DE3640023A1 - Process for machining metals, and lubricant compositions for this process - Google Patents

Abstract

The process for machining metals uses oxidation products of homo-or co-polymers of 1-olefins or esterification or saponification products of these oxidation products as lubricants. The oxidation products are solid and preferably have melting points above 90@C, acid numbers above 5mg of KOH/g and a dicarboxylic acid content of more than 10% by mass. The lubricants can be used in the pure form or in the form of compositions in which they are present as a mixture with lubricant additive and/or suspending agents, dispersing agents or solvents known per se.

Description

The invention relates to a method for machining metal under Use of a lubricant.

The lubricant is said to be the friction between the workpiece and the tool reduce the dissipation of friction heat, chips and metal abrasion away from the processing zone and protect the materials from corrosion.

It is known in metal cutting to meet these needs Use lubricants made from mineral oils and synthetic oils with or without high pressure additives, animal and vegetable oils, fats and Waxing and their derivatives, e.g. B. soaps or esters based on fatty acids. The lubricants are often used to improve the cooling effect Mixture with water used.

The well-known lubricants result in metal cutting unsatisfactory results in many ways. Often not desired high cutting performance, tool life and dimensional accuracy as well as the surface quality of the workpieces. In addition, the conventional Lubricants, especially for difficult metalworking processes, to achieve a noticeable smear effect in general choir, high-pressure additives containing sulfur and phosphorus are required. Do this Discoloration and corrosion of the metal surfaces, health risks for the Employees and high environmental pollution.

The invention has for its object in metal cutting improve outcomes and health risks as well as environmental pollution to reduce.

This object is achieved according to the invention by machining metal is carried out using a synthetic lubricant characterized in that the lubricant is selected from a group consisting of from oxidation products of polymers of 1-olefins and esterification and saponification products of the oxidation products mentioned and mixtures of the substances mentioned, this lubricant in pure form or in a mixture with other, known mixture components of lubricants is used.  

Among those used as lubricants in the method according to the invention Oxidation products of polymers of 1-olefins are oxidation products of Homopolymers of C₂-C₁₈ alkenes with a terminal double bond, preferably of C₂-C₁₂ alkenes, especially of ethene, propene, 1-butene, 3-methyl To understand 1-butene, 1-pentene-1-hexene and 1-octene, and of copolymers these 1-olefins with one another, and also copolymers of these 1-olefins with bis up to 50, preferably up to 30, in particular up to 20, but especially up to 15 % By mass of oxygen-containing 1-olefins. Polymers are e.g. B. the commercially available Polyethylenes, polypropylenes, polybutylenes etc., as they are known Processes, for example by high, medium or low pressure polymerization be preserved. Copolymers of 1-olefins simultaneously contain at least one two different 1-olefin building blocks. These include e.g. B. Polyethylenes with a content of up to 30, preferably up to 20, in particular up to 10 % By mass of other 1-olefins such as propene, 1-butene, etc. Also recently copolymers of ethylene available under the name LLDPE higher 1-olefins are to be counted for this. Copolymers of 1-olefins with oxygenated olefins are e.g. B. Copolymers of ethylene with vinyl esters the carboxylic acids such as vinyl acetate or vinyl propionate, further with vinyl ethers or 1,2-ethylenically unsaturated carboxylic acids and their derivatives such as acrylic acid, Methacrylic acid, ethacrylic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, Itaconic acid, mesaconic acid or the esters of these acids. The The polymers used are subject to structure and molecular size no limit. For example, polymers with high or low degrees of branching are used. It is also possible to use low molecular weight waxy polymers with molecular weights between 200 and 20,000 (Melt viscosities approx. 5 to 100,000 mPa s at 160 ° C) and higher molecular weight plastic-like polymers with molecular weights between 20,000 and 5,000,000 to use. Conveniently, they have molecular weights above 200, especially above 2000 and above all over 20,000, melting points over 100, preferably over 115 and especially above 120 ° C, melt viscosities at 160 ° C above 100, preferably over 1000, especially over 10,000 and especially over 100,000 mPa s, and degrees of crystallization over 10, preferably over 30, in particular over 40 and above all over 50%.

