EP0020246B1 - Cooling device for hot rolled elongate laminated products - Google Patents

Description

The invention relates to the field of heat treatments of rolled products and relates more particularly to a device for cooling long products in movement, in particular bars and concrete bars.

Such devices generally consist of a tube inside which the product and the coolant circulate, and the two ends of which are respectively equipped with a water supply, or injection head, and with a separator allowing avoid cooling water being entrained with the product at the outlet of the tube (FR-A-1584095). To avoid phenomena of heat build-up, which by local vapor formation, reduce the efficiency of heat exchanges, water is injected under high pressure, so as to form a blade circulating at high speed. The product to be cooled is also driven at a high speed, the circulation of water is usually carried out in co-current, with the passage of the product, in order to avoid entrainment of water by the latter, quickly leading to stagnation of the liquid and therefore a deterioration of the heat exchanges by the formation of a vapor film. This phenomenon is particularly marked with concrete bars because of their high running speed and the fact that they are generally crenellated. However, it is well known that, in the case of a co-current circulation, the efficiency of the heat exchanges is less good than in that of a counter-current circulation and that it is therefore necessary to longer tube length or higher water flow for the same cooling.

There are known water supply heads with adjustable slot, capable of being interposed between two aligned cooling tubes and which, by adjusting the width of the slot, makes it possible to adjust the ratio of the water flow rates in the two tubes. The circulation of the water naturally takes place in opposite directions in each of the tubes, so that the water and the product to be cooled circulate against the current, in one of the tubes and in co-current in the 'other tube.

These known supply tubes (see for example FR-A-2298378) generally consist of two coaxial tubular parts with conical fitting each comprising a central passage for the product in movement and delimiting between them an annular chamber for introducing the water, extended by a slot also annular formed between two frustoconical bearing surfaces provided respectively on the inner and outer tubular pieces, this slot being adjustable by axial sliding of the inner tubular piece, forming a socket, in the main body constituted by the outer tubular piece.

However, supply heads of this type, the movable sleeve of which is floating, therefore remote and independent of the cooling tube, do not appear to be able to be retained for cooling devices using a sheet of water in which any discontinuity in the passage of water would go against the establishment of a laminar flow at high speed.

In particular, the flat cam mechanism mounted at the top of a rotary control axis perpendicular to the displacement of the sleeve, as described in the pre-mentioned French patent application, may be suitable when the sleeve is floating. On the other hand, such a solution is hardly suitable for a device according to the invention in which the sleeve is integral with the cooling tube of which it constitutes the terminal part, since the control axis would work in torsion under a very high torque for manage to set in motion the socket-tube assembly which can reach several meters in length, or even beyond.

The object of the present invention is to provide improvements to the aforementioned cooling devices, in order to improve their performance as well as to facilitate, in the supply head, the sliding of the internal tubular part for adjusting the slot, when this part constitutes the end part of one of the two cooling tubes.

To this end, the subject of the invention is a device for cooling long rolled products in movement comprising a water injection head interposed between two aligned cooling tubes traversed by a blade of water and through which said product travels. , device according to which the injection head, ensuring the sealed connection between these two tubes at one of their ends, consists of two coaxial tubular pieces with conical interlocking each comprising a central passage for the product in movement and delimiting between them an annular water introduction chamber extended by an annular slot formed between two frustoconical bearing surfaces of the two tubular parts, respectively male and female and provided respectively on the inner tubular part and in the outer tubular part, said slot being adjustable in length and width by axial sliding of the internal part in the external part, and in which, relative in the given direction of travel of the product to be cooled, the outer part provided with the tapered female seat is connected to the downstream tube, the inner piece provided with the tapered male seat being connected to the upstream tube so as to ensure, on the one hand, a main water flow in the downstream tube circulating co-current with the moving product and, on the other hand, a secondary water flow against the current in the upstream tube, the axial sliding of the inner part in the outer room being obtained by cooperation between two sliding surfaces and two clamping surfaces arranged perpendicular to the sliding surfaces; one of the sliding surfaces being provided on the external surface of the internal part (FR-2 298 378, and characterized in that the other sliding surface is provided on the internal surface of the external part and in that said clamping surfaces are formed one by an annular ring provided on the inner part and the other by a shoulder of the outer part.

According to one embodiment of the invention, the depth of engagement of the interior part in the exterior part and defining the length and the width of the slot, is adjusted by interposing thickness shims between the annular crown of the part inner and the corresponding shoulder of the outer part.

The device according to the invention may furthermore include means for separating the moving product and the water layer arranged at the free end of each of two tubes.

Preferably, the device according to the invention comprises the features according to claim 4.

• -la figure 1 schématise l'ensemble d'une installation de refroidissement,
• - la figure 2 est une vue en coupe axiale d'un premier mode de réalisation de la tête d'injection,
• - la figure 3 est une vue en coupe axiale d'un autre mode d'exécution de la tête d'injection.

