GB2108148A

GB2108148A - Cooling-lubricating pastes and liquids

Info

Publication number: GB2108148A
Application number: GB08223019A
Authority: GB
Inventors: Miklos Perl
Original assignee: Csepel Autogyar
Current assignee: Csepel Autogyar
Priority date: 1981-08-11
Filing date: 1982-08-10
Publication date: 1983-05-11
Also published as: RO86699B; GB2108148B; RO86699A; ATA294482A; SU1503684A3; PL140001B1; FR2511391A1; PL237835A1; HU185944B; DE3229159A1; CS236678B2; FR2511391B1; DD202587A5; AT382883B

Abstract

A cooling-lubricating paste comprises water, a bentonite having a grain size of at most 70 microns, e.g., 5.0 to 30.0% by weight and optionally an oil conventionally used in combination with water-based cooling-lubricating liquids, in a conventional quality and amount and optionally further additives, preferably improving lubrication. The properties of cooling-lubricating liquids conventionally employed during shaping and cutting metals and other materials are improved by admixing 0.1 to 20% by weight of additives liable to precipitation from the above liquids, e.g. disinfectants and aroma materials with 30.0 to 80.0% by wt. of water, 5.0 to 30.0% by wt. of the above bentonite and 30.0-50.0% by wt. of the above oil.

Description

SPECIFICATION Cooling-lubricating paste and an additive for cooling-lubricating liquids The invention relates to a cooling-lubricating paste and a process for improving the properties of cooling-lubricating liquids known in the art.

More particularly the invention concerns coolinglubricating pastes which can be used during shaping and cutting metals and other materials and a process by which the properties of known cooling-lubricating liquids can be improved.

There are numerous cooling-lubricating materials known in the art which can be employed during working metals and other materials. By these materials the deterioration of tools due to warming up can be avoided and the smoothness of the materials worked is improved.

It is essential that these materials should be harmless to humans and the environment easily removable, i.e. washable, and their use should be economic.

For simultaneous cooling and lubrication generally liquids, e.g. oily emulsions, are employed but in case of form tools operating at high working speeds and surface pressure, liquids do not provide a satisfactory cooling.

There are alternative methods known in the art to solve this problem and some compositions devoid of the above-listed disadvantages are even commercially available.

A cooling liquid disclosed in the Austrian Patent Specification 31 3,452 contains heavy metal salts and solves the above problems essentially by chemical reactions. Since this composition contains nickel, cobalt and iron sulfates and nitrites, it is poisonous and should therefore be handled carefully.

According to the Swiss Patent Specification 481,208 alkanol amines and glycols are added to conventional cooling emulsions. In some cases, however, these additives result in skin diseases.

In the German Patent Specification 239,895 a lubricating composition, essentially consisting of oil, aluminium powder and graphite powder is described. Due to the presence of aluminium, the temperature of the material to be worked around the site of application should exceed the melting point of aluminium. This composition can therefore be employed in roll mills only.

By the compositions disclosed in the German Patent Specification 1 594 532 the smoking of lubricating materials can be reduced but the application of these compositions is also restricted to roll mills.

The heat resistance can be increased by using synthetic oils and synthetic fats as well, but these materials are extremely expensive and strongly contaminate the environment. The latter materials include the paste produced by the firm Cincinatti (Holland) and a cutting liquor, marketed under the name "Dundy" by the firm Daniel and Jäger (Stuttgart). At high cutting speeds, however, also these materials decompose accompanied by the formation of vapours and gases which are detrimental to health.

A further problem to be faced in case of certain cooling liquids is the propagation of various bacteria therein. According to the Swiss Patent Specification 508,035 the addition of certain reactants, e.g. formaldehyde, may solve this problem, but due to the volatile character of this compound, however, an unreasonably large amount is required to obtain the desired result.

Moreover, this reactant can cause skin diseases and its vapour contaminates the atmosphere. The use of other similar disinfecting agents is accompanied by analogous problems.

The improvement of known coolinglubricating pastes is further rendered difficult by the fact that most of the conventional additives used for this purpose, e.g. lubricating agents, such as soaps, graphite, sulfur quickly precipitate from these liquids and therefore it is extremely difficult to produce stable, homogenous products.

