RU2386058C2 - Repair method of motor axial bearings of locomotives - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: repair method of motor axial bearing consisting of body and babbit layer consists in the fact that the previous babbit layer is removed from bearing surface before tinning. Scale and other foreign particles are removed from the bearing and flux is applied to the bearing. And the surfaces which are not subject to filling and tinning are coated with paint, and after that the tinning process is begun. Quality of tinned surface is checked and then it is filled with babbit. After that mechanical processing is started, which consists in boring the inner surface of bearing according to diametre of neck of axle of wheel pair. At that, there additionally made at mechanical processing stage inside the bearing after it has been bored are annular grooves along the edges of bearing at certain distance from edges and of certain width and depth, which allow forming a labyrinth sealing when the neck of axle of wheel pair is worn. Values of dimensions of grooves depend on the bearing type.

EFFECT: reducing consumption of lubricants during operation of bearing, increasing carrying capacity of oil wedge of the insert, decreasing the bearing wear and tear, increasing its service life, decreasing the probability of lubrication penetration into the casing of gear mechanism of traction engines, decreasing the probability of dust and moisture penetration into bearing, reducing labour input when servicing axle boxes.

6 dwg

Description

The invention is used in railway transport and relates to a method for the restoration of motor-axial bearings of locomotives (electric locomotives, diesel locomotives), extending their resource.

A device MOS, used on electric locomotives [1].

Motor-axial bearings of traction engines of locomotives are one of the most material-intensive products of bronze and brass used in railway transport.

The motor-axial bearing is a dynamically loaded friction unit, on which traffic safety, operational reliability, scope of maintenance, overhaul runs and repair of the entire wheel-motor block (KMB) depend to a large extent.

The motor axial bearing shell structurally perceives a significant part of the unsprung weight of the traction motor. MOSFETs operate under severe conditions of dynamic loads from vertical bumps and lateral rail pressure during locomotive movement, as well as the effects of traction and braking forces. In addition, the MOSFET runs in the open air without any heating of the lubricant; therefore, the regime of boundary and pre-seize friction is possible. In this regard, mutually exclusive requirements are imposed on their design to ensure the same degree of strength and high anti-friction properties. Strength is ensured by doping with tin and zinc, antifriction properties - by a high content of lead.

Each liner of motor-axial bearings consists of two parts: the outer casing 5 and the inner babbitt layer 6 - in one of which, facing the axle box, a window 7 is made for supplying lubricant (Fig. 1). The MOS body is cast from brass or bronze, its inner surface is flooded with babbitt and bored in diameter 205.45 ^+0.09 mm. The liners have collars 8, fixing their position in the axial direction (figure 1). From turning the liners are protected by a key 9 (figure 2).

Domestic electric locomotives are equipped with axleboxes (containers) of MOSFETs (from 16 to 24 units on each locomotive, depending on the number of axles of the wheelset), designed to accommodate oil lubrication and wool knocking, with which the lubricant is fed to the rubbing surfaces of the axle of the wheelset. Each axle box capacity contains 4.2 kg of grease. Refueling of these axle boxes is carried out every 72 hours at the locomotive maintenance points (PTOL), the consumption of lubricating compositions is quite large, since the gap of the MOS of locomotives is in the range from 0.3 to 2.5 mm. On average, about 244 kg of grease per one axle box per year, and 4.88 tons per electric locomotive. For one year, PTLO serves 16,200 locomotives, therefore, 79056 tons of expensive lubricant costing 727315 thousand rubles are consumed.

The operation of the MOS axle box (Fig. 3) is as follows: braids 16 made of wool padding in contact with the motor-axial bearing 17 are immersed in lubricant 15, which rises up along the braids 16, thereby lubricating the surface of the bearing 17. If the level of lubricant in the chamber 10 has dropped below the level of the channel 13, then air will begin to flow from the chamber 10 into the chamber 11, and the vacuum in the chamber 11 will decrease, as a result of which the lubricant from the chamber 11 enters the chamber 10 through the channel 12, the level of the channel 13 is set according to the axle box threshold, shown by the line 14 [1].

Filling with babbit is the easiest way to restore MOS. Babbits are antifriction alloys with a low coefficient of friction, with good run-in, low melting points and provide multiple maintainability of the structure. But in modern operating conditions, the majority of high-tin babbitts do not satisfy the requirements for fatigue strength and are relatively expensive in cost due to the high tin content.