The invention will in any case be clearly understood in the light of the description which follows, given by way of purely illustrative example with reference to the attached drawing boards in which:

• FIG. 1 schematizes the whole of a cooling installation,
• FIG. 2 is a view in axial section of a first embodiment of the injection head,
• - Figure 3 is an axial sectional view of another embodiment of the injection head.

In order not to overload the figures, the processed product has not been shown, but its scrolling direction is indicated by an arrow and, throughout the text, the concepts of upstream and downstream will be defined relative to this scrolling direction. In all the figures, identical elements are designated by the same references.

In Figure 1, we can see at 1 the injection head, at 2 the downstream cooling tube, tightly connected to the latter and at the free end of which is disposed a separator 3. The upstream cooling tube 4 also comprises a separator 5 arranged at its free end, the other end being connected in leaktight manner to the injection head 1.

The cooling water enters the injection head 1 through the supply lines 6. Three of them are visible in this figure, but the supply could be carried out using a single line, or four or six, etc ... to ensure a better distribution, the arrivals can be balanced or voluntarily unbalanced to give the water a helical movement.

Inside the injection head 1, which will be described in more detail below, the water separates into two streams in opposite directions: a main stream downstream, a secondary stream with a lower flow rate, which is usually set at around 10-20% of the main flow, upstream.

The downstream current passes through the downstream tube at high speed and arrives in the separator 3 which ensures its evacuation. This separator 3 is identical to that described in FR-A-4 455 499 which will be referred to for more details, if necessary. It is essentially constituted by a box comprising two opposite lateral openings in the extension of the tube 2 through which the product surrounded and its liquid envelope and the dried product arrive and exit respectively. A water inlet 7 makes it possible to produce in the box a jet perpendicular to the downstream current, so as to cause its shearing. The latter is facilitated by weakening of the current using deflectors arranged in the box. The water is discharged through the collector 8.

The upstream current passes through the tube 4, then is separated from the product and evacuated by means of the separator 5 and the collector 10. The separator 5 is identical to the separator 3, although of smaller dimensions, but the product enters there through the upstream orifice and leaves it through the downstream orifice to engage in the tube 4.

In order to ensure uniform cooling while preventing the product from coming into contact with the walls of the cooling tubes, the latter are provided with one or more centering devices 11, only one of which has been shown on the downstream tube in order to do not overload the figure unnecessarily. These devices are identical to those described in FR-A-2 446 861 to which reference will be made if necessary. They essentially consist of a tubular element, coaxial with the cooling tube and of smaller internal diameter, having peripheral channels formed in its thickness.

Figures 2 and 3 will be described simultaneously because they have essential differences only at the level of the adjustment means.

The injection head 1 essentially consists of two coaxial parts 12 and 13 fitted one inside the other and cooperating together to ensure the circulation and the adjustment of the cooling water flow rates. The part or socket 12 is pierced with a central cylindrical channel 14 for the passage of the product and the cooling water, and has an internal diameter slightly smaller than the internal diameter of the cooling tube 4, so as to be connected to the latter, at its upstream end, forming a funnel. Its opposite end has a frustoconical bearing 15 to which corresponds a frustoconical recess 16 of the body 13, of substantially equal taper. The frustoconical recess 16 is extended downstream by a cylindrical duct 17, of the same internal diameter as that of the cooling tube 2 and secured to the latter by means of a flange 18 fixed to the body 13 by the screws 19. Upstream, the recess 16 is extended by an annular recess 33 inside which open the conduits 6 for introducing the cooling water.

The frustoconical bearing surface 15 of the frustoconical sleeve 12 is extended, upstream, by a bearing surface 21 which cooperates with a corresponding bearing surface 22 of the body 13 to ensure the longitudinal sliding of the sleeve 12 in the body 13. The bearing surfaces 15 and 21 , according to the relative position of the parts 12 and 13, define with the annular recess 33 a chamber 20 for introducing water, opening downstream in an equally annular slot 23 delimited by the bearing surfaces 15 and 16. This slot communicates at its other end with the circular channels 14 and 17.

The pressurized water, arriving via the supply lines 6, therefore enters the introduction chamber 20, passes through the slot 23 and separates at the outlet into two streams of opposite directions, a main stream directs towards the downstream and a secondary current, of lesser flow, directed upstream. The flow rate of the downstream current is determined by the pressure drop between the introduction chamber 20 and the downstream end of the tube 2 which is at atmospheric pressure. Only the water "in excess" compared to the flow rate thus determined, goes upstream, therefore towards the cooling tube 4. This pressure drop can be varied by increasing or decreasing the internal diameter of the tube 2, but this requires significant modifications to the installation. It is therefore preferable to keep this diameter constant and to act upstream of the tube. For this, provision is made to be able to vary the dimensions of the slot 23 by modifying the relative position of the parts 12 and 13. By sliding the frustoconical sleeve 12 inside the body 13, the thickness is in fact modified simultaneously and the length of the slit and, therefore, the pressure drop. We can thus adjust the ratio of upstream and downstream flows in a fairly wide range of values and therefore precisely control the two cooling stages so as to impose on the product a chosen thermal law and thus obtain the final structure and mechanical properties. desired.

