DE19525407A1 - Lubrication process for heavy forming - Google Patents

Abstract

A process for lubricating metallic workpieces during forming operations by drawing, deep-drawing or cold extrusion is characterised in that a non-homogeneous mixture of (a) 40 to 90 % by volume of a water-miscible cooling lubricant concentrate, (b) 10 to 60 % by volume of a non water-miscible cutting oil, (c) 0 to 25 % by volume of a sulphur-based lubricant additive and (d) 0 to 20 % by volume water is applied on the workpiece. The percentages of the constitutive elements of the mixture add up to 100 %.

Description

The invention relates to a method for lubricating workpieces Metal, especially steel or aluminum for forming processes Drawing or deep drawing. To enable particularly heavy forming a workpiece is prepared on the workpieces immediately before forming applied inhomogeneous mixture, the essential components of which are concentrated entered a water-miscible coolant emulsion and a non-water soluble cutting oil.

When shaping metals by drawing or deep drawing hen, possibly also associated with the punching out of parts Lubricant needed, the main purpose of which is to reduce friction between tool and workpiece. An overview of the shaping Metalworking processes and the commonly used for this Aid is, for example, Ullmann’s Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A15, 479-486 (1990). The spectrum the forms of supply of the aids considered are sufficient from oils to oil-in-water emulsions to aqueous solutions. Practice Certainly, the basic liquids are further components as in for example viscosity regulators, defoamers or corrosion inhibitors added. Lubricants, especially in oil-based systems, for example, so-called "EP additives". For the formation of Emulsions usually require the use of emulsifiers. In In many cases, the agents are also stabilized by biocides.

Today paraffin or mineral oils are preferred as oil components used. There are also so-called synthetic lubricants ("synthetic oils") such as polyolefins. Ecology The advantages of using oils on a native basis can be  for example in the form of native triglycerides or modification products of these, wax esters, fatty acid esters of polyols or longer-chain dials expect kylether.

On the one hand, the oils come as such in the form of so-called "non-water mixtures cooler lubricants. They then have the advantage of metals not to attack chemically and to provide good corrosion protection. The good lubricating effect is also an advantage. The main disadvantage lies in the low heat capacity of water-immiscible cooling lubricants, so that the heat generated in the forming processes is dissipated poorly becomes.

Of the non-water-miscible cooling lubricants, also as "cutting oils" or "metalworking oils", one distinguishes the water miscible cooling lubricants, which are in the form of a low-water or water free concentrate come on the market and at the user through Vermi with water in a cooling lubricant emulsion in the form of an oil-in-what water emulsion to be transferred. As a rule, about 5% aqueous Emulsions. The advantage of this type of coolant is good cooling effect, based on the thermal properties of the water rests. The lubricating effect caused by the oil content of the emulsion is sufficient for most machining processes in machining. However, this must be ensured by adding suitable corrosion inhibitors be that the possible due to the presence of the aqueous phase Cor rosion of the metallic workpieces does not occur.

For forming processes in which there is more to good lubrication than good When heat dissipation arrives, it is also possible to concentrate the water mixable cooling lubricant little diluted or undiluted. Come the machined workpieces that are still water-miscible Cooling lubricant concentrate are wetted during later processing steps in contact with a dilute aqueous cooling lubricant emulsion, the adhering concentrate is absorbed by the emulsion and serves to complement them. In contrast, the use of non-water mix oils that are not absorbed by the circulating coolant emulsion be taken disadvantageously.  

In practice, there was the problem that with particularly heavy shaping mungs associated with a strong flow of the workpiece material are the lubricating effect of the concentrates of water-miscible cooling lubricants substances are not sufficient. A tear of the material is then observed and / or welding with the tools so that after a few Forming processes become unusable. The use of a non-water mixba Ren cutting oil, however, has the disadvantage that this the service life of the in aqueous cooling coming into contact with the workpiece in later steps lubricant emulsion adversely affected.

The task therefore was to find a lubrication method that on the one hand guarantees a good lubricating effect and on the other hand that aqueous cooling lubricant later coming into contact with the workpieces emulsion not adversely affected.

This problem is solved by a method for lubricating work pieces of metal for forming processes by drawing, deep drawing or cold extrusion, characterized in that an inhomogeneous mixture

• a) 40-90% by volume of a concentrate of a water-miscible cooling lubricant fabric emulsion,
• b) 10-60% by volume of a water-immiscible cutting oil,
• c) 0-25% by volume of a lubricant based on sulfur and
• d) 0-20% by volume of water,

where the sum of the components adds up to 100% on the workpiece applies.

The invention is based mainly on the contrary to the usual Leh practice a non-water-miscible cutting oil with the concentrate to mix a water-miscible coolant emulsion. That was Not considered so far since you can get these two components does not receive a stable homogeneous mixture, but rather when left standing phase separation observed. Accordingly, it is required in the present invention Lich, the water-miscible coolant emulsion and with water immiscible cutting oil due to mechanical energy input, for example  se by stirring, to mix intensively with each other and in the inhomogeneous Keep mixture. The term "inhomogeneous mixture" means here that the cutting oil is not in the water-miscible coolant emulsion is emulsified, but mechanically with such a droplet size is distributed here that after the end of the mechanical vermi quickly, for example within half an hour, as separate ones Phase separated again. The task within the scope of the invention tion required lubrication effect is only achieved if that Cutting oil in the mechanical mixture with such a drop size is that after the end of the mechanical force a phase spontaneously separation takes place. Accordingly, the formulation of the water-miscible Concentrate the cooling lubricant emulsion to ensure that only as much Emulsifier is used that this for emulsifying the oil component of the water-miscible coolant concentrate is sufficient, but not water-miscible cutting oil is not added to this emulsion concentrate emulsified. In the case of such emulsification of the cutting oil, the is indicated, for example, by the fact that when the mixture is left to stand there would be no phase separation within half an hour Inadequate lubrication.

