FR2638736A1 - PROCESS FOR PRODUCING FIBER MOLDED BODIES, ESPECIALLY REFRACTORY, AND MOLDED BODIES OBTAINED BY THIS PROCESS - Google Patents

Abstract

Process for producing molded fiber bodies using a preparation containing water, incombustible and / or refractory fibers, at least one binder and optionally other customary addition materials. Fiber moldings 12 are made from the preparation, dried and optionally heat treated and / or fired. A preparation is used whose consistency allows projection. The preparation is projected into an opening of a tunnel mold 2 having at least one wall arranged as a conveyor belt 1; and through the tunnel mold, by means of the conveyor belt, the preparation projected into the tunnel mold and shaped into a molded strand of fibers 11, having its cross section fixed by the tunnel mold, is transported.

Description

PROCESS FOR PRODUCING NOVEL FIBER BODIES, NOTAMXENT

  REFRACTORIES AND MOLDED BODIES OBTAINED BY THIS PROCESS

  The invention relates to a method for producing fiber molded bodies using a preparation containing water, incombustible fibers and / or refractory fibers, at least one binder and possibly other usual additives, bodies. nmoulés in fibers being produced from the preparation, dried and

  possibly heat treated and / or cooked.

  It is known to produce molded bodies of ceramic fibers using a vacuum-suction process (see patent

  German DE-OS 34 44 397). This requires large amounts of water.

  For example, in the case of the vacuum-suction process, 1000 1 to 10 kg of fibers are added. During drying, the water must be removed and then purified. This involves environmental problems and

is complicated and expensive.

  In the vacuum suction process, organic binders are used. These are a significant cause of nuisance when drying or cooking the fiber molded body. When a fiber molded body is produced by the vacuum-depressurization process, the fibers are inevitably oriented in layers. The fiber molded body then has the drawback of being capable of breaking down into layers, in particular under the effect of alternating thermal stresses, since the fibers are only weakly bonded to one another from one layer to another. Another drawback: due to this arrangement of the fibers, the fiber molded body has different thermal insulation values in the longitudinal direction and

in transverse direction.

  In addition, the possible thickness of the fiber molded bodies and

  their stability is bound, so that the process with aspiration-

  - depression is practically unsuitable for the rational production of molded bodies of fibers such as, for example, light bricks

in fibers.

  It is also known to produce linings or coatings by means of a spraying machine. The fibrous material is then directly projected onto the wall to be lined. The possible thickness of such a coating is however also limited. In addition, surfaces are obtained from which fiber particles can be easily detached. Furthermore, the success of such a process depends to a large extent on the care taken by the operating personnel of the projection device. German patent DE-AS 26 18 813 and European patent EP-A2-213 707 describe fibrous masses for projection. It is also known to produce fiber mats by needling. It is however impossible to carry out by needling

bricks molded in fibers.

  The object of the invention is to propose a method with which

  can achieve with a simple apparatus a molded body of fibers.

  The invention also aims to provide a molded body of fibers

  suitable for the construction of a lining.

  According to the invention, the first mentioned object is achieved by the fact that a) a preparation is used whose consistency allows projection;

  - b) the preparation is projected into an opening of a mold -

  tunnel; c) a tunnel mold is used, at least one wall of which is arranged as a conveyor belt; and - d) is conveyed through the tunnel mold, by means of the conveyor belt, the preparation projected into the noule-tunnel and comfortable in the form of a strand molded in fibers, having its cross section

fixed by the tunnel mold.

  The water content of the preparation is therefore significantly lower than in the case of the process with suction-depression. When drying, only significantly smaller amounts of water should be removed. The mold fixes at least two dimensions of the fiber molded body. The projection is then carried out using a tunnel mold whose opening in which the preparation is projected is flared in

funnel shape.

  Mineral binders are sufficient to obtain a semi-liquid pasty preparation, so that environmental problems

  inherent in organic binders disappear.

  In a preferred embodiment of the invention, a tunnel is used as a mold which, on the underside, is closed by a conveyor belt. The preparation is sprayed on one side of the tunnel and transported through it by the conveyor belt. Two dimensions (height and width) of the fiber molded body are then determined by the cross section of the tunnel. It is a tube having the cross section of the molded fiber bodies which comes out of the tunnel. The ease of implementation of the process obviously requires only a little material

  complicated. The process can be carried out continuously.

