EP0235602B1 - Process for measuring and grinding a rail head profile - Google Patents

Abstract

By means of several measuring sensors (C1 to C6), the distance (h1 to h6) from several generatrices (s1) to s6) of the rail-head profile to a reference base are measured and are compared as actual values with predetermined desired distance values. The grinding heads, which are set to a specific generatrix and which grind a facet at an angle of inclination corresponding to the position of each generatrix, are always lifted off automatically when this facet reaches the position corresponding to the desired distance value in relation to the reference base. Because the distance to a particular generatrix, on which is located the vertex line of two adjacent facets of a pair of facets, is measured as an actual value, any two adjacent facets can be checked simultaneously by means of one and the same measuring sensor (C1 to C6). The two facets of a pair of facets are ground by means of a double grinding head set to the vertex line and having two grinding wheels, the grinding planes of which form a predetermined working angle ( alpha ) with one another which corresponds to the desired profile. The control of the grinding heads therefore merely involves a simple comparison between desired values and actual values of distances; furthermore, double the number of facets can be checked by means of a specific number of measuring sensors, and consequently the rail profile can be approximated as closely as possible.

Description

The invention relates to a method for measuring and rectifying the profile of a rail head and a grinding car for implementing the method.

A process and a car of this kind are known from document CH-A-606 616. This known process essentially comprises the following phases:

As quantities representative of the state of the rail head, the average amplitude of the short wave wavelength deformations, the amplitude of the long wavelength wave deformations and the amplitude of the profile defect of the head mushroom are measured. , these quantities being obtained by means of a circuit for shaping the data delivered by probes. The signals corresponding to these quantities are introduced into a computer, into which are also introduced the known values of the working power of the grinding tools such as for example the grinding pressure, the speed of advance of the grinding tools, l angle of inclination of the grinding tools and the speed of advance of the grinding vehicle along the track. This computer is designed so that it delivers signals according to a recorded calculation program, these signals corresponding to the set values of the various working data of the grinding tools. These set values are introduced into control circuits which control the grinding tools. It is carried out in such a way that the quantities representative of the condition of the rail mushrooms are measured both before and after grinding by means of two measuring carriages placed in front and behind the rectification vehicle. Corrections are made on the basis of the second measurement made after rectification.

This process and the calculation and control circuits necessary for its implementation are obviously quite complicated. In addition, the approximation of the target profile of the rail head is obtained by controlling in particular the grinding pressure, the grinding speed, the inclination of the grinding tool and the speed of advance of the vehicle, these working quantities being dependent on a set value which is itself determined as a function of the grinding depth. It does not appear from the document when it is necessary to stop the grinding so that the set profile is approximately obtained optimally along one or more generators and no relationship is given between the generators on which the probes are adjusted and the generators to which one or more grinding tools are adjusted in order to grind a corresponding facet.

According to the method of measuring the profile of the rail head described in document EP-AO 044 885, the distances between a reference base and the two generators located on the edges of the running surface of the rail as well as a generator are determined. intermediate, in order to obtain the curvature of the running surface of the rail. For this purpose, on the one hand, the deflection of the arc of the rail running surface at the location of the intermediate generator is determined, on the one hand, and the inclination of the connecting cord, on the other. the two external generators relative to the track plan. The measurement is carried out by means of electronic sensors not in contact with the rail, for example capacitive, optical or eddy current sensors.

Document EP-AO 032 214 also discloses a grinding car in which the grinding pads movable in height, on which several grinding tools are mounted, are angularly adjustable relative to the rolling grinding frame, in a plane perpendicular to the axis of the track. In addition, each grinding unit is individually orientable relative to its grinding wheel and it can be applied against the track with a determined inclination.

A known device for the continuous measurement of the profile of the head of a rail (EP-A-O 114 284) is equipped with several mechanical probes produced and arranged so as to have a small footprint.

The object of the present invention is to simplify and to design the measurement and the rectification of the rail mushrooms so that the approximation of the target profile can be carried out with more accuracy than hitherto and by means of control devices. relatively simple.

This object is achieved, for the process, by the features of claim 1, and for the grinding car, by the features of claim 8.

The essential advantages reside in the fact that, according to the invention, the setpoint profile is characterized simply by the distances directly measured between the reference base and a sufficient number of generators, without these direct measurements having to be transformed into others quantities such as angle tilt, arrow or the like; similarly, the grinding necessary to reach the setpoint profile is controlled simply by a comparison, easy to perform electronically, between the actual distances and the setpoint distances, which makes it possible to approach the setpoint profile in a simple, direct manner and optimal, because the grinding operation on each generator is automatically interrupted when the difference between the set distance and the actual distance reaches 0.

