RU2456144C2 - Method of forming rail head profile - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed method relates to metal-working industry, particularly, to working rail head by laser. Laser beam is located at angles to axis of symmetry of machined rail, feed direction and beam rotational axis. Note here that laser power is fed in pulses with duration governed by angle of laser beam contact with processed material and laser beam rotation speed.

EFFECT: shaping rail head by concave shaping line formed in laser beam rotation.

6 dwg

Description

The invention relates to the field of metalworking industry.

Known methods of forming the working profile of the rail head by grinding, planing, milling [1].

The method of milling disk profile milling cutters equipped with interchangeable polyhedral inserts (SMP) (В23С 3/00 - RU 2001100690/02 C2, 2001), includes milling the rolling surface of the rail and one or two radius surfaces, conjugated with the side faces of the head. In passing milling, a rolling surface and one or both radius surfaces conjugated with the side faces of the head are simultaneously machined with a milling cutter. Previously, the radius surface of the rail head from the side of the former inoperative face can be machined with one mill.

In this case, disk profile milling cutters are used (B23C 5/14 - RU 2001107733/02 C1, 2001). The milling cutter contains teeth from separate cutting inserts (SMP) mounted in sockets made in the housing, the cutting inserts being deployed relative to each other along the planes of their contact to ensure equality of the rear cutting angles in the middle of each cutting insert.

The disadvantages of this method are the difficulty of manufacturing the tool, low tool life, due to the high hardness of the processed material, low quality of the treated surface due to the vibrations inherent in discrete stock removal methods.

A known method for grinding rails and a device for its implementation (No. 2272858, RU IPC EB 31/13).

The disadvantage of this method is low productivity, and for editing the profile abrasive wheel requires the use of a special profile bar, which must be made for each profile of the rail.

A known method for grinding rails [2], in which the rail-grinding train forms the profile of the rail head.

The disadvantage of this method is the low quality of the processed surface, since non-profile abrasive circles are used in this method, as a result of which the rail head profile is approximated by discrete straight-line sections, the vertices of which during operation are stress concentrators that reduce the service life of the rails.

The technical problem to which the invention is directed is to improve the quality of the treated surface, the formation of the required physical and mechanical properties of the surface layer, reducing the cost of the processing process.

The technical result is achieved by the fact that a pulsed laser beam is used as a tool, which is positioned at an angle relative to the axis of symmetry of the rail, at an angle to the feed direction and at an angle to the axis of rotation of the beam, after which the profile of the rail head is formed by a concave production line, which is obtained by the movement of the pulsed laser beam relative to a given axis of rotation. At each point of the rail head profile, the pulsed laser beam lies in a plane tangent to the profile at this point. The allowance is removed discretely and when moving the rail, a predetermined profile is formed on the entire rail head. In this case, the laser radiation is supplied by pulses, the duration of which depends on the angle of contact of the laser beam with the processed material and the speed of rotation of the laser beam.

In the particular case, if the processed section of the rail head profile is given a hyperbolic curve, then the path of the pulsed laser beam is an arc of a circle of radius R1 (Figure 2), in other cases, the path of the pulsed laser beam is determined by the tangent lines at each point of the processed profile.

The radiation parameters are assigned in such a way as to obtain the required physicomechanical properties of the surface layer during thermal treatment of the rail head surface with a given quality of the processed surface and maximum productivity. For this, various substances (for example, oxygen) can be added to the treatment zone.

The lack of mechanical interaction between the rail and the tool (pulsed laser beam) avoids the phenomenon of technological heredity, and therefore, improve the quality of the resulting surface. The cost of processing with a laser beam is significantly lower than with milling and grinding.

The method is illustrated by drawings: in Fig. 1 shows a diagram of an installation of a pulsed laser beam at an angle to the axis of rotation, Fig. 2 shows a diagram of an installation of a pulsed laser beam at a required distance from the axis of rotation, Fig. 3 shows a diagram of an installation of a pulsed laser beam at an angle to the axis of symmetry of the rail, Figure 4 shows a diagram of the installation of a pulsed laser beam at an angle to the feed direction, Figure 5 shows a diagram of the processing of the rail head, Figure 6 shows a diagram of the formation of a full profile of the rail head by two mpulsnymi laser beams.

