EP0059675B1 - Apparatus for rapidly cooling metallic pipes - Google Patents

Abstract

The device according to the present invention is an improvement on the conventional devices for quenching metal tubes (3) by immersion into a tank (4) of liquid at ambient temperature. This device comprises in particular a deflector (18) positioned below the tube at the time of its immersion. This deflector distributes the contact of the cooling fluid on the surface of the tube (3). It allows a more homogeneous cooling and avoids asymmetric deformations of the tube (3). An air injection system fastened to the end of the tube to be treated is associated with this deflector. This device will be particularly useful in installations for treating very long, thin tubes.

Description

The present invention relates to a device for cooling by immersion of hot metal tubes, devices which can, for example, intervene in the tube manufacturing cycle either immediately after hot forming of the tube, or for a specific heat treatment, such as for example quenching treatment.

The manufacture of metal tubes, and in particular steel tubes, generally requires forming, heat treatment and finishing operations.

It is common to have to perform quenching or hyper quenching operations requiring rapid cooling from a high temperature.

Different techniques have been developed so far for quenching the tubes.

A first family of techniques consists in parade treatment. In this process, the hot tube is cooled by a liquid distributed by a sprinkler ring around the tube. This method often requires, to avoid longitudinal deformations of the tube, to advance the tube with a helical movement, to plug the ends to prevent any untimely entry of water. It often even requires, in order to obtain a homogeneity of treatment in the longitudinal direction, to carry out the cooling at the outlet of a reheating oven which maintains the adequate temperature substantially constant in the rear part of the tube during its advance movement.

In the particular case of long and thin steel tubes produced by the glass spinning process which leave the spinning press between 1100 ° C. and 1200 ° C., there is a very short time of the order of twenty seconds to execute the operator. The running speed in the quenching installation which, for such tubes, would be of the order of 30 m / min, does not make it possible to carry out a correct heat treatment at the running past for 15 m tubes, current length in the glass spinning process, and it is necessary to have recourse to a treatment made subsequently to obtain good quality tubes.

Furthermore, beyond a certain thickness of products to be treated, it is necessary, in order to obtain a sufficiently high cooling rate at any point in the section of the tube, to cool the interior of the tube by an appropriate device.

The parade technique leads to installations important in dimensional terms, complex in mechanical terms, the use of which is restrictive.

The second family of techniques consists of immersion treatment. In this case, the method consists in completely and quickly immersing in a cooling tank filled with a coolant, the hot tube taken out of the hot forming tool or the hot treatment oven.

This method has the advantage of being simple and rapid, but has the major drawback of subjecting the tube to irregular cooling conditions, both on the length and on the section, given, in particular, the very irregular penetration of the coolant inside the tube. As a result, when the products treated are thin tubes or with a high external diameter / thickness ratio, for example greater than 20, significant longitudinal deformations known as “in the sleeve of a shirt” making it impossible or considerably hampering the subsequent work of the tube. ; discomfort which, despite dressing operations, can be found on the quality of the finished products.

Various proposals have been made to date to improve the technique of immersion quenching. This is how we tried to regulate the cooling rate by creating a strong agitation stirring of the cooling bath or by immersing the inclined tube in the coolant, to favor the more regular introduction of the coolant to inside the tube.

In fact, none of these techniques has solved the basic problem, since the introduction of water into the interior of the tube is done randomly and it is not possible to control the straightness of the tube after cooling. . This problem is particularly sensitive at mid-length of the tube. Finally, during the immersion of a horizontally positioned tube, the lower generatrix of the tube is in contact with the cold liquid before the upper part.

The present invention relates to a rapid cooling device by immersion of hot metal tubes of great length. This process does not have the drawbacks described above and leads to regular cooling. The tubes, after treatment according to the invention, do not present any notable anomaly of straightness which requires a special treatment before the continuation of the manufacture.

