cold rolling of sheet metal. Aqueous emulsions for the non-cutting cold working of metals contain sulfated esters, among other things higher fatty acids with at least 12 carbon atoms and mono- or polyhydric alcohols (DT-PS 9 50 591 as well as condensation products from neutral oils, fatty acids or fatty alcohols with at least 12 carbon atoms and non-ion-active water-solubilizing compounds (DT-AS 10 43 561). The watery ones According to DT-AS 12 57 335, lubricating emulsions for cold rolling sheet metal consist of palm oil, Cottonseed oil, di-n-butyl sebacate, n-butyl stearate, 2-ethylhexyl phthalate or dioctyl sebacate as lubricating oil in addition to a certain proportion of alkali chromate, dichromate or chromic acid and polyalkylene glycol monophenyl ether derivative. Tallow and rapeseed oil form the fat base of the aqueous emulsions for cold rolling according to DT-AS 10 53 701, whereby ^ i zuäätzli =! i manoglycerin fatty acid ester Can be part of the emulsions. Fat components in connection with an emulsifier for the fat and phosphoric acid are in the Lubricants of DT-AS 11 03 498 in the production of bare metal pipes made of ferrous materials, in particular steel, through non-cutting cold forming of tube blanks or pre-drawn ones Tubes included.

The use of certain polyalkylene glycols or their esters has also been proposed many times and ether in the form of aqueous dispersions as lubricants for metalworking (see CH-PS 3 95 408, DT-PS 9 77 489). The oil-free, aqueous lubricating, cutting and cooling fluid for metalworking according to the published patent application N6545IVd / 23c also has a surface-active, optionally etherified or esterified polyalkylene polyol of certain composition. Contains a lubricating mixture, especially for rolling, milling and drilling metal according to CH-PS 3 96 276 a smaller amount of a soluble polyoxyalkylene with a negative solubility coefficient, the lubricant for rolling metal according to OE-PS 2 15 580 a smaller amount of a diester of a polyoxyalkylene glycol. Other lubricants containing polyalkylene glycol are listed in DT-AS 11 04 104, the published German patent application C 11 447 IVc / 23c, DT-AS 10 52 042 proposed.

Satisfactory lubricants for hot rolling steel products have not yet been available been. The construction of today's high-speed hot strip mills, the larger steel

Plate and continuous potting operations have created an urgent need for hot working lubricants to minimize surface damage in finished products and to extend the life of the work and counter rolls used to roll the steel. The difficulty in the creation of suitable lubricants will be apparent when one considers that continuous hot rolling procedures are carried out at temperatures in the range of about 870 to 115o C ^0.

In a typical continuous steel hot rolling mill, the line can consist of a scale breaking roughing stand, four or more four-roll roughing machines, a finishing scale crusher and 6 or more tandem four-roll finishing stands exist. Driven raw goose rollers transport the steel from the stand Framework. Steel plates are fed to the track at temperatures in the range of approximately 1093 to 1315 ° C. The steel plates are rolled to the desired thickness, and the rolled product is made into desired Cut lengths or rolled up in one piece. The four-roll finishing stands exist each from a pair of driven work rolls, between which the steel is processed and his Thickness is reduced. The work rolls work together with backup or pressure rolls, which provide additional support to the work rolls and ensure a greater reduction per pass. A description of such a continuous hot strip mill can be found in »The Making, Shaping and Treating of Steel ", 8th Edition, pp. 894-902 (1964), published by US Steel Corp.

The aim of the invention was to provide a method for the mechanical processing of deformable Metals at high temperatures using a synthetic lubricant. In this In the process, a lubricant suitable for shaping steel products should be used (Plates, rods, strips, sheets, beams, rods, rails) and especially for continuous working hot strip mills. Their suitability should also focus on the hot processing of Copper, brass, aluminum, magnesium and titanium range.

The subject of the invention is a method for the mechanical processing of a hot, deformable metal using a synthetic, liquid, organic lubricant, in which c'ie following Procedural measures are carried out:

1) heating this metal to a temperature at which it is in a deformable state, especially at a temperature of 870 to 1315 ° C,

2) Applying and evenly distributing a liquid consisting of fatty acid polyol ester Lubricant, its polyol component 2 to 12 hydroxyl groups and its fatty acid component Has 12 to 22 carbon atoms on the machining surface of a machining element, before this with the heated deformable metal under a certain processing pressure comes into contact to a separating medium on the contact surfaces of this machining surface and to create the surface of this metal

which is characterized in that a trimethylolethane-tritallow fatty acid ester is used as the liquid lubricant, the tetraoleate of pentaerythritol, the trimethylolpropane triiali oil ester, the glycerol trital oil ester, the di-pentaerythritol polycoconut fatty acid ester or mixtures thereof, or one with fatty acids modified alkyd resin used.

