EP0094703B1 - Sustaining device and control mechanism for the synchronisation of the displacement of a travelling bridge - Google Patents

Description

The subject of the present invention is a rotary overhead crane consisting of load-bearing beams connected together by connecting crosspieces to form a rigid rectangular frame provided in the vicinity of the corners, with movable ball-and-socket levitation devices each supported on a guided swivel base along a circular raceway by horizontal rollers resting on concentric rails in order to take up the forces oriented in a diametrical direction.

The revolving crane is used mainly in a nuclear power plant. It is generally located at the top of the containment which includes the primary circuit consisting of the reactor, steam generators, primary pumps, the pressurizer and certain safety devices. This enclosure is closed by a dome and is covered internally with a welded steel sealing skin.

There are known swing bridges or powerful polar bridges made by the firm Vevey. The known bridges each rotate on a circular track, inside the nuclear reactor building. This circular track is supported by a series of metal brackets integral with the aforementioned enclosure. It consists of a box girder on which a rail is fixed by toads. The radius of curvature of the track is guaranteed by a pre-centering of the rails with very tight tolerances.

The box beam is fixed to the brackets in a very specific manner in order to limit the horizontal forces between the track and the brackets during a variation in the diameter of the enclosure. These variations can be caused by prestressing, shrinking and bending, as well as the building test pressure and the effect of temperature.

Two supporting beams are connected to each other by two crosspieces, each resting on two bogies each comprising two rollers. A curved surface key, welded to the chassis of each bogie in its center, constitutes the support surface of the crosspiece.

The rollers have a slight taper ensuring a constant circumferential speed over the width of the rail. The entire bogie is slightly inclined to ensure good contact between the roller and the rail, which takes account of the deflection of the swing bridge under maximum load.

The rotary bridge is guided by pre-stressed horizontal rollers arranged at the four corners of the bridge. These rollers are independent of the bogies and integral with the crosspieces.

The rotation system is driven by four DC motors with constant separate excitation. They are coupled in series of two per side. Any offsets of the bridge are signaled to the driver by limit switch contacts of the pre-stressed guide rollers.

This revolving bridge has the serious disadvantage of showing a tendency to jamming and even to jamming after a sometimes relatively short operating time.

If the axle is off-center, the driver can center the bridge thanks to the fact that the latter is fitted with two independent static drives supplying the motors of the rotation system. These maneuvers are however difficult to execute. The bridge operator must then call on an authorized person to center the bridge. Despite this precaution, it sometimes happens that the bridge gets stuck and can only be released by means of pulls.

By US Patent No. 3009583, there is known a gantry crane lifting device provided with two hooks intended to be actuated simultaneously despite that they are carried by individual hoist-carrying carriages, for example for handling large objects dimensions. The carriages are guided transversely along two guide rails carried by load-bearing beams connected to each other at their ends by cross beams suspended from a train of moving parts traveling along a longitudinal raceway.

The suspension of the crosspieces is carried out by a spherical support attached below the raceway, to each of the moving parts by two flanges arranged on either side of the raceway and of the support.

The variations in length of the supporting beams, the differences in the spacing of the raceways and the play due to a deviation of the bridge due to a lack of synchronism of the trains of moving parts, are compensated by a pendulum movement more or less pronounced spherical supports suspended from the flanges. However, it can be seen that in this lifting device, no means of measuring the deformations or the displacement of the lifting devices with respect to a reference point is suggested. Besides, it could not be achieved. This known lifting device therefore excludes any possibility of carrying out a fully automatic control of the synchronism of movement of the crew trains.

Similarly, the German patent application No. 2004737 discloses a device for controlling and regulating the translation synchronism of a rolling lifting device such as a bridge or a gantry crane. The deviations of a translation roller of the rolling lifting device with respect to a reference line of a rail or a guide cable, are measured using a movable claw enclosing the rail. The claw can slide transversely along a guide fixed to the chassis of the crane and is integral with a potentiometric sensor also mounted on the chassis of the crane.

