Patent Description:
Steel wheels from trains running on steel rails cause for wear and fatigue damage to both components. Wear and fatigue damage on rails mainly occur on the head and shoulders of the rails. High traction forces, acceleration and/or deceleration and curving of trains all contribute to the occurrence of such wear and rolling contact fatigue damages. For extending the life of rails, a minimization of damages to a related track and/or vehicle components as well as a minimization of noise and vibration, which are issues to passengers and nearby residents, are required. It is therefore necessary that rails are maintained.

To avoid a replacement of entire rails with surface irregularities such as corrugations, near surface defects and millscale, a maintenance is often performed by on-site treatment of rails. Therefore, often a wagon is equipped with grinding tools which allow metal removal by, for instance, grinding or milling of the rail surface with the help of stones performing movements to remove metal. The related abrasive blocks are usually connected to a drive which performs oscillating movements. Rotational grinding, oscillating block grinding, planing, milling and rotational planing are all common mobile rail treatment methods used to either bring rails in shape or keep rails in shape. Each of these methods have their specific advantages and disadvantages.

Often ridges and irregularities can be removed from rail head surfaces by means of a travelling on-track planing, shearing and grinding machine with related tool supports. The tool supports provided for each rail are typically pivotally interconnected through spacers adjustable in length transversely of the longitudinal axis of the machine. A set of tools is arranged opposite one another for each rail. The tool support is provided with guide rollers guided firmly along the upper surface and outside of the rail head. The known drives for grinding usually have a relatively small stroke which is often tried to be compensated by higher frequencies or forces with which the abrasive block is pressed onto the rail.

The machining tools and related machines for rail treatment usually leave the removed metal on or next to the rail. Hence all debris - including a mixture of water, dust, abrasive residue and metal - produced by the existing technologies stays behind on the tracks which requires additional and subsequent cleaning in case of rails surrounded, for instance, by asphalt. In existing grinding machines a relatively short longitudinal or sliding movement of a grinding block is performed due to the nature of the rotational to linear movement mechanism which often means debris remains between stone and rail and is not cleared which in turn results in low metal removal. A rotational to linear movement mechanism is often achieved through gearboxes with excenter mechanisms.

In existing machines often multiple blocks are fitted in a sort of moving ruler or bar and cooling water is delivered roughly from the sides of the grinding blocks. The existing rail grinding technology only works with the use of significant amounts of water for cooling the stones, typically this technology requires a few thousands of liter water to function, water is sprayed ahead and behind each grinding stone. Hence, significant amounts of water are wasted.

<CIT> describes a device for grinding rails of a track which device is equipped with a frame which is movable on the track by means of rail bogies. Grindstones which are each associated with a rail and are disposed one behind the other in the longitudinal direction of the rail are provided on said frame, wherein each grindstone can be adjusted in the vertical direction by means of a drive unit or can be delivered to the running surface of a rail. At least one grindstone is designed to be rotatable by <NUM>° about a vertical axis by means of a dedicated rotary drive.

<CIT> relates to the field of mechanical equipment for use in rail maintenance, in particular to a rail grinding machine. The rail grinding machine comprises a fixed base, a grinding motor, a grinding head, a horizontal driving unit, a grinding head swinging driving unit, a frame and a feeding driving unit, wherein the feeding driving unit can be used for driving the grinding motor to move along the axis of the motor; the feeding driving unit is arranged on the frame through a shaft; the grinding head swinging driving unit can be used for driving the feeding driving unit to swing axially on the frame; the frame is connected to the horizontal driving unit; the horizontal driving unit is connected with the fixed base; the horizontal driving unit can be used for driving the frame to move horizontally. By adopting the rail grinding machine disclosed in this document, multi-degree-of-freedom motion of the grinding head is realized, profile grinding can be realized on a steel rail during grinding, and the grinding effect is enhanced; a linear guide rail on which the motor is arranged is fixed on a driving box, and meanwhile the linear guide rail is arranged on the side face of a feeding servo motor to form an eccentric structure, so that the problems of mechanical failure and poor grinding effect caused by vibration are solved.