Oxidation products of the polymers are to be understood as products which in the generally arise from air oxidation of the polymers. Your manufacture can done by known methods, e.g. B. from low molecular weight polymers by mixing the polymers in the molten state with air or particularly advantageous from higher molecular weight polymers by treating the  Polymers at elevated temperatures with air in the solid state or in molten state finely divided in an inert dispersant. The Oxidates have acid numbers between 5 and 150, preferably between 10 and 70, advantageously between 15 and 50, in particular between 20 and 45 mg KOH / g, and melt viscosities between 5 and 100,000, preferably between 50 and 50,000, advantageously between 100 and 30,000, in particular between 500 and 20,000, especially between 1000 and 15,000 mPa s at 160 ° C. Your melting points lie above 90, preferably above 100, in particular above 110, above all above 115 ° C. The melting points of the oxidates of copolymers are rather in the lower of the specified ranges. In particular oxidates with a high content of Dicarboxylic acids (over 10, preferably over 20, advantageously over 40, in particular over 60, especially over 80% by mass), as is the case with the oxidation of higher molecular weight Polymers (molecular masses over 5000, preferably over 10,000) are formed, and Oxidates with at the same time comparatively high melting points, high melt viscosities, possess high crystallinity and high polarity as lubricants excellent in metalworking even in difficult cases Properties.

The esterification and / or saponification products of the oxidates are obtained by the oxidates with mono- or polyhydric alcohols or with mono- to trivalent metal ions or with ammonium ions partially or completely esterified or saponified or first partially esterified and then the free ones Partly or completely saponified carboxyl groups.

The following are mainly considered as esterification components: monohydric C₁ to C₂₂ alkanols, dihydric alcohols such as 1,2-ethanediol, 1,2-propanediol, 1,4-butanediol or ether alcohols such as diethylene glycol and higher polyalkylene glycols, furthermore higher alcohols such as trimethylolpropane or pentaerythritol , optionally in a mixture with one another. As saponification components are usually Li⁺, Na⁺, K⁺, Mg ²⁺ , Ca ²⁺ , Ba ²⁺ , Zn ²⁺ , Pb ²⁺ , Al ³⁺ , NH₄⁺ and ammonium ions of organic amines in the form of their hydroxides, Carbonates, acetates, stearates and other salts used, optionally in a mixture with one another. The esterification or saponification is generally carried out in a known manner by stirring the molten oxidates with the esterification or saponification components, if appropriate in the presence of suitable catalysts, to the desired degree of esterification or saponification. The esterification or saponification can also be carried out by intimately mixing the solid powdered, suspended, dispersed or dissolved oxidates with the solid powdered, suspended, dispersed or dissolved reactants. When using suspended, dispersed or dissolved reactants, the resulting product can be used in the moist, optionally in suspended or dispersed form, or after drying in powder form for the process according to the invention. In one embodiment, the saponification products can be prepared by stirring the oxidation products or the partially pre-esterified oxidation products in the molten state, optionally with the addition of emulsifiers, with the saponification component dissolved or dispersed in water. This results in aqueous solutions or dispersions of the saponification products which, as such, can also be used advantageously for the process according to the invention.