We preferably proceed in such a way that when measuring distance, we measure the distance between the reference base and a line of fact formed by the intersection of two neighboring facets of a pair of facets and we compare this measurement with the set distance between this line of reference and the reference base and the two facets of this pair of facets are ground up to the line of the line by means of two grinding wheels whose grinding planes form a determined working angle corresponding to the target profile. An additional advantage is thus obtained by the fact that by means of a single measurement, that is to say a single sensor, two facets can be measured and controlled simultaneously, so that with a determined number of sensors a twice the number of facets is controlled, a greater number of facets making it possible to achieve a particularly good approximation of the set profile.

• La figure 1 est une vue latérale d'une voiture de rec­tifiage selon l'invention.
• La figure 2 est une vue de face du châssis de meulage.
• La figure 3 est une vue schématique des capteurs d'une tête de mesure.
• La figure 4 représente schématiquement une double tête de meulage avec ses deux meules.
• La figure 4a représente schématiquement la construction d'une double tête de meulage.
• La figure 5 montre, sur une coupe transversale d'un rail, comment sont effectués la mesure et le meulage de la surface de roulement.
• La figure 6 illustre, sur une coupe analogue à celle de la figure 5, la mesure et l'ébarbage d'un bourrelet de la partie extérieure du rail.
• La figure 7 est un schéma bloc du dispositif de commande et d'affichage.
• La figure 8 illustre le meulage sur une coupe analogue à celle de la figure 6.
• La figure 9 est un détail de la figure 8 dans la zone du bourrelet.

The accompanying drawing shows, by way of example, an embodiment of the invention.

• Figure 1 is a side view of a grinding car according to the invention.
• Figure 2 is a front view of the grinding frame.
• Figure 3 is a schematic view of the sensors of a measuring head.
• Figure 4 shows schematically a double grinding head with its two grinding wheels.
• Figure 4a shows schematically the construction of a double grinding head.
• Figure 5 shows, on a cross section of a rail, how the measurement and grinding of the running surface are carried out.
• Figure 6 illustrates, on a section similar to that of Figure 5, the measurement and deburring of a bead of the outer part of the rail.
• Figure 7 is a block diagram of the control and display device.
• FIG. 8 illustrates the grinding on a section similar to that of FIG. 6.
• Figure 9 is a detail of Figure 8 in the area of the bead.

FIG. 1 represents a grinding car 2 with two axles 3 movable on track 1 and provided at one of its ends with a measurement frame 4. This measurement frame 4 has a measurement head 5 for each of the tracks 1, as shown diagrammatically in FIG. 2. On each of the measuring heads are fixed sensors C working without contact. In the example considered, according to FIG. 3, each measuring head 5 is provided with seven probes C1 to C7. The two measuring heads 5 are supported on the middle of the rail by a shoe 6 and are articulated on the car 2 by a connecting rod 10. The measuring heads 5 are guided laterally by rollers 7 rolling on the inside of the rails 1 against which they are held in abutment by a spacer device 8 mounted between the two measurement heads by means of a hydraulic cylinder 9.

In addition, a device fixed to the chassis of the grinding car 2 and acting hydraulically on the two measuring heads 5, represented diagrammatically in FIG. 1 by the arrow 11, ensures that the pads 6 are in permanent contact with the rails with a sufficient force. It is thus ensured that during the advance of the grinding car, each sensor C follows a determined generator of the rail head.

The axes of the sensors C1 to C6 are aligned on six generators s1 to s6, as shown in FIG. 3. These six prescribed generators are approximately evenly distributed over the region of the running surface of the rail which extends over a mean arc of the profile of the rail head. This medium arc has a relatively large radius generally about 300 mm and the rays passing through the ends of this arc form with the radius passing through the middle of the arc, i.e. the middle of the rail head , an angle of about 15 °.

In the example according to FIG. 3, a seventh sensor C7 is provided, indicated only by its axis, which is adjusted on a generator s7. This C7 sensor is used, as will be explained further on by means of FIGS. 6, 8 and 9, to the extent of the bead generally appearing on the outside of the rail 1 and commonly known as the "outside radius".

The sensors C are, for example, inductive measuring instruments. Each sensor C is arranged so as to measure the distance h separating it from the generator on which it is adjusted. The measurement frame 4, which rests on the middle of the rails by pads 6, thus constitutes a reference base from which the distances h are measured continuously. The reference points of this base are, in the example according to FIG. 3, the lower ends of the sensors C. The grinding car 2 is equipped between its two axles 3, with two grinding units 12 and 13 by rail, these units being fixed to the chassis 20 of the car in a known manner and resting on the rails. Each of the grinding units 12 and 13 has two grinding head supports 14 and 18 each carrying a double grinding head 15, respectively 19 provided with two grinding heads 16 and 16ʹ, respectively 17 and 17ʹ, as shown schematically for the grinding unit 12 in FIG. 1.