According to the invention a method for the mechanical processing of deformable metals, such as

ίο z. B. Steel, created by cutting the metal up heated to a deformable state and by means of a working element with one acting on the metal Working surface exerts a working pressure on the surface of the metal, whereby the Working surface the synthetic, organic, liquid lubricant feeds and evenly on this distributed before the work surface is brought into contact with the heated deformable metal, around a separating medium at the contact area between the work surface and the surface of the To create metal.

The invention provides synthetic lubricants which are effective in hot strip steel strip operations can be used. The lubricants are in the liquid state or in the form of aqueous Dispersions on the metalworking elements, such as. B. the work rolls of a steel strip hot rolling mill, applied by any available device that provides a uniform, continuous Film generated on the surface of the work rolls. The liquid lubricant can with With the help of a spray device on both the upper and the lower counter roller on the outlet side of the Scaffolding are applied so that the lubricant in the point of engagement between the working and the counter roll is transported. At this point the lubricant will be uniform across the surfaces the work and the counter roll distributed. The lubricant can be applied to one or more of the scaffolds Finished route can be applied. The application of the lubricant is generally to the pivot point framework the finishing line or those stands that are most subject to roll wear, limited. If desired, the lubricant can also be applied to the roughing or roughing rollers will. In the actual rolling operations, it has proven to be advantageous to place the work rolls in front of them the entry of a rod into the special framework to which the lubricant is to be applied to keep from lubricants. When the lubricant is present on the work rolls, the The rod is not properly gripped and the steel tape may stick to the roller because of the coefficient of friction is reduced by the application of a lubricant and the roller to slack tends.

The esters of fatty acids and polyols can be prepared by known methods, e.g. B. by Heating in a still with direct thermal fusing of the components or without catalysts. Such catalysts can be acids, Lewis acids, metal oxides, metal hydroxides and the like. The water is then removed in a suitable manner. The azeotropic removal of the water of reaction, the distillation of the water of reaction in vacuo and the removal of the water of reaction by means of Gas transmission can be used. The ester products can be used directly in an anhydrous state

or in the form of an aqueous dispersion with the aid of suitable Devices are used as lubricants for hot metalworking. Mixtures of Esters can be used, or they can be mixed with mineral oil fractions or other solvents for special applications are diluted. In addition, separation aids such as silica can be finer Clay, fly ash, Fuller's earth, graphite, talc and the like are used in conjunction with the lubricants especially if they are used for metal casting and blacksmithing.

In addition to the abovementioned polyol fatty acid esters, alkyd resins modified with fatty acids can also be used be used as a lubricant. These include condensation products from fatty acids, usually Mixtures thereof, one or more polyols and a dicarboxylic acid. About these dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, Succinic acid, adipic acid, azelaic acid, sebacic acid and condensation products of Maleic anhydride with various masses, such as. B. Rosin.

The compounds or products mentioned can be used as lubricants in conjunction with mineral oils and / or solvents are applied. Alkyd resins modified with fatty acids can make water or use other solvents as thinners.

In the following, the compositions and preparation will be particular to illustrate the invention useful lubricant for continuous strip steel hot rolling mills described (The parts of the components in the examples are parts by weight.)

lubricant

Tallow fatty acids 840 parts

Trimethylolethane 120 parts

These components were mixed and heated while nitrogen was bubbled through the bottom of the reaction flask to remove the water of reaction. Temperatures of about 260 to 274 ^° C. were used while stirring the mixture. After about 54 parts of water had been removed, the reaction was stopped. The product was a brown liquid consisting predominantly of trimethylolethane-tritallow fatty acid ester.

Lubricant 2

oleic acid 1120 parts

Pentaerythritol 136 parts

Toluenesulfonic acid 0.1 part

Xylene 50 parts

This mixture was heated to temperatures up to about 204 ⁰ C, while the Reaktionswas "it was removed by azeotropic distillation, the xylene layer was continuously returned. After 70 parts of water of reaction had been removed, the xylene was evaporated in vacuo, leaving a yellow liquid product which consisted essentially of the tetraoleate of pentaerythritol.

