WO1997002909A1

WO1997002909A1 - Lubricating process for heavy-duty forming operations

Info

Publication number: WO1997002909A1
Application number: PCT/EP1996/002904
Authority: WO
Inventors: Hartmut Rieger; Helga Holzapfel; Hans-Peter ÖLSCHER; Wiltrud Klose; Karl Sigg
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1995-07-12
Filing date: 1996-07-03
Publication date: 1997-01-30
Also published as: EP0837744A1; EP0837744B1; DE19525407A1; DE59601619D1

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

"Lubrication Process for Heavy Forming"

The invention relates to a method for lubricating workpieces made of metal, in particular steel or aluminum, for forming processes by drawing or deep drawing. In order to enable particularly heavy forming operations, an inhomogeneous mixture prepared immediately before the forming operation is applied, the essential components of which are a concentrate of a water-miscible cooling lubricant emulsion and a non-water-soluble visual cutting oil.

When shaping metals by drawing or deep drawing, possibly also in connection with punching out parts, lubricants are required, the main purpose of which is to reduce the friction between the tool and the workpiece. An overview of the shaping metalworking processes and the aids usually used for this purpose can be found, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A15, 479-486 (1990). The spectrum of the forms of supply of the auxiliaries in question ranges from oils to oil-in-water emulsions to aqueous solutions. Other components, such as, for example, viscosity regulators, defoamers or corrosion inhibitors, are usually added to the base liquids. Lubricants, for example so-called "EP additives", are still common, especially in oil-based systems. The use of emulsifiers is generally necessary for the formation of emulsions. In many cases, the agents are also stabilized by biocides.

Today paraffin or mineral oils are preferably used as oil components. In addition, so-called synthetic lubricants ("synthetic oils") such as polyolefins can also be used. Ecological advantages can be achieved when using oils on a native basis, with for example in the form of native triglycerides or modification products thereof, wax esters, fatty acid esters of polyols or longer-chain dialkyl ethers.

On the one hand, the oils are used as such in the form of so-called "non-water-miscible" cooling lubricants. You then have the advantage of not chemically attacking metals and providing good corrosion protection. The good lubricating effect is also an advantage. The main disadvantage lies in the low heat capacity of non-water-miscible cooling lubricants, so that the heat generated during the forming processes is dissipated only with difficulty.

A distinction is made from non-water-miscible cooling lubricants, also referred to as "cutting oils" or "metalworking oils", which are water-miscible cooling lubricants which come on the market in the form of a low-water or water-free concentrate and which are mixed by users with water in a cooling lubricant emulsion be transferred in the form of an oil-in-water emulsion. As a rule, approximately 5% aqueous emulsions are produced. The advantage of this type of cooling lubricant is the good cooling effect, which is based on the thermal properties of the water. The lubricating effect caused by the oil content of the emulsion is sufficient for most machining processes in metal-cutting manufacturing. However, by adding suitable corrosion inhibitors, it must be ensured that the corrosion of the metallic workpieces, which is possible due to the presence of the aqueous phase, does not occur.

In the case of forming processes in which a good lubricating effect is more important than good heat dissipation, it is also possible to use the concentrate of a water-miscible cooling lubricant in a slightly diluted or undiluted form. If the processed workpieces, which are still wetted with the water-miscible cooling lubricant concentrate, come into contact with a dilute aqueous cooling lubricant emulsion in later processing steps, the adhering concentrate is absorbed by the emulsion and serves to supplement it. In contrast, the use of non-water-miscible oils, which are not absorbed by the circulating cooling lubricant emulsion, is disadvantageous. In practice, there was the problem that the lubricating effect of the concentrates of water-miscible cooling lubricants is not sufficient in the case of particularly heavy formations which are associated with a strong flow of the workpiece material. One then observes tearing of the material and / or welding with the tools, so that they become unusable after a few forming operations. On the other hand, the use of a non-water-miscible cutting oil has the disadvantage that it adversely affects the service life of the aqueous cooling lubricant emulsion which comes into contact with the workpiece in later steps.

It was therefore the task of finding a lubricating process which on the one hand guarantees a good lubricating effect and on the other hand does not adversely affect the aqueous cooling lubricant emulsion which comes into contact with the workpieces.

This object is achieved by a method for lubricating metal workpieces for forming processes by drawing, deep-drawing or cold extrusion, characterized in that an inhomogeneous mixture is formed from

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 additive based on sulfur and d) 0-20% by volume .-% Water,

with the sum of the components adding up to 100% onto the workpiece.