Each grinding head support 14 and 18 is pivotable in a manner known per se in a plane perpendicular to the axis of the track and adjustable in height. Figure 4 shows schematically the grinding head support 14 in the raised position. It can be pivoted by a determined angle β and its axis B can be directed on a determined generator s. It can also be raised and lowered.

In the example according to FIG. 4, the angle of inclination β is equal to the angle formed by the horizontal H with the tangent T to the profile of the rail 1 at the point of intersection of the axis B of the support of grinding head 14 and generator s. For geometric reasons, this angle of inclination β is equal to the angle between the radius of the profile of the rail passing through the generator s and the perpendicular bisector of the rail.

In addition, the two grinding heads 16, 16ʹ, respectively 17, 17ʹ can be individually oriented relative to their support 14, respectively 18, in a plane perpendicular to the axis of the rail and they can be moved in the direction of their axis. of rotation. In this way the two grinding heads of each support 14 and 18 can be adjusted relative to each other so that their grinding planes intersect at a prescribed working angle α, as shown schematically in FIG. 4 for the support 14. The two flat grinding wheels 16a and 16aʹ of the two grinding heads 16 and 16ʹ are shown here with their axes of rotation A, respectively Aʹ, the grinding planes of these grinding wheels forming the working angle α . During a working phase, this double grinding head 15 simultaneously forms the two facets f and fʹ indicated in dashed lines in FIG. 4.

The angle of inclination β of the grinding head support does not necessarily have to be defined relative to the inclination of the bisector of the angle formed by the axes of rotation A and Aʹ of the grinding heads, respectively relative to the axis of symmetry B of the grinding head support, but it can refer to another reference line of this support, for example to the axis of rotation of one of the grinding heads 16 or 16ʹ this above all when this grinding head is mounted fixed relative to the support of grinding heads and only the other grinding head is adjustable for adjustment of the working angle α relative to the support of the grinding heads. In this case, the angle of inclination of the double grinding head coincides with the angle of inclination of one of the grinding wheels and therefore of the corresponding facet.

Figure 4a schematically shows a double grinding head with a grinding head support 14 on which are mounted one behind the other the two grinding heads 16 and 16ʹ with their drive motors 16b and 16ʹb and their flat wheels 16a and 16ʹa. The head holder 14 essentially consists of support parts such as the part 28, on which the grinding heads 16 and 16ʹ are fixed, an L-shaped frame 23, a lever 27 connecting the lower ends of the part support 28 and the frame 23 and a jack 24 mounted between the upper end of the support piece 28 and the middle of the frame 23. The frame 23 is suspended from the chassis 20 of the car 2 so that its part upper 23a is supported on a guide segment 21 in an arc of circle on which it can move by sliding or rolling.

The lever 27, articulated at an intermediate point on the frame 23, has its other end articulated at the end of a pneumatic cylinder 25, the other end of which is attached at 26 to the support 23 and which serves to relieve the double head of grinding and adjusting the force with which the wheels 16a and 16ʹa are applied against the rail 1. The cylinder 25 is double-acting. In extension there raises the grinding head holder by means of the lever 27, while in retraction it presses the grinding wheels 16a and 16ʹa against the rail 1.

For the tilting of the whole of the double grinding head, that is to say for the placement of the angle of inclination β, there is provided a jack 22 mounted approximately horizontally between one of the sides of the frame 20 and the upper arm 23a of the L-shaped frame 23. This double-acting cylinder 22 ensures the movement of the frame 23 on the arc of a circle of the guide segment 21. During this movement the frame 23 pivots around its articulation on the lever 27 by driving the support 28 by the jack 24 which then functions as a rigid bar between the frame 23 and the support 28, which in turn pivots with the grinding head 16 around its articulation on the lever 27. In the example considered the other grinding head 16ʹ, located behind the grinding head 16, is rigidly fixed to the frame 23, so that when the frame 23 pivots, the two grinding heads are driven simultaneously, the grinding head 16ʹ directly and the head of grinding 16 via the adjustment cylinder 24.

To adjust the working angle α between the grinding wheels 16a and 16ʹa, respectively between the two facets to be ground by means of these grinding wheels, only the grinding head 16 is moved relative to the other grinding head 16ʹ by means of the cylinder 24, the position of the grinding head 16ʹ relative to the frame 23 being invariable. The working angle α is preferably adjustable between 0 ° and 10 °, either continuously or step by step. In the case of grinding the running surface of the rail, these steps can correspond, for example, to 1 °, 2 ° and 4 °.