These linear displacements of the poten sensor tiometric which are directly linked to the deviations in the trajectory of the aforementioned roller, are used to correct said trajectory and in particular the perpendicularity of the bridge or the gantry crane with respect to the raceway.

This known control and regulation device however generates the disadvantage of only tolerating small deviations necessarily less than the width of the rim of the translation roller. Any additional deviation would initially derail the hoist.

The present invention aims to remedy the above drawbacks. It relates to a rotating overhead crane consisting of carrying beams connected together by connecting crosspieces to form a rigid rectangular frame provided in the vicinity of the corners, with movable ball-bearing lifting devices each bearing on a girder base guided along a circular raceway by horizontal rollers resting on concentric rails in order to take up the forces oriented in a diametrical direction, characterized in that at least one horizontal roller is carried by one of the connecting crosspieces and in that the ball-and-socket lift devices are provided with a unidirectional sliding plate with very low coefficient of friction allowing displacement in a diametral direction according to the forces transmitted by the above-mentioned horizontal rollers.

In a particular embodiment, the horizontal guide roller is fixed mounted at the mid-point of a connecting cross-member by pressing simultaneously on two circular rails concentric with the raceway of the bed bases of gyration.

According to a feature of the invention, each turning bed is made up of a box carried by two axles and provided with rollers. An axle is mounted on a fixed bearing integral with the box, the other axle is movable relative to the box and is mounted on this box so as to be able to oscillate in a vertical plane around a longitudinal shaft perpendicular to the vertical plane passing through the mobile axle.

Each swivel base is advantageously provided with two horizontal guide rollers ensuring the positioning of the latter on the raceway.

According to another particular feature of the invention, means for taking information relating to the positioning of the bridge are mounted at the level of each of the mobile supports mounted between the carrying beams and the swivel bases.

The aforementioned data acquisition means advantageously consist of potentiometric sensors of linear displacements.

The invention also relates to a method for controlling and adjusting the gyration synchronism of a rotating overhead crane, characterized in that information is taken of the positioning of the overhead crane at a mobile reference support.

In a particular implementation of the method according to the invention, the positioning of the overhead crane is controlled with respect to a reference bed base using a potentiometric linear displacement sensor which translates any deviation in analog voltage and d '' a delinearization and switching network which corrects the speed reference of the regulator.

Other details and particularities of the invention will emerge from the following detailed description of an embodiment of the invention illustrated, by way of nonlimiting example, by the appended drawings.

• la figure 1 est une vue en plan du pont roulant tournant suivant l'invention et d'une partie du chemin de roulement circulaire ;
• la figure 2 est une vue en élévation latérale d'un sommier mobile ;
• la figure 3 est une vue en élévation latérale du pont montré à la figure 1 ;
• la figure 4 est une vue en plan d'un sommier de giration du pont roulant tournant ;
• la figure 5 est une vue en coupe verticale suivant la ligne V-V du sommier de giration montré à la figure 2 ;
• la figure 6 est une vue de bout suivant la flèche X du sommier de giration montré aux figures 4 et 5 ;
• la figure 7 est un schéma synoptique du montage électronique de commande du moteur d'un des sommiers ;
• la figure 8 est un schéma électronique d'une des cartes d'un module électronique de commande auquel est raccordé un capteur de déviation linéaire ;
• les figures 9 et 10 illustrent deux formes possibles d'irrégularité dans le mouvement de giration du pont : déhanchement et déplacement du pont parallèlement à lui-même.

In these drawings:

• Figure 1 is a plan view of the rotary traveling crane according to the invention and part of the circular raceway;
• Figure 2 is a side elevational view of a movable bed base;
• Figure 3 is a side elevational view of the bridge shown in Figure 1;
• Figure 4 is a plan view of a swivel base of the rotary traveling crane;
• Figure 5 is a vertical sectional view along line VV of the swivel base shown in Figure 2;
• Figure 6 is an end view along arrow X of the gyration bed shown in Figures 4 and 5;
• FIG. 7 is a block diagram of the electronic control assembly of the motor of one of the bed bases;
• FIG. 8 is an electronic diagram of one of the cards of an electronic control module to which a linear deviation sensor is connected;
• FIGS. 9 and 10 illustrate two possible forms of irregularity in the gyration movement of the bridge: wobbling and displacement of the bridge parallel to itself.