The invention is therefore mainly based on mixing a non-water-miscible cutting oil with the concentrate of a water-miscible cooling lubricant emulsion, contrary to the usual teachings in practice. This has not been considered so far, since a stable homogeneous mixture cannot be obtained from these two components, but rather a phase separation is observed on standing. Accordingly, according to the invention, it is necessary for the water-miscible cooling lubricant emulsion and the water-immiscible cutting oil to be introduced by mechanical energy input, for example by stirring, mix intensively with one another and keep in the inhomogeneous mixture. The term "inhomogeneous mixture" here means that the cutting oil is not emulsified into the water-miscible cooling lubricant emulsion, but is mechanically distributed therein with such a droplet size that it rapidly changes, for example within half an hour, after the end of the mechanical mixing separated phase separated again. The lubricating effect required in the context of the task according to the invention is only achieved if the cutting oil is present in the mechanical mixture with a drop size such that a phase separation occurs spontaneously after the mechanical force has ended. Accordingly, when formulating the water-miscible concentrate of the cooling lubricant emulsion, care must be taken that only so much emulsifier is used that it is sufficient for emulsifying the oil component of the water-miscible cooling lubricant concentrate, but the non-water-miscible cutting oil is not additionally emulsified in this emulsion concentrate. In the case of such emulsification of the cutting oil, which is indicated, for example, by the fact that no phase separation occurs within half an hour when the mixture is left to stand, the lubricating effect would be insufficient.

The process according to the invention can therefore be carried out by mixing the above components a) and b), if appropriate together with the other components c) and d), by stirring in a mixing container and, with the stirrer running, via a removal line to the factory piece. Alternatively, the individual components can be fed to a multi-substance nozzle and sprayed onto the workpiece together. In the simplest case, a two-component nozzle is sufficient for this purpose, through whose one supply line the water-miscible components and through the second supply line the non-water-miscible components are supplied.

The method according to the invention is based on the joint use of two components which are not homogeneously and stably miscible with one another. The individual components are known in the prior art as cooling lubricants or as concentrates for cooling lubricant emulsions. For example, component a) can be an emulsion concentrate which is composed of 30 to 50% by weight of an oil component, preferably mineral oil, which if desired contains sulfurized fractions, and 10 to 20 wt .-% water. The rest of 100% by weight consists of emulsifiers, preferably based on fatty alcohol ethoxylates, of corrosion inhibitors, preferably based on amine soaps, ethanolamine soaps and / or ethanolamides, and, if appropriate, of further auxiliaries or additives known for this product group in the prior art Active ingredients.

A non-water-miscible cutting oil is suitable as component b). Preference is given to oils on a native basis, in particular on an ester basis. Examples of these 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, in particular trimethylol propane being used as the polyol component. Component b) can also be mixtures of such oils. The oils can contain additional auxiliaries, in particular EP additives, for example in the form of sulfurized compounds, antioxidants and corrosion inhibitors.

embodiments

For a manufacturer of steel rims for car wheels, the task was to replace chlorine-containing lubricants with chlorine-free systems for ecological reasons. During production, blanks are punched out of steel strips and formed in several, sometimes considerable, forming stages (drawing, deep drawing). When using a chlorine-free, water-miscible concentrate of a cooling lubricant emulsion, strong welds on the pressing tools and cracks in the edges of the formed workpieces already occurred after about 10 work steps. The problem was solved by producing an inhomogeneous mixture of the following components in a batch container with stirring and applying it to the material to be formed in an amount of about 6 to 8 ml per wheel disc: a) 50% by volume of a water-miscible concentrate of a chlorine-free cooling lubricant emulsion consisting of 40% by weight of mineral oil, 40% by weight of emulsifiers based on fatty alcohol ethoxylates and corrosion inhibitors and 20% by weight of water (P3-multan ^R 81-3, Henkel KGaA, Dusseldorf),

b) 15% by volume of a non-water-miscible cutting oil based on fatty ester (P3-multan ^R 201, Henkel KGaA, Düsseldorf)

c) 20% by volume of a sulfur-containing lubricating additive (P3-multan ^R EP1, Hen¬ kel KGaA, Düsseldorf) and

d) 15 vol% water

Using this mixture, the tool life could be increased more than a hundredfold. When this mixture was left to stand, the phases separated within 10 minutes. When the formed wheels were subsequently rinsed off with a water-mixed cooling lubricant emulsion, the concentrate / cutting oil mixture easily emulsified into them.

Claims

claims

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

with the sum of the components adding up to 100% onto the workpiece.

2. The method according to claim 1, characterized in that the mixture of components a) and b), optionally together with c) and d), is produced by stirring in a mixing container and is applied to the workpiece via a removal line with the stirrer running .

3. The method according to claim 1, characterized in that the component a) optionally together with the components c) and d) via a supply line of a two-component nozzle, component b) via a different supply line of 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 wt .-% of an oil component, preferably mineral oil, which contains sulfurized portions if desired, and 10 to 20% by weight of water, the remainder consisting of 100% by weight of emulsifiers, preferably based on fatty alcohol ethoxylates, corrosion inhibitors, preferably based on amine soaps, ethanolamine soaps and / or ethanolamides, and of further 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 oil based on ester, preferably selected from native triglycerides or their modification products, wax esters, fatty acid esters of monoalcohols with 4 to 12 C. -Atoms or fatty acid esters of polyols or mixtures thereof, where the oil can contain additional auxiliaries, in particular EP additives, antioxidants and corrosion inhibitors.