As a variant, it will however be possible to provide that the two grinding heads 16 and 16ʹ can be moved individually relative to the frame 23, each by a jack corresponding to the jack 24.

It is also possible to individually assign a pneumatic cylinder 25 and a lever 27 to each of the grinding heads 16 and 16ʹ of a double grinding head so that the grinding pressure is individually adjustable for each wheel.

In the case where a grinding head holder 14 is equipped with more than one pair of grinding heads, the grinding heads working on the same facet, that is to say adjusted to the same angle of inclination, can be controlled by a common pneumatic cylinder so that they work with the same grinding pressure.

In order to obtain a good approximation of the target profile of the rail head during a rectification, the actual profile in the area of the running surface of the rail should be measured and checked on at least 6 generators and the complete profile on minus 14 generators. The grinding of the running surface of the rail will be described below.

If, for the measurement and control of the running surface of the rail, six sensors fitted on six corresponding generators are provided and if a facet is ground along each generator, as can be easily imagined, the rolling profile is approached by six facets, this is generally insufficient. It is frequently required that the running surface of the rail is approached by at least twelve facets each having a width of 4 to 5 mm so that the ridge formed by two adjacent facets is not too marked and that it is erased relatively quickly by the rolling stock.

However, it is advantageously possible to double the number of facets to be checked by keeping the same number of sensors by measuring not the distance between the middle of a facet and the sensor, but by measuring this distance at the ridge of a pair. of neighboring facets. For a given working angle α between the grinding wheels generating the neighboring facets, it is without other possibility to determine the set distance between a sensor and a ridge line, distance for which the two facets approach optimally the profile of setpoint, in particular are located in planes tangential to the setpoint profile. For this reason, double grinding heads 15 and 19 are provided, the two grinding heads of which are adjustable to the desired working angle α.

The installation is therefore arranged in such a way that a sensor C and one of the grinding head holders 14, 18 are adjusted on the same generator coinciding with the ridge line of the two adjacent facets which must be ground by this double grinding head. A single sensor C thus simultaneously measures and controls the position of two facets so that with a given number of sensors, six sensors in the example considered, the target profile of the rail running surface is approached by a number twice as many facets, twelve facets in the example considered.

FIG. 5 diagrammatically illustrates the control of the profile of the running surface of the rail by means of six sensors C1 to C6 directed on the generators s1 to s6 and permanently measuring the distances h1 to h6 between these sensors and the reference line 0 before and during the grinding operation. This reference line 0, corresponding to the lower ends of the sensors defining the reference base has been represented by a horizontal line in FIGS. 5, 6, 8 and 9 for simplicity. The six generators s1 to s6 coincide with the ridge lines of two neighboring facets grinded simultaneously by the two grinding wheels 16 and 16ʹ of a double grinding head 15 (Figure 4). The planes of the two grinding wheels of each double grinding head form a given angle α1 to α6 adapted to the set profile. Since each of the generators chosen s corresponds to a given angle of inclination α, the installation is preferably arranged so that the two grinding wheels of a grinding head holder, when adjusting this holder head on a specific generator, are automatically adjusted to a working angle α corresponding to this generator.

The internal arc and the external arc of each rail, generally called internal radius and external radius, can in principle also be controlled by means of the sensors described. However, each of these arcs, whose radius is significantly smaller than the radius of the intermediate arc forming the rolling surface, should be controlled by at least four sensors, so that at least 14 sensors in total would be required to full measurement of the profile of a rail. For this reason it is generally advantageous to control and grind the interior and exterior arcs by another method and with a device for grinding as described in document EP-AO 125 348 in the name of the same applicant. This known grinding device works with direct monitoring and control of the grinding heads. It is recommended to grind at least the internal radius guiding the wheels laterally by this known process.

However, it is also possible to grind the outer radius, which generally has a more or less pronounced bead after a certain period of use, and if necessary also the inner radius, according to the method and with a machine according to the present invention. For an internal arc or radius extending over a large angle and which must be rectified fairly accurately, it is necessary to work with at least four sensors. On the other hand, the grinding of the arc or external radius can be advantageously carried out by means of a single sensor in the region of the bead as will be described below.

FIG. 6 schematically illustrates the arrangement of the double grinding heads associated with the sensors C1 to C6 by the indication of their angles of inclination β which they exhibit respectively when they are added to each of the generators s1 to s6, and by l working angle α corresponding between their two grinding planes. Negative β values refer to half of the rail head located on the inside. The running surface of the rail extends on each side of the perpendicular bisector up to an angle of 15 °. In addition, FIG. 6 schematically illustrates the rectification of the external arc of the rail 1 by means of a single sensor C7 indicated only schematically and which controls the generator s7 also indicated in FIG. 3, and by means of a double head ali grinding gned on the generator s7, whose values α and β are given and whose inclination is modified step by step.