There is a technological process of filling MOS with a new brand of babbit BK2TS (GOST 1209-90), which has increased fatigue strength and due to the low tin content (only 2%) is cheaper. However, BK2Ts babbitt requires a more sophisticated casting technology: higher melting temperature, strict restrictions on the melting time and pouring time.

Currently, to restore MOS and extend their service life in locomotive depots, the method described below is used (according to the technological map approved by the chief engineer of the locomotive depot).

The method includes the following steps,

1) Before tinning, the surface of the MOSFET is cleaned of the old babbitt layer in the furnace at a temperature of 500-520 ° C. Cracks, spalls and other defects are detected on cleaned cases. Such cases are rejected. On the rest, traces of dirt, oils, grease, emulsion, rust are removed. After degreasing the bearing, it is washed with cold and then hot (at least 80 ° C) water. The surface thus prepared must not be touched with hands so as not to leave any traces of fat.

2) The surface intended for pouring with babbitt, as well as the grooves for attaching the babbitt, are mechanically cleaned of soot and other foreign particles. To do this, you can use disk brushes made of steel wire with electric or pneumatic drive.

3) The bearing housing heated in an electric furnace to 400-420 ° C is coated with a flux using felt, tow or hair brushes. As a flux, a mixture is used consisting of zinc chloride (40%), tin chloride (2%), potassium chloride (1%), ammonium chloride (1%), hydrochloric acid (2%) and water. On a carefully degreased surface of the flux spreads in an even layer. If this does not occur, degrease the surface again.

4) The surface to be poured is covered with paint (1 kg of chalk powder, 1 kg of water, 45 cm ^{3 of an} aqueous solution of water glass with a specific gravity of 1.2-1.3 g / cm ³ ) or a solution of refractory clay in relation to water 1: one. The bearing thus prepared is heated in an electric furnace to 400-420 ° C, after which tinned-lead solder POS-20 is then tinned.

5) Checking the quality of tinning. The brilliant appearance of the tinned surface indicates the quality of the process. If discoloration is visible, then overheating has been allowed, and tinning should be carried out again.

6) The bearings are filled with calcium babbit. In molded bearings, the babbitt must have at least: 0.70% calcium, 0.55% sodium and 0.25% zinc (the alloy of babbitt can be any one used in repairs of a motor-axial bearing). The crucible, cleaned of soot and slag, is placed in the electric furnace so that the babbit inside it is heated evenly over the entire height. To reduce the fumes of alloying elements in the new babbitt, you must first put in the crucible the addition of the old babbitt in the form of remelted ingots, and load the new babbitt into the molten metal. Dry and clean ingots of the new babbitt are heated to 80-100 ° C. At higher temperatures, calcium and sodium burn out. To ensure uniform composition of the alloy prior to casting, the babbitt in the crucible is intensively mixed, and slag is removed from the surface.

Bearings are centrifugally filled. The tinned bearing housing, heated to 400-420 ° C, is installed in the chill mold. The alloy is poured into a chill mold from a crucible with a capacity equal to the full pouring of one bearing to complete the process in one go. The stream of metal should be short with a minimum cross section. The bearing is removed from the chill mold or centrifugal cup not earlier than after 10 minutes for further cooling. A dull silver color, as well as a clean, smooth surface without shrinkage, foreign particles and other defects, indicates the observance of the quality of the process.

7) Checking the tightness of the molten metal to the bearing housing is checked by tapping. A rattling sound requires re-melting. In addition, the quality of the fill is checked for the hardness of the samples from each heat.

8) The bearings made according to all the requirements of the technical process go into machining, where they are bored to the diameter of the neck of the axle of the wheel pair over the entire inner surface, after which they go to the assembly of the wheel-motor blocks.

The disadvantages of the typical technology during the operation of the MOS is:

- low bearing capacity of the oil wedge of the liner (increased wear and tears of babbitt, heating);

- grease getting through the MOS gap along the axis of the wheelset into the gear casing (mixing of lubricating compositions) [2];

- intensive consumption of lubricating compositions;

- moisture penetration into the MOSFET (stimulation of the corrosiveness of petroleum acids, which destructively affect non-ferrous metals);

- dust entering the MOSFET (reducing the quality of the lubricant, increasing the probability of heating);

- negative impact on the environment.

The aim of the invention is:

- improving the safety of train traffic;

- reduction of negative environmental impact;

- reduced consumption of lubricants during the operation of the MOS;

- increase the bearing capacity of the oil wedge of the liner;

- reduction of wear of the MOSFET, increase of its resource;

- reducing the likelihood of motor-axial lubricant entering the gear housing of the traction motors;

- reducing the likelihood of dust and moisture entering the MOS;

- reducing the complexity of the maintenance of axle boxes MOS.

