DE2519905B2 - Process for the production of deep-drawn and / or ironed cans from tinplate - Google Patents

Description

25th

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 when pegging, which is in Water contains emulsified oil, 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 in the manufacture of this 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 κ machines on which in one stroke when the Stamp head, which is inserted into the cup, by several arranged one behind the other with the same axis Ironing rings the wall thickness of the cup is reduced. The material flows in the axial direction, and on this way the height of the can is increased.

During the ironing process, there is a relatively high 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. The concentrations are 5 to 20% oil in water 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 and require additional units.

When using alkaline detergents for washing, a multi-stage treatment is necessary several flushes required. Here, the cans are flushed with a final rinse 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 also mineral oil-free Sliding additions. From this it can be seen that there is a sufficient lubricating effect during cold forming can only be achieved with a relatively complex composition of the cooling lubricant and that this cooling lubricant must also contain mineral oil-free sliding states. Striking is also that for press bending operations, in which usually not so great a material deformation takes place like a 5-10% aqueous emulsion is suggested for ironing. Only for Processes that take place after mechanical expansion, i.e. where no more cold deformation takes place and where a good lubricating effect is no longer important, 0.1 to 5% aqueous solutions are used Emulsions and, in the test measuring process, 2-4% aqueous emulsions are used. From this he can Those skilled in the art can only conclude that a sufficient lubricating effect is only achieved when the cooling lubricant is used in a relatively high concentration of 5-10%. However, the higher the concentration, 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

serially and / or ironed cans made of tinplate to create, in particular the cleaning of the cans after ironing or deep drawing is simplified, but also the lubricant and coolant have a simple composition with good lubricants and Has 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 percent by weight 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 up to now 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 as pure substances in a precisely defined composition are present. Vegetable and mineral oils also contain esters of fatty acids with glycerine, however, these are not synthetic esters and their composition is not precise either Are defined. In addition, many of the esters contained in mineral oils are not physiologically harmless. 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 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 are added.

A person skilled in the art could not have foreseen that synthetic and physiologically acceptable esters in Form of pure substances in a concentration of up to 3 percent by weight with the addition of a non-ionic Wetting agent without other other lubricants and also in this low concentration of preferably 1% has an excellent cooling and lubricating effect when ironing cans from tinplate result. The essence of the invention is that without special additives, only by using Physiologically harmless synthetic esters in the form of pure substances, especially without Lubricant can achieve an excellent cooling and lubricating effect during ironing.

All physiologically acceptable esters can be used as esters, for example those in food law regulations are recognized. For this purpose, z. B. Di-2-ethyl-hexyl-sebacate, Dibutyl sebacate, acetyl tributyl 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 facilities for heating of the rinsing water or solvent are also omitted.

Since the oil content in the rinsing water also remains very low, the 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 To use additional lubrication and cooling when making the bowl, it is the same here as well System as described for ironing can be used. A cleaning of the bowls between the bowl pulls and the ironing process, which takes place a short time later, is omitted.

Various other publications (see DE-AS 11 86 042, 10 52 042, 16 44 871, 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). This high-performance lubricating oil is said to be used because of its high thermal stability 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. consists. This drawing lubricant contains less

Furthermore, for example, a drawing lubricant quantity is also aliphatic polyklycol ester, however

known (see. DE-AS 10 52 042), which is used here as an emulsifier. The real lubricant!

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

Mainly from animal fats, e.g. B. 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, the cans being rinsed with water after ironing are characterized in that as an oil in the lubricating and cooling agent! synthetic and Physiologically harmless esters in the form of pure substances in a concentration of up to three Percentage by weight with the addition of a nonionic wetting agent and optionally a corrosion inhibitor can be used to prevent corrosion on machine parts. 2. The method according to claim 1, characterized in that the esters in a concentration of about 1 percent by weight can be used. 3. The method according to claim 1 or 2, characterized in that the ester is di-2-ethyl-hexyl sebacate is used.