The initial real profile is designated by a and the target profile by b. In phantom is also indicated a theoretical roughing profile b + 0.2 mm exceeding the set profile b by a height of 0.2 mm. In case it is necessary to remove large quantities of material, it is recommended to first carry out rough grinding with maximum grinding pressure until the given roughing profile is reached and only then grind until the set profile b is reached with reduced pressure.

It is assumed that the inner arc of the rail 1, which extends, in the example considered, over an angle of _15 ° to _80 °, and rectify by means of side grinders according to the known prior process mentioned above. For working the rail running surface, the following adjustment should be made: for the double grinding heads aligned on the generators s1 and s4, β = 0.5 °, _0.5 ° and α = 1 ° respectively; for the double grinding heads aligned on the generators s2 and s5, β = 4.5 °, respectively _4.5 ° and α = 3 °, and for the double grinding heads aligned on the generators s3 and s6, β = 10 , 5 °, respectively - 10.5 ° and α = 3 °. Each of the halves of the rolling surface is thus approached by six facets having angles of inclination of 0 °, 1 °, 3 °, 6 °, 9 ° and 12 °, if the two grinding heads of FIG. 4 are symmetrical relative to the median axis of the double grinding head defining the angle β.

For the control of the external arc the sensor C7 is aligned on the generator s7 passing through the contact point of the tangent at 45 ° to the theoretical roughing profile, that is to say on the radius forming an angle of 45 ° with the rail bisector. For this double grinding head aligned on the generator s7, the two grinding discs form a working angle α = 6 ° in the example considered. This double grinding head is first of all adjusted to an angle of inclination β of 20 °, for example, and it grinds in this position the bead e until the sensor C7 measures a predetermined distance for which the grinding wheel located on the interior side is precisely in a plane tangential to the roughing profile. The grinding process is then interrupted and the double grinding head is adjusted to a tilt angle β = 30 °, after which the grinding is repeated until a new predetermined distance is reached for which the disc again of the inner wheel is in a plane tangent to the roughing profile. The predetermined roughing profile is reached by a final grinding step at the inclination β = 45 °. The same grinding operation is then repeated step by step in the area of the sensor C7, with reduced pressure, until the set profile b is reached.

It is naturally also possible to carry out the grinding operation for each inclination β by renouncing the use of a roughing profile, that is to say by grinding until the disc of the grinding wheel reaches directly the tangential plane to the set profile.

Each double grinding head is preferably angularly adjustable over an angle of _15 ° to + 45 °, that is to say over the whole of the rolling surface and of the external arc, so that at if necessary, each of the double grinding heads can work along each of the generators. The working angle α is preferably adjustable continuously or in steps up to 10 °.

The step-by-step grinding of the external arc described makes it possible to control several pairs of grinded facets successively, by means of a single sensor, which naturally simplifies the installation extraordinarily and reduces the number of sensors required. In addition, six facets are advantageously obtained in three steps, which makes it possible to achieve a good approximation of the set profile of the external arc. In the example considered, according to FIG. 6, an approximation of the external arc is obtained with the values given α and β by facets having inclinations equal to 17 °, 23 °, 27 °, 33 °, 42 ° and 48 °.

The deburring of the bead e in the region of the external arc of the rail, as described, can naturally also be carried out by means of a single grinding wheel aligned on the generator s7 and whose grinding plane is adjusted successively to inclinations gradually increasing. In this case, the outer arc of the rail is approached by fewer facets than when working with a double grinding head, but the number of steps is however increased. In the example considered, if the angles given β represent the inclination of the grinding wheel, it would be three facets having the inclinations 20 °, 30 ° and 45 ° which would all be controlled with the same sensor C7 set on the facet at 45 °.

The control and display device will now be described with the aid of FIGS. 7 to 9. According to the block diagram of FIG. 7, this device, installed on the grinding car, comprises an analyzer 30 to which the outputs of all the sensors C measurement heads are connected and which receives the signals delivered by these sensors C which represent the actual distances measured h. In this analyzer 30 are recorded the different theoretical profiles of the tracks in the form of distances that the reference profile of the rail to be rectified must present between the given generators and the reference line 0.

In the example considered according to FIGS. 8 and 9, which corresponds to the example according to FIG. 6, the six reference distances h1 to h6, in the area of the rolling surface, which are controlled by the sensors C1 to C6 , are saved in the analyzer. The setpoint profile b defined by its setpoint distances refers to the distance h0 between the generator of the medium, that is to say the axis of the rail, and the reference line, distance which is determined by the shoe 6 (Figure 3) based on the middle of the rail and by the construction of the measuring equipment and which is therefore constant. At the start of grinding, we almost always obtain both positive and negative differences △ h between the target profile b and the actual profile a, as shown in Figure 8. The final position bʹ of the target profile is naturally low enough that there is no more negative difference. The middle of the rail should be ground accordingly.

