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.

In existing machines often multiple blocks are fitted in a sort of moving ruler or bar and grinding blocks can only be fitted straight, but not angled. This results in low flexibility also in relation to the allowed surface shapes of the rail heads and the way they can be treated. The grinding blocks also cannot be pressed on the rail individually, but only in a fixed series of 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.

Rotational to linear movement mechanism is often achieved through gearboxes with excenter mechanisms, for instance a Latest Plasser system via linear horizontal hydraulic cylinders and/or actuators. These are typically used on tramway systems.

The <CIT> describes a travelling on-track machine for removing irregularities from the rail head surface of laid rail tracks and further relates to a method for removing irregularities, such as ridges and laps, from the rail head surface of at least one rail of a laid track using a plane carriage which is pivotally connected to the planing machine and designed to be vertically and laterally guided along the rail head and which is provided with only one planing tool per rail. Hence a significant removal of metal and thus a faster, but also more flexible approach related to the surface shape remains a challenge.

<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.

It is an object of the invention to provide a method and a related machine for mobile rail treatment with improved characteristics.

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

The invention aims inter alia in improving the rail's longitudinal profile combining both high metal removal with 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.

According to the invention a vehicle for machining a rail by grinding and/or planning is provided, comprising a metal abrasive module, an eccentric drive performing an eccentric movement, at least two abrasive blocks connected with the eccentric drive, and a force exerting drive pressing at least one abrasive block onto the rail, wherein the metal abrasive module and/or at least one of the abrasive blocks is - preferably individually - tiltable around an axis parallel to the rail, and wherein at least one of the abrasive blocks is individually pressable onto the rail. The invention also provides a machining technology for mobile rail treatment which is suitable for implementation in a vehicle or train.

The invention allows for high performance mobile rail treatment suitable for removing rail surface irregularities such as corrugations, near surface defects and millscale. Furthermore, high metal removal capabilities combined with leaving a very low residual machining roughness are achieved by the invention. An abrasive block tiltable around an axis parallel to the rail allows a complex machining of the metal surface and therefore - related to rails - the head and/or shoulder. The metal removal can therefore be performed individually and better adapted to the local form or desired form. This can allow to shape rails to complex forms or profiles with the shape of individual curves.

In case the abrasive blocks are individually pressable onto the rail, the aforementioned advantages related to the tiltable abrasive blocks apply here as well - the individually pressable abrasive blocks support shaping the rail's surface to an individual form. The invention also provides a machining technology for mobile rail treatment which is suitable for implementation in a vehicle or train.

The vehicle may also be a wagon or a train car or another mobile service car including those used for trams and/or trains or other rail bound vehicles. The abrasive block may comprise a hard material in form of a stone and/or crystal and/or ceramic and/or a material compound including several materials. The abrasive block can be manufactured by pressing, casting, hot embossing or other methods allowing to produce a block that is hard and/or stable enough for removing metal from a rail by grinding and/or planning. Further, the abrasive block basically can have a relatively simple outer geometry in form of a cuboid, but a free-formed, individually designed geometry can be of advantage especially when considering special forms of the rail surface.

The eccentric drive usually comprises a drive which is coupled to a turning motor, wherein the eccentric drive transforms the oscillation or other motion of the motor into eccentric movements.

A translational movement component of at least one of the abrasive blocks is longer than the length of said abrasive block. In this way the removed metal, which may often stay between the rail and the abrasive block for several periods of the oscillating movement of the abrasive block, is moved faster to the sides of the abrasive block. Hence the removal rate of the mobile rail treatment is increased since the abrasive block is more in direct contact with the rail surface.

In one embodiment of the invention, the eccentric movement has a scotch yoke type mechanism. The Scotch Yoke is a reciprocating motion mechanism which transforms the linear motion of a slider into rotational motion or vice versa. The piston or other reciprocating part is directly coupled to a sliding yoke with a slot that engages a pin on the rotating part. The location of the piston versus time typically is a relatively simple harmonic motion, for instance a sine wave having constant amplitude and constant frequency which produces a constant rotational speed. The advantage of a scotch yoke type mechanism can be the realization of a high amplitude - especially of the translational component of the movement - and/or a high acceleration and/or a high pressure and/or a high velocity, which may all contribute to an increased removal rate of metal of the rails.

In another realization of the invention multiple abrasive blocks are coupled together which can therefore work as a sliding ruler. Typically, every further added abrasive block increases the length of the rail which can be treated simultaneously. However, it is also advantageous to limit the length of each abrasive block so that removed metal is moved more efficient to an outside of an abrasive block. Hence, it is advantageous to limit the overall length of each abrasive block and use multiple abrasive blocks which can also be positioned individually.

In a preferred embodiment of the invention, the eccentric drive is driven by a variable frequency electric motor and/or a hydraulic drive. A variable frequency electric motor allows for adjustment of the power and rounds per minute and hence the rotational speed. Further these can be relatively efficient in power consumption. A hydraulic drive is often already available and therefore, no extra motor or drive is required.

In a further realization of the invention the abrasive module can be tilted from vertical towards an outer side and/or inner side of the rail. This allows, e.g., for shaping the head and/or the shoulder of a rail. Conventional system in state of the art allow only a fixed angle towards the rail which reduces the possibilities to efficiently reshape rails.

In a special embodiment of the invention, the vehicle and the abrasive module further comprises a debris suction head in the vicinity of the contact surface of the metal abrasive module with the rail. This allows to remove at least most of the removed metal from the rail and no or only little of the removed metal is left in the vicinity after treatment of the rail.

Further it is preferred that the invention comprises a guide roller in the vicinity of the metal abrasive module and/or abrasive block, wherein the guide roller is in contact with the rail allowing i. for machining rails in tight curves. The guide roller may also contribute to less vibrations of the system and it may also comprise an opening near the surface of the rail for suction of removed metal.

In a further realization of the invention at least two abrasive modules are each connected to an individual guide roller. This can significantly improve the quality of the guiding mechanism, improve security measures etc. and hence allow narrow curves.

The abrasive module is connected to a guide roller with a - preferably integrated - debris suction head. The suction head can be located in front or in the rear of the guide roller and. It can also be thought of - preferably multiple - suction heads or channels, which - in a special embodiment - may be distributed and/or integrated around the guide roller.

The invention further comprises a method for machining a rail by grinding and/or planing, comprising the steps of approaching a surface to be machined until contact with a metal abrasive module having 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, performing eccentric movements with the metal abrasive module while pressing the metal abrasive module onto the rail.

The method can further comprise the step of suction of debris and/or metal chips in the vicinity of at least one of the abrasive blocks. By this an improved removal of the removed metal can be realized.

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 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>. <FIG> basically depicts the abrasive block of <FIG> in a 3D-view.

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

Claim 1:
Vehicle for machining a rail (<NUM>) by grinding and/or planing,
comprising a mobile chassis and a metal abrasive module (<NUM>) for grinding and/or planning a rail, the metal abrasive module (<NUM>) comprising
- an eccentric drive (<NUM>) performing an eccentric movement,
- at least two abrasive blocks (<NUM>) connected with the eccentric drive (<NUM>), and
- a force exerting drive (<NUM>) pressing at least one abrasive block (<NUM>) onto the rail (<NUM>),
wherein the metal abrasive module (<NUM>) and/or at least one of the abrasive blocks (<NUM>) is tiltable around an axis parallel to the rail, and
wherein at least one of the abrasive blocks (<NUM>) is individually pressable onto the rail.