The practical implementation of the method is as follows.

The pulsed laser beam is set at an angle α to its axis of rotation at a predetermined distance from the laser head L and at a minimum distance R2 from the machined surface of the rail head. The axis of rotation is set at an angle β to the axis of symmetry of the rail and at an angle γ to the feed direction. Then, when the pulsed laser beam rotates around the axis with a frequency n, a predetermined profile of the rail head is formed along the contact line from the starting point to the end. In this case, the beam moving from position 1 to position 2 forms a contact angle σ.

In this case, a pulsed energy supply is used. The pulse is supplied in such a way that it acts when the laser beam rotates only on an arc of a circle limited by the total contact angle σ _Σ .

σ _Σ = σ + σ ₁ + σ ₂ ,

where σ is the angle of contact of the beam with the treated surface,

σ ₁ - angle of incidence,

σ ₂ is the angle of run.

The pulse duration τ is determined by the formula:

,

,

where n is the beam rotation frequency, min ^-1 .

The location of the pulsed laser beam at an angle β relative to the axis of symmetry of the rail and at an angle γ to the feed direction is necessary for forming the profile of the rail head with various geometric parameters.

The required angle of inclination of the pulsed laser beam relative to the axis of rotation α is determined by the formula:

,

,

where R ₂ , R ₃ are the radii of the producing surface formed by the pulsed laser beam at the corresponding points of the profile curve of the rail head, mm;

x ₃ - coordinate along the X axis of the corresponding point of the curve of the profile of the rail head, mm

Moreover, the sign of the angle α does not affect the geometric parameters of the resulting rail head profile.

The trajectory of the pulsed laser beam in the area of the total contact angle can be an arc of a circle of radius R1, in this case, receive a section of the profile of the rail head in the form of a hyperbolic curve. If it is necessary to form sections of the rail head profile represented by a segment of a straight line, an arc of a circle, or another curve, as well as their combination, the beam path in the plane A of the perpendicular axis of its rotation will be a curve through which all straight lines tangent to the obtained rail head profile pass .

In counter-processing, when the beam is rotated towards the rail, at the initial point of contact, the beam contacts the treated surface. In the processing along the way, when the beam is rotated in the same direction as the rail, the beam contacts the untreated surface at the initial point of contact.

To form a complete profile of the rail head from the right side surface to the left side surface without reinstallation, two pulsed laser beams are used, which are located on the left and right relative to the axis of symmetry of the rail.

To form special rail profiles, two or more pulsed laser beams are used, which are positioned at respective angles relative to the axis of symmetry of the rail, and each of which forms part of a given profile of the rail head.

Literature

1. Melentyev L.P., Poroshin V.P., Fadeev S.I. Maintenance and repair of rails. M .: Transport 1977.160 s.

2. Albrecht V.G. Profile processing of rails by grinding trains with active working bodies. V.G. Albrecht, Krysanov L.G., Abdurashitov A.Yu., Shmiga Yu.N.; M .: TECHINVEST, 1999.

Claims (1)

A method for forming a rail head profile, including translational movement of the rail and processing the surface of the rail head with a processing tool, characterized in that a pulsed laser beam is used as a processing tool, which is oriented at an angle relative to the direction of the rail feed, at an angle to the axis of symmetry of the rail and under angle to the axis of rotation of the beam, after which the profile of the rail head is formed by a laser beam, which is moved around its axis of rotation for a sequential disk re-removal of the allowance from the machined surface of the head, while at each point of the profile of the rail head the laser beam is placed in a plane tangent to the profile of the head at this point, while the pulse width of the shaping laser radiation τ is determined by the formula:

where σ _Σ = σ + σ ₁ + σ ₂ is the total angle of interaction of the beam with the surface to be treated, and σ is the angle of interaction of the beam with the surface to be treated, σ ₁ is the angle of incidence, σ ₂ is the run angle, an is the frequency of rotation of the laser beam.

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