DE2519905C3 - Process for the production of deep-drawn and / or ironed cans from tinplate - Google Patents

Description

The invention relates to a method for producing deep-drawn and / or ironed cans made of tinplate, in which a lubricant and coolant is used at least during ironing, the contains oil emulsified in water, the cans being rinsed with water after ironing.

Both beverage cans and food cans have been made seamless for some time by deep drawing and Ironing produced. In addition to aluminum, tinplate is increasingly being used for this purpose unalloyed steel sheet, which is provided with an electrolytically deposited tin layer, is used.

In the first stage of the production of such cans, a cutting tool is made from the sheet metal Cut round blank and in the same machine stroke formed into a bowl by deep drawing in the stop. This process is usually carried out on presses with several parallel tool sets, from the broadband beginning, executed. As long as the bowl wall is not ironed during the bowl production, i. H. in their thickness is reduced by a narrow drawing gap, if tinplate is used, that during manufacture is sufficient The usual oiling of the material for lubrication. The tool is additionally cooled in the Usually not.

A transport and distribution system is used to transport several bowls that are provided in parallel so-called ironing presses supplied. These are ·> ■; Machines on which in a stroke when the punch head, which is inserted into the cup, passes through several ironing rings arranged one behind the other with the same axis reduces the wall thickness of the cup will. The material flows in the axial direction and in this way the height of the can is increased *

During the ironing process, there is a relatively large surface pressure between the material and the tool in the forming zone. In addition, an amount of heat corresponding to the forming energy is released. That requires additional lubrication and intensive cooling during the deformation process. the Machines are usually equipped with a system for liquid cooling, which may be centralized for several parallel machines are used.

For cooling and lubrication, an emulsion of complex compounds has hitherto been used Lubricating oils used in water The oils are mixtures of vegetable oils and mineral oils that are each provided with special additives. as Concentrations of 5 to 20% oil in water are common.

In this previously common way of working, it is necessary to remove the cans after the deformation process to clean in a complicated and expensive process. This is necessary so that the corrosion protection required interior painting and, in many cases, desired printing of the exterior wall with subsequent Protective coating has adequate adhesion and no lubricant residues in the for filling with Doses intended for food remain.

In principle, two different methods are used for cleaning, both of which are complex machine systems.

When using alkaline detergents for washing, a multi-stage treatment is necessary several flushes required. Here the cans are rinsed in a final rinsing process rinsed with plain water. In addition, a complicated sewage treatment plant must be installed in order to prepare the used, oil-enriched alkali lye before it is drained.

In another system, the cleaning is done with organic solvents, such as. B. stabilized Chlorinated hydrocarbons. This procedure requires a gas-tight, closed washing system. Around To be able to use the expensive solvent several times is the installation of a distillation device necessary for processing.

For example, a water-emulsifiable cooling lubricant for the production of welded pipes is by Cold forming known (see. DE-OS 21 56 567), from is composed of several substances. In addition to alcohols or ethers or esters, it contains alkylphenol polyglycol ethers, preferably nonylphenol polyglycol ether with 7 moles of ethylene oxide from detergent Substance, furthermore an emulsifier or emulsifier mixture and above all, mineral oil-free sliding additives. From this one can see that a A sufficient lubricating effect during cold deformation can only be achieved with a relatively complicated one Can achieve composition of the Kühlschmiers'offes and that this cooling lubricant also must contain mineral oil-free sliding states. It is also noticeable that for press bending operations in which Usually there is no such strong deformation of the material as a 5-10% deformation in ironing aqueous emulsion is suggested. Only for processes after mechanical F.XDanding take place where there is no longer any cold deformation and where there is no longer a good lubricating effect is 0.1 to 5% aqueous emulsions and 2-4% in the test measuring process Aqueous emulsions used From this, the expert can only conclude that sufficient lubricity effect can only be achieved if the cooling lubricant * substance is used in a relatively high concentration of 5 ^ 10%, but the higher the concentration ^ Trätioh, the more expensive the cooling lubricant is.

The invention is based on the object of providing a simplified method for the production of deep-drawn

Genuine and / or ironed cans made of tinplate, in particular the cleaning of the cans is simplified after ironing or deep drawing, but also the lubricant and coolant has a simple composition with good lubricating and cooling effect.

This is achieved according to the invention in that the oil in the lubricant and coolant is synthetic and Physiologically harmless esters in the form of pure substances in a concentration of up to 3 weight percentages percent with the addition of a nonionic wetting agent and optionally a corrosion inhibitor for Avoid corrosion on machine parts.