In these various figures, the same reference notations designate identical or analogous elements.

As illustrated in FIG. 1, the revolving overhead crane according to the invention consists of support beams 1 in boxes connected to each other by crossbeams 2 of connection in welded construction to form a rigid rectangular frame generally designated by the reference notation 3. This rigid frame 3 is supported in the vicinity of each corner on gyration bases 4 to 7 by means of mobile levitation devices consisting of spherical supports (Tetron SF support) composed of a ball joint 12 allowing movements of rotation up to 0.06 radian and a horizontal sliding plate 13 unidirectional up to 44.8 mm with very low coefficient of friction, a sheet of stainless steel veneer, a core 15 and a base 16 with a flat underside. The relatively low coefficient of friction is obtained thanks to the insertion of a Teflon strip loaded with glass fibers and glued to the core of the ball joint 12. This spherical support allows a good distribution of the weight and load of the crane turning on the four bed bases 4 to 7 while allowing horizontal movements in the direction of the arrows Y (Figure 9). It provides the four box springs 4 to 7 and the supporting frame with a freedom of oscillation with respect to one another so as to take up without tension the variations in the deflection of the bridge under maximum load.

A lifting trolley 18 fitted with redundant winches 19 and a rigorously vertical lifting reel 18 ′ travels along the above-mentioned carrying beams.

The four box springs 4 to 7 which carry the rotary traveling crane move on a circular raceway 20 arranged for example inside the confinement enclosure 21 of the nuclear reactor.

The raceway consists of a box beam 22 made of AE36 steel on which two rails 24 made of high strength steel are fixed by toads 23. The rails 24 are adjusted in the best conditions with epoxy injection ensuring perfect contact between the components. They are then machined to very precise tolerances by a mobile boring machine.

The box beam 22 is fixed to the brackets by means of hooped neoprene supports with epoxy injection between the adjustment systems.

This fixing system aims to limit the horizontal forces between the track and the brackets during a variation in the diameter of the enclosure. These variations can be caused by prestressing, shrinkage and creep, as well as the building test pressure and the effect of the sun or temperature.

Each turning bed 4 to 7 consists of a box 25, carried by two axles 26, 27, provided with rollers 28, one of which is motor and the other carrier. The rollers 28 have a slight conicity guaranteeing a constant circumferential speed over the width of the rail 24. The axes of the rollers are oriented towards the center of the bridge in order to guarantee a correct rotational movement. The axle 26 is mounted on a fixed bearing 26 'integral with the box 25. The other axle 27 is movable relative to the box 25 and is mounted on this box 25 so as to be able to oscillate in a vertical plane around an axis longitudinal 29 perpendicular to the vertical plane passing through the axle 27. This ensures a homogeneous distribution of the load of each box spring on its four rollers 28 and good contact between roller 28 and rail 24. A clearance 30 is provided on the side walls of the box 25 to allow pivoting of the other box. Each of the bed bases 4 to 7 is guided by two horizontal rollers 31 mounted on it. A horizontal guide roller 31 ′, secured to a cross member 2, guides the support frame 3. The total weight of the bridge is around 400 tonnes. The maximum hook load is 530 tonnes.

The drive motors 32 to 35 of each of the bases 4 and 7 are asynchronous motors with a ring of normal construction. The control equipment for these motors consists of thyristor variable speed drives, for example Statovar devices with four quadrants produced by the firm Telemechanics.

The “Statovar 4 quadrant” variable speed drive is generally used for movements with high maneuver rates and up to high powers and speeds. It makes it possible to obtain progressive starts and decelerations and allows very reduced approach speeds for delicate positioning.

Regulation operation is obtained by adjusting the stator voltage and therefore the torque produced. This is modified by the variation of the conduction angle. The variation of the conduction angle thus makes it possible to modify the supply voltage of the motor and, consequently, its torque.

