RU2845846C1 - Plastic biodegradable lubricant for railway equipment - Google Patents

Abstract

FIELD: rail vehicles.

SUBSTANCE: invention can be used to reduce the wear of rails and wheel pairs of locomotives and cars. Disclosed is an environmentally friendly lubricant for the lubrication of the "wheel-rail" contact zone of rail transport, containing vegetable oil as a base oil, as a thickener – lithium-calcium soap of 12-oxystearic acid, as well as an additive that improves tribotechnical properties, sodium tetraborate and sebacic acid, anticorrosion additive triethanolamine.

EFFECT: invention provides easy removal of lubricating material after application, increases degree of its biodecomposition, increases anticorrosion protection, reduces wear and prolongs service life of rails and wheels while reducing power consumption for traction of rolling stock.

1 cl, 3 tbl, 3 ex

Description

Field of technology

The present invention relates to an environmentally friendly plastic lubricant used in the field of railway transport for lubricating the wheel-rail contact zone and heavily loaded friction units with linear contacts in order to reduce wear of rails, wheel pairs of locomotives and wagons and reduce environmental pollution, containing biodegradable oil as a base oil.

Greases with extreme pressure additives are widely used due to their excellent wear resistance and load-bearing capacity, for example, in bearings and transmission systems of automobiles, industrial equipment, modern vehicles, industrial, construction and marine equipment, as well as in various other mechanical means used in the ferrous metallurgy and in railway transport and other industries, in particular for lubrication of the wheel-rail contact zone of rail transport (hereinafter referred to as lubrication).

Application areas: railway transport, mechanical engineering, metallurgy, etc.

State of the art

Typical formulations of EP greases are mainly those that contain additives such as olefin sulfides, fat and oil sulfides, sulfur-phosphorus-containing EP additives, molybdenum disulfide, molybdenum-containing organic compounds, lead compounds and zinc dithiophosphate in various types of greases.

To ensure the operation of rolling bearings of locomotive axle box assemblies, the domestic lubricant "Buksol" is currently used [Patent RU 2114162], which has the following composition: lithium soap of 12-hydroxystearic acid; lithium soap of oleic acid; zinc dialkyl dithiophosphate; an additive based on nitrated oil and petroleum oil that solidifies at a temperature not exceeding -40°C.

Due to the tightening of operating conditions for rail transport associated with increased speeds and environmental pollution, this lubricant does not meet these requirements.

Lubricant compositions containing sodium thiosulfate are known, which have excellent anti-seize properties (see Japanese patents No. 3131690, No. 1135965 and US No. 4923625), however, for the said compositions, wear resistance is not satisfactory due to the increased possibility of corrosion, since sodium thiosulfate has the property of absorbing moisture.

For heavily loaded friction units of railway transport with linear contacts (wheel - rail, gear transmissions of reducers), a plastic lubricant described in patent RU No. 2102442 is used, containing in wt. %: lithium soap of stearic acid - 4-20; molybdenum disulfide - 0.1-3, nitrated oil product AKOR-1 - 1.0, diphenylamine - 1.0 and petroleum oil up to 100.

The common ingredient in the lubricants described above is molybdenum disulfide, which mainly determines the load-bearing capacity of friction units. A decrease in the concentration of molybdenum disulfide in the lubricant leads to a loss of its lubricating properties.

Aqueous lubricating compositions have been proposed (RU Patent No. 2220189 Published: 27.12.2003 Bulletin No. 36 "Lubricant for use on railways and for heavy loads") this lubricant contains, wt.%: 60-90 water, 5-18 binding agent, 3-32 friction modifier, 3-32 solid lubricating agent, but they are considered impractical in Swiss application No. 669207A5, which discusses a method of using an aqueous dispersion of graphite to coat or paint the sides of rails, this method is rejected due to the fact that the aqueous dispersion is easily washed off.

Also known is an invention (patent RU No. 2374312) relating to a method for producing aqueous lubricating compositions intended primarily for lubricating tribo-coupled steel surfaces, such as the rail-wheel system, tractor-trailer and other friction units subject to heavy loads. The main disadvantage is a fairly narrow range of operating temperatures, and in addition, they do not have sufficient environmental characteristics.

