DE945283C - Coating compound for the cold forming of metals - Google Patents

Description

Coating composition for the cold working of metals The invention relates on the composition of coating compounds for metal surfaces that are used for the Used in the cold forming of metals, e.g. B. deep drawing of metal objects, are excellently suited.

When cold drawing, shaping. and other types of metal processing Workpieces, such as sheet metal, plates, rods and wire, by cold working it is It is important that the processing is managed in such a way that at the high pressure applied no slag or tar formation takes place on the metal. According to the usual Both the workpiece and the tools, e.g. B. the molds or rollers, with a coating-forming compound or a lubricant for the entire duration of the Deformation process covered. Many species are used in technology for this purpose applied by coating compounds and lubricants. However, long experience has shown that often a given composition, which for certain working processes and metals is excellently suited, becomes completely unusable when the working conditions or the metal can be changed.

To be of the highest degree of general applicability, should the coating-forming mass eliminates the friction between the sliding surfaces of the workpiece and the tool significantly reduce. This property depends not only on the lubricating properties of the agent under the prevailing conditions but also on the thickness of the coating. The thickness of the coating must be sufficient. Leg to prevent mechanical destruction at the high pressures applied and around. the desired properties when the temperature increases on the surfaces of sliding metal parts during the forming process.

Besides these. essential requirements, other properties are also desirable for coating-forming compositions of this type. The following are to be mentioned here: easy application to the workpiece and tool and "easy removal, the ability of the heat to spread and its adhesiveness -on metallic-surfaces. In addition, the dimensions must be resistant and may be even for long periods of time. Storage should not change. The coating compound must also be essentially indifferent to the metal of the workpiece and the tool in order to prevent corrosion of these parts. to avoid: The coating masses meet the composition according to the invention, as on herid. special application examples will be shown._ will, each of the mentioned requirements and: have in addition: still.kdrrosion-preventing properties, - which -they to: ear smoke. in the case of - the "cold -formulated and - particularly suitable for other purposes - @.-'- v @ r. @ @ 'G, t @ s! @ o It was possible to get some silicones, -iiäm = borrowed Alkylpolysiloxanes, in Kcirilxxnat @ n with chlorinated paraffins -a common '-Witkgng: exercise; the to: Coating dimensions.: Reit: extremely tough surface adhesion and liervoremender: corrosion-preventing property leads .. eten .. dissolves @ rigs # -der .. the means of inuttels for the bexdei # I # ompö # ienten o by means of an emulsion in another carrier, on metallic or other. pbetfläclea. eihheitiich äif- "°. erer. e "when excited;

. g is wished, however- may: for some. Purposes a solvent - with n: i.edrigeretn @ änpfdtitck- be more suitable. . "Among the large number of Polysildxandervaae that can be used for the purposes of the invention, the previous investigations for the -alkylpolysiloxanes have shown. As they are from the hydrolysis of the corresponding halosilanes or: Alkoxysitarien. Are. Obtained.: A preferred effect. For example, for the desired purpose, a product has given excellent results, which has been prepared by hydrolysing and condensing a mixture of amyltrichlorosilane and triethoxysilane in a ratio of 5: r parts by weight This polysiloxane would condense to the point at which it forms "a viscous liquid". The products contain silicon-bonded hydrogen and silicon-bonded alkyl groups. Another polymerization product which is well suited for the purposes of the invention is made from "ethyldichlorosilane as This compound has been completely hydrolyzed and: partially condensed nsed; so that the product finally obtained is essentially a mixture. from l (C2II5) HS i 0] " and I TO [(C2 H5) H Si.O] mH, where n and m are integers and denote the degree of polymerization. Si-H bonds are in this polysiloxane also present, and it seems that this internal structure of the polymeric molecule can partly be regarded as the reason for the aforementioned effectiveness of these substances according to the invention and is usually used as an additive to mineral oils. Among the large number of compounds currently available for this purpose, halogenated aliphatic substances, such as the chlorinated paraffins and fatty acid derivatives, have proven to be particularly useful. that it does not tend to decompose at the metal temperatures which are considered in deep drawing, which are often in the region of 25 ° to 300 °. In. Many cases are, chlorinated paraffins -with one. Chlorine levels of 3o to 4o weight percent have been used with success.

The solvent or emulsion-forming component of the finished Mixture serve: essentially as a carrier; about the easy application of a thin . and. uniform layer of the 'actual coating constituents on the metal surface . to enable flat .. Many.: known solvents can: for this :: be used, ahead -: .. däfi ver =. .g- occupied, -.

inert:, are and: a whowögene liquid solution. ' he, b, n. zu . , f -ri ...