For the sake of clarity, we have shown in FIG. 8 only the distances h0, h3, h4 and h6 and in FIG. 9 only the distances h5 and h6. For the profile of the external arc in the area of sensor C7, the intermediate setpoint distances h7 (20 °) and h7 (30 °) are recorded, as well as the final setpoint distance h7 (45 °), as shown. in Figure 9, at the end of execution of the step-by-step grinding of the external arc described above. These stored setpoint distances are compared with the actual distances measured in the analyzer 30 and the resulting control orders are sent to a control unit 31 which directly controls the different grinding heads so that each grinding head is raised automatically in its non-working position when the actual distance measured by the corresponding sensor corresponds to the set value.

Furthermore, in the example considered, a tracer 32, a recorder 33 and a display device 34 are associated with the analyzer 30. In practice, it is sufficient that at least one of these devices is installed.

The plotter 32 draws the actual measured profile on the basis of the actual measured distances and makes it possible to make a visual comparison of the measured profile with the set profile, the difference in distance △ h being indicated for each generator. Since the profile modifications are directly influenced by the geometry of the track and do not generally appear suddenly, it is enough to draw the profiles every 20, 50 or 100 m, which can be done automatically; it is also possible for the attendant to manually obtain the profile drawings, for example for each change of the profile, for example, before, at mid and after a transition curve and every 100 m in a solid curve or on a straight line. This tracer is above all very useful during the preparation of the work if the profiles are drawn before the grinding operation, because the attendant is thus able, relatively simply, to set up a special grinding program for each section channel specific.

The recorder 33 reproduces, for each sensor, the difference in distance △ h as a function of the path traveled, these differences can be first of all positive or negative, as already mentioned. In the example of Figures 8 and 9 the differences in distance distance h5, △ h6 and △ h7 are positive while the differences in distance △ h1, △ h2 and △ h3 are negative, the difference in distance △ h4 being practically zero. This reproduction of the values △ h by the recorder 33 makes it possible to know the longitudinal undulations of the rail along a generator and also to identify any transverse undulations by comparing the records along all the generators. Measures to compensate for longitudinal undulations are not the subject of the present invention and can be taken into consideration in a known manner, as described for example in document DE-B-2 843 649 by the same applicant. What is important here is that the graphic recording of the differences in distance along the generators makes it possible to clearly know the undulations of the rails, which was not without other possible by means of the recordings of the profile of the rail head proposed until 'here.

The optical display 34 has three rows of control lamps 35 arranged in a matrix, the number of columns corresponding to the number of generators controlled. The installation is arranged in such a way that the control lamps of the upper row light up when and as long as the distance difference from the generator concerned is positive while the lamps of the lower row are lit as long as the difference distance from the corresponding generator is negative, the lamps in the middle row only light up when the difference in distance from the corresponding generator corresponds to the set distance within the tolerances allowed. For example, it is advisable to provide red lamps for the upper and lower rows and green lamps for the middle row. Since three control lamps are allocated to each sensor, it is possible to simply monitor at a glance the actual state of the profile and determine along which generator it is still necessary to remove from the matter. In order to prevent the lamps from flashing continuously, in particular when the actual profile approaches the setpoint profile, the analyzer can control the control lamps so that they are only switched on every 20, 50 or 100 m correspondingly to the difference in distance measured in these intervals.

By means of the control device described, the relatively large amount of information, that is to say the distance values delivered by the sensors, is processed automatically almost instantaneously and used for the automatic control of the grinding heads. Both treatment and measurement are simple since distances are simply measured and control is based on distances. It is therefore not necessary to measure any other characteristic quantity of the rail profile, such as for example angles, or to carry out calculations on the basis of measurement information by means of a particular computer. The grinding speed, the grinding pressure or the speed of the grinding machine advance also do not in principle play a role in obtaining the desired profile since this profile is controlled and achieved simply on the basis of '' a comparison of setpoint and actual distances. The control of the grinding force and the grinding speed is only used for the purpose of performing grinding operations in a rational and fast manner.

In addition to recording the reference distances in the analyzer, it is naturally necessary to prescribe and place the values of the angles of inclination β of the double grinding heads and of the working angles α of the two grinding wheels of each double head. grinding, according to the desired profile of the rail, these values depending on the generator along which the grinding is carried out.