Surprisingly, it was found that in the production of iron-drawn cans from tinplate, where there is significant cold deformation of the material, synthetic esters emulsified in water, the are physiologically harmless, in a much lower concentration than the mixtures used to date from vegetable oils and mineral oils in which lubricants and coolants can be used. That at The lubricant and coolant used in the method according to the invention has an extremely simple composition and can also be used in a very low concentration. Prerequisite for this is, however, that the synthetic esters are pure substances in a precisely defined composition are present. Vegetable and mineral oils also contain esters of fatty acids with glycerine, JO however, Sk.1i is not synthetic Esters, and their composition ·; ng is not exact Are defined. In addition, many of the esters contained in mineral oils are not physiologically unacceptable. It it has been shown that a very low concentration of synthetic and physiologically harmless Ester in water is sufficient to ensure the desired lubrication. The use of ester in a concentration of about 1 percent by weight is advantageous here. To ensure perfect wetting to the tinplate and the tools as well as easy drainage of the lubricant and coolant, the nonionic wetting agent, e.g. B. polyethylene glycols or polyoxyethylene compounds added.

A person skilled in the art could not have foreseen that synthetic and physiologically harmless esters in the form of pure substances in a concentration of up to 3 percent by weight with the addition of a nonionic wetting agent without other other lubricants and even in this low concentration of preferably 1% would provide excellent cooling and Resulting lubricating effect when ironing cans from tinplate. The essence of the invention lies in the fact that, without special additives, only through the use of physiologically harmless synthetic esters in Vi form, pure substances, in particular also without lubricant ¹ ! can achieve an excellent cooling and lubricating effect during ironing.

All physiologically acceptable esters can be used as esters, for example those in Legal legal provisions are recognized, For this purpose, z. B, Di ^ AthyUHexyuSebazat, Dibutyl sebacate, acetyl ributyl citrate and others. Because of the relatively low synthetic content Ester, the lubricant and coolant can be washed off with normal: cold water. the then the thin ester layer remaining on the cans hinders the painting and that Printing on the can does not affect its usability for beverages and food in not in any way, as physiologically harmless esters are intentionally used.

The commercially available corrosion inhibitor is to be avoided because of the high water content of the emulsion corrosion on machine parts may be added.

The small amount of lubricant in connection with the metal tin is sufficient for the deformation process to run without difficulty. An additional advantage was found that the cooling is considerably improved compared to the previously common lubricants.

For further treatment of the cans, a simple immersion or spraying with cold water is sufficient without any additives and subsequent drying. The remaining on the can wall, evenly Distributed thin layer of the physiologically harmless ester can be perfectly painted or printed without affecting the paint adhesion or the paint flow.

Because of the simple rinsing process, it is easily possible to do without a separate washing machine and the spraying device at a suitable point on the can transport system that is already in place a subsequent hot air drying tunnel. The usual devices for heating the rinsing water or solvents are also omitted.

Since the oil content in the rinsing water also remains very low, wastewater treatment is considerably simplified. Demulsifiers can be added in a collecting container. The small amount of oil floats and can be easily separated from the water.

Should it be due to the tool design of the cup train, z. B. because of a simultaneous low Wall ironing or because of the high production speed, may also be necessary the production of bowls an additional seal and cooling the same system as described for ironing can also be used at this point. A cleaning of the bowls between the drawing of the bowl and the ironing process that takes place a short time later not applicable.

Various other publications (cf. DE-AS 11 86 042, 10 52 042, 1644 871, SU-PS 4 32 172, GB-PS 7 58 061, Ind. Engng. Chem. 45. 1777 to 79 August 1953) also deal with Lubricants, however, none of these publications suggests that they are physiologically harmless Esters in the form of pure substances should be used in concentrations up to 3 percent by weight. Rather, they describe compositions in which the sliding behavior between tool and Workpiece is achieved by typical high-quality lubricants, which are also correspondingly more expensive. in the Otherwise, these lubricants often serve a different purpose.

So is z. B. a process for the production of an ester serving as a high-performance lubricating oil is known (See DE'AS 11 86 042). Because of its high thermal stability, this high-performance lubricating oil is said to be suitable for Propulsion units are used by missiles. This high-performance lubricating oil is by no means used in Used in the form of an oil-in-water emulsion, but in its pure form. Besides that the use in its pure form would result in a very high consumption when ironing cans, even then is absent

5 6

The required cooling effect exists. This drawing lubricant contains less

Furthermore, for example, a Zjehschmiermittel amount is also aliphatic polyklycol ester, however

known (see. DE-AS 10 52 042), which is used as an emulsifier in one of the actual lubricants

aqueous emulsion is used, but that is in the beef tallow.

Mainly from animal fats, e.g. beef tallow 5

Claims (3)

Patent claims: 1. Process for the production of deep-drawn and / or ironed cans from tinplate, in which a lubricant and coolant is used at least during ironing, which is described in Water contains emulsified oil, with the cans are rinsed with water after ironing, characterized in that as oil in the lubricant and coolant, synthetic and physiologically harmless esters in the form of pure substances in a concentration of up to three percent by weight with the addition of a non-ionic Wetting agent and, if necessary, a corrosion inhibitor to prevent corrosion on machine parts be used. 2. The method according to claim 1, characterized in that that the esters are used in a concentration of about 1 percent by weight. 3. The method according to claim 1 or 2, characterized in that the ester Di 2 ethyl hexyl sebacate is used.