It is therefore highly desirable to produce a cooling-lubricating paste which has a satisfactory cooling and lubricating effect, i.e. good adhesion and heat-resistivity.

We have surprisingly found that bentonite, due to its good swellability, can form pastes with different liquids, including water-based coolinglubricating liquids.

We have further found that a desired pulpy consistency can be achieved by a proper adjustment of the grain size of bentonite. If a bentonite grist having a mixed grain size contains also grains exceeding 70 microns, it is impossible to achieve a consistency meeting the highest technical demands.

Accordingly, the invention relates to a coolinglubricating paste for cutting and shaping metals and other materials, comprising water, 5.0 to 30.0% by weight of bentonite having a grain size not exceeding 70 microns and optionally any oil conventionally used in water-based coolinglubricating liquids and optionally further additives improving the lubricating properties.

A preferred composition according to the invention comprises water, bentonite and a conventional oil. More preferably, it consists of 40.0 to 60.0% by weight of water, 5.0 to 30.0% by weight of bentonite and 10.0 to 50.0% by weight of oil.

According to a further preferred embodiment of the invention, the compositions according to the invention contain additives for improving the lubricating properties, preferably one or more soap (stearates) and/or graphite and/or sulfur in an amount of 1.0 to 10.0% by weight, provided that the total amount of said additive(s) and bentonite is at most 30.0% by weight. The compositions may further contain preferably 5.0 to 20.0% by weight of a disinfecting agent and/or 0.1 to 1.0% by weight of aroma materials.

The most preferred additives are soaps, e.g.

calcium, magnesium, aluminium or zinc stearates; graphite: sulfur; disinfecting agents, e.g.

formaldehyde; and aroma materials.

According to a further aspect of the invention there is provided a process for improving the properties of cooling-lubricating liquids which comprises admixing 0.1 to 20% by weight of additives easily precipitating from coolinglubricating liquids, preferably additives improving the lubricating properties, disinfectants and/or aroma agents with a mixture of 30.0 to 80.0% by weight of water, 5.0 to 30.0% by weight of bentonite and optionally 30.0 to 50.0% by weight of a conventionally used oil, and finally, admixing the mixture obtained with a cooling-lubricating liquid.

By the process according to the invention the applicability of known cooling-lubricating liquids can substantially be improved, since in this way the properties of known cooling-lubricating liquids can be improved by conventional additives, preferably soaps, graphite, sulfur and/or aroma agents and/or disinfecting agents, which could not be used before, due to their liability to precipitation from aqueous liquids.

The cooling-lubricating pastes according to the invention have the following advantages: a) The fixed humidity of bentonite is deliberated at a temperature of 500 to 7000C, therefore it is capable of cooling even at temperatures at which oils burn.

b) The formation of vapours and gases is considerably decreased.

c) Bentonite, after taking up water, has good lubricating properties per se, therefore the lubricating properties of the paste are also better than of those containing oil only.

d) The pastes can contain also additives which usually quickly precipitate from liquids, e.g. soaps, graphite, sulfur, aroma materials, disinfectants, etc., and thus the properties thereof are further improved.

e) The known emulsion-stabilising effect of bentonite makes it possible to inhibit the precipitation of various additives by admixing the known cooling-lubricating liquids with a mixture of the paste according to the invention and said additives.

f) As a result of the use of the bentonite it will be possible to ensure that biological purification of the cooling-lubricating liquid by a lower disinfectant concentration than the level that gives rise to skin sensitivity, by preparing a paste having a high disinfectant (bactericide) concentration and adding it to the coolinglubricating liquid, which then has a low disinfectant concentration.

g) The pastes according to the invention unlike the known synthetic pastes or fats, are easy to wash off.

Further details of the invention are given in the following Examples, which are for illustration and not for limitation of our invention.

Example 1 A deep-drawing process was to be carried out.

The object was to prepare a 40 mm high pot-like piece with a diameter of 70 mm from a 2 mm thick steel plate. Conventionally the steel plate must be phosphatased to obtain the desired result. Otherwise the surface of the part will be worn, broken and the wall-thickness will not be uniform.