• un bloc gradateur de puissance agissant sur la tension statorique, désigné dans son ensemble par la notation de référence 37 ;
• un module électronique de commande désigné dans son ensemble par la notation de référence 38 ;
• un ensemble électromécanique constitué de contacteurs de puissance et de contacteurs auxiliaires ;
• un ensemble d'organes périphériques.

This “Statovar 4 quadrant” variable speed drive includes:

• a power dimmer block acting on the stator voltage, generally designated by the reference notation 37;
• an electronic control module designated as a whole by the reference notation 38;
• an electromechanical assembly consisting of power contactors and auxiliary contactors;
• a set of peripheral organs.

The electronic control module 38 comprises a transformer and three electronic cards interconnected with one another.

The first of these cards is the elementary electronic card (SF, LK301) which groups together a supply circuit 43 rectified and filtered to ± 26 V, a safety circuit 44 controlling the stabilized supply at 15 V, as well as the presence and the order of the phases and compliance with a speed threshold fixed at 130% of the nominal speed, an adaptation circuit 45 for the return signal corresponding to the stator current, a synchronization and ignition circuit.

• un circuit d'adaptation du signal de retour tachymétrique, permettant de régler ce dernier à 10 V pour la vitesse nominale ;
• un circuit élaborant le signal de référence, avec réglage des vitesses maximales et des vitesses réduites de ralentissement dans les deux sens de marche ;
• un circuit de régulation avec amplification de l'écart, détection de son signe, transformation en valeur absolue, élaboration du signal de commande des allumeurs ;
• un circuit logique d'inversion validant par des signaux le gradateur qui doit être mis en action. Le choix dépend du signe de l'écart sauf dans les zones de marche en grande vitesse où le gradateur correspondant au sens moteur est maintenu en pleine conduction. Les signaux de validation sont asservis au signal du circuit de sécurité d'une part et à la position enclenchée du contacteur de ligne 46 d'autre part. En l'absence de signal de validation, la logique d'inversion délivre un signal qui bloque les impulsions d'allumage et ouvre la boucle de régulation ;
• un comparateur contrôle le ralentissement avant l'arrêt et délivre le signal de coupure du frein lorsque la vitesse est inférieure à 5 % de sa valeur nominale ;
• un relais assure la sortie de la commande de frein sous la dépendance de la carte suivante.

The second elementary electronic card 41 (SF _l LK302) has the main function of regulating the speed of the drive motor (s) 32 to 35. It comprises:

• a circuit for adapting the tachometric feedback signal, making it possible to adjust the latter to 10 V for the nominal speed;
• a circuit developing the reference signal, with adjustment of the maximum speeds and reduced speeds of deceleration in both directions of travel;
• a regulation circuit with amplification of the difference, detection of its sign, transformation into absolute value, elaboration of the igniter control signal;
• a logic inversion circuit validating by signals the dimmer which must be put into action. The choice depends on the sign of the deviation except in high speed walking zones where the dimmer corresponding to the motor direction is kept in full conduction. The validation signals are slaved to the signal of the safety circuit on the one hand and to the engaged position of the line contactor 46 on the other hand. In the absence of a validation signal, the inversion logic delivers a signal which blocks the ignition pulses and opens the regulation loop;
• a comparator controls the deceleration before stopping and delivers the brake cut-off signal when the speed is less than 5% of its nominal value;
• a relay ensures the output of the brake control under the dependence of the following card.

The third electronic card 42 (SF _i LK304) has for main function the control of brake logic and rotor contactors 46. It has a ramp adjustable separately for each direction of travel whose output remains blocked as long as the brake is not applied loose.

In order to ensure a perfect geometry of the turning movement and in particular to avoid decentring the above-mentioned rotating overhead crane, the synchronization of the turning is checked, by adjusting the speed of at least one of the motors 32 to 35 mounted on the bed bases of gyration 4 to 7.

For this purpose, an information acquisition is carried out on the positioning of the traveling crane at one of the mobile supports carrying the cross-member provided with a horizontal guide roller 31 ′. This support is the mobile support of the reference bed base 4.