In the case of a semi-automatic control, the attendant adjusts the double grinding heads on the basis of the observations of the indicating devices, by adjusting their angle of inclination on the corresponding generators and adjusts their two grinding heads to the angle of work α assigned to the corresponding generator. To facilitate this manual control, each grinding head holder is equipped with a working angle indicator and a selector for adjusting exactly one grinding head holder on one of the generators.

The grinding operation is carried out in such a way that you first grind along the generators with large positive distance differences and, as far as negative differences appear, in the central region of the running surface, until the measuring device is lowered with the shoe 6 by a value such that all the negative differences disappear. In the example according to FIGS. 6, 8 and 9 all the double grinding heads are first of all adjusted on the generators s5 to s7 and one works with a maximum grinding pressure until the roughing profile b + 0.2 mm in Figure 6 is reached. For fine grinding, the double grinding heads are then distributed over all the generators for which the difference in distance is positive, a double grinding head being automatically raised to its out of working position if it is brought to a generator having a difference in distance negative or close to 0. Then grind with reduced pressure until the setpoint profile b is reached. The grinding force is preferably controlled step by step or continuously depending on the thickness of the material to be removed. It is also possible, as soon as the setpoint profile is reached along one or more generators, to adjust all the grinding head holders, manually or automatically, on the generators for which it is still necessary to remove the matter. The grinding operation is thus streamlined because all the grinding heads can be used continuously. In all cases, the grinding operation is automatically interrupted. only on a generator as soon as the difference in distance disappears.

The grinding operation can also be performed fully automatically. In this case, the corresponding values α and β are stored in the analyzer and the analyzer 30 and the control unit 31 also issue control commands by which the double grinding heads are automatically directed to the generators to be ground, the corresponding working angle α is also simultaneously placed. Such a control program can be arranged, for example, so that during the first grinding pass all the grinding heads are concentrated on the generators s6 and s7 and then on the generators s5 to s7, until the profile of roughing b + 0.2 mm is reached. In this case, the grinding force is continuously adjusted as a function of the thickness of the material which remains to be removed. The machine then proceeds to fine grinding for which the double grinding heads are directed to the different generators and are driven with a reduced grinding pressure until the set profile b is reached.

To be complete, it should be noted that the grinding of a rail head profile must almost always be carried out in a large number of passes, because during each pass only a relatively small amount of material, representing only a fraction of the thickness of material to be removed, can be ground. When approaching the target profile and working with a reduced grinding pressure, generally only one tenth or a few tenths of a mm is removed on each pass. The grinding car must therefore pass over the track section several times. to be corrected and it is preferably ground in the two directions of movement of the car. For this reason it is sufficient to install a single measuring chassis fitted with sensors at either end of the grinding car. Thus, depending on whether the measurement chassis is located at the front or at the rear of the car, one measures either immediately in front of or immediately behind the grinding heads, which is perfectly sufficient to measure the real profile with sufficient accuracy. .

By the method and by means of the device according to the invention, the measurement of the real profile is thus reduced, on the one hand, to simple distance measurements without the need to measure or calculate complicated profile quantities and the control of the grinding is carried out simply on the basis of a comparison of set distances and actual distances. On the other hand, the invention makes it possible, by means of a determined number of sensors, to control a double number of facets, so that by means of a relatively small number of sensors it is possible to obtain a profile that optimally approaches the setpoint profile.

The invention is not limited to the exemplary embodiment described, but it is susceptible of numerous variants, above all as regards the constructive execution of the movable double grinding heads. A grinding head holder can additionally carry more than one pair of grinding heads, i.e. more than one double grinding head so that two double grinding heads or more can be adjusted simultaneously on the same generator. In principle, it is also possible to measure distances to use mechanical probes in contact with the rails. The command described by means of a simple comparison of actual values and distance setpoints naturally also applies in the case where the actual distances to each individual facet are measured, in particular the distances in the middle of each facet and where, from correspondingly, a sensor controls only one facet and the grinding car works with individually adjustable grinding heads.

Claims (13)

1. A process of measuring and grinding the profile of a rail head, according to which, to determine the actual profile, the distances from a reference base defined by a measuring frame to several generatrices distributed transversely over the profile are measured, and on the basis of a comparison between actual and desired values, the rail head is ground approximately according to the desired profile by the grinding of several facets with different angles of inclination predetermined to correspond to the desired profile, characterized in that the said distances are measured continuously as actual values and are compared with desired distance values during the grinding operation, and that, whenever a ground facet reaches the position corresponding to the desired distance value, the grinding wheel grinding this facet is lifted off.

