SK278675B6 - Method of hardening the running surfaces of the crossing frogs and frog wedges - Google Patents

Abstract

The crossing frog with the crossing frog shim is placed on the flexible bed in between its rail ends and than it is acting with the pressure waves on the running planes, while this waves are created as a result of repeated explosions caused by the plastic explosive and the detonation speed closed to this explosive is 6000 up to 7500 m/s and the detonation pressure is 15 000 up to 40 000 MPa, while the surface hardness value is 350 up to 400 HB and the reinforment values is closed to 20 up to 28 mm, while the ratio of the yield value to the tenacity value is equal to 0,7 up to 0,8. The crossing frogs are coated by the plastic explosive, while the side excess of the cover is 3 up to 5 mm of the back closed to the running plane and to the distance of 30 up to 50 mm of the peak closed to the crossing frog shim in the layer of 2 up to 3 mm, in the case the density of the plastic explosive is 1,5 up to 1,7 g.cm-3.

Description

Technical field

The present invention relates to a method of reinforcing austenitic manganese steel running surfaces of frogs and frogs on rails.

BACKGROUND OF THE INVENTION

The frogs and frogs are made of austenitic manganese steels and, due to their intended use, their high resistance to wear associated with contact stress, in particular impact, is essential. Up to now, this resistance has been achieved by strengthening their running surfaces only during rail operation by contact with the wheel surface. However, in the first phase of use, when the material used is still very soft, the running surface is reduced and the roll is rolled in the transverse direction with the material folded into the lateral surfaces. This first run-in phase therefore forces us to produce frogs and feather wedges with an elevation of 1.5 to 2 mm, which, after driving around 10 to 12 million tons of load, will reduce the running surface and at the same time achieve a hardening of the running surfaces. 60 to 80 million throughput. The necessary elevation of 1.5 to 2 mm for the running-in phase of the frog poses difficulties, especially in high-speed railways, when their operation must initially take into account its rapidly changing height. A disadvantage is also the necessity of additional removal of rolled material from the sides by grinding, which causes interruption of the track operation. Said service life can no longer be substantially increased either by the choice of another material, by heat treatment or by other known technical measures. Reinforcing the surface, for example in other cases by the conventional rolling method, does not allow the required depth of reinforcement to be achieved and remains without affecting the extension of the frog life. Up to now, this method only achieves the strengthening of the narrow surface layer, which in this case would be completely eliminated by the contact forces of the wheels on the running surfaces of the frogs.

SUMMARY OF THE INVENTION

These disadvantages are overcome by the method of reinforcing the traveling surfaces of the frogs and the frog wedges of austenitic manganese steels according to the invention. It is based on the fact that the frog is placed between its rail ends on a flexible bed between the rail ends, then the traveling surfaces are subjected to pressure waves from repeated explosions of a plastic explosive with a detonation velocity of 6000 to 7500 m / s and a detonation pressure of 15000 to 40000 MPa achieve a surface hardness of 350 to 400 HB and a hardening depth of 20-28 mm with a ratio of the yield strength R _{p0, 2} to a strength R _m, equal to the value 0.7 to 0.8. The plastic explosive is applied to the running surfaces of the frog with a lateral overlap of 3 to 5 mm from the back of the running surface and to a distance of 30 to 50 mm from the tip of the frog wedge in a 2 to 3 mm layer. ³

An advantage of the method of strengthening the running surfaces of the frogs and frogs according to the invention is that the life of the frogs and frogs is increased by at least double. The production of frogs shall be made possible without exceeding their running surfaces, which in the first phases of operation makes it difficult to cross the switches. Unwanted initial rolling of the material and subsequent grinding of the frogs sides are eliminated. Extending the service life and eliminating the grinding of the flanks of the frogs ultimately means a reduction in the number of track closures and increased traffic flow.

DETAILED DESCRIPTION OF THE INVENTION

For example, a frog with a feather wedge is placed between its rail ends on a flexible bed, the rail ends being at least 10 cm away from the flange so as not to distort the frog. The flexible bed consists of fine float sand with a particle size of up to 10 µm in a 600 mm layer. A plastic explosive, the explosive component of which is a pentaerythritol tetranitrate having a detonation velocity of 7000 m / s and a detonation pressure of 18000 MPa, is adhered to the running surfaces after drying by a burner. When bonding a plastic explosive, care is taken that the plastic explosive adheres closely to the surface of the base material without the formation of bubbles. The plastic explosive is applied to the running surfaces in a layer of 3 mm thickness at a density of 1.5 g / cm @ 2. The plastic explosive is also placed on the lateral surfaces within 4 mm of the back of the running surface to prevent the material from bending to the sides and within 40 mm of the tip of the flange to avoid excessive deformation of its end. An electric detonator initiates an explosion. The detonator is placed as close as possible to the tip to spread the pressure wave to the wider part. To achieve the required hardness of 380 HB on the surface, the explosion is performed twice, with a hardening to a hardness of about 225 HB reaching a depth of 25 mm. Since the consolidation method according to the invention can only be carried out with completely healthy fodder castings, a gammagraph or ultrasound check is performed in advance and defective castings are excluded.

In carrying out the firming method according to the invention, it is necessary to observe all the safety regulations, in particular the regulations on handling explosives.

Claims (1)

PATENT CLAIMS Method of strengthening austenitic manganese steel running surfaces and cross-wedges on rails, characterized in that the frog with a cross-wedge is deposited between its rail ends on a flexible bed, then the pressure surfaces are subjected to pressure waves with repeated blows from the repeated burst detonation 6000 to 7500 m / s with a detonation pressure of 15000 to 40000 MPa up to a surface hardness of 350 to 400 HB and a reinforcement depth of 20 to 28 mm at a yield strength ratio R _{p0 2} to an ultimate strength R _m of 0.7 to 0 8, wherein the plastic explosive is applied to the running surfaces of the frog with a lateral projection of 3 to 5 mm from the back of the running surface and to a distance of 30 to 50 mm from the tip of the frog wedge in a 2 to 3 mm layer; 7 g / cm ³ .