. # Convinced. 's, Ü'1 s .ub ": a fL" e ngeü.eines. do it. -. Solution quick drying: - srnit el erg. K -. u- Ix g - g. t wish - a common solvent for fats. University.! Oils. hä: .t ei #% ase advantages w% e. rioch wide .. 'below. au s # p leftei £ .ög «niili rQb '#. # mittä Paschen . ri- compounds like "2'richlorath." Ieü, Petrsaiather :. or. Gasoline-with. . .y a flange point of: about 40 °. suitable Dieseschurig: -. or -the excelneh Preferred application form of the coating composition: 9o to -95 percent by weight of solvent and 5: his ro percent by weight of the mixture of silicone. and chlorinated paraffin. One. The preparation with which satisfactory results were obtained consisted of 20 g of the above-described copolymer of amyltrichlorosilane and triethoXysilane; " 70 g of a 40% chlorinated paraffin and 100% of trichlorethylene. Exchange: the polysiloxane for the Made from ethyl dichlorosilane, vönnene. "Product in the same proportion also gave a very useful coating composition. For special protective purposes or for other reasons, additives of various types can be incorporated into the compounds described above. When working with non-drying coatings, oils such as hydrogenated castor oil or fatty acids and their derivatives can be added in small amounts of about 2 to 10 percent by weight to improve slipperiness.

The finished coating as normally used can be conveniently applied to metal parts, for example by using the Brush or rub the workpiece with it shortly before molding. Because of the quick Evaporation of the solvent makes the coating adhere well within a few seconds formed, and it occurs between the application of the mass and the following shaping Operation did not cause any delay worth mentioning. If desired - and sometimes may this be the preferred mode of operation - the coating can be applied a long time before the Shaping are applied. Thanks to its great toughness and adhesiveness it persists over long periods of time without being weakened. The previously upset The coating then also serves to protect the metal surface during storage and receives this in one. State of the execution of the shaping process permitted without additional pre-treatment.

When working on a large scale, the piece of metal to be deformed can advantageously coated on the sheet metal rolling mill with the mass according to the invention and then in the cold forming machine without any further pretreatment further processed as it comes out of the roller. Due to the oil dissolving properties of the solvent content of the preparation is the coating of the metal sheet in the Rolling mill very relieved. The oil-coated ones normally produced in the rolling mill Sheets only need to be immersed in such a lubricant bath or continuously to be passed through such a bath. with what is present in this operation 01 is detached on the surface of the metal sheets and added to the coating layer will. When the solvent evaporates almost immediately, it forms on the surface of the sheet metal a firmly adhering coating, which the sheet metal that this protects effectively even after extended. Storage .in. one for the cold working condition is suitable without further treatment or lubrication.

The coating composition according to the invention is excellent because of its Spreading properties economical in use. In many. Trying was found that is, areas of 51 square meters and larger are sufficiently coated with about q: 50 g of the mass can be. Since the applied coating film is extremely thin, is a subsequent cleaning of the sheet after deformation is unnecessary and often not at all desirable. This factor brings and has operational improvements further savings in the use of the coating compound result. However, there the film is a non-conductor for the electric straw, it can with some types of processing, z. In electroplating, it may be desirable to remove the coating. this can be done by any known stripping technique, for example by placing the coating in a bath of the solvent contained in the coating forming agent Composition according to the invention is contained, peeled off.

The coating composed according to the invention was used for comparison in Cold deformation tests corresponding to those used in technology for production in Great common practice applied. In all of these experiments, the invention was found composite coating composition as completely satisfactory and over the substances used up to now in their application accordingly or mostly superior. In those cases where the usual procedure is based on long experience regarding allowed a satisfactory solution to the problems encountered during cold forming, satisfied. also the coating composition composed according to the invention. About that however, it also proved to be easier to apply and to use more pleasant and economical, as there is no special one after the cold forming process Operation was required for cleaning.

Under the particularly harsh working conditions when cold drawing exists an important property of the coating-forming material is that it is suitable is to prevent the die from "burning in". Talking about baking the die man, when a small piece of metal welds onto the die. With everyone In the subsequent drawing processes, the welded-on piece scratches the workpiece and becomes larger, whereby an interruption for the purpose of cleaning the die is necessary will:.