On the reference base 4, a potentiometric linear displacement sensor 47 determines the displacement of the fulcrum of the bridge with respect to the correct position, both in center search and in wobbling. This potentiometric sensor 47 is connected in series in the elementary electronic card 41 (SF _i LK302) of the electronic control device 38 to a potentiometer 48 and the assembly is adjusted so as to form a resistance of 800 Ohms between the wires connected to the terminals 51 and 67 of said SF ₁ card LK302, and introduces permanent information acting on the speed reference of the governor (Figure 8).

The contactors 46 are controlled by the electronic control module 38 to activate 1 to 4 sections of rotor resistors 46 ′ of ohmic value well determined for slip values to the motors adjusted as a function of the starting and braking characteristics.

Each dimmer 37 supplies the stators of two motors in parallel. Tachometric dynamos 49 to 52 equip each motor 32 to 35. The voltages supplied are connected in series and regulate the speeds.

Each dimmer 37 is made up of three groups of 2 thyristors 53 to 62 mounted head to tail and possibly protected by overcurrent relays 63 to 66. Each group is connected in series with a stator phase.

A deviation of the actual bearing point of the reference support frame 3 from a fixed point, less than 10 mm is negligible. The positioning of the support frame 3 relative to the reference base 4 is then considered to be correct.

The acceptable difference on the other bed bases is greater than that which can be accepted on the reference bed base 4. An anchoring device 67 retains the traveling crane in the event of an earthquake.

Endstops not shown, for example causing the bridge to lock. are provided at a distance of 56 mm for the reference base 4 and the neighboring base 5 while these distances can reach 100 mm for the two bases 6, 7 carrying the other connecting cross member 2.

A predetermined difference in pulses reduces the speed reference of the regulator, driving the bed bases 4, 5 in advance until the return to the correct position.

The center of gyration is controlled by the sensor 47 mounted between the support beam 1 and the reference bed base 4, the sensor 47 translates a linear displacement in analog voltage, proportional to the difference and acting in correction on the speed reference, via a delinearization and switching network.

Example 1

A first possible form of irregularity in the gyration movement of the bridge consists in the displacement of the box springs 6, 7 of one of the crosspieces 2 of the support frame 3 while the box springs 4, 5 of the other crossbeam 2 remain fixed ( Figures 9). Consider for example that the cross member 2 carrying in the direction indicated by the arrow Y the guide roller 31 'remains fixed. A swaying causes the support points to move along the abscissa in the direction indicated by the arrow X. For a maximum allowed swaying of 300 mm (displacement BB '= 300 mm), the four corners of the rigid support frame will undergo the following displacements:

A movement in a direction outside the raceway is assigned the + sign. The sign of this development is - if the displacement BB 'takes place in a direction internal to the raceway.

The deviation at point 1 corresponds to the reference bed base 4 will result in an elongation of the potentiometric linear deviation sensor.

If this elongation causes a deviation of the position of the movable fulcrum from the theoretical position greater than 10 mm, the potentiometric sensor 47 translates the linear displacement into analog voltage proportional to the difference. A positive movement increases the stator current and increases the speed of the drive motors 32 and 33 via a delinearization and switching network, controlling the bed base in advance until returning to the correct position.

Example 2

A second possible form of displacement of the rotating overhead crane is by displacement simultaneous four box springs 4 to 7 (Figure 10) in the same direction Y. It is in fact a translation of the support frame 3 parallel to itself, for example during the reversal of the drive motors 32 to 33 of the box springs 4, 5 of one of the crosspieces 2. This displacement may be desired for example to position the hook in the center of the building for certain delicate operations.

It can also be the consequence of an error due to the accidental reversal of the direction of travel of the drive motors 32, 33 or 34, 35 of the bed bases 4, 5 or 6, 7 of one of the cross members 2.

The maximum displacement allowed in translation is 200 mm on the ordinate. To this displacement correspond the following deviations of mobile supports on the abscissa:

The signs affected by the movements correspond to those of Example 1.

A positive movement increases the stator current and increases the speed of the drive motors.