The method according to the invention can therefore be carried out by that the above components a) and b) optionally together with the further components c) and d) by stirring in a mixing container mixes and with the stirrer running through a sampling line to the factory piece. Alternatively, the individual components of a more Feed the fabric nozzle and spray onto the workpiece together. Im simple In most cases, a two-component nozzle is sufficient, through whose one feed line the water-miscible components and through their second supply line one which supplies non-water-miscible components.

The method according to the invention is based on the joint use of two components that are not homogeneously and stably miscible with each other. Are there the individual components as cooling lubricants or as concentrates for cooling lubricant emulsions known in the prior art. For example component a) is an emulsion concentrate that is composed is from 30 to 50 wt .-% of an oil component, preferably mineral oil, the  if desired contains sulfurized portions, and 10 to 20 wt .-% Was ser. The remainder to 100 wt .-% consists of emulsifiers, preferably on Ba sis of fatty alcohol ethoxylates, from corrosion inhibitors, preferably based on amine soaps, ethanolamine soaps and / or ethanolamides, and optionally from others for this product group in the prior art known auxiliaries or active ingredients.

A non-water-miscible cutting oil is suitable as component b). Before There are oils based on native ingredients, especially those based on esters. Examples for this are native triglycerides or modification products thereof, Wax esters and fatty acid esters of monoalkanols with 4 to 12 carbon atoms, for example tallow fatty acid ethylhexyl ester or transesterified rapeseed oil, and fatty acid esters of polyols, the polyol component in particular Trimethylolpropane can be used. Component b) can also Gemi represent from such oils. The oils can contain additional additives contain, in particular EP additives, for example welded in the form compounds, antioxidants and corrosion inhibitors are called.

Embodiments

For a manufacturer of steel rims for car wheels, the task was for ecological reasons chlorine-containing lubricants through chlorine-free Systems to replace. During manufacture, blanks are made from steel strips punched out and in several, sometimes considerable forming stages (drawing hen, deep drawing). When using a chlorine-free water miscible concentrate of a cooling lubricant emulsion already appeared about 10 operations strong welds on the pressing tools as well Cracks in the edges of the formed workpieces. The problem could be solved in that an inho in a batch container with stirring mogene mixture of the following components and in an amount of about 6 to 8 ml per wheel bowl to be manufactured on the mate to be formed rial was applied:

• a) 50% by volume of a water-miscible concentrate of a chlorine-free cooling lubricant emulsion consisting of 40% by weight mineral oil, 40% by weight Emulsifiers based on fatty alcohol ethoxylates and corrosion inhibitors gates and 20% by weight water (P3-multan® 81-3, Henkel KGaA, Düssel Village),
• b) 15% by volume of a non-water-miscible cutting oil based on fat ester (P3-multan® 201, Henkel KGaA, Düsseldorf),
• c) 20% by volume of a sulfur-containing lubricating additive (P3-multan® EP1, Hen kel KGaA, Düsseldorf) and
• d) 15 vol% water.

Using this mixture, the tool life could be more than be a hundredfold. When this mixture was left to stand inside a phase separation within 10 minutes. When subsequently rinsing the formed wheels with a water-mixed cooling lubricant emulsion the concentrate / cutting oil mixture easily emulsified into this.

Claims (6)

1. Process for lubricating metal workpieces for forming processes by drawing, deep drawing or cold extrusion, characterized in that an inhomogeneous mixture

• a) 40-90% by volume of a concentrate of a water-miscible cooling lubricant emulsion,
• b) 10-60% by volume of a water-immiscible cutting oil,
• c) 0-25% by volume of a lubricant based on sulfur and
• d) 0-20% by volume of water,

where the sum of the components adds up to 100% on the Applies the workpiece. 2. The method according to claim 1, characterized in that the Mi Component a) and b), optionally together with c) and d), by stirring in a mixing container and while running Applies the stirrer to the workpiece via an extraction line. 3. The method according to claim 1, characterized in that the compo nente a) optionally together with components c) and d) a feed line of a two-component nozzle, component b) via another Supply line to a two-component nozzle and together on the workpiece sprayed on. 4. The method according to one or more of claims 1 to 3, characterized ge indicates that component a) is composed of 30-50 % By weight of an oil component, preferably mineral oil, the desired if contains sulphurized fractions, and 10 to 20 wt .-% water, wherein the rest 100% by weight from emulsifiers, preferably based on Fatty alcohol ethoxylates, corrosion inhibitors, preferably based of amine soaps, ethanolamine soaps and / or ethanolamides, and from there are other auxiliaries or active ingredients.   5. The method according to one or more of claims 1 to 4, characterized ge indicates that component b) is an ester-based oil, preferably selected from native triglycerides or their modifi ornamental products, wax esters, fatty acid esters of monoalcohols with 4 up to 12 carbon atoms or fatty acid esters of polyols or mixtures here from, the oil additional auxiliaries, in particular EP additives, Antioxidants and corrosion inhibitors can contain.