A cooling-lubricating paste was prepared to carry out the process. A 1:1 emulsion was prepared from water and a cooling-lubricating oil preparate "K-22" (manufactured by Magyar Komáromi Olajipari Vállalat, Hungary). Thereafter a paste was prepared by admixing 95.0% by weight of said emulsion and 5.0% by weight of bentonite. Since bentonite has a very high liquid (in particular water-based liquid) absorbing capacity, no special stirring is required to prepare the paste. If the emulsion is stable, a homogenous paste is obtained using the above proportions even without stirring; stirring merely accelerates production.

An unphosphatased plate was smeared by the paste obtained and deep-drawing was performed in a conventional manner. The surface of the obtained piece was smooth and its wall-thickness was uniform.

Example 2 By wortex thread-cutting lathe, ball-thread was prepared at a speed of 300 m/min. Required surface quality: Ra=2.5 microns.

To carry out this procedure the part was conventionally pre-treated either by the Cincinatti paste or by the concentrated cooling-oil preparate Dundy 9107-KA of the firm Daniel and Jigger referred to before. The working life of the tool was 2 hours. Due to the high temperature an extremely heavy gas evolution was observed and in addition, the concentrated Dundy-liquid even caused various skin diseases. The harmful effect of the Dundy-liquid could be reduced by dilution but simultaneously the life of the tool was diminished, too.

A paste was prepared by admixing 30.0% by weight of bentonite, 56.0% by weight of water and 14.0% by weight of the Dundy-liquid. The life of the tools treated by the paste obtained was increased by about 50%, the gas and vapour formation disappeared and no harmful effect on the skin was observed.

Example 3 In a procedure described in Example 2 a paste was prepared from oil K-22. The paste contained 13.0% by weight of bentonite, 45.0% by weight of water and 42.0% by weight of oil K-22. The result was identical with the result obtained by using the paste according to Example 2.

Example 4 In a procedure described in Example 1, a paste prepared as follows was employed: to a 1:1 (vol./vol.) mixture of water and oil K-22, 5.0% by weight of bentonite and 6.0% by weight of calcium stearate was added. After applying the paste obtained on an unphosphatased plate as described in Example 1 the surface quality became excellent even compared with Example 1.

Example 5 As mentioned before, the inhibition of bacteriological processes is a major problem when using cooling-lubricating pastes. If such processes have already started as a first treatment conventionally about at least 0.5% of disinfectant should be added to the emulsion. In such conventional pure or pretreated emulsions the bacteriological processes can be avoided by 0.1 to 0.1 5% of a disinfectant. These concentrations are high and therefore the risk of skin diseases is also high.

In conventional pastes and emulsions, disinfectants should generally be used in large concentrations since they quickly precipitate from the emulsions and are liable to decomposition. To avoid this undesired effect an emulsion-forming paste was prepared.

A first treatment in accordance with the present invention was carried out in case of a metal cutting machine operated in one shift. A new, pure emulsion having the same composition as the original cooling-lubricating liquid used for the machine was prepared. 60.0% by weight of that liquid were admixed with 20.0% by weight of bentonite and 20.0% by weight of formaldehyde.

At the end of each shift 30 g. of this paste were added into a 100 lit. tank of the metal cutting machine. As a result, a formaldehyde concentration of 0.006% by weight was obtained in the cooling-lubricating liquid. The treatment resulted in the purification of the liquid from bacteriological point of view within 16 hours.

It can be concluded that the use of the formaldehyde-containing paste according to the present invention reduces the concentration of disinfecting agent required to achieve the desired result to 1/20~1/30 of the level conventionally used. Instead of an emulsion, pure water may be also used to prepare a paste. In this case the paste consists of 60.0% by weight of water, 20.0% by weight of bentonite and 20.0% by weight of formaldehyde. In the bacterical purification process the latter paste proved equally effective. The aqueous paste is advantageous in that it can successfully be employed in combination with every coolinglubricating liquid.

The cooling-lubricating pastes according to the invention containing bentonite provide a longer life than the cooling-lubricating liquids they are combined with and in the same time eliminate the side effect detrimental to health.

Claims

1. Cooling-lubricating paste for cutting and shaping metals and other materials, which comprises water, 5.0 to 30.0% by weight of bentonite having a grain size of at most 70 microns and optionally an oil conventionally used in combination with water-based coolinglubricating liquids, in a conventional quality and amount and optionally further additives, preferably improving lubrication.

2. A paste as claimed in claim 1, which comprises 40.0 to 60.0% by weight of water, 5.0 to 30.0% by weight of bentonite and 10.0 to 50.0% by weight of oil.