Another property of considerable importance in cold drawing of metals is the degree of surface adhesion that the coating-forming agent used Has mass or the lubricant. This effect can easily be observed if. the coating is used on a piece of Werlirstück or a raw sheet on which when pulling a flange to be formed. The larger the one inherent in the cover Degree. The more extensive the flange becomes, the more surface adhesion is. Excessive However, surface adhesion causes breakage of the raw sheet. In practice, the Drawing, except for the light drawing processes for thin ones. Sheet metal, always the die a pressure pad or hold-down device assigned to the outer edge of the raw sheet metal the die presses before the punch touches the rolling plate. The purpose of this hold-down consists in preventing creases from forming on the edges of the raw sheet. By However, changing the pressure on the hold-down device can reduce the width of the process formed flange can be varied. Accordingly, the surface adhesion of the coating must be within the Area, which is due to the setting of the hold-down device can be mastered.

The coating composition composed according to the invention was used for comparison tests on a technical scale for the cold drawing of coffee pots made of stainless steel applied. Here = with dry soap was the usual aid up to now. In the In the first three attempts, the polysiloxane component of the composition was a copolymer of 8o mole percent amyltrichlorosilane and 20 mole percent triethoxysilane. In the fourth The experiment was the polysiloxane used, a polymer of ethyldichlorosilane. at in all four trials the extreme pressure additive was a chlorinated paraffin with approximately 4o% chlorine content and the solvent trichlorethylene. The ratio of silicone the high pressure component was 1: 2 in test i; r: 5 in experiment 2; 1 : 15 in attempt 3 and -1: 5 in attempt 4.

After evaporation of the solvent was that formed in all experiments Coating anchored excellently in the metal surface. When heating test strips of the metal, the coating adhered firmly to the metal in tests r and 2, but showed in tests 3 and 4, tendency to run off the metal. The network capability and The toughness of the film was satisfactory in all tests, but exceptionally high in tests i and 2. The drawing properties were under the usual working conditions of the coated metal was excellent in each of the four attempts. With none of the Attempts were made to rub or seize the form, and the surface gloss the finished item was clear and unspoiled.

The soap used according to the rules of previous practice is water-soluble and somewhat hygroscopic, while the coating composition composed according to the invention does not have these properties. Because of this, it had to be coated with soap Steel are drawn soon after their application, while those with the invention- composite coating mass provided raw sheets even after storage of have been drawn for up to 4 months and longer with satisfactory results. About that In addition, the previously used soap had to be washed off as soon as it was pulled. This operation comes with the one provided with a coating according to the invention Metal completely eliminated.

In many cases of cold working, it is necessary to use the Anneal the metal blank between two successive operations. at Some of the auxiliaries used according to the state of the art, such as oil and soap, veru: Csacht this intermittent annealing causes charring and contamination of the metal; if not in each case the glow one. Cleaning process is attached. When using the coating composition composed according to the invention leads to the interim Glow neither to char nor to contaminate the coated raw metal: this one Advantage makes many cold forming processes much easier, as it saves time and money Work entails.

Corresponding attempts at deep-drawing toasting parts; Oil seal rings and many other technical-scale articles confirm the above Observations.

As an example of a further application of the coating compound in the Cold working should be mentioned that a sheet coated with the lubricant has cold rolling properties which 'are superior to those of a sheet not treated in this way. According to a certain test design, a thickness of 2, q.6 mm hot rolled carbon steel sheet coated with the new mass and in seven rolling passes cold rolled to a thickness of 0.25 mm. After the so far The methods customary in the art were normally 10 to 12 rolling passes for this purpose necessary. In addition, the sheet metal provided with the coating was cleaner and a glossier surface than the sheet metal rolled by the usual methods.

Claims (4)

PATENT CLAIMS: i. Coating compound for the cold forming of metals, consisting of a mixture of polysiloxanes with the structure Si-O-Si; their silicon atoms have an alkyl radical and / or a hydrogen atom, and chlorinated paraffin with 3o to 4o percent by weight of chlorine in a weight ratio of 1 part of polysiloxane 3 to 4 parts of chlorinated paraffin. 2. Coating composition according to claim i, characterized characterized in that the polysiloxane is a condensation product of 5 parts by weight Amyltrichlorosilane with 1 part by weight of triethoxysilane or a polymerization product from hydrolyzed ethyl dichlorosilane. 3. Coating composition according to claim i or 2, characterized by an additional content of a volatile organic Carrier. 4. Coating composition according to claim 3, characterized by a content of trichlorethylene, petroleum ether or heavy gasoline in an amount of 9o to 95 percent by weight of the total mass. Energized publications: USA. Patent Nos 2413582, 2447483, 2 456 496 2 511 25 0;. French patent specification No. 954 151-.