The saponification products, less the esterification products, are opposite to the underlying oxidates generally increased melting points and melt viscosities on. The melting points of the saponification products are over 100, preferably over 110, in particular over 120, advantageously over 130, especially above 140 ° C, the melt viscosities above 100, preferably above 500, in particular over 1000, advantageously over 3000, especially over 5000 mPa s at 180 ° C. For the esterification products apply rather the lower of the ranges specified. The Esterification and / or saponification products possess in relation to the oxidates lubrication properties further optimized in certain respects through a special given combination of comparatively high melting points, high melt viscosities, high crystallinity and a special balance between polar and non-polar parts. Have been particularly advantageous all the saponification products proved, the lubricating films with especially outstanding Form sliding, adhesive and release properties as well as increased tear resistance and these properties even under extreme pressure and temperature loads maintained. The esterified and especially the saponified oxidation products are suitable therefore, in a very special way, for use as a lubricant difficult processes of metal cutting, z. B. when it occurs high specific pressures and high speeds, preferably in heavy workable metals such as steels, especially high-alloy steels, also stainless steels, e.g. B. acid-resistant chrome and chrome-nickel steels.

The oxidation products and their esterification and saponification products can for the process according to the invention alone, in a mixture with one another or  Mixture with substances other than lubricants for working metals be used. Other mixture components include, for example, mineral oils, vegetable or animal oils, fats, waxes or resins as well as fatty acids, Fatty alcohols, soaps, synthetic resins or oils, preferably polyalkylene glycols and their derivatives, low molecular weight polyethylenes and esters in Consider. Furthermore, the lubricants in the method according to the invention usual additives such as high-pressure active ingredients (e.g. chlorine, sulfur or phosphorus-containing substances), AW active ingredients, furthermore pigments and fillers, emulsifiers, Solubilizers, surfactants, wetting agents, viscosity improvers, thickeners, Adhesion improvers, binders, defoamers, anti-fog additives, corrosion inhibitors, Metal deactivators, preservatives and antioxidants to round off of the properties are added.

The oxidation products and the esterification and / or saponification products of the Oxidates can be used as lubricants in the form of the process according to the invention of powders, pastes, suspensions, dispersions or solutions. For pastes, Suspensions, dispersions and solutions preferably serve water, mineral oils, natural or synthetic oils and chlorinated hydrocarbons, if necessary in a mixture with one another, as a suspension, dispersion or solvent. As special Polyalkylene glycols have proven to be advantageous due to their solubilizing properties Effect both in the preparation of the invention Lubricants as well as when they are removed from the metal surface. The Preparation of the suspensions and dispersions can be made with the addition of known ones ionic or nonionic emulsifiers and wetting agents. The dispersions are generally highly transparent and allow observation of the Workpiece during machining. To achieve a high cooling effect it is convenient to apply the lubricants in aqueous dilution. The dilutions generally contain 0.1 to 20, preferably 0.5 to 10, especially 1 up to 5% by mass of the concentrates.

The method according to the invention can be used for all types of machining of metals are advantageously used, for example when turning, Milling, drilling, sawing, planing, shaping, scraping, cutting, broaching, grinding, Honing, lapping or rubbing. The advantages of the invention are particularly evident How to work with difficult machining processes, e.g. B. in high-performance thread cutting, Tapping, broaching or high-speed grinding.  

The method according to the invention is advantageously suitable for processing all of them common metallic materials, e.g. B. of base materials such as cast iron and Malleable cast iron, of low-carbon or high-carbon steels, non-, low- or high-alloy steels, stainless steels, non-ferrous metals, such as magnesium, Aluminum, copper, brass, bronze, zinc, lead, nickel, chrome, manganese, titanium, Zircon, tungsten, molybdenum and their alloys. In particular, they come Advantages of the method according to the invention when processing difficult metals to wear, e.g. B. in austenitic and ferritic steels, especially in high-alloy, before all stainless steels, preferably stainless steels, e.g. B. acid-resistant chrome or chrome-nickel steels.

Due to the excellent lubrication and cooling effect of the lubricants used are compared to known in the inventive method Process generally higher cutting speeds, also higher dimensional accuracy as well as better surface quality of the workpieces and longer service life the tools reached. Cold welding with the associated impairments of the workpiece surfaces due to scoring and impairment of the Tool life due to welding does not occur or only to a significantly reduced extent Measurements on.

