EP2761089B1

EP2761089B1 - Tangential grinding machine

Info

Publication number: EP2761089B1
Application number: EP12717657.6A
Authority: EP
Inventors: Claudio Favaron
Original assignee: Fama Srl
Current assignee: Fama Srl
Priority date: 2011-04-26
Filing date: 2012-04-20
Publication date: 2015-12-30
Anticipated expiration: 2032-04-20
Also published as: ES2561409T3; CN103518020B; WO2012146540A1; EP2761089A1; ITVE20110025A1; CN103518020A

Description

The present invention relates to a tangential grinding machine.
Tangential grinding machines are known for regenerating the worn profile of rails on site, comprising a grinding device consisting essentially of a grinding wheel of abrasive material which when rotated removes by abrasion a part of the material with which it comes into contact.
These known machines, i.e. the assembly comprising the grinding device with its abrasive tools, the rotational drive members, its adjustment and replacement systems, and all the other accessory members which ensure their correct operation, currently present a series of limits and drawbacks which the present invention proposes to eliminate.
One of these drawbacks derives from the fact that each grinding device consists generally of a disc of abrasive material, or grinding wheel, designed to operate with its circumferential edge.
As this abrasive disc wears with time, and hence its working circumference decreases, its axis of rotation has to be shifted in relation to the workpiece to be ground, in order to always ensure mutual contact. In all cases a complex adjustment and control system is required and which in any event does not eliminate all the problems related to vibration and oscillation of the grinding wheel.
A further drawback of a tangential grinding wheel is the fact that to re-profile a rail an apparatus with a negative contour is required, such an apparatus being of high cost.
Another drawback of this apparatus of negative contour is the need to displace its "barycentre" parallel to the axis of the worn grinding wheel such as to continuously regenerate the original profile, with consequent high wastage of abrasive material.
In the case of grinding machines used specifically to restore the profile of railway, tramway and/or subway rails, another drawback is the fact that known grinding machines for rails generally use "cup" grinding wheels, which operate on a narrow longitudinal band of the rails to be ground. This implies the use of several grinding wheels, and as they are mounted on trucks a large number of these must be available to operate on adjacent bands which together cover the entire profile of the rail. An excessive and often unacceptable overall size is involved, together with imperfect execution of the work because of the inevitable faceting presented by the rails on termination of the work. The final rail therefore presents a polygonal profile instead of the original radiused profile, with the cusps being flattened out and the profile being rounded by the subsequent passage of the train wheels, causing a continuous mechanical and metallurgic shock on the rail surface. In addition, those cup wheels which operate on the rail lateral surface are hindered by the presence of natural obstacles such as points, guide and containing blades at the points and, in the particular case of tram-rails, the cement and asphalt plus the actual rail counterblade.
A further drawback is that cup grinding wheels generally have to work on both rails simultaneously for mass balancing reasons. This makes it more difficult to carry out grinding work on a single rail, such as the central earth rail or the outer lateral live rail for subway trains.
WO 91/17310 discloses a base structure mounted on wheels which can slide on rail and two first frames mounted on the base structure.
EP 0843043 discloses a tangential grinding machine comprising a support frame for at least two tangential grinding wheel for grinding a rail. The support frame is mounted on a framework which is movable vertically under the control of a hydraulic or a pneumatic system mounted on the machine.
According to the invention all these drawbacks are eliminated through a tangential grinding machine as described in claim 1.
The present invention is further clarified hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of the base structure, the first frame and the second frame of the grinding machine according to the invention;
Figure 2 shows it in the same view as Figure 1 but with the addition of the support plate, and;
Figure 3 shows it with the grinding unit mounted.