The most common lubricant for the above systems is a consistent lubricant consisting of mineral oils and various additives. Most of this lubricant is lost immediately after the mating surfaces come into contact due to poor adhesive properties, which leads to the need for excessive material consumption and environmental pollution with non-biodegradable components.

U.S. Patents 5,173,204 and 5,308,516 state that in a rail-wheel system, the lubricating composition should be applied to 25% of the wheels used in the system. Given that the effect is most pronounced in curves, a lot of lubrication, time, and effort are required to ensure sufficient lubrication.

In order to function properly as a lubricating and protective coating on the rail and wheel flanges, rail grease must meet certain requirements, the most important of which are: it must have a paste-like consistency, which makes it suitable for pumping and uniform distribution on the rails; it must have good adhesion and must not be easily washed away by rainwater; it must have a high load-bearing capacity and be resistant to high pressure; it must be stable and functional over a wide temperature range from -20°C to +100°C.

However, consistent grease has serious limitations in its use and pollutes the environment.

Lubricating compositions containing solid lubricants and a polymer medium, among other components, have been used as an alternative to consistent lubricants, and these lubricants have the advantage of forming a film on the metal surface and, accordingly, providing better adhesion. However, as the lubricant dissipates, the polymer medium can also pollute the environment.

Traditionally, the basis of consistent lubricants for railway transport are mineral oils containing emulsifiers and various additives to provide such characteristics as viscosity and anti-seize properties. However, due to the expansion of the use of lubricators due to the increasingly widespread introduction of high-speed trains in the UK, it was decided to use plastic lubricants that are biodegradable and non-toxic. In particular, the BioRail lubricant produced by Whitmore's is well known, based on vegetable oils. Tests of this lubricant were carried out on class 1 railway tracks in the USA and Canada and showed good results. The disadvantage of the lubricant is the narrow range of atmospheric temperatures at which it is operational.

On Russian railways, the use of track rail lubricators helps reduce wear on rails and wheel pairs of locomotives and cars, reduce noise and vibration levels when trains move through populated areas, and ensure rational use of energy. The stationary track rail lubricator SPR-02-M.1 is designed for the metered application of lubricant to the rail in order to reduce the resistance forces to movement when trains pass sections of curves and turnouts. Railway lubricant SPL (TU 32 CT 2186-93) is a mixture of mineral oils thickened with insoluble soaps of higher fatty acids, with the addition of adhesive, anti-corrosion, anti-friction and hydrophobic additives. It is operational at temperatures from -30 ° C to + 60 ° C.

Railway grease CenterOil Puma-ML is a railway semi-liquid grease made from high-quality raw materials. The grease recipe is based on mineral base oils. Lithium soap of stearic acid is used as a thickener. The composition includes antioxidant and anticorrosive additives and molybdenum disulfide. The grease is produced according to TU 19.20.29-005-62027624-2022. Puma-ML grease is operational at temperatures from - 30 ° C to + 110 ° C.

The closest analogue of the invention is the composition of the lubricating composition according to patent WO 03018729 A1. This invention describes a non-toxic biodegradable consistent lubricant for mechanisms that are subject to high loads, such as track curves on railways, wheel flanges of railway cars and locomotives. The consistent lubricant has the following composition: refined and deodorized soybean oil 72.0 wt. %, zinc stearate 15.5 wt. %, alkoxylated polyol phosphate ester 1.1 wt. %, non-activated bentonite 4.8 wt. %, propylene carbonate 1.1 wt. %, water 1 wt. %, soy protein 4.4 wt. %. In this composition, propylene carbonate and water used as an activator for bentonite can be replaced with a tenfold amount of alcohol and water. Due to the tightening of operating conditions of railway transport, associated with an increase in speeds, loads and duration of tribounits, this lubricant does not meet these requirements. Increased wear and other damage are observed.

The claimed plastic lubricant and its closest analogue have in common the features that characterize their composition: lubricants may contain a mixture of oils as a base; thickened with a soap thickener.

As a result of the conducted patent research, no similar technical solutions known from the prior art that are characterized by the required set of features were identified.

Disclosure of invention

The aim of the invention is to create a biodegradable plastic lubricant.