The inventive method is also characterized in that lubricants are used that do not contain any harmful substances and also do not contain any substances such as chlorine, sulfur or phosphorus, by which the properties the machined materials, e.g. B. due to discoloration and corrosion, be adversely affected and the environment is heavily polluted. The lubricants do not have a corrosive effect on metals, but have a protective effect against corrosion. After They can be edited as required using simple means and methods, for example using conventional alkaline, neutral and acidic cleaners or using organic solvents, residue-free using standard cleaning processes remove from the metal surface. A special advantage of the invention The method also consists in that the lubricants used also by a simple vacuum heat treatment, for example in the preliminary stage a post-heat treatment of the workpiece, residue-free by evaporation have it removed from the workpiece surface.

Examples 1 to 8

The following oxidation products of polymers of 1-olefins are considered Lubricants used in metalworking:

The lubricants are in the solid state with electrostatic application used when turning gray cast iron at a cutting speed of 35 m / min. The machining results given in the table are achieved. The results are consistently better than when using comparable conventional ones Lubricant. Even more improved results are obtained if the lubricants are saponified with sodium or calcium hydroxide before use were.

Examples 9 to 16

The same oxidation products as in Examples 1 to 8 are in aqueous alkaline dispersions are transferred by being melted together with the amounts of potassium hydroxide calculated according to the acid number and together with emulsifiers (5% by mass of ethoxylated fatty alcohol, based on Oxidate) are dispersed in hot water. It becomes finely divided, highly transparent Obtain dispersion concentrates with a solids content of 30%. The concentrates are diluted with water for use. More about the properties  The dispersions in the application concentration are shown in the following table.

The dispersions listed in the table are used as cooling lubricants at Drilling carbon steel used at a cutting speed of 65 m / min. The machining results given in the table are obtained. The results can be further improved if the lubricant small amounts of fatty acid-based soaps or hydrolysis-resistant phosphorus compounds, e.g. B. phosphonic acids.

Conventional cooling lubricants result in comparison to those in the table specified lubricants under the same conditions significantly shorter drill life. The same realistic quality gradation results when using the Lubricant for grinding or honing.

Examples 17 to 24

The oxidation products from Examples 1 to 8 are combined with the equivalent Amount of potassium hydroxide and 30% by mass of polyethylene glycol on the oxidation products, in a mineral oil with a viscosity of 10 mm² / s (20 ° C) dissolved at elevated temperature. The following table receive the lubricant listed.  

The lubricants are tested in an automatic threading machine. The working speed of each lubricant is set so that the tool breaks within 6 to 8 hours. The one with the individual Lubricants maximum achievable cutting speeds are based on the per time required for the finished part. The processing results determined in this way are given in the table. The results can be further improved if the lubricants contain high-pressure additives containing phosphorus, sulfur or chlorine be added.

Conventional lubricants consistently deliver under the same conditions worse results.

Examples 25 to 32

The oxidation products from Examples 1 to 8 are the same as in Examples 17 to 24 converted into lubricants, but instead of the mineral oil liquid polyglycol made up of ethylene oxide and propylene oxide units is used. The same tests are carried out as for the Examples 17 to 24. The test results are of the same order of magnitude as in Examples 17 to 24 and show the same quality gradation among themselves.

Claims (11)

1. A process for machining metals using a synthetic lubricant, characterized in that the lubricant is selected from a group consisting of oxidation products of polymers of 1-olefins and esterification and saponification products of the oxidation products mentioned and mixtures of the substances mentioned, this lubricant being used in pure form or in a mixture with other, known mixture components of lubricants. 2. The method according to claim 1, characterized in that the oxidation products are oxidation products of polymers which are selected from a group consisting of