On each of the bed bases, end of travel stops signal and possibly cause the immediate stop of the bridge after a displacement of 56 mm for the bed bases 4 and 5 and after a movement of 100 mm for the bed bases 6 and 7. This system authorizes linear variations inherent in the construction of the raceway, thermal expansion, possibly the prestressing of the concrete of the wall of the enclosure which carries the raceway.

Compared to other known control methods, the method according to the invention provides information on the position of the rotating crane totally independent of the number of turns made by the above-mentioned bridge.

In addition, it allows the bridge to operate in translation over a distance of approximately 200 mm, while ensuring perfect regularity of the turning movement without off-center of the bridge. This translation makes it possible to precisely reach the center of the reactor which corresponds to the center of the building and thus ensures the correct handling of the cover of the reactor vessel.

Claims (13)

1. A rotating travelling bridge crane consisting of bearing girders connected together by tie plates (2) to form a rigid rectangular frame (3) equipped in the vicinity of its corners with mobile, ball-jointed supporting devices each resting on a slewing support beam (4 to 7) guided along a circular runway by horizontal rollers (31) resting on concentric rails (24) in order to absorb the forces oriented in a diametral direction (X), characterized in that at least one horizontal roller (31') is carried by one of the tie plates and in that the ball-jointed supporting devices (12) are equipped with a unidirectional slide plate (13) with a very low friction coefficient allowing displacement in a diametral direction (X) according to the forces transmitted by the above-mentioned horizontal rollers (31).

2. A travelling bridge crane, characterized in that the horizontal guide roller is mounted fixedly to the centre point of a tie plate (2) and rests simultaneously on two concentric circular rails (24) on the runway of the slewing support beams (4-7).

3. A rotating travelling bridge crane according to claim 1 or claim 2, characterized in that each slewing support beam consists of a case (25) carried by two axles (26, 27) and equipped with rollers (28), one axle (26) being mounted on a fixed bearing firmly attached to the case, the other axle (27) being mobile in relation to the case (25) and mounted on this case (25) so as to be able to oscillate in a vertical plane around a longitudinal shaft (29) perpendicular to the vertical plane passing through the mobile axle.

4. A rotating travelling bridge crane according to any one of claims 1 to 3, characterized in that each slewing support beam is equipped with two horizontal guide rollers (31) ensuring positioning thereof on the runway.

5. A rotating travelling bridge crane according to any of claims 1 to 4, characterized in that means for recording information relating to the positioning of the bridge are mounted at the level of one of the movable bridge bearings mounted between the bearing girders (1) and the slewing support beams (4 to 7).

6. A rotating travelling bridge crane according to claim 5, characterized in that the above-mentioned information recording means consist of linear displacement potentiometer pickoffs (47).

7. A rotating travelling bridge crane according to any one of the preceding claims, characterized in that each support beam (4 to 7) is equipped with a reciprocating engine (33 to 35) of the asynchronous, three-phase, slip ring type equipped with drive and control means and with safety devices.

8. A rotating travelling bridge crane according to claim 7, characterized in that the drive means comprise a naturally ventilated power staging block (37) comprising thyristors (53 to 62), control circuits, current transformers (39) for measuring the stator current, an electronic control module and an assembly of peripheral members.

9. A rotating travelling bridge crane according to any one of the preceding claims, characterized in that the voltage representing the speed obtained is supplied by a tachometric dynamo (49 to 52) at the end of the drive shaft.

10. A process for controlling and regulating the slewing synchronism of a rotating travelling bridge crane according to any one of the preceding claims, characterized in that one of the points of a tie plate (2) is forced to follow a strictly circular trajectory.

11. A process according to claim 10 characterized in that information regarding the positioning of the travelling bridge crane is recorded at the level of a movable reference bridge bearing.

12. A process according to claim 11, characterized in that positioning of the travelling bridge crane is controlled in relation to a reference support beam (7) by means of a linear displacement potentiometer pickoff (47) which translates any separation into an analogous voltage and of a delinearisation and switching network which corrects the reference speed of the regulator.

13. A process according to claim 12, characterized in that a predetermined impulse difference reduces the reference speed of a regulator, piloting ahead one support beam until the correct position is regained.

Images