The technical task of the invention is to create a lubricant for use in railway transport, capable of withstanding high specific loads, ensuring long-term operability of mating pairs by preventing contact fatigue damage, reducing wear of wheel-rail friction pairs, and not having a negative impact on the environment. The lubricant may contain antioxidant, anti-seize, anti-friction and other additives.

The technical result is an environmentally friendly biodegradable plastic lubricant for track rail lubricators and other heavily loaded friction units with linear contacts, which has the following characteristics: ease of removal after use, harmlessness to the environment, anti-corrosion protection, reducing wear and increasing the service life of rails and wheels, reducing energy consumption for rolling stock traction and having a biodegradation degree of at least 80% (according to the ASTM D-5864 method) or GOST 32427-2013.

The stated objectives are achieved by an environmentally friendly biodegradable plastic lubricant containing 12-hydroxystearic acid 5.0-8.2 wt. % as a thickener, calcium hydroxide 0.14-0.23 wt. %, lithium hydroxide 0.34-0.54 wt. %, as additives improving tribotechnical properties: sodium tetraborate 2.0-4.0 wt. %, sebacic acid 1.5-3.5 wt. % and triethanolamine 2.0-10.0 wt. % as an anti-corrosion additive; as a base oil, a biodegradable base - vegetable oil (for example, unrefined rapeseed or sunflower) - up to 90 wt. %.

The proposed lubricant is a low-temperature, water-resistant antifriction lubricant intended for lubricating friction units, operating in the temperature range from -30°C to +60°C.

Unlike its closest analogue, the proposed lubricant additionally contains additives that improve tribotechnical properties - sodium tetraborate and sebacic acid; instead of zinc stearate, it contains lithium-calcium soap of 12-hydroxystearic acid; does not contain bentonite, in addition, the declared plastic lubricant differs in the ratio of ingredients.

Implementation of the invention

To obtain the lubricant, 30% of the total amount of vegetable oil and the calculated amount of 12-hydroxystearic acid are loaded into a reactor with a stirrer and heated to a temperature of 80-85°C. After melting, a lithium hydroxide suspension is added with vigorous stirring (alkali:water ratio of 30:70). After 1 hour, a calcium hydroxide suspension is added (alkali:water ratio of 30:70). Water is evaporated at a temperature of 95-105°C. Then 30% of the total amount of vegetable oil is introduced into the reactor. The temperature of the reaction mixture is increased to 120-140°C. The mixture is maintained at a temperature of 120-140°C until it becomes homogeneous, then heated to the melting point of soaps 190-200°C until a transparent melt is obtained, after which the reaction mass is maintained at this temperature for 30 minutes, then heating is stopped. With intensive stirring, the remaining 40% of the total amount of vegetable oil is added. At a temperature of 65-70°C, triethanolamine is added, at a temperature of 55-60°C, sodium tetraborate is added, at a temperature of 45-50°C, sebacic acid is added.

The plastic biodegradable lubricant obtained in this way in relation to the prototype has improved indicators characterizing the rheological and mechanical properties of the lubricant. As a result of improving these indicators, the plastic lubricant acquires increased performance in friction units. This property of the plastic lubricant, confirmed experimentally during operational tests in various climatic zones.

To illustrate the proposed technical solution, samples of plastic lubricant were prepared in a known manner.

The characteristics of the obtained lubricants at different ratios are presented in Table 2.

Table 3 presents the results of comparative performance tests of lubricants manufactured according to examples 1 and 3.

The experimental lubricants have shown high efficiency when used in the operation of rolling stock. When used, they significantly reduce rail wear and sharply reduce wheel damage.

Claims (2)

An environmentally friendly lubricant for lubricating the wheel-rail contact zone of rail transport, containing vegetable oil as a base oil, characterized in that the lubricant contains lithium-calcium soap of 12-hydroxystearic acid as a thickener, sodium tetraborate and sebacic acid as additives that improve tribotechnical properties, in addition, the lubricant contains triethanolamine as an anti-corrosion additive in the following component ratios, wt.%: 12-hydroxystearic acid 5.00-8.20 calcium hydroxide 0.14-0.23 lithium hydroxide 0.34-0.54 sodium tetraborate 2.00-4.00 sebacic acid 1.50-3.50 triethanolamine 2.00-10.00 vegetable oil 73.53-89.02