<CIT> describes a device intended to be displaced along track rails and comprising a frame guided by the rail provided with a grinding wheel which grinds through its periphery. To uniformly distribute the wear resulting from contact with the rail on all its active surface, the grinding wheel is driven, in addition to the continuous rotation supplied by a driving motor, in an alternating motion transverse to the track by means of an actuating mechanism. This actuating mechanism comprises a motor-gear assembly driving an eccentric shaft on the eccentric of which the movable support is hinged.

<CIT> describes a mobile rail grinding machine which comprises a machine frame extending in a longitudinal direction, and undercarriages supporting the machine frame on the track rails for movement in an operating direction. A mounting frame is supported on the track rails by flanged wheels, and a drive vertically adjustably connects the mounting frame to the machine frame. At least one rail head grinding unit is arranged on the mounting frame and comprises an abrasive belt having opposite ends, a storage spool holding one of the belt ends and a collecting spool holding the opposite belt end whereby the abrasive belt may be reeled off the storage spool and onto the collecting spool, and a pressure element arranged to press the abrasive belt against the surface area of the rail head off which the irregularities are to be ground. The grinding unit is positioned adjustably horizontally and in the longitudinal direction, and a driving mechanism imparts an oscillating motion to the grinding unit, which motion is superimposed on the movement of the machine frame in the operating direction.

<CIT> describes that in order to increase the grinding performance and the smoothing effect, grinding tools are provided, in addition to continuous grinding motion caused by progressive advancement of work, with a further grinding motion which superposes the first-mentioned grinding motion. This additional grinding motion is carried out in alternating, mutually opposite directions by a drive device. The latter comprises a double-armed lever, which can rotate about a shaft, and a single-armed lever which can pivot about a pin. The two levers are connected to each other in an articulated manner via a rigid connecting strap. The levers can be set in pivoting motion via an eccentric shaft and a crank mechanism. Said pivoting motion can be transmitted, via rods onto the tool holder accommodating the grinding tools.

<CIT> describes a device for smoothing the rail head surfaces of railroad rails and especially relates to a device for smoothing the rail head surfaces of railroad rails with a plurality of chute grinding stones connected in series and under variable contact pressure, which are fastened in a frame moved by a crank drive, while the rail can be continuously advanced by a feed device. It is provided that the hydraulic or mechanical contact pressure acting on the individual slide blocks is graduated in such a way that the smallest contact pressure is exerted on the slide block lying in front in the direction of rail advance and increasingly greater contact pressures are exerted on the subsequent slide blocks.

It is an object of the invention to provide a method for machining a rail by grinding and/or planing.

According to the invention, this object is addressed by the subject matter of claim <NUM>. Preferred embodiments of the invention are described in the sub claims.

The invention aims inter alia in reducing the amount of required water and improving the mobile rail treatment by an increased removal rate combined with low wear on an abrasive block by efficient cooling and water delivery, leaving a very low residual roughness from the machining process and without leaving any significant dust and/or debris on the track. Further, the invention improves mobile rail treatment by using a method which does not produce any sparks.

The invention relates to a method for machining a rail by grinding and/or planing, comprising the steps of approaching the surface to be machined until contact with a metal abrasive module having at least one abrasive block, wherein the metal abrasive module is mounted on a vehicle, and performing movements with the abrasive block while pressing the abrasive block onto the rail, further guiding a fluid and/or a coolant to the contact surface of the rail and the abrasive block through a first hollow channel in the abrasive block. In this way the metal removal rate can be significantly increased.

Preferably the method further comprises the step of suction of debris and/or metal chips in the vicinity of the abrasive block through the first hollow channel. This allows at least the suction of debris etc. for every abrasive block.

The method further comprises the step of alternating suction of debris and/or metal chips in the vicinity of the abrasive block through the first hollow channel and guidance of coolant through the first hollow channel.

