EP0312843B1 - Process for heat exchange and its use in the controlled cooling of rolled products - Google Patents

Description

The invention relates to a device for temperature-controlled cooling of rolling stock during and after the roll deformation in successively arranged, flowed through water guide tubes, which in a nozzle head adjust the water with a presettable inlet pressure from a rolling nozzle which is brought into a feed pipe and which has a changeable ring nozzle - And definable outlet cross-section is supplied, the size of the outlet cross-section and / or the inlet pressure being dimensioned such that the ring nozzle becomes effective as an injection nozzle, mixtures of the water emerging from the outlet cross-section with air sucked in from the feed pipe with correspondingly different proportions of the mixture generated, and with a downstream wiper nozzle head.

In a known device of this type (US-A-2624178), a mixing chamber is arranged upstream of the feed pipe for the rolling stock brought into it, into which a pipe with a conical tip provided with a central through opening for the rolling stock protrudes. This conical tip forms an annular nozzle with the conical inner wall of the mixing chamber. To the Mixing chamber is tangentially connected to a water supply. The water supplied passes through the annular gap of the nozzle into the passage area of the rolling stock and swirls with air flowing in through the passage opening of the rolling stock. The swirled water-air flow travels through the guide tube in the opposite direction to the conveying direction of the rolling stock.

This device is not only structurally very complex and in particular uneconomical for a cooling section with a plurality of guide tubes arranged one behind the other and subject to high wear due to the high rolling stock speed, the main disadvantage is that the supply of air through the passage opening of the rolling stock is dependent on the Air flow rate depends on the rolling stock cross section. In addition, this air access cross-section changes abruptly each time the rolling stock runs in and out, so that the setting and maintenance of predeterminable mixing ratios of water and air can practically not be achieved with this device.

A similar proposal (GB-A 2 143 452), according to which the swirled water-air flow should not move in the opposite direction but in the conveying direction of the rolling stock through the guide tube, brought about an improvement in maintaining the mixing ratio of water and air, but was also able to do so do not guarantee the setting and maintenance of the mixing ratio over the entire cooling process. Another proposal (DE-A 27 14 019) to form the water-air mixture outside the guide tubes and to direct them to an opening of the guide tubes with spray tubes could not prevail in practical operation and also required a considerable amount of design effort.

The invention has for its object to improve the devices mentioned above so that this setting and control of the mixing ratio of water and air and its maintenance during the cooling process is made possible.

This task is accomplished by a remotely controllable actuator for setting the outlet cross-sections of the ring nozzles and an elastically supported, cross-section of the outlet, which can be arranged in and out of the cover position, behind the outlet of the rolling stock guide tube through which the water-air mixture flows and in front of the wiper nozzle head covering deflection cover released. The device allows the desired heat transfer coefficients to be changed and such numbers to be reproducibly set with the rest of the essentially unchanged initial conditions, such as water inlet pressure and water inlet temperature. The pressure and flow conditions within the respective rolling stock guide tube can be kept in equilibrium and stable. In conjunction with the remote-controlled setting of the outlet cross section of the ring nozzles, the elastically supported deflection cover deflects the cooling water jet emerging from the outlet downwards, if no rolling stock is moved through the rolling stock guide tube during breaks. In the case of larger diameters of the cooling tubes and the rolling stock, the deflection cover prevents the cooling water jet from acting on the rolling stock behind the outlet of the cooling tube, the cooling water jet the opposite wiper jet of the wiper nozzle head breaks through and may cause malfunctions. There is also the possibility according to the invention of providing the sensors which detect and report the swivel angle position of the deflection cover and the circumferential position of the rolling stock and a control device connected downstream thereof, which controls the swivel angle of the deflection cover in such a way that its outer edge maintains a definable distance above the rolling stock through it. This measure prevents the edge of the deflection cover from resting on the outer circumference of the rolling stock and thereby causing changes or damage to the rolling stock surface.

Finally, in an advantageous further development, there is also the possibility of dividing the rolling stock guide tube into two partial tubes if the mathematically required length of a single tube would result in an excessive pressure drop in the tube. In this case, the respective output and input of these partial tubes would be coaxially opposite each other at the front, the input of the second partial tube in a known manner as an inlet funnel and the output of the first partial tube from a tube section which tapers conically in the flow direction and which is in a cylindrical shape Pipe section merges, are formed, the tapered pipe section and the cylindrical pipe section have longitudinal recesses open to the pipe center axis. The total cross section of these longitudinal recesses is dimensioned such that the through cross section of these two pipe sections is approximately equal to the through cross section of the first partial pipe.

The division of the rolling stock guide tube has the further advantage that, in the event of any malfunctions during cooling operation, the sections of the rolling stock located in the guide tubes can be more easily removed from these shorter tubes.

