The invention relates to the field of foundry and intended for applying marking onto wheel plates produced by a casting technique for steel railway wheels of freight car trucks for a 1520 mm rail track.

US 3038755 A, 12 June 1962, discloses a cast steel railway wheel comprising a hub having an axial bore; a rim concentric with the axial bore; and a wheel plate extending radially from the hub toward the rim.

The closest prior art to the proposed technical solution is deemed to be RU 2087246 CI, published on 20.08.1997. RU 2087246 discloses a cast steel railway wheel having marks, the wheel comprising a hub having an axial bore; a rim having a rolling surface and a ridge; . and a wheel plate defined by outer and inner surfaces and connected to the rim by a peripheral part of the wheel plate and to the hub by a central part of the wheel plate.

It is known in the art to apply marks onto an all-rolled railway wheel in a cold state after mechanically treating the side surface of the rim from the outside of the wheel prior to thermal strengthening (see State Standard («TOCT») 10791- 2011 «AII-Rolled Wheels. Specifications*, date of entry 2012-01-01. Electronic Fund of Legal and Normative Technical Documentation : http ://

www, sudrf, kodeks.ru/dQCumerit/1200085777).

It seems that the known methods are not perfectly suitable for applying marks onto a cast steel railway wheel. In particular, the impact method is inefficient, as it is hardly compatible with mechanical treatment of a cast steel block and reduces strength of the manufactured railway wheel.

The closest prior art to the proposed technical solution is deemed to be a method for casting a railway wheel bearing marks, the method including producing a casting sand mould through green moulding by placing a casting model into a moulding box, filling the moulding box with moulding sand and compacting the moulding sand, wherein the marks are applied after mould compaction by contacting the mould face with a die bearing the marks with adjustable pressure using a laser beam or ultrasound (see. US 5329982, published on 19.01.1994; RU 2087246 CI, published on 20.08.1997).

A mark impression on a cast steel railway wheel as obtained through green moulding in sand moulds does not have distinct contour lines. There is

substantially low improvement in the imprint quality as a result of casting a railway wheel with marking applied after moulding sand compaction, which evidently makes other methods of casting with marking application onto the wheel casting more favourable, in particular, such methods as moulding in cold- hardening mixtures or vacuum-film moulding.

A technical problem, unsolvable by known technical solutions, is as follows. In casting a railway wheel with application of marks onto it, in addition to a requirement, according to which marking should not decrease service durability and reliability of the wheel and be applied in places of the least operating stresses, another requirement needs to be respected, according to which marks (writings or symbols) should be clearly visible, preserve for the whole duration of a railway wheel service life in all conditions and modes specified in the normative technical documentation. The requirements imposed on a marked cast steel railway wheel and on a method for its casting with marking application are satisfied by practicing the proposed group of inventions.

Practicing the claimed apparatus provides maintaining strength of a cast steel railway wheel having marks.

This is provided by a cast steel railway wheel having marks, the wheel comprising a hub having an axial bore; a rim having a rolling surface and a ridge; and a wheel plate defined by outer and inner surfaces and connected to the rim by a peripheral part of the wheel plate and to the hub by a central part of the wheel plate, wherein the marks are positioned on the plate at a distance of their inner and outer boundaries from an axis of the wheel, the distance corresponding to a part of a nominal diameter value of the rolling circle of the wheel and the distance being in a range of 1/(3.544-3.138).

In one embodiment, the marks may be applied on the inner or outer surface of the wheel plate. The marks applied in the process of producing a railway wheel through a casting method and located on the wheel plate in the specified range, do not impair strength of the cast steel railway wheel. Boundaries of the claimed range of positioning of the marks correspond to the area of the least normal stresses on the wheel plate of the cast steel railway wheel, occurring in operation of the cast steel railway wheel, thereby maintaining maximum fatigue and static strength of this area in the wheel and in the cast steel wheel thus marked.

The claimed method for casting a railway wheel having marks provides an improved sharpness of contour lines in the produced marks which remain visible during service life of the railway wheel.

In providing this, the method comprises producing a casting mould by placing a casting model into a moulding box, filling the moulding box with moulding sand, compacting the moulding sand, and applying the marks onto the face of the casting mould with dies having the marks. The claimed method differs from the prior art in that the casting mould is produced by cold-hardening mixtures or through the vacuum-film method, wherein the marks are transferred from the dies onto the face of the casting mould while compacting the moulding sand, and the dies having marks are fastened to the casting model of the wheel casting bottom or top at a distance of inner and outer mark boundaries from the axis of the wheel, the distance corresponding to a part of a nominal diameter value of the rolling circle of the wheel and the distance being in a range of 1/(3.544-3.138).

In one embodiment, the dies having marks are fastened on the plate part of the casting model concentrical with the axial bore of the wheel.

In one embodiment, the dies having marks are made as replaceable plates.

In another embodiment, the moulding sand is compacted manually or by machine moulding.

Applying marking on a railway wheel in the process of its casting, obtained in the mould of cold-hardening mixture or made through the vacuum-film method, in conjunction with transferring marking to a casting mould in the process of compacting the moulding sand and ensuring that the marks are positioned on the plate portion of the wheel, enables to provide an imprint of the marks, which are clearly visible in operation of the freight car and which remain for the whole duration of a cast steel railway wheel service life in all conditions and modes of its operation.