• - Homopolymers of C₂-C₁₈ alkenes with a terminal double bond, preferably C₂-C₁₂ alkenes and in particular of ethene, propene, 1-butene, 3-methyl-1-butene, 1-pentene, 1-hexene and 1-octene,
• - Copolymers of such 1-olefins with one another and
• Copolymers of such 1-olefins with up to 50, preferably up to 30, in particular up to 20 and especially up to 15 mass% of oxygen-containing 1-olefins,

3. The method according to claim 2, characterized in that the manufacture The polymers used in the oxidation products have molecular weights of more than 200, in particular over 2000 and especially over 20,000, melting points over 100, preferably above 115 and above 120 ° C, melt viscosities at 160 ° C above 100, preferably over 1000, especially over 100,000 and especially over 100,000 mPa s, and degrees of crystallization over 10, preferably over 30, in particular have over 40 and above all over 50%.   4. Process according to claims 1 to 3, characterized in that the oxidation products Acid numbers between 5 and 150, preferably between 10 and 70, advantageously between 15 and 50 and in particular between 20 and 45 mg KOH / g, Melt viscosities between 5 and 100,000, preferably between 50 and 50,000, advantageously between 100 and 30,000, in particular between 500 and 20,000 and before all between 1000 and 15,000 mPa s at 160 ° C, melting points over 90, preferably above 100, in particular above 110 and above all above 115 ° C, and a dicarboxylic acid content above 10, preferably above 20, advantageously above 40, in particular over 60, especially over 80% by mass. 5. The method according to claim 4, characterized in that the oxidation products Acid numbers between 10 and 70 mg KOH / g, melt viscosities between 50 and 50,000 mPa s at 160 ° C, melting points above 100 ° C and a dicarboxylic acid content above 20% by mass. 6. The method according to any one of claims 1 to 5, characterized in that the Esterification products of the oxidates esterified with mono- or polyhydric alcohols and the saponification products with mono- to trivalent Are metal ions or ammonium ions. 7. The method according to any one of claims 1 to 6, characterized in that the Esterification and saponification products of the oxidation products by mixing the powdered solid, suspended, dispersed or dissolved oxidation products with the solid, suspended, dispersed or dissolved esterification components or saponification components in solid, suspended, dispersed or in dissolved form and in solid, suspended, dispersed or dissolved form can be used. 8. The method according to any one of claims 1 to 7, characterized in that the Esterification and saponification products Melting points above 100 ° C, preferably above 110 ° C, in particular above 120 ° C, advantageously above 130 ° C, and above all above 140 ° C, and melt viscosities at 180 ° C above 100 mPa s, preferably over 500 mPa s, in particular over 1000 mPa s, advantageously over 3000 mPa s and especially above 5000 mPa s. 9. The method according to claim 1, characterized in that the lubricant in Mixture with mixture components is used, which are selected from the  Group consisting of mineral oils, vegetable or animal oils, fats, Waxes or resins, fatty acids, fatty alcohols, soaps, synthetic resins or oils, esters, polyalkylene glycols or their derivatives, high-pressure active ingredients, AW active ingredients, pigments, fillers, emulsifiers, solubilizers, Surfactants, wetting agents, viscosity improvers, thickeners, adhesion improvers, binders, Defoamers, anti-fog additives, anti-corrosion agents, metal deactivators, Preservatives and antioxidants, as well as mixtures of two or more of these mixture components. 10. The method according to claim 1, characterized in that the lubricant used in a mixture with a suspension, dispersion or solvent which is selected from a group consisting of water, mineral oils, natural or synthetic oils, polyalkylene glycols or chlorinated hydrocarbons, and mixtures of two or more of these agents. 11. Lubricant composition for use in a method according to Claim 1, characterized in that it is an actual lubricant contains, which is selected from a group consisting of oxidation products of polymers of 1-olefins and the esterification and saponification products these oxidation products and mixtures of two or more of these substances, these lubricants being solid, suspended, dispersed or dissolved in a suspension, dispersion or solvent, and wherein the composition optionally further mixture components known per se of lubricant compositions.