Preferably the method further comprises the step of suction of debris and/or metal chips in the vicinity of the abrasive block through a second hollow channel within the abrasive module. Especially in case of guiding coolant through the first channel, the suction of debris and/or metal chips can be performed simultaneously allowing again for higher removal rates.

The invention further allows a machining of a rail by grinding and/or planing, comprising the steps of approaching a surface to be machined until contact with a metal abrasive module with at least two abrasive blocks connected with a vehicle, tilting the metal abrasive module and/or at least one abrasive block parallel to a desired surface form, and performing eccentric movements with the metal abrasive module while pressing the metal abrasive module onto the rail.

Such an embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention.

<FIG> schematically shows a vehicle on rails having a metal abrasive module <NUM> with three abrasive blocks <NUM>, wherein a guide roller <NUM> is attached to the metal abrasive module <NUM>. The vehicle may also be a wagon or a train car or a service or maintenance car and allows to carry the metal abrasive module <NUM> to the place where a treatment of the rails is required.

In <FIG> one embodiment of the metal abrasive module <NUM>, which can be attached to a chassis or a frame of the vehicle, with three abrasive blocks <NUM> and a guide roller <NUM> is shown. Further, the force exerting drive <NUM> for pressing the abrasive blocks <NUM> is depicted, which has the form of a hydraulic cylinder. The hydraulic cylinder presses also the part of the metal abrasive module <NUM> downwards in direction of the rails <NUM>, which performs the eccentric movements.

The metal abrasive module <NUM> is schematically depicted in <FIG> with abrasive blocks <NUM> being positioned in different angles in a. ) towards the head of the rail <NUM> and with magnified excerpts of each of the three shown cases in <FIG> a. By tilting the abrasive blocks <NUM>, an adapted or optimized treatment of the profile form of the rails can be realized.

In <FIG> one embodiment of the guide roller <NUM> is shown in more detail from a side perspective. The guide roller <NUM> is illustrated with a debris suction head <NUM> adjacent to the guide roller <NUM>. It can also comprise a channel for a vacuum and can have a separate suspension. The roller is usually made of steel, but can be of any other material which is adequate to a specific application.

In <FIG> schematically depicts the guide roller <NUM> of <FIG> in a perspective which is <NUM> degrees turned. Also shown is a mount in the middle of <FIG> for attaching the guide roller <NUM> to the metal abrasive module <NUM>. In the left part of <FIG> a hydraulic cylinder is depicted that exerts force onto the lower part of the guide roller <NUM>.

<FIG> schematically depicts two side views a. ) of one embodiment of the abrasive block <NUM> which can substantially have the form of a cuboid. A recess <NUM> on one or two upper portions may serve for mounting the abrasive block <NUM> onto a rail system or another mounting or clamping mechanism or systems for holding the abrasive block <NUM>. In the abrasive block <NUM> a simple hollow channel <NUM> is shown having the form of a cylindric bore allowing to guide a cooling fluid to the contact surface of the abrasive block <NUM> and the rail <NUM>. <FIG> basically depicts the abrasive block of <FIG> in a 3D-view including the hollow channel <NUM> in form of a vertical and straight cylinder. The upper part of the cylinder has a wider diameter. This may allow bigger tolerances related to the positioning of the abrasive block <NUM> towards an outlet of a possible fluid delivery device or a suction device which both can be integrated in the metal abrasive module <NUM>.

Further, for the sake of clearness, not all elements in the drawings may have been supplied with reference signs.

Claim 1:
Method for machining a rail (<NUM>) by grinding and/or planing, comprising the steps of
- approaching the surface to be machined until contact with a metal abrasive module (<NUM>) having at least one abrasive block (<NUM>), wherein the metal abrasive module (<NUM>) is mounted on a vehicle,
- performing movements with the at least one abrasive block (<NUM>) while pressing the abrasive block (<NUM>) onto the rail (<NUM>),
- guiding a fluid and/or a coolant to the contact surface of the rail (<NUM>) and the at least one abrasive block (<NUM>) through a first hollow channel (<NUM>) in the at least one abrasive block (<NUM>).