The cooling device, object of the invention, comprises means for transferring upstream the hot tubes, a quenching tank containing the cooling liquid, an immersion device, means for transferring the hot tubes onto the device. immersion, means of clamping the tube, means of recovery, removal and downstream transfer of the tubes. It comprises a longitudinal deflector in the general shape of a trough or angle iron, placed at the lower right and at a short distance from the tube without being in contact with it. This deflector precedes the tube in the manner of a bow at the time of its first contact with the coolant then, when it descends into the tank containing the liquid. At the moment when, during the descent of the tube, its lower generatrix reaches the level of the liquid, the latter has been moved aside and projected on both sides by the deflector. The first contact between the tube and the liquid is thus slightly delayed. In addition, this first contact, instead of being made by the lower generatrix of the tube, is made symmetrically along two lateral generatrices close to those corresponding to the section of the tube by a horizontal diametral plane. During its descent into the tank at the front of the tube, the deflector creates swirls and a symmetrical circulation of the liquid around the tube.

The cooling device also includes a high-flow air injection system secured to one end of the tube to be treated. This system injects pressurized air into the tube during the descent into the tank and immersion maintenance phase.

In parallel, a plurality of pipes for circulating and stirring the coolant is distributed longitudinally in the tank, the liquid of which is maintained at a homogeneous temperature close to room temperature before immersion.

Before immersion, the tube is positioned longitudinally on the immersion device, air injection side, and kept fixed in this position by a shoe, in order to allow the subjection of the air introduction system.

The operation of the cooling device will now be explained.

A hot tube to dip or hyper dip, at least one end of which ends in a straight cut substantially perpendicular to the axis of the tube, is brought by a horizontal conveyor and parallel to the axis of the tank. The tube is positioned relative to the tank using a retractable stop located at the front or rear end of the tube. The tube is then supported by a lateral transfer system consisting, for example, of tilting arms keyed onto a common shaft, which moves it from the conveyor position to the immersion system position. The immersion device collects the tube which is immediately immobilized longitudinally in this position by a clamping system carried by the immersion device, controlled by a pneumatic cylinder located near the end used to position the end which is ends with a clean cut. The air injection system constituted by an air nozzle is applied to the end of the tube on the side where it has been immobilized. The tube is then suddenly immersed in the coolant by lowering the immersion device and then kept immersed for the time necessary to obtain the desired cooling.

In the tube descent phase, the deflector creates, in contact with the coolant, a vacuum, which causes the lower generatrix of the tube to drop to a level lower than that of the coolant in the tank, before returning to contact. some cash. Immediately afterwards, the coolant passes over the wings of the deflector and simultaneously comes into contact with the tube along two lateral generators adjacent to the diametrically opposite generators. There is thus a symmetrical cooling from the first contact with the liquid.

Simultaneously, but prior to the start of the descent, an air nozzle carried by a flange forming a joint and abutting on the tube, is introduced into the end of the tube which has a clean cut and which has been previously clamped. Air is injected at a high rate through this nozzle continuously during the entire treatment. During the descent and maintenance in immersion, the nozzle with its flange remains immobilized at the end of the tube by a mechanical follower device associated with the tank. We ensure, in this way, the permanence of air circulation in the tube throughout the treatment, avoiding that it, thanks to the clamping device, moves away from the injection device d compressed air, whether under the pressure created by air or by shrinking due to cooling. The water which can penetrate inside the tube by the interstices between the flange and the tube is pulverized and entrained at high speed by the air current. This helps to homogenize the temperature inside the tube while helping to cool it.

The main purpose of the deflector is to make the circulation currents of the cooling fluid symmetrical during the descent phase. It is therefore important that, without being in contact with the tube, it is located at the immediate lower right of the latter. It can take several embodiments, for example the shape of a more or less open V-shaped angle iron, or, for example, the shape of a semi-circular rounded cradle or trough. To fulfill its function, the deflector must be adapted to the size of the tubes to be treated. This can be obtained, among other things, by adjusting the width of its wings or, if it is in the form of an angle, by opening its folding angle or, finally, by adjusting the vertical distance which separates it from the tube. The deflector extends, substantially continuously, over the entire length of the immersion device, but its construction can be such that it allows the passage of the supply and removal arm of the tubes.