  The cross section of the tunnel is adapted to the cross section of the fiber molded bodies. Fibrous molded bodies of various cross sections can be manufactured by simple modification or adjustment of the tunnel. By adapting the quantity of preparation projected per unit of time in the tunnel, and the speed of advance of the conveyor belt, it can be ensured that the straight section of the tunnel will always be filled

mixing or preparation.

  A fiber molded body, produced by the aforementioned method, is distinguished by the fact that the fibers within this molded body have random orientations, and that the binder is mineral. The random, tangled distribution of fibers within the molded body improves the stability of the latter. The fiber molded body has great resistance to temperature fluctuations. In addition, the thermal conductivity of the fiber molded body is the same in all directions. At least in its four sides formed by the transport of the tube through the tunnel, the fiber molded body has a smooth surface. The tendency for the fibers to be pulled from the surface is

significantly reduced.

  The process indicated makes it possible to modify, within wide limits, the content of binder to the content of fillers, so that the properties of the fiber-coated body can be

  easily adapted to specific conditions of use.

  The characteristics and advantages of the invention will become apparent

  more fully in the description presented in the following, at

  by way of nonlimiting example, with reference to the appended drawing, the figures of which represent: - Figure 1, schematically, the course of the process; and - Figure 2, on a larger scale, in section taken along

  of line II-II of Figure 1, an elevational view of the mold.

  A conveyor belt 1 has been provided above which a tunnel 2 is mounted. This tunnel 2 has side walls 3, 4 as well as an upper part 5. GCt below, the tunnel 2 is closed by the conveyor belt 1. On its first side 6, the tunnel 2 is flared in the form of a funnel, by a wall 7 extending its upper part 5. The side walls 3, 4 can also be flared correspondingly. On its side 8 opposite side 6, the tunnel 2 has the cross section (width B and height H) of the strand molded in fibers to be produced. The cross section of the tmunnel 2 can be easily adjusted to the cross section of the molded fiber bodies which it is for example to produce, by dimensioning so

  corresponding the side walls 3, 4 and the upper part 5.

  A projection head 9, directed towards the tunnel 2, is arranged in front of the flared funnel-shaped side 6 of the tunnel 2. The projection head 9 is connected to a projection machine 10 of a common type, in which produces a mixture of ceramic fibers, a mineral binder in an aqueous medium and water. The addition and mixing of the binder in an aqueous medium and of water can also take place directly in the projection head 9. Optionally, fillers

  are also brought to the projection machine 10.

  Like ceramic fibers6, short, chopped fibers up to 25 mm in length are used, most of which have a diameter of 3 pu. The fibers consist of 47% by weight of Al2CO and 53% by weight of SiOn, for use temperatures up to 1260C. For higher temperatures of use, fibers having 95% by weight of A12C3 are used

and 5% by weight of SiOn.

  One uses a binder of colloidal SiO2 which, in commercially available preparations, is 40 to 60 in water. The percentage of binder can reach Up to 20% by weight relative to the fibers, filler material possibly included. Of

  preferably a weight percentage of 10 X to 15 t of binder is used.

  A1203 or Zro [suitable as fillers. For special use cases, charcoal dust can also be used as a filler material which oxidizes, under exothermic reaction, when it is subjected to the action of heat. One can also use as filler plastics known under the trade name wovolake ", which, when subjected to a reductive baking form a carbon skeleton in the body molded in fibers. It is also possible

  use fibers with corresponding properties.

  The percentage of fillers in the mixture can be freely chosen, within wide limits, depending on the conditions of use of the molded rod, or of the molded bodies, made of fibers. This is how the fiber molded sausage can contain up to 90%

weight of fillers.

  The density of the strand molded in fibers, or of the bodies molded in fibers which it is to manufacture, can be established by varying the length of the fibers, the percentages of binder and of filler material (s), the pressure of discharge of the mixture, which is typically 0.5 bar, and the speed of the conveyor belt 1. As a general rule, the density of the strand molded in fibers, as a material

  light, is between 300 and 500 kg / nP.

  The preparation described is projected, by the projection head 9, in the direction of the tunnel 2, onto the conveyor belt 1. The movement of the conveyor belt 1 in the direction of the arrow P has the effect that the mixture enters the flared side in the form of a funnel 6 of the tunnel 2 in which it is pulled, the direction of projection of the head 9 promoting this movement. Ia funnel shape on the side 6 leads to a compaction of the mixture towards the cross section B, H. The fibers are uniformly distributed in the mixture, randomly. The movement of the conveyor belt 1 has the effect that a dimensionally stable rod 11, made of the packed mixture, having the

  straight section B, H. comes out continuously through the open side 8 of the tunnel 2.