A device according to the invention, which consists of a fixed nozzle head connected to the water supply with a conical funnel attachment and a rolling-material inlet pipe projecting and axially displaceable into this with a tapered start, can be designed as known from DE-U-71 34 676, that the inlet pipe is connected to the nozzle head by a screw thread and carries a worm wheel outside the nozzle head, which can be driven by a worm shaft. There is also the possibility of designing the device in such a way that levers connected to an actuator are articulated at the end of the rolling stock inlet pipe located outside the funnel attachment of the nozzle head and are rotatably mounted about an axis running at a distance transversely to the center axis of the rolling stock inlet pipe. The levers can engage as a pair of levers with a sliding cam arranged at their free end in an annular groove arranged at the end of the rolling stock inlet pipe and with their other end can be fixedly connected to the axle mounted above or below the rolling stock inlet pipe, which at one free end has one on one Piston cylinder unit carries the actuated lever. There is still the possibility that To connect inlet pipes of a plurality of nozzle heads arranged in parallel next to one another via levers rotatably mounted about a common axis with the actuator.

Avoid the latter forms of training, the disadvantage that is possible when using worm gears that the screw thread and worm wheel become stuck due to self-locking, and the setting of a plurality of nozzle heads arranged in parallel next to one another can be synchronized via a single drive.

Figur 1

die Gesamtvorrichtung von der Seite gesehen im Axialschnitt,

Figur 2 u. 3

Einzelheiten aus Fig. 1 ebenfalls im Axialschnitt in vergrößertem Maßstab,

Figur 4 u. 5

eine weitere Einzelheit aus Fig. 1 im Axial-und im Radialschnitt im vergrößertem Maßstab,

Figur 6 u. 7

Temperaturdiagramme von Abläufen der Arbeitsverfahren,

Figur 8

eine andere Ausbildungsform der Vorrichtung im Axialschnitt und

Figur 9

einen Schnitt nach der Linie A-A durch Fig. 8.

The invention is explained in more detail with reference to the embodiment shown in the drawing. Show in the drawing

Figure 1

the overall device seen from the side in axial section,

Figure 2 u. 3rd

1 also in axial section on an enlarged scale,

Figure 4 u. 5

1 shows a further detail from FIG. 1 in axial and radial section on an enlarged scale,

Figure 6 u. 7

Temperature diagrams of work processes,

Figure 8

another embodiment of the device in axial section and

Figure 9

a section along the line AA through Fig. 8th

As can be seen from FIGS. 1 to 3, a rolling stock guide tube FR consisting of partial tubes 2a and 2b is arranged in a fixed manner in the housing 1 in a housing 1. The nozzle head DK is placed on the input side E of the partial tube 2a and a centering projection ZA on the output side A of the partial tube 2b, behind which a deflection cover 4 is articulated in the housing 1 outside the tube part 2b. A wiping nozzle head ADK is also arranged in a fixed manner in the housing 1 at a distance behind the outlet A of the partial pipe 2b. The nozzle head DK and the scraper nozzle head ADK are connected to the water supply line ZL with a distribution pipe 5. A collecting trough 6, which leads to a drain 7, is arranged below the partial pipes 2a and 2b and the nozzle head DK of the centering projection ZA and the wiping nozzle head ADK.

As can be seen from FIG. 2, the nozzle head DK forms with a conical funnel attachment 8 and a thread-guided rolling stock inlet pipe 9, the conical tip 9a of which extends into the conical funnel attachment 8, an annular nozzle whose outlet cross section extends by turning the rolling stock inlet pipe 9 in the thread 8a of the nozzle head DK is changeable. The rotary drive consists of a worm wheel 10 placed on the rolling stock inlet pipe 9 and the worm shaft 11 meshing therewith, the drive of which is not shown. The water is fed to the nozzle head DK in the direction of arrow R3 from the distribution pipe 5 (FIG. 1). The conical funnel attachment 8 of the nozzle head DK is connected to the inlet E of the guide tube FR.

As shown in FIG. 3, the deflection cover 4 is arranged behind the output A of the wire guide tube FR in a manner not shown on the housing 1 about a pivot bearing DL, which is supported elastically by springs or other elements, not shown, from the dash-dotted line Deflection position in the passage position shown in full lines is pivotable. The wiping nozzle head ADK arranged behind this deflecting cover 4 in the direction of flow indicated by R6, like the nozzle head DK with a conical funnel attachment 12 and an inlet pipe 13, forms an annular nozzle whose outlet cross section is opposite to the direction of flow R6.

In the flow direction R6 in front of the deflection cover 4 (FIG. 4), as is known, a pipe extension 14 is arranged at the outlet A of the rolling stock guide pipe, which has a pipe section 14a which tapers conically in the flow direction and a cylindrical outlet pipe section 14b adjoining it (see FIG . 4 and 5). Both pipe sections 14a and 14b have longitudinal grooves 16 open towards the pipe center axis, here with a cross-section in the form of a circular section. The total passage cross section of these longitudinal grooves 16 is approximately as large as the passage cross section of the partial pipe 2a to be fed.