As can be seen from the figures, the machine according to the invention comprises substantially a base structure 2 mounted on four wheels 4 with their rim 6 slidable on the rails 8 to be ground.
Removably applied to the base structure 2, external to the wheels 4, there are frames 10 supporting rollers 12, the function of which is to elongate the support plane of the base structure 2 for possible long wave grinding.
Horizontal sections of two first L-shaped frames 18, raisable vertically by cylinder-piston units 16, are slidable on the crosspieces 14 of the base structure 2.
The frame 18 can be moved horizontally by cylinder-piston units 22 which urge said frame outwards until abutment means 24, rigid with it, come into contact with the head 26 of the rail 8.
The vertical and horizontal sections of the frame 18 are connected together by a curved portion 28 comprising a plurality of holes 30.
Engaging said holes 30 there is a second frame 32 hinged to the first frame 18 and provided with two forks 34 to which two bars 36 are pivoted, rigid with an annular portion 38 provided with an L-shaped bracket 40 rigid with the end of a piston rod 42 of a cylinder 44 acting as a shock absorber.
A plate 46 is applied in a positionable manner to the annular portion 38, and locked to said portion by stops 48.
Said plate 46 supports a motor 50 which operates an abrasive grinding wheel by means of a pulley 52.
For its operation, the machine of the invention is firstly transferred to the site on which that section of rail to be ground is located, after which the procedure is as follows:

the frame 32 is adjusted with respect to the curved portion 28 such as to slightly incline the axis of the grinding wheel 54 to the longitudinal axis of the rail 8 (inclination variation),
the plate 46 is adjusted relative to the annular portion 38 such as to vary the angle which the axis of the grinding wheel 54 makes to the axis of the rail (convergence variation),
the cylinder-piston units 44 or reducers 45 are operated to bring the grinding wheel 54 into contact with the rail, and the cylinder-piston units 22 are operated such that the sensors 24 lie in contact with the rail head,
the motor 50 is operated to rotate the grinding wheel 54.

It is evident that by virtue of the oscillating configuration of the annular portion 38, the grinding wheel is always in contact with the rail head, even if plane irregularities exist, so effectively eliminating all vibrations.
The grinding wheel implements its abrasive effect by virtue of the operating pressure on the cylinder-piston units 44, suitably regulated by pressure reducers, while wearing down in accordance with a certain profile having a radius independent of the worn contour of the rail by virtue of its particular disposition (inclination, convergence and translation relative to the rail). For each radius of the rail profile there corresponds a suitably positioned tangential grinding wheel.
If the profile does not correspond exactly to that required, the inclination of the second frame 32 to the curved portion 28 and/or the position of the plate 46 relative to the annular portion 38 have merely to be varied such as to vary the inclination or the convergence of the grinding wheel to the rail.
From the aforegoing it is apparent that the tangential grinding machine according to the invention completely eliminates the negative contour which continuously reprofiles the grinding wheel by making the regeneration of the profile of the tangential grinding wheel take place by the abrasive wear due to the contact between the grinding wheel and rail (self-profiling).
By virtue of this application the rail becomes both a material to be ground and a negative contour, which continuously regenerates the profile of the tangential grinding wheel, so also eliminating the entire wastage of abrasive material caused by traditional tangential systems.

Claims

A tangential grinding machine slidable on rails to be ground, comprising:
- a base structure (2) mounted on wheels (4) slidable on the rails (8) to be ground,

- two first L- shaped frames (18) provided with means (20, 22) for their vertical movement relative to said base structure from and towards the rails and transverse to them,
characterised by comprising:

- two curved portions (28) connecting the two portions of the two L-shaped frames (18) and comprising a plurality of holes (30),

- a second frame (32) engagable selectively in one of said holes (30) of each curved portion (28), said frame being provided with means (34) for hinging thereto an annular portion (38) to which a plate (46) is rotoidally connected,

- means (42, 44) for moving said annular portion (38) relative to said frame (32),

- an electric motor (50) positioned on said plate (46), the shaft of said electric motor being connected via a pulley (52) to an abrasive grinding wheel (54) located in a position below said plate (46).
A machine as claimed in claim 1, characterised in that frames (10) for supporting rollers (12) longitudinally aligned with the wheels (4) are removably applied to the base structure (2).
A machine as claimed in claim 1, characterised in that each first frame (18) is provided with abutment means (24) which abut against the rails to halt its transverse travel.
A machine as claimed in claim 1, characterised in that the second frame (32) is provided with forks (34) to which two bars (36) rigid with the annular portion (38) are pivoted.
A machine as claimed in claim 1, characterised in that the plate (46) is locked relative to the annular portion (38) by stops.
A machine as claimed in claim 1, characterised by comprising reducers (45).