Lubricant 3

Tall oil distilled 855 parts

Trimethylolpropane 135 parts

Boron trifluoride etherate 0.1 part

This mixture was ^{heated to about 163 °} C. and kept at this temperature while the

ίο water of reaction was distilled off. After 52 parts Water had been removed with a vacuum applied towards the end of the reaction, this resulted formed product as a yellow oil consisting essentially of the trimethylolpropane tritallic oil ester.

Lubricant 4

Tall oil head fractions 1000 parts

Glycerin 92 parts

This mixture was heated to about 260 to 274 ° C, with a nitrogen flood for better Distilling off the water was applied. After about 50 ml of water of reaction had formed, the reaction was stopped and a dark brown liquid resulted, consisting essentially of Glycerin trital oil ester consisted.

Lubricant 5

Coconut Fatty Acids 1000 parts

Dipentaerythritol 254 parts

This mixture was heated to about 163 ° C. until 85 to 90 parts of water of reaction had been removed was. The reaction product was a somewhat viscous yellow-brown liquid consisting essentially of dipentaerythritol polycoconut fatty acid ester duration.

According to the invention it has been found that the polyol esters of long-chain fatty acids (their smallest chain length 16 carbon atoms) are extremely suitable lubricants for steel hot rolling mills, if one is with Fatty acid esters of shorter chain lengths or the previously known polyethylene glycol esters compares.

(1) The auto-ignition temperatures are higher and the tendency to evaporate is lower for the higher molecular weight esters than the lower esters.

(2) The presence of too high an oxygen content with free active hydrogen is the cause of an almost explosive flammability.
(3) Easily flammable materials are the cause of large volumes of dense smoke, which obstructs the view (of the worker in the overhead crane), or of asphyxiating fumes.

The need for relatively low volatility and relatively poor flammability becomes clear when one takes into account the temperatures involved in hot rolling steel. The slabs can have temperatures from 870 to 1260 ^0C. At this temperature, heat is transferred to the processing rollers, which ultimately have to be coated with lubricants. If the lubricant is too volatile, its presence will be too short lived to function. If the product burns down quickly.

Triglyceride

0.05mm pressure

0.001mm print

Tricaprine (C 10) 213 ° C 159 ° C

Trilaurin (C 1? Λ 244 ° C 188 ⁰ C

Trimyristine (C 14) 275 ⁰ C 216 ° C

Tripalmitine 298 ° C 239 ^C C

Tristearin (C18) 313 ° C 253 ⁰ C.

Soybean oil 308 ° C 254 ⁰ C

B - flammability

The smoke points, flash points, fire points and self-ignition of fats correspond to those under A. The values given in the table, the higher the boiling point, the less likely they are to burn and for steam generation. This applies either to the material itself or to the burning of the fat.

Materials are rated with regard to their relative tendency to burn as follows:

its concentration drops so rapidly that it does not act as a lubricant.

This can be seen from the following test material.

A - Vapor pressure glycerides ⁰ C

A hot plate with a pyroceram surface was brought to 538 ° C. Then a carefully aligned one Drops (0.1 ml) were dropped on the surface and observed. The results are below summarized:

Product smoke and fire

to red oil ester from

Pentaerythritol

Red oil ester of trimethylol propane

Red oil ester of glycerine

Purified, highly viscous white oil

Diethylene glycol

tall oil ester
ao polyethylene glycol

tall oil ester

Tall oil esters Oleic acid esters
₂ . Naphthenic acid oil

Pluronis L-64 Igepal CO smokes white -

No fires

smokes white -

No fires

Fire, black smoke

Fire, black smoke

Fire, black smoke. Fire, black smoke

Fire, black smoke

Fire, black smoke

thick black

smoke

immediately flame

immediately flame

926 ° C reaction

0.1 ml of oil, heated from ambient temperatures to 926 ° C and 705 ° C

oil Seconds to Flame formation smoke (see code) 926 ° C 705 ° C 926 ° C 705 ° C Soybean oil esters 12-5-14 45 3-4 3 oleic acid 12th 49 2 3 Tall oil 12th 40 2 3 Distilled tall oil 14th 45 2-3 3 Glyceryl trioleate 13.5 - 4th - High viscosity white oil 6th 20th 3-4 4th

Code (smoke rating) 0 no black smoke

1 dark clean

2 black, no carbon soot

3 black - small soot particles

4 black - large soot particles and flakes

boiling point Dear one

Boiling point at atmospheric pressure,

assuming no decomposition takes place. 55 compared to erythro-esters

are more permanent.