According to the invention, the device is operated as follows:
The rolling stock (the wire rod) D is brought from a feed tube, not shown, in the direction of arrow R6 (FIGS. 1 and 2) into the inlet tube of the nozzle head DK and further into the input side E of the wire guide tube FR. The cooling water passed through the distribution pipe 5 into the nozzle head DK passes through the outlet cross section of the ring nozzle formed by the conical tip 9a of the rolling stock inlet pipe 9 and the inner wall of the conical funnel attachment 8 into the considerably larger cross section behind this conical funnel attachment 8 a. By turning the rolling stock inlet pipe 9 in the thread 8a of the nozzle head DK, the conical tip 9a of the rolling stock inlet pipe 9 shifted axially in the direction of entry R6 until the negative pressure generated by the entry of the water from the exit cross section of the ring nozzle into the larger cross section of the conical funnel attachment 8 from the inner tube part of the rolling stock inlet pipe 9 contains the air surrounding the wire rod D in the pre-calculated subset. The resulting water-air mixture is then carried on in the rolling stock guide pipe FR, enclosing the outer circumference of the wire rod D, cools it down during the passage through the rolling stock guide pipe FR and, after leaving the rolling stock guide pipe FR in the outlet A, in a known manner through one of the direction of travel R6 inclined opposite water jet from the ring nozzle of the wiper nozzle head ADK from the peripheral surface of the wire rod D removed. The baffle cover 4 is in this operating phase in the passage position shown in full lines in FIG. 3. When the continuous wire rod D has left the exit A of the rolling stock guide tube FR and no further wire rod follows, the deflecting cover 4 moves into the deflection position shown in dash-dot lines and causes the cooling water jet emerging from the output A of the rolling stock guide tube FR to be deflected downwards, while at the same time maintains or stabilizes the pressure conditions necessary for the passage of rolling stock through the rolling stock guide tube FR. As already explained, deflecting the cooling water jet with the aid of the deflecting cover 4 prevents the cooling water jet from breaking through the opposing water jet of the wiping nozzle head ADK and thereby causing malfunctions or making it necessary that the water jet from the wiping nozzle head ADK must be considerably strengthened. which would result in a large additional water consumption.

The rolling stock guide pipe FR is, as can be seen from FIG. 1, divided into two partial pipes 2a and 2b. The outlet and the inlet of the two partial tubes 2a, 2b are coaxially opposite each other at the separation point at the front. The inlet of the second pipe section 2b is designed in a known manner as an inlet funnel and the outlet of the first pipe section 2a (see FIGS. 4 and 5) has pipe sections 14a and 14b which taper conically or cylindrically in the flow direction for centering the rolled material strand run. In order to ensure that the rolling stock D when it passes through these two pipe sections 14a and 14b is surrounded by a still sufficient jacket of the water-air mixture, the cooling effect of which is less than that of a water jacket consisting only of water, the passage cross section is through these two Pipe sections 14a and 14b of the tube extension 14 have been enlarged by longitudinal grooves 16.

An example of the cooling process when the wire rod passes through the rolling stock guide tube FR is indicated in a diagram in FIG. 6. The diagram shows the temperature profile of the outer circumference of the wire rod with curve 1, the average with curve 2 and the core with curve 3 and shows that the wire rod has already been cooled for 8 seconds after leaving the rolling stock guide tube FR so that a the entire wire rod cross-section has been reduced to 600 ° C. However, the required low heat transfer coefficient can only be achieved with a water-air mixture with a high proportion of air and requires a very long cooling tube that is not suitable for rolling operation.

From the diagram according to FIG. 7 it can be seen that a similar result can be achieved with rolling stock guide tubes arranged one behind the other, the total length of which is only half as long as that of the rolling stock guide tube according to FIG. 6 (cooling in 4 seconds). Different heat transfer coefficients are set by different dimensioning of the proportions of air and water in the water-air mixture, so that a drop below the surface temperature below a material-dependent surface temperature is avoided.

In the embodiment according to FIGS. 8 and 9, the end 9b of the rolling stock inlet pipe 9 located outside the funnel neck 8 of the nozzle head DK is mounted in a longitudinally displaceable manner in the nozzle head DK and is secured against rotation by a locking bolt 17. It has an annular groove 18 into which slide cams 19 engage, which are arranged at the free ends of a pair of levers 20 which are seated on an axis 21 which is supported in bearings 22 in the housing 1 of the device. The axis 21 runs below the rolling stock inlet pipe 9 transversely to its central axis. A control lever 23 is fixedly connected to the axis 21 and is articulated to a piston-cylinder unit (not shown) with the aid of the longitudinal connection 25.