The purpose of the air injection device in the tube is to avoid random introduction of the coolant into the tube. The air flow and speed in the tube must be sufficient to ensure a large forced circulation. The nozzle section and the air pressure at this level must be sufficient to ensure this circulation. The section of the air nozzle must be adapted to the interior section of the tube to be quenched. Satisfactory operating conditions are obtained with the air under pressure from the network, that is to say of the order of 5 effective bars by using an internal section ratio of the tube to be cooled to nozzle section of the order of 3.

The coolant circulation and agitation injectors distributed longitudinally in the tank operate throughout the cooling period, from the start of the descent phase. This homogenizes the temperature of the coolant in the tank and promotes the removal of calories from the tube by the coolant. The liquid in the tank is, moreover, recirculated at a constant level and its average temperature is maintained by a refrigeration system external to the quenching tank itself, at a value close to ambient temperature.

At the end of the cooling in the tank, the tube is raised out of the coolant. The air injection is then stopped, the air nozzle is uncoupled and the tube is freed from its clamping. The tube is taken up by a removal device which lifts and laterally transfers the tube to lead to the later stages of manufacturing. In general, a conveyor parallel to the axis of the tank ensures this operation. The removal device can, for example, consist of tilting arms and a momentary stop position can be provided to allow the drainage of the tube above the tank.

The device which is the subject of the invention can be designed so that the upstream and downstream conveyor systems are separate or combined. When combined, the tubes are brought in on the same side with respect to the tank and by the same means as the transfer of the tube to the manufacturing stations following. Likewise, the lateral transfer system from the conveyor tube to the immersion system, the immersion system and the tube take-up system for lateral transfer after quenching, can be distinct or common in whole or in part, a single device ensuring then the two or three functions without departing from the scope of the present invention.

All the lateral transfer devices used in the context of the present invention are of known and traditional design.

The cooling device, object of the invention, can be used as a quenching system, either at the outlet of the heating furnace, or at the outlet of the tube hot forming tool, such as, for example, a glass. It is particularly well suited to the treatment of thin tubes with a large external diameter to thickness ratio, generally greater than 20, and a long length, of the order of 10 to 20 m.

• La figure 1 représente une vue de dessus d'ensemble du dispositif de refroidissement.
• La figure 2 représente une coupe selon un plan courant A-A de la fig. 1.
• La figure 3 représente, en position immergée, le système d'assujettissement de la buse à air sur l'extrémité du tube selon la coupe B-B de la fig. 1.
• La figure 4 représente le système d'assujettissement de la buse à air sur l'extrémité du tube selon la coupe C-C de la fig. 3.
• Les figures 5A-5B-6A et 6B représentent différentes réalisations de déflecteurs fixées sur le dispositif d'immersion des tubes.
• La figure 7 représente en coupe une variante de réalisation du dispositif de trempe.

In order to better understand the invention and its characteristics, an embodiment will be described by way of non-limiting example, with reference to the appended drawings in which:

• Figure 1 shows an overall top view of the cooling device.
• FIG. 2 represents a section along a current plane AA of FIG. 1.
• FIG. 3 represents, in the submerged position, the securing system of the air nozzle on the end of the tube according to section BB of FIG. 1.
• FIG. 4 represents the securing system of the air nozzle on the end of the tube according to the section CC of FIG. 3.
• Figures 5A-5B-6A and 6B show different embodiments of deflectors fixed to the tube immersion device.
• Figure 7 shows in section an alternative embodiment of the quenching device.

We first describe a cooling device for which the tubes are conveyed by a single device located on one side of the quenching tank and for which the device for lateral transfer from the conveyor to the immersion system, the device. immersion and the recovery and lateral transfer device of the tubes is common.