From this it can be seen that C16 and C18 esters are desirable; you can see that penta

Evaporation even be Fatty acid, length

Glycerides - estimated boiling point

Pentaerythritol ester - estimated boiling point The flash points of substances are also an indication of the durability at elevated temperatures

Compound ⁰ C

C8 265 ° C 365 ° C Butyl stearate 188 609550/406 ClO 343 ° C 426 ° C Diglycol oleate 143 C12 385 ° C 482 ° C Diglycol stearate 143 C14 438 ° C 538 ° C Di-2-ethylhexyl succinate 157 C 16 482 ° C 594 ° C Glyceryl trioleate 271 C18 521 ° C 638 ⁰ C Primetalg 269

17th

The higher molecular weight esters have less tendency to burn than the lower esters.

The following guidelines can be derived from this:

1. Products should contain as many ester groups as possible without an excess of oxygen in the system;

2. Use of C 16 fatty acids and higher fatty acids;

3. Use of esters instead of compounds with free hydroxyl groups.

The lubricants according to the invention are for the continuous production of hot-rolled flat steel plates, Steel strips, sheets and rods, as well as other metals and alloys, such as Copper, brass, aluminum, magnesium, titanium, etc., useful. The lubricants are as well for other hot metal processing methods such as extrusion, forming, forging, continuous Potting, etc., usable. The lubricants have the property of both the surface of the To wet work elements as well as that of the metal surface to be processed and to rest on them to distribute, thus creating a separating medium between the surface of the work elements and the metal to be processed.

According to the present invention, special lubricants with predetermined viscosities, pour points and lubricating properties used for all types of hot rolling operations. These lubricants ensure excellent wetting of the surfaces of the hot rolls and form one Film that remains on the surface of the rollers and creates a separating buffer zone, whereby the Oxide formation or sticking to the surface of the work and counter roll is prevented. The lubricants perform their lubricating function and then melt away, leaving behind residues on the belt surface at the end of the rolling process is avoided. The molecular film remains on the strip long enough to allow a to transfer a certain amount of lubricant to the subsequent framework.

The invention offers numerous advantages and leads to a reduction in maintenance costs for the Equipment of strip rolling mills.

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The use of the lubricants according to the invention for machining steel bars at temperatures in the range of about 870 to 1150 ° C offers the following advantages:

1. The lifespan of both the counterpart and the Work rolls is extended. Today's increased roller speeds result in a greater one Friction and increased roller wear generated.

2. The rolling time is considerably reduced by fewer roll changes, which results in a results in increased production. The welding of scale to the roll surfaces is reduced.

3. The quality of the hot rolled strips, e.g. B. their surface finish is improved. The enormous friction that occurs between the strip and the work rolls leads to cracks or other damage in the metal surface, which are reduced by the lubricant.
4. The strips are pickled better (by reducing the scale carried along, rolled-in scale, etc.). The pickling speeds can be increased with less rolled-in scale.

5. The amount of from the roller surface when * 5 pulling a roller used (work or counter roller) metal to be removed is reduced. This results in a greater production per Set of rollers.

6. Lower loads on the hot rolls are made possible (lower power consumption).

7. Savings in man-hours on mechanical Work through less frequent roll changes. (Assembly and disassembly of work rolls and Support bearings.)

8. Work roll inventory required because of frequent changes may be reduced will.

9. Lower acid consumption during pickling. Overall, the product quality is high and Furthermore, a higher yield is achieved, and because of the reduced damage to the hot rolls. A porous surface that is caused by worn * work rolls is susceptible to penetration much more exposed to impurities, which ultimately lead to rolled-in dirt The costs for the waizen renewals are thus considerably reduced.

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Claims (2)

Patent claims: 1. Method of mechanically working a hot available metal using a synthetic, liquid, organic lubricant in which the following procedures be performed : 1) heating this metal to a temperature at which it is in a malleable state is located, in particular at a temperature of 870 to 1315 ° C, 2) Applying and evenly distributing a liquid lubricant consisting of fatty acid polyol ester, the polyol component of which has 2 to 12 hydroxyl groups and the fatty acid component of 12 to 22 carbon atoms, on the machining surface of a machining element before it comes into contact with the heated, deformable metal under a certain machining pressure comes to create a separation medium on the contact surfaces of this machining surface and the surface of this metal, characterized in that as as liquid lubricant a trimethylolethane tritallow fatty acid ester, the tetraoleate of pentaerythritol, the trimethylolpropane trital oil ester, the Glycerine trital oil ester, the dipentaerythritol poly coconut fatty acid ester or mixtures thereof, or an alkyd resin modified with fatty acids is used. 2. The method according to claim 1, characterized in that the lubricant in the form of a aqueous dispersion is used.