FR2632286A1 - ROLLER FOR HANDLING STEEL PRODUCTS MOVING INSIDE AN OVEN - Google Patents

Abstract

Roller for handling and conveying steel products inside a heat treatment furnace, characterized in that it consists of a tube 12 cooled, preferably with water, comprising a plurality of discs 14 circular perpendicular to the axis of said tube, each of these discs being provided with a tread 16 in contact with the product moving in the furnace, the discs being separated by an insulating refractory 18.

Description

The present invention relates to rollers intended to ensure the

  handling of steel products moving inside a furnace

heat treatment.

  It is known that, when moving a steel product inside an oven, this product must be brought to a determined temperature level, which requires the handling and conveying system of said product to be designed and produced according to the thermal ambient conditions defined for this product (high temperature in general) and also according to the

  product characteristics (load, nature, etc.).

  Furthermore, it is necessary that the solution adopted to ensure the movement of this steel product inside the furnace allows the product to move at different speeds, slow or high, to hold

account of industrial imperatives.

  Finally, the longevity of the handling and conveying system must be sufficiently long with respect to the other mechanical systems used in the furnace, that is to say that this handling system must be able to maintain

its initial level of performance.

  To solve the problems thus posed, the solutions currently known are of two types which are either suitable for heavy products, but which do not allow movement of the product at high speed (these are installations of the straddle spar type), either without limits in terms of the speed of movement of the product, but whose current designs are ill-suited in the case of a heavy product (these are installations of the

roller type).

  Among the roller type installations, the technique of conventional rollers made of centrifugal refractory steel is known, which has the disadvantage of being at the limit of the possible for temperatures greater than or equal to 1100 degrees, this solution comprising a cooled central tube. to water requiring a significant installed heating power, in order to compensate for the heat losses of these tubes. -We also know a handling system with ceramic rollers, but such a system presents problems of fragility with respect to mechanical shock. Finally, the also known system of providing a double-envelope roller proves to be too

  complex in terms of its realization.

  The present invention therefore proposes to provide a solution

  original technique to the problems posed above.

  To this end, it relates to a roller for handling and conveying steel products inside a heat treatment furnace, characterized in that it consists of a tube cooled, preferably with water, comprising a plurality of circular disks perpendicular to the axis of said tube, each of these disks being provided with a tread in contact with the product moving in the oven, the disks being separated by a

insulating refractory.

  According to a characteristic of this invention, the geometry of the discs is calculated so as to limit the thermo-mechanical stresses as well as the

heat losses.

  According to an exemplary embodiment of the invention, each of the discs consists of a spacer preferably comprising openworked parts, the fixing of the tread on said spacer being ensured by a

weld bead.

  According to the invention, the tread is regularly split on its inner circumference so as to facilitate its expansion. The fixing of each spacer on the cooled tube is ensured by lugs welded on the

  tube, ensuring both the load and the heat flow.

  Other features and advantages of the present invention

  will emerge from the description given below with reference to the accompanying drawings

  which illustrate various embodiments thereof without any limiting character. In the drawings: FIG. 1 is a schematic view in front elevation and partial vertical section of a first embodiment of a handling roller device according to the invention; Figure 2 is a schematic view on a larger scale showing a portion of a handling roller according to the present invention; Figure 3 is an axial sectional view illustrating the method of fixing by welding the spacer constituting a disc of a handling roller according to the invention; Figure 4 is a view similar to Figure 2, illustrating a second embodiment of a handling roller according to the present invention; Figure 5 is a sectional view through a vertical plane of another example

  for producing a handling roller according to the invention.

  Figure 6 is a partial sectional view through a diametrical plane of the roller illustrated in Figure 5, Figure 7 is an end view of another embodiment of a handling roller according to the invention and Figure 8 is a sectional view through a diametral plane of the roller

illustrated by figure 7.

  Referring firstly to Figure 1 which schematically shows a first embodiment of a handling roller for steel products moving inside an oven. The LO steel product has been designated by the reference 10 and it may consist, for example, of a slab or a strip moving continuously inside.

  from the oven where it is supported by the handling rollers.

  Each of these rollers consists of a central tube 12 preferably cooled with water, supporting a plurality of discs such as 14 arranged L5 perpendicular to the axis of the tube 12, each of these discs 14 being provided with a strip bearing 16 which is in contact with the product 10. The discs 14 are separated by an insulating refractory 18 intended to reduce losses

  thermal at tube 12 and discs 14.

  In the embodiment illustrated in FIG. 1, the discs are constituted by the spacer 14 - tread 16 assembly, their design meeting two requirements: one of a thermal nature, aimed at reducing and & controlling the losses and the other of thermo-mechanical order aiming to obtain an acceptable level of stresses, in the disc and in the tube 12 cooled to

the water.

  ! 5 In the embodiment illustrated in FIG. 2, each spacer 14 which, with its tread 16, constitutes one of the disks of the handling roller, has perforated parts 20, circumferentially in its width, and perforated parts 22 and 24, transversely to its width, respectively in the lower and upper part. The openwork parts 20, 22, 24 give rise to radiative type exchanges, making it possible to limit and control the heat losses by conduction, by reducing the conductive path in the spacer 14. Furthermore, these openwork parts have the advantage of

  reduce the contact surfaces at interfaces 26, treads-

  spacers and 28 tube spacers 12. In fact, at these interfaces 26-28, the thermal exchanges depend considerably on the quality of the contacts, which even if it is initially defined by the quality of the machining, is

  likely to vary over time by matting.