The quench line includes, fig. 1 and fig. 2, a conveyor 1 equipped with rollers 2 on which a tube to be treated 3 moves here of 0 100 mm. The tank 4 is constructed parallel to the conveyor 1. It consists of a parallelepipedal block open at the top, made of sheet metal, placed on a base 5. The level of the coolant in the tank is represented by 6. Here, the tank is filled with water whose temperature is maintained near ambient temperature by a conventional external device not shown. A plurality of lateral tubes 7 for water inlets is distributed throughout the tank and is supplied by general piping 8. The evacuation of the tank, allowing the level to remain constant, is not shown.

The lateral transfer device conveyor-immersion system and the immersion system consists of seven arms 9 with two branches 10-11 which are evenly distributed over the entire length of the tank. The branches 10 of the arms 9 ensure the removal and deposition of the tube 3 of the conveyor 1, the branches 11 constitute the immersion device. The arms 9 are mounted on a common shaft 12 rotating in a plurality of bearings 13 mounted on beams 14 between the conveyor 1 and the tank 4. They are respectively marked 9a to 9g.

The arms 9 are mounted in alignment with the shaft 12 so that the tube is submerged horizontally. They are moved simultaneously by a jack 15 fixed in two extreme positions corresponding to the conveyor position for the branch 10 and immersion for the branch 11. The branch 10 manipulates the tube by its rounded 16. The branch 11 manipulates the tube by its internal angle 17, as shown in fig. 2.

An angle iron 18 is fixed on the branches 11 at a location located at the lower right of the tube 3 and close to the latter when the tube 3 arrives at level 6 of the liquid. This angle 18 extends over the entire length of the tank, from the first arm 9a to the last arm 9g. A device for clamping the tube, not shown, conventionally constituted by a jack acting on a movable arm, the whole carried on the arm listed 9g fig. 1, located in the immediate vicinity of the securing system of the air injection nozzle on the end of the tube, ensures the clamping of the tube 3 in the interior angle 17 of the arm 9g during immersion.

The device for securing the air injection nozzle 19 to the tube is shown in detail, FIGS. 3 and 4. The entire system is carried by a special arm 20 mounted on the common shaft 12 and subjected to the same movements as the arms 9. The arm 20 includes at 21 an interior angle similar to the angles 17 on which the tube 3 rests.

The air injection nozzle 19 is mounted on a flange 22 joining with the end 23 on the clamping side of the tube 3. This flange is carried by an arm 24 pivoting about an axis 25 integral with the arm 20.

The flange 22 is pushed permanently against the end 23 of the tube 3 having a straight cut and previously positioned longitudinally by the rod 26 moved by the spring 27, a stop being provided so that the rod does not come out of its bore . However, this movement of the flange towards the tube is compensated by a contrary movement caused by the cam 28 acting on an idler cylindrical roller 29 mounted on the pivoting arm 24. The cam, mounted on the shaft 30 rotating around the two bearings 31- 32 fixed to the arm, is driven in rotation during the descent of said arm for the immersion of the tube 3 by the system of two bevel gears, one of which is fixed and the other is mounted on the camshaft 30. The profile of the cam is such that the flange 22 is pressed against the end of the tube 3 in the submerged position, the nozzle 19 then being engaged in the tube 3, as shown in Figures 3 and 4, and spaced from the end of the tube in the high position, before immersion or after immersion, the front end of the air injection nozzle 19 being released from the tube 3 to allow lateral transfer thereof.

The nozzle 19 is mounted by thread on the flange 22 so as to be able to adapt the nozzle diameter to the inside diameter of the tube 3 to be treated. The nozzle diameter is generally such that the ratio between the internal section of the tube 3 and the section of the nozzle 19 is of the order of 3.

The compressed air taken from the standard compressed air network at 5 bars in the workshop is brought to the nozzle 19 by a flexible conduit not shown.