The essence of the claimed apparatus can be seen with reference to the following drawings in which :

FIG. 1 illustrates a radial section view of a railway wheel ;

FIG. 2 illustrates railway wheels with variants of positioning the marks on the railway wheel plate;

FIG. 3 illustrates railway wheels with a diagram of stress distribution on the railway wheel plate for the variants of positioning the marks in FIG. 2.

A cast steel railway wheel having marks (FIG. 1) comprises a hub 1 and a rim 2 which are connected with each other through a wheel plate 3 defined by inner 3.1 and outer 3.2 surfaces. The railway wheel has a nominal diameter D of the rolling circle of the wheel. The hub 1 has an axial bore 1.1. The rim 2 is defined by a rolling surface 2.1 and a ridge 2.2. Marks 4 are applied on the wheel plate 3 concentrical with the axial bore 1.1. An inner boundary 4.1 of the marks 4 is spaced at least at a distance A, an outer boundary 4.2 of the marks 4 is spaced at most at a distance B from an axis 0-0 of the wheel, the distances A and B corresponding to fractions 3.544 and 3.138 of the nominal diameter D,

respectively. For variants 1, 2, and 3 for positioning the marks 4 on the wheel plate 3 (FIG. 2), the inner boundaries 4.1 are spaced at the distances Al, A2, and A3, respectively, from the axis 0-0 of the wheel.

The method for casting a railway wheel having marks is performed as follows.

A railway wheel casting is made in casting moulds obtained through moulding in cold-hardening mixtures or through the vacuum-film method, which provide higher quality imprint of marks in comparison with the known methods for producing castings in sand moulds through green moulding. Dies in a form of replaceable die plates having marks 4, the dies provided in the mirror image, are mounted onto the casting model. Mounting locations of the replaceable die plates on the casting model positionally correspond to the wheel plate 3 and are located so as to place the marks 4 at a distance of 270-305 mm on the cast steel railway wheel as measured from the axis of the wheel having a rolling circle diameter of 957±7 mm, which corresponds to a distance in a range of (3.544-3.138) of the parts of a nominal diameter value of the rolling circle of the wheel.

The replaceable die plates are fixed, for example, in dovetailed slots.

The replaceable die plates are mounted onto a casting model of the wheel casting bottom or top depending on whether the marking is applied onto the inner 3.1 or outer 3.2 side of the wheel plate 3 , correspondingly. Applying marks 4 onto the inner side of the wheel provides for higher sharpness of the marks 4 due to pressure forces that the liquid melt weight exerts on contours of recesses of the marks formed by the replaceable die plates of the casting model in the bottom part of the moulding box. Applying marks 4 onto the outer side of the wheel, in comparison to their application onto the inner side, provides for easier legibility of the marks 4 in operation of the freight car.

When marking 4 is applied onto the inner 3.1 surface of the wheel plate 3, the bottom casting model with attached replaceable die plates is placed into the moulding box of the bottom and the moulding box is filled with a cold-hardening mixture or moulding sand depending on a moulding method. Moulding sand is compacted in the bottom moulding box manually or by machine moulding methods and then the moulding box is taken off the casting model, providing a half mould of the bottom. Thus, a half mould face receives an imprint of the marks 4 in the form of recesses.

Then the same sequence of operations is repeated to produce a half mould of the top, with an exception of the operation of preliminary attachment of replaceable die plates. Then the top half mould is assembled with the bottom half mould producing the casting mould. Melt is poured into the casting mould. While filling the cavity of the mould, due to its high flowability the melt completely fills recesses of the marking imprint elements, forming marks projecting from the surface of the wheel casting, fixing on the casting as the melt consequently sets.

A place for marking application on the wheel plate part of the cast steel railway wheel, experiencing the least operating stresses, is selected based on estimations of static and fatigue strength of the wheel, which enabled to determine a stress-strain state of the wheel under mechanical and thermal loads, most critical in operation. Estimations have been conducted for a railway wheel of wheel pairs of freight car trucks for a 1520 mm railway track, having a rolling circle diameter D of 957±7 mm. Three variants of marking locations (FIG. 2), positioned radially along the wheel plate 3 at a different distance from the axis O- O of each of the three wheels: Al =217 mm, A2=258 mm, A3=274 mm, have been considered. Stresses in wheel plate 3 areas of each of the three wheels were distributed as shown in FIG. 3 : with the maximum value in the variant 1 and with the minimum in the variant 3.

The estimations revealed an optimal range of marking 4 location on the wheel plate 3 (variant 3), corresponding to the best wheel performance in terms of static and fatigue strength. The inner boundary of the mark 4 should be located at a distance of at least 270 mm from the axis 0-0 of the wheel.

Radial height of the marks 4 is formed in the range of not more than 305 mm from the axis 0-0 of the cast steel railway wheel.

Marks 4 contains brief passport information about a cast steel railway wheel, its manufacturer and data needed for mounting and operation of the railway wheel. According to standard requirements the following information is applied onto the cast steel railway wheel plate 3 : two last digits of the year of manufacture of the wheel; a cast steel number; a designation of a manufacturer; a number of the wheel according to manufacturer's numbering system; an additional code, identifying ownership of the wheels.