Known sliding bearing fluid friction [3] (Fig.6), containing an integral sleeve (1) having grooves made insulated and located at a predetermined distance from each other to seal the bearing from the ends (2). This is done to ensure sealing of the bearing from the ends in order to better damp it under dynamic loads.

However, this solution for locomotives has several disadvantages:

- this proposal takes into account the specifics of the operation of sliding bearings under shock transverse forces (since it is designed to operate the bearing in the conditions of reciprocating movements);

- there is no possibility of creating a labyrinth seal to prevent the lubricant from leaving the bearing (on the axle of the wheelset and on the ground);

- in the proposed device of the sliding bearing, the grooves are proposed to be isolated and from one edge on the sliding bearing (2), as well as the grooves (4) are cut on the spike (3), which will not allow for only relatively rotating movements (as is the case with the rotation of the wheel pairs) to provide resistance to the lubricant exit from both ends of the sliding bearing, and the use of grooves on the spike (in this case, on the axis of the wheelset, is unacceptable and prohibited by the rules of technical operation, in connection with the occurrence of large asatelnyh stresses on the wheelset axis);

- high level of lubricant consumption due to this solution.

The proposed method consists in the fact that, at step 8, during machining inside the motor-axial bearing, after it is bored to the diameter of the neck of the wheel pair axis, to produce annular grooves along the edges of the MOS at a distance K from the ends, the width of the groove b and the depth h (Fig. .four). Dimensions depend on the type of MOS (electric locomotives, diesel locomotives).

When the motor-axial friction bearing is operating, sections of the neck of the axle of the wheelset 19 lying in the planes of the grooves will not practically wear out, and annular protrusions 18 are formed on the neck (Fig. 5). As a result, a labyrinth seal is formed. Oil consumption through pairing becomes less. With the increase in natural wear of the working area of the neck of the axis of the wheelset 19, the formed protrusions on the necks become higher than 18 (Fig. 5). And, as a consequence of this, the consumption of lubricants is further reduced, which reduces the negative impact on the environment, the labyrinth seal increases the bearing capacity of the oil wedge of the liner, reduces wear of the MOS, increasing its life, reduces the likelihood of motor-axial lubricant getting into the gear housing of the traction gear engines, reduces the likelihood of moisture and dust entering the MOS.

Wear of the neck of the axle of the wheelset is allowed no more than 6 mm (⌀ 205-199 mm).

Bibliography

1. Electric locomotive VL85. Operation manual [text] / B.A. Tushkanov, N.G. Pushkarev, L.A. Pozdnyakova et al. - M .: Transport, 1995. - 480 pp., Ill., Tab.

2. More attention to motor-axial bearings [text] / L.M. Lorman. // Locomotive. - 2004. - No. 11. - S.21-25.

3. Patent No. 265624, USSR: IPC F16c - No. 1263371 / 25-27; declared 08/12/1968; publ. 07/27/1970 / Liquid friction sliding bearing. Applicant and patent holder V.T. Matveenko.

Claims (1)

A method for restoring motor-axial bearings of locomotives, which includes the following steps: preparing the surface of the motor-axial bearing before tinning, which consists in cleaning the old babbitt layer in the furnace at a temperature of 500-520 ° C; cleaning of soot and other foreign particles of the motor-axial bearing, which consists in processing a disk brush made of steel wire; coating of an axial motor bearing with a flux, consisting in the use of a mixture consisting of zinc chloride, tin dichloride, potassium chloride, ammonium chloride, hydrochloric acid and water; coating the surface with paint not subject to pouring, and tinning, which consists in coating clay and tinning with tin-lead solder; quality control of tinning, which consists in the brilliant appearance of a tinned surface; pouring with babbitt, which consists in pouring by centrifugal method; checking the fit of the cast metal to the bearing housing, which consists in tapping the motor-axial bearing; mechanical processing, which consists in boring the inner surface of the motor-axial bearing under the diameter of the neck of the axle of the wheel pair, characterized in that in addition to the step of machining inside the motor-axial bearing after its boring under the diameter of the neck of the axis of the wheel pair, annular grooves are made along the edges of the motor-axial bearing at a distance K from the ends, width b and depth h, allowing the labyrinth seal to form when the neck of the wheelset axis is worn.

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