Different technological solutions can be envisaged for adjusting the dimensions of the slot. Two of them are illustrated, by way of example, in FIGS. 2 and 3.

In the embodiment corresponding to FIG. 2, the depth of engagement of the frustoconical sleeve 12 inside the body 13 is adjusted by means of shims such as 24, of different thicknesses, interposed between the internal wall of an annular ring 25, adjacent to the bearing 21, provided on the sleeve 12 and a corresponding shoulder 26 of the body 13. The assembly is held in position by tightening by means of an external flange 27 fixed to the body 13 by the screws 28. O-rings are provided wherever necessary to seal the assembly.

This embodiment is of very simple design, but it has the disadvantage of requiring disassembly and a change of shim each time that one wants to modify the dimensions of the slot.

The variant shown in Figure 3, more elaborate, allows to obtain a continuous variation and a finer adjustment without requiring disassembly. For this, the annular ring 25 of the first embodiment is replaced by a ring 29 having on its internal face a thread 30 which cooperates with a thread 31 of the external wall of the body 13. By screwing and unscrewing, one can vary in continuous the depth of engagement of the frustoconical sleeve 12 inside the body 13. The two parts are held in the chosen position by blocking screws such as 32 abutting against the shoulder 26 formed by the face end of block 13.

Advantageously, the tube 4 consists of two parts fitted one inside the other, a short length portion 34 secured to the frustoconical sleeve 16 and able to slide inside the rest of the tube, so as to be able to make vary the dimensions of the slot by acting only on the frustoconical sleeve 12, without affecting the rest of the installation.

The invention is not limited in its scope to the examples described, in particular as regards the adjustment means and the means for maintaining the relative position of the frustoconical sleeve relative to the body. It is of general application to any long product running, but is particularly advantageous for concrete bars and rods whose final metallographic structure must be well controlled to give them the desired mechanical characteristics.

Claims (4)

1. A cooling device for continuously rolled elongated products, comprising a water injection head (11) located between two aligned cooling tubes (2, 4) through which pass a thin layer of water, with the product continuously travelling between said tubes, device according to which said injection head (1) obtaining a watertight connection between said tubes at one of their ends, is made up of two coaxial tubular parts (12, 13), conically fitting into each another, each of said parts showing a central passage for the continuously travelling product, and both parts defining between them, for the introduction of water, an annular chamber (20) extending into an annular slit (23) provided between two frusto-conical bearings of the tubular parts, respectively male (15) and female (16) respectively provided on inner tubular part (12) and in outer tubular part (13), said slit having adjustable length and width by axial sliding of inner part (12) in outer part (13), a device in which, with respect to the direction of continuous running of the product to be cooled, the outer part (13) provided with the female frusto-conical bearing (16) is connected to the downstream tube (2), the inner part (12) provided with the male frusto-conical bearing (15), being connected to the upstream tube (4) so that is obtained, on the one hand, in downstream tube (2), a main rate of flow of water in the direction of travelling of the product to be cooled and, on the other hand, in upstream tube (4), a secondary flow of water opposite to said direction, the axial sliding of inner part (12) in outer part (13) being obtained by a cooperation of two sliding bearings and two tightening bearings perpendicularly arranged to the sliding bearings; one (21) of the sliding bearings being provided on the outer surface of the inner part (12), characterized in that the other sliding bearing (22) is provided on the inner surface of outer part ( 13), and in that said tightening bearings are made up respectively by an annular ring (25) or (29, 32) provided on inner part (12) and by a shoulder (26) or (26') of outer part (13).

2. A device according to claim 1, characterized in that the depth of inner part (12) entering outer part (13), which depth defining the length and the width of slit (23), is adjusted through interposition of shims (24) between the annular ring (25) of inner part (12) and the corresponding shoulder (26) of outer part (13).

3. A device according to claim 1, characterized in that it further comprises, for separating the continuously travelling product from the thin layer of water, means (3, 5) arranged at the free end of each of the two cooling tubes.

4. A cooling device according to claim 3, characterized in that it comprises in at least one of the cooling tubes, at least one centering device (11) constituted by a tubular element coaxial to the cooling tube, the inner diameter of which is smaller than the inner diameter of said tube, said element having peripherical channels longitudinally grooved in its thickness.

Images