FIGS. 5A, 5B, 6A and 6B show various nonlimiting embodiments of angles 18 used as a deflector.

Fig. 5A shows an embodiment in which the angle iron 18 consists of two parts, one fixed 39 fixed by welding to the arm 11 and two wings 40 and 41 adjustable. The width of the opening at the end of the angle iron is adjusted by sliding the thread-bolt assembly 42 in the notch 43 of the wings 40 and 41.

In the embodiment of FIG. 6A, the angle iron 18 is of defined dimensions, but it is fixed to the arm 9 by a threaded rod-bolt assembly 44 sliding in a vertical slot 45 located at the right interior of the angle 17 in the branch of the arm 11. The angles are attached in a coupled manner on either side of the branch 11. The adjustment of the angles 18 is intended to make the circulation of water symmetrical during the descent in immersion of the tubes. It is therefore necessary that the adjustment of the angle is substantially adapted to the outside diameters of the tubes to be treated. This is obtained here by adjusting the wings or by the relative vertical position of the angle iron. Angles can also be used, the angular opening of the wings of which is adjustable.

• Le tube chaud 3 est amené du four et positionné longitudinalement sur le convoyeur 1. Les bras 9, par leur branche 10, viennent prendre en charge le tube 3 dans les arrondis 16, comme représenté en pointillé, fig. 2. Une première rotation des bras 9 amène la partie rectiligne 46 de la branche 11 sensiblement horizontale, légèrement inclinée vers le niveau 6 et maintient le bras dans cette position.

The cooling device works as follows:

• The hot tube 3 is brought from the oven and positioned longitudinally on the conveyor 1. The arms 9, by their branch 10, come to support the tube 3 in the rounded 16, as shown in dotted lines, fig. 2. A first rotation of the arms 9 brings the rectilinear part 46 of the branch 11 substantially horizontal, slightly inclined towards the level 6 and maintains the arm in this position.

The tube is thus transferred from 16 to 17 by rotation without sliding on the rectilinear part 46. The system is designed in such a way that the immersion device constituted by the branch 11 and the angle 17 is not immersed when the tube comes from 16 to 17, while the rectilinear part 46 is substantially horizontal. At this level, the front end of the air nozzle 19 is set back enough to allow the free passage of the end of the tube 3.

The tube is then clamped by the jack acting on a movable arm mounted on the arm 9g. The arm 9 then continues their rotation according to arrow F and, simultaneously, the air is injected into the tube 3. The tube is rapidly immersed by continuing the rotation of the arms 9. During the rotation of the arms 9, by the play of the cam 28 and the rod 26, the nozzle holder flange 22 is pressed against the blunt end of the tube 3, thus allowing mainly air to enter the tube. The tube 3 is kept submerged for the time necessary for it to cool down to the desired temperature. The tube is then raised by rotation back from the arms 9. The air is blown into the tube until the horizontal portion 46 passes straight, which makes it possible to empty the tube 3 of all the water which would have could get inside. Continuation of the backward rotation of the arms 9 causes the tube to pass from angle 17 to rounding 16. The cold tube is then deposited on the conveyor 1 which discharges it towards the rest of the production line. Another hot tube can be brought in for treatment. During the entire service life of the tank 4, the coolant is vigorously stirred by the side tubes 7 and maintained at room temperature by an external refrigeration system not shown.

The duration of the cycle depends on the tubes to be treated. It is of the order of 30 seconds, without counting the actual immersion time, which is a function of the nuance of the metal and the dimensions of the tube.

The installation described has proved to be particularly advantageous for tubes of great length (greater than or equal to 15 m), of diameter 70 to 150 mm, having a high diameter to thickness ratio of the order of 25. They leave the treatment without appreciable longitudinal deformation.

The operating cycle of the cooling device is such that it can be used either at the outlet of a heating oven, or at the outlet of a hot forming tool, such as for example a glass spinning press, in order to subject the metal to quenching or hyper quenching.