3. A paste as claimed in claim 1 or claim 2 which comprises in addition to water, bentonite and oil one or more additives improving lubrication, preferably a soap (stearate), graphite or sulfur, in an amount of 1.0 to 10.0% by weight, provided that the total amount of said additive(s) and bentonite is at most 30.0% by weight.

4. A paste as claimed in any one of claims 1 to 3, which comprises as a lubrication-improving additive one or more of the following compounds: calcium stearate, magnesium stearate, aluminium stearate, zinc stearate in a total amount of 3 to 10% by weight.

5. A paste as claimed in claim 1 or claim 2 which comprises 5 to 20% by weight of a disinfectant in addition to water, bentonite and oil.

6. A paste as claimed in any one of claims 1 to 5, which comprises 0.1 to 1% by weight of an aroma material in addition to water, bentonite and oil.

7. A process for improving the properties of cooling-lubricating liquids, which comprises admixing 0.1 to 20% by weight of additives liable to precipitation from cooling-lubricating liquids, preferably disinfectants and aroma materials, with a mixture of 30.0 to 80.0% by weight of water, 5.0 to 30.0% by weight of bentonite having a grain size of at most 70 microns and optionally 30.0 to 50.0% by weight of an oil of a conventional quality conventionally used in combination with water-based cooling-lubrication liquids and admixing the composition obtained with said cooling-lubricating liquid.

8. A process as claimed in claim 7 which comprises adding 30 g of emulsion prepared from a mixture of 60.0% by weight of water, 20.0% by weight of bentonite and 20.0% by weight of formaline to 100 lit. of a cooling-lubricating liquid.

9. A paste for use in cooling and lubricating a workpiece made of metal or other materials during cutting or shaping, which paste comprises water and bentonite having a grain size of not more than 70 microns.

10. A paste as claimed in claim 9, wherein the paste contains not more than 40% by weight of bentonite.

11. A paste as claimed in claim 10, wherein the paste contains from 5 to 30% by weight of bentonite.

12. A paste as claimed in any one of claims 9 to 11, wherein the paste contains an oil of the type conventionally used with water-based cooling-lubricating liquids.

13. A paste as claimed in claims 11 and 12, wherein the paste comprises, by weight, 40 to 60% of water, 5 to 30% of bentonite and 10 to 50% of oil.

14. A paste as claimed in any one of claims 9 to 13, which includes one or more additives for increasing lubrication and/or for disinfecting the paste and/or for providing an aroma.

15. A paste as claimed in claim 14, wherein the lubricating additive is one or more of a soap, graphite or sulfur.

16. A paste as claimed in claim 14, wherein the soap is one or more of the following compounds: calcium stearate, magnesium stearate, calcium stearate and zinc stearate.

17. A paste as claimed in claim 15 or claim 16, wherein the total amount of soap present lies in the range of from 3 to 10% by weight.

18. A paste as claimed in claim 15 or 16, wherein the total amount of the or each lubricating additive present lies in the range of from 0.1 to 10% by weight.

19. A paste as claimed in any one of claims 16 to 18, wherein the total amount of lubricating additives plus bentonite does not exceed 30% by weight.

20. A paste as claimed in any one of claims 14 to 19, which contains from 5 to 20% by weight of a disinfectant.

21. A paste as claimed in any one of claims 14 to 20, which contains 0.1 to 1% by weight of an aroma-providing additive.

22. A paste substantially as hereinbefore described in any one of Examples 1 to 5.

23. A process for improving the properties of a conventional cooling-lubricating liquid, which process comprises admixing the paste according to claim 1 or the ingredients thereof with the cooling-lubricating liquid and from 0.1 to 20% (based on the weight of the paste) of one or more additives liable to precipitate from coolinglubricating liquids.

24. A process as claimed in claim 23, wherein the paste comprises 30 to 80% by weight of water, 5 to 30% by weight of bentonite, 0.1 to 20% (based on the weight of the paste) of one or more of said additives and optionally 30 to 50% by weight of an oil conventionally used in combination with water-based cooling-lubricating liquids.

25. A process substantially as hereinbefore described in Example 5.

26. A cooling liquid produced by a process as claimed in any one of claims 8, 9 or 22 to 24.