  Preferably, the fixing of the tread 16 on each of the spacers 14 is ensured by welding 30. The contact surfaces being reduced, the welding surface then imposes a proportion of contact of purely conductive type sufficient to ensure almost the entire transfer

  thermal by conduction between these contact surfaces.

  The exchange surfaces thus defined in the roller according to the present invention, which are purely radiative or conductive, have the advantage of remaining constant over time and making it possible to calculate the heat losses and the temperature gradients in the tube 12, in the spacer 14 and in the tread 16 of each disc, these characteristics of the roller being

constant over time.

  The fixing of each spacer 14 on the water-cooled tube 12 is preferably ensured (FIG. 3) by lugs such as 32-32 ′ which are welded to the tube 12 and which transmit both the load and the flow thermal, these tabs providing a certain flexibility, as regards the fixing of each disc (14-16) on the tube 12, while allowing a radial expansion of the disc without increasing the stresses in the tube 12 and in the disc too considerably . These legs can be provided either from the same

  either side of the disc and the spacer.

  According to the invention, the tabs such as 32 32 ′ ensure both the transmission of the load, the flexibility of the disc / tube attachment and the control of the heat losses and the temperature distribution of the disc as a function of the length / section of the leg, location and surface of the

welding of the tab on the tube.

  The adjoined parts 22-24 of each spacer 14 have the advantage of relieving the stresses in particular in the spacer which undergoes a significant thermal gradient and it is possible, according to the invention, to provide relaxation slots such as 34 when the stresses in the spacer reach

too high a value.

  In order to facilitate the expansion of the tread, it can be provided with slots such as 36, regularly distributed over its inner circumference. In the embodiment illustrated in FIG. 4, each of the discs 38 supported by the water-cooled tube 12, is made up of a monobloc assembly also comprising perforated parts 40 and relaxation slots 42. As well as as can be seen in FIG. 4, these relaxation slots 42 open onto the external circumference of the disc which constitutes the rolling surface on which the steel product to be conveyed rests. Here again, the discs 38 are separated by an insulating refractory 18 reducing the heat losses at the tube 12 and the discs 38, this refractory material 18 being able to be

  covered with a refractory strip 44.

  In the exemplary embodiment illustrated by FIGS. 5 and 6, each of the disks 46 mounted on the water-cooled tube 12 consists of a one-piece assembly 0 provided with relaxation slots 48, the fixing of each disk on the tube 12 being produced by means of a leg 50 preferably welded

  on the outer circumference of the tube 12.

  The variant of the roller according to the invention, illustrated by the figures? and

  8 is intended for conveying thin slabs.

  In this variant, the disc 14 'is in one piece and it comprises on the one hand perforated parts 22' 24 ', like the disc 14 described above with reference to FIG. 4 and, on the other hand side tabs 32' "which are welded on the same side of the disc and which are also welded on the cooled tube 12, as

  described above with reference to Figure 3.

  W0 The discs or the spacers which constitute them can be made of special alloys and these discs can be of the combed type, in order to remedy

  to the drawbacks which may result from creeping of the slabs between two rollers.

  As can be understood from reading the above description,

  the invention provides a solution to the problem set out in the preamble to the

  Z5 presents description by limiting the heat flow between the products

  handled and the central tube 12 cooled with water, the geometry of the discs being calculated so as to limit, as has been specified above, on the one hand

  thermomechanical constraints and on the other hand heat losses.

  It remains to be understood that the present invention is not limited to the various embodiments described and shown, but that it encompasses

all variants.

Claims (8)

  1- Roller for handling and conveying steel products inside a heat treatment oven, characterized in that it consists of a tube (12) cooled, preferably with water, comprising a plurality of circular discs (14) perpendicular to the axis of said tube, each of these discs being provided with a tread (16) in contact with the product moving in the oven, the discs being separated by a refractory insulator (18).   2- Roller according to claim 1, characterized in that the geometry of the discs is calculated so as to limit the thermomechanical stresses as well as heat losses.   3- Roll according to one of claims 1 or 2, characterized in that   each of the discs consists of a spacer (14) preferably comprising perforated parts (20, 22, 24, 22 ', 24') fixing the tread   (16) on said spacer being provided by welding (30).   4- Roller according to any one of the preceding claims,   characterized in that the tread (16) is regularly split <36)   on its inner circumference so as to facilitate its expansion.   - Roll according to any one of the preceding claims   characterized in that the fixing of each spacer or of each disc on the cooled tube is ensured by lugs (32, 32 ', 32' ') welded on the tube, ensuring both the load and the heat flow, either on the same side either of   on either side of the disc or spacer.   6- Roller according to any one of the preceding claims, characterized in that the tabs (32, 32 ', 32' ') are designed so as to ensure both the transmission of the load and the flexibility of the disc / tube attachment and control of heat losses and temperature distribution of the disc or spacer depending on the length / section of the tab and the location as well as the surface of the welding of the tabs on the tube cooled.   7- Roller according to any one of the preceding claims,   characterized in that each spacer is provided with relaxation slots 34,   preferably provided on the perforated parts (22, 24) of said spacer.   8- Roller according to claim 1, characterized in that each disc is made in a single piece (38, 46) and it has perforated parts (40) and relaxation slots (42) which, preferably, lead to its   outer circumferential surface.   9- Roller according to any one of the preceding claims,   characterized in that each disc has a tab (50) ensuring its attachment to the water-cooled tube (12).   - Roll according to any one of the preceding claims,   characterized in that the insulating refractory lining 18 separating each of the   discs is covered with a refractory strip (44).