2. A process as claimed in claim 1, characterized in that the measured actual value is the distance (h) to a particular generatrix (s1 to s7), which coincides with a vertex line of two adjacent facets (f, fʹ), that this actual value is compared with the desired value of the distance between this vertex line and the reference base, and that the two facets of a pair of facets are ground by means of a double grinding head (15, 19) having two grinding wheels set to the vertex line and the grinding planes of which form a predetermined working angle (α) with one another which corresponds to the desired profile.

3. A process as claimed in claim 2, characterized in that in the grinding of a lateral lap (e), the distance to the rail surface is measured by means of only one measuring sensor (C7) along a predetermined generatrix (s7), and that the grinding operation is carried out in the region of this generatrix by means of at least one grinding wheel in several grinding steps, the grinding wheel being oriented differently in each of these, in such a way that the angle of inclination (β) of the grinding plane is increased in succession after each step and, during each grinding step, grinding is interrupted when the distance between the generatrix and the reference base reaches a predetermined intermediate desired value (h7 (20°), h7 (30°), at which the facet obtained forms at least approximately a tangential plane to the desired profile of the rail head, whereupon the following angle of inclination is set and grinding begins once again.

4. A process as claimed in claim 3, characterized in that the said grinding in steps of a lap (e) is carried out by means of a double grinding head, the two grinding wheels of which form a specific working angle (α).

5. A process as claimed in claim 3, characterized in that the measuring sensor (C7) is set approximately to the 45° tangent, and during each grinding step the said angle of inclination (β) is progressively adjusted by 10° to 15°.

6. A process as claimed in claim 1, characterized in that in the event that considerable quantities of material with a thickness of, for example, more than 0.2 mm are to be ground off, grinding is first carried out with a high grinding force until a rough profile (b+0.2 mm) predetermined as an intermediate desired profile is obtained, and that subsequently, in a separate precision-grinding operation, grinding is carried out with a reduced grinding force until the final desired profile (b) is obtained.

7. A process as claimed in claim 1, characterized in that those grinding wheels set to a generatrix which has already reached its desired distance from the reference base are automatically adjusted to another generatrix, along which the desired distance has not yet been reached.

8. A rail-grinding car for carrying out the process as claimed in claim 1, with a measuring frame (4) which carries several measuring sensors (C1 to (C7) adjustable to predetermined generatrices of the rail head and preferably working without contact, with several grinding heads (16, 16ʹ, 17, 17ʹ) which are adjustable in terms of height and inclination, and with control and indicator devices, characterized in that the control device has an analyzer (30) which is connected to the outputs of all the measuring sensors (C) and which receives signals corresponding to the measured actual values of the distances, that this analyzer (30) is also designed to store the desired values of the distances of all the generatrices (s1 to s7) of the desired rail profile, to compare said values with the measured actual values and to send commands to a control unit (31) which is designed to lift all the grinding heads (16, 16ʹ, 17, 17ʹ) off automatically into an inoperative position when the generatrix ground by said grinding heads reaches its desired distance.

9. A rail-grinding car as claimed in claim 8, characterized in that at least one pair of grinding heads (16, 16ʹ; 17, 17ʹ) forming a double grinding head (15, 19) is mounted in a common grinding-head carrier (14; 18) which is pivotable and which can be aligned with a predetermined generatrix (s1 to s7), and that the two grinding heads (16, 16ʹ; 17, 17ʹ) of a double grinding head (15; 19) are pivotable relative to one another and, to grind pairs (f, fʹ) of adjacent facets in one grinding operation, can be adjusted so that their grinding planes form a predetermined working angle (α) corresponding to the desired profile.

10. A rail-grinding car as claimed in claim 9, characterized in that the analyzer (30) and the control unit (31) are designed to align the grinding heads automatically with the generatrices (s1 to s7) to be ground, and to control the grinding force as a function of the thickness of the material to be removed.

11. A rail-grinding car as claimed in claim 10, characterized in that the analyzer (30) and the control unit (31) are designed to adjust the grinding heads, when these are set to a generatrix (s1 to s7), to the corresponding angle of inclination (β) automatically.

12. A rail-grinding car as claimed in claim 8, characterized in that in order to carry out the process as claimed in claim 2, the analyzer (30) and the control unit (31) are designed to adjust the working angle (α) of each double grinding head (15, 19) as a function of the generatrix (s1 to s7) with which this double grinding head is aligned.

13. A rail-grinding car as claimed in claim 8, characterized in that the indicator devices connected to the analyzer (30) have a curve tracer (32) for recording the actual profile and the desired profile and for indicating the distance differences ( h) and/or a recorder (33) for the continuous graphical recording of the positive and negative distance differences and/or a visual display (34) having lamps (35) which are arranged in the form of a matrix and which indicate for each generatrix (s1 to s7) whether the existing distance difference is positive or negative or vanishes.

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