When the piston-cylinder unit is actuated and the pivotal movement of the actuating lever 23 brought about, the pair of levers 20 pivots in the same sense and by the same pivot angle. The rolling stock inlet pipe 9 is displaced in one direction or the other of the arrow F in the nozzle head DK via the sliding cams 19 engaging in the annular groove 18 and thus the outlet cross section of the nozzle head formed between the funnel neck 8 and the conical tip 9 of the rolling stock inlet pipe 9 DK changed.

When a plurality of nozzle heads are arranged in parallel next to one another, corresponding lever pairs can be arranged on axis 21 in a manner not shown on this axis 21, the joint pivoting angle of which is then determined by the actuating lever 23 via the piston-cylinder unit.

List of reference numbers

1

casing

2a

Partial pipe

2 B

Partial pipe

3rd

Support bracket

4th

Deflection angle

5

Manifold

6

Collecting tank

7

Drain

8a

thread

8th

Funnel approach

9

Rolled material inlet pipe

9b

End (of the rolling stock inlet pipe 9)

9a

conical tip

10th

Worm wheel

11

Worm shaft

12

Funnel approach

13

Inlet pipe

14a

conically tapered pipe section

14

Pipe neck

14b

Cylindrical outlet pipe section

15

16

Longitudinal grooves

17th

Locking pin

18th

Ring groove

19th

Sliding cams

20th

Pair of levers

21

axis

22

warehouse

23

Control lever

24th

25th

Steering connection

E

Entrance / entry side

DK

Nozzle head

FR

Rolling pipe

A

Exit / exit side

ZA

Centering approach

ADK

Scraper nozzle head

ZL

Water supply

Claims (6)

1. Device for the temperature-controlled cooling of roll stock during and after the roll working in successively arranged roll stock guide tubes (FR), which are flowed through by water and to which in a nozzle head (DK) the water is fed with presettable feed pressure from an annular nozzle (8, 9c), which has a changeable, settable and fixable outlet cross-section and which surrounds the roll stock brought up in a feed tube, wherein the magnitude of the outlet cross-section and/or of the feed pressure is so dimensioned that the annular nozzle (8, 9a), becoming effective as injection nozzle, produces mixtures of the water issuing from the outlet cross-section with air sucked out of the feed tube with appropriately different proportions in the mixture and with a stripper nozzle head (ADK) arranged downstream, characterised by a remotely controllable setting drive (8a, 10, 11) for the setting of the outlet cross-section of the annular nozzles (8, 9a) and a resiliently supported deflecting cover (4) which is arranged behind the outlet (A) of the roll stock feed tube (FR) flowed through by the water-air mixture and in front of the stripper nozzle head and which partly covers the cross-section of the outlet (A) and is bringable into and out of a covering position.
2. Device according to claim 1, characterised by sensors detecting and reporting the angular position of the deflecting cover (4) and the circumferential position of the roll stock, and a control unit which is arranged downstream of the sensors and so controls the pivot angle of the deflecting cover (4) that the outer edge thereof stops at a fixable spacing over the through-flowing roll stock.
3. Device according to claim 1, characterised by levers (20) which are pivoted at the end (9b), which is disposed outside the funnel projection (8) of the nozzle head (DK), of the roll stock inlet tube (9), are rotatably mounted about an axis extending at a spacing transversely to the centre axis of said tube and are connected with a setting drive.
4. Device according to claim 3, characterised thereby that the levers (20) as a lever pair engage by slide cams (19), which are arranged at their free ends, in an annular groove (18) arranged at the end of the roll stock inlet tube (9) and are fixedly connected by their other ends, with the axle (21), which is mounted above or below the roll stock inlet tube (9) and which carries at a free end a setting lever (23) articulated to a piston-cylinder unit.
5. Device according to claims 3 and/or 4, characterised by a plurality of nozzle heads (DK) arranged parallelly beside one another, the roll stock inlet tubes (9) of which are connected with the setting drive by way of levers (20) rotatably mounted about a common axle (21).
6. Device according to one or several of claims 1 to 5, characterised thereby that the roll stock guide tube (FR) is divided into two part tubes (2a, 2b), the respective outlet and inlet of which lie coaxially opposite one another at a spacing at the ends, wherein the inlet of the second part tube (2b) in known manner is an inlet funnel and the outlet of the first part tube (2a) consists of a tube portion (14a) which conically narrows in flow direction and passes over into a cylindrical tube portion (14a), and at the same time both tube portions (14a, 14b) have groove-like longitudinal recesses (16) which are open towards the tube centre axis and the total cross-section of which is so dimensioned that the throughflow cross-section of these two tube portions (14a, 14b) is approximately equal to the throughflow cross-section of the first part tube (2a).

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