  The speed of the conveyor belt 1 and the flow rate of the preparation supplied by means of the projection head 9 are mutually harmonized, so that there is no collapse reducing the cross section B, H of the flange 11. The friction produced between the flange 11 and the sides 3, 4 and the upper part 5 of the tunnel 2 has the effect of smoothing the relevant surfaces of the flange 11. The surface of the flange 11 applied to the conveyor belt 1 becomes smooth under the weight of the

sausage 11.

  Following the conveyor belt 1, a section 12 of the flange is moved on a plate of a batch of plates 13. The plate 13 with the section 12 is moved through a dryer 14. No particular problem concerning the effluent air is not present in the dryer 14, since there is no organic binder in the flange 11 or else

in sections 12 of it.

  After the dryer 14, the sections 12 can be cut to the lengths of the fiber molded bodies to be obtained. It is also possible to first place the dried sections 12 on a tunnel oven carriage 15, and to bake them in a tunnel oven not shown in detail. This eliminates the withdrawal or contraction of the bodies

  molded in fibers, occurring at high operating temperatures.

  As the devices described for producing the fiber molded bodies are simple, the process is also very quickly adaptable to the manufacture of fiber molded bodies having different dimensions and compositions, the usual dimension being worth

64 mm to 114 ma x 230 mm.

  The fiber molded bodies thus produced are stable, both overall in the presence of alternating thermal stresses and with regard to their free surface in the case of the lining.

of a volume.

  In another embodiment of the process, the preparation can also be sprayed into a series of molding boxes open only at the top, which are then demolded from the top.

REVEIDICATIO! S

  1. Process for producing fiber molded bodies using a preparation containing water, non-combustible fibers and / or refractory fibers, at least one binder and possibly other usual additives, fiber molded bodies being made from the preparation, dried and optionally heat treated and / or cooked, characterized in that - a) a preparation is used whose consistanoe allows projection;

  - b) the preparation is projected into an opening of a mold -

  tunnel; c) a tunnel mold is used, at least one wall of which is arranged as a conveyor belt; and - d) is conveyed through the tunnel mold, by means of the conveyor belt, the preparation projected into the tunnel mold and is comfortable in the form of a strand molded in fibers, having its cross section

fixed by the tunnel mold.

  2. Method according to claim 1, characterized in that a tunnel mold is used, the opening of which is projected into

  the preparation is flared in the form of a funnel.

  3. Method according to any one of the preceding claims,

  characterized by the fact that the preparation is produced in a

  projection which is directed on the opening of the tunnel.

  4. Method according to any one of the preceding claims,

  characterized by the fact that the molded rod is cut into the mold-

  tunnel, and that each section is brought, by the conveyor belt, to

  a plate on which it is dried.

  5. Method according to claim 4, characterized in that

that we cook the dried section.

  6. Method according to any one of claims 4 or 5,

  characterized by the fact that the dried and / or baked section is cut

  length of bricks molded in fibers.

  7. Method according to any one of the preceding claims,

  characterized by the fact that a preparation is used in which at least one binder is added and mixed with the fibers, in proportion

  5 to 20% by weight, based on the weight of dry fibers.

  8. Method according to claim 7, characterized in that the weight proportion of binder is 10 S.

  9. Method according to any one of the preceding claims,

  characterized in that a preparation is used in which, in addition to the fibers, non-combustible fillers are used

and / or refractory.

  10. Method according to claim 9, characterized in that one uses a preparation containing fillers at a rate

from 10 to 45% by weight.

  11. method according to claim 10, characterized in that

  whether A12k or ZrO2 is used as a filler.

  12. Method according to any one of claims 1 to 11,

  characterized in that a preparation is used which contains, in addition to the fibers and any incombustible and / or refractory fillers, fine-grained carbon or a plastic material

  which, during a reductive cooking, generates a carbon skeleton.

  13. Body molded in fibers, made of incombustible and / or refractory ceramic fibers linked by a binder, characterized in that it is produced by the process according to any one of

previous claims.

  14. body wound in fibers according to claim 13, characterized in that the fibers within the molded body have orientations

  random, and the binder is a mineral binder.