Fig. 7 shows in section an alternative embodiment of the cooling device in which the hot tubes 47 are brought by a roller conveyor on one side of the cooling tank 48 and discharged cold on the other side of the tank by a non-conveyor represented. The arm 49 serves as a lateral transfer of the hot tube to the immersion device.

The immersion device is represented by the branch 51 of the arm 50 equipped with an angle iron 52, as in the embodiment described above. The immersion is done by rotation of the arm 50 and the exit from the cold tube by the opposite rotation of the arm 50.

The device for securing the air injection nozzle at the end of the tube is unchanged. He is not shown here.

Another variant of the immersion device may allow the tubes to be immersed in an inclined manner, one end being in contact with the cooling fluid before the other end.

The inclination which may be a few degrees, can be obtained by a continuous relative angular offset of the arms 9 relative to each other, or by thicknesses of the branch in the vertical direction at right angles to the variable and increasing angle 17 continuously for the different arms 9 distributed along the tank or by any other suitable means.

It is understood that the present invention is not limited to the embodiments described above by way of example, and that it can receive any desirable embodiment.

Claims (15)

1. Apparatus for rapidly cooling hot metal tubes comprising upstream transfer means for hot tubes, a quenching tank, an immersion device, means for transferring the hot tubes on to the immersion device, means for damping the tube, means for picking up, removal and downstream transfer of the cold tubes, characterised in that the immersion device comprises a longitudinal deflector (18) disposed at the lower line of and spaced from the tube (3) to be treated, so as to produce a symmetrical circulation of the cooling liquid around the tube during the phase of downward movement into the tank, and an air injection system (19) which is fixed to an end (23) of the tube to be treated, for blowing air into the tube at a high rate during the phase of downward movement into the tank and keeping it in an immersed condition.

2. Apparatus according to claim 1, characterised in that the cooling tank is provided with a plurality of cooling liquid injectors (7) which are distributed longitudinally in the tank.

3. Apparatus according to claim 1 or claim 2, characterised in that the same transfer means is used for the feed and the removal of the tubes.

4. Apparatus according to claim 1 or claim 2, characterised in that the means for transferring the hot tubes on to the immersion device, the immersion device itself and the device for picking up the cold tubes are totally or in part common.

5. Apparatus according to claim 1 or claim 2, characterised in that the deflector (18) extends continuously over the whole of the cooling tank.

6. Apparatus according to claim 1 or claim 2, characterised in that the deflector extends discontinuously over the whole of the cooling tank to permit the passage of handling arms.

7. Apparatus according to any one of claims 1, 2, 5 or 6, characterised in that the deflector is in the form of an angle member, the limb portions of which are extended by sliding plates (40, 41).

8. Apparatus according to any one of claims 1, 2, 5 or 6, characterised in that the deflector is adjustable in vertical position.

9. Apparatus according to any one of claims 1, 2, 5 or 6, characterised in that the angle member is adjustable in respect of its angle of opening.

10. Apparatus according to any one of claims 1, 2, 5 or 6, characterised in that the deflector is in the form of a rounded channel member.

11. Apparatus according to claim 1 or claim 2, characterised in that the air injection means is removable and can be introduced into the tube at the beginning of the phase of downward movement, then fixed to the corresponding end of the tube during the phase of downward movement and immersion of the tube.

12. Apparatus according to any one of claims 1, 2 or 11, characterised in that the means for fixing the air injection means (13) to the end of the tube is carried by a special arm (20) and comprises another arm (24) which oscillates about an axis member moved by a pushrod (26) and a cam (28) actuated by a set of gears.

13. Apparatus according to anyone of claims 1 to 12, characterised in that the tube is immersed in an inclined position in the tank containing the cooling liquid.

14. Use of the apparatus according to any of claims 1 to 13 at the discharge from a heating furnace.

15. Use of the apparatus according to any of claims 1 to 13 mounted at the discharge of a hot shaping apparatus such as an extrusion press.

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