MXPA00012803A - Steam injection press platen for pressing fibrous materials - Google Patents

Abstract

A distribution platen (16), for use in a fiberboard press (10), having a molding cavity (17) and including a steam injection conduit (26) providing fluid communication into the molding cavity (17) from a remote supply of steam (28). The distribution platen (16) further includes a steam venting conduit (30) which provides fluid communication from the molding cavity (17) to a remote location. The press platen (16) allows for the continuous flow of steam into the molding cavity (17) through the dedicated steam injection conduit (26), and the continuous flow of steam and moisture from the molding cavity (17) through the dedicated venting conduits (30).

Description

VAPOR INJECTION PRESS PLATE FOR PRESSING FIBROUS MATERIALS FIELD OF THE INVENTION The present invention relates in general to the presses used to press fiber boards and more particularly, to a press plate used to press a conglomerate efficiently and effectively.

BACKGROUND OF THE INVENTION 10 Fiberboard products (particle boards) are formed by pressing and heating a conglomerate of resin-coated wood fibers until the resin cures and adheres the wood fibers together, forming a solid product of the wood. type of wood. The fiber boards are typically manufactured in the form of an MDF (Fiberboard Medium Density). MDF found its place in many industries as a low-cost functional table as an alternative to more expensive solid woods. Although the M DF can be used in many applications, the relatively low density of its fibers (ie, less than 0.7) is usually not sufficient to withstand details formed by the pressed in relief. For this purpose, a high density fiberboard (HDF) should be used. A conventional press used to compress a high density fibrous conglomerate and resin (or binder) to a particular molded configuration includes two opposing plates which together define a mold cavity. Typically, at least one plate through conduction such as through the use of electric heating resistors or by passing through appropriate conduits located in at least one of the plates. Although existing presses have been successful in manufacturing fiberboard products using only heat of conduction (hot pressing), current manufacturing demands require faster press cycles and the use of stronger resins. at elevated temperatures to produce fiberboard products with more pronounced, higher density and sometimes coarser details. The 0-fold increase in the curing speed of the material (or fibrous conglomerate) can be made by introducing steam into the conglomerate. The steam can be introduced into the mold cavity from a plate. The injected steam passes through "channels" or interstitial spaces in the fibrous conglomerate located within the molding cavity 5, and is dragged from the conglomerate by vacuum, or a suitable pressure differential through appropriate openings and conduits provided in the plate opposite. This known cross flow method for steam injection transfers the heat of the steam to the material that forms the fibrous conglomerate by convection of the heat 0 which effectively elevates the core temperature of the conglomerate rapidly and uniformly and allows the resin to cure uniformly and fast . One such press for the production of fiber boards by steam injection is currently available in Sunds 5 Defibrator, I nc. of Norcross, Georgia The press uses two plates of - uA, * »t. ^ J, .a.Ass. í vapor distribution; a * Upper plate injects steam downward into the molding cavity and material while the opposite lower plate vents the steam (and any resulting moisture or condensation) from the bottom of the material. 5 While this existing "cross-flow" press design allows steam to heat all areas of the conglomerate evenly and effectively, it prevents the use of a relief-forming plate where a surface of the cavity remains "clean", free of any injection nozzle, mesh, groove or opening so that it can be formed in relief the surface of the pressed material. U.S. Patent No. 4,168,877 issued to D.W. Nyberg describes a fiber board pressing system by steam injection which includes two opposing press plates defining a mold cavity into which the fibrous conglomerate is placed and press to obtain the desired configuration. Only a bottom plate is a fluid distribution plate that includes conduits and openings to provide fluid communication between the mold cavity and the external source of steam and a ventilation system separated by control valves. The upper plate does not include openings or nozzles ventilation or injection. The operation of the system of US Pat. No. 4,162,877, after placing the fibrous conglomerate within the molding cavity, steam is introduced from the supply of steam through the ducts and openings of the lower plate and is injected into the mold. pressed fibrous conglomerate located inside the cavity ad molding machine After a selected period of time, the control valves operate to close the steam supply then open the mold cavity to the ventilation system. The ventilation system uses the distribution plate to draw heat and moisture from the molding cavity. Because the opposite (top) plate of US Patent No. 4,162,877 is "clean", it can be used as a relief plate in order to print details on the pressed fibrous conglomerate, but only if the conglomerate has a lower density to 0.7. In In any higher density conglomerate, according to the patent, a mesh should be used to help prevent air entrapment in the conglomerate adjacent to the upper plate. The air that is trapped in the conglomerate prevents proper curing of the resin binder and therefore produces imperfections and weak spots in the final product. Unfortunately for many relief press applications the density of the fibrous conglomerate is greater than 0.7, and any use of a wire mesh as indicated in US Patent No. 4,188,877 would preclude the use of a plate with a surface for embossing. the opposite dish. Another problem that arises with the press plates described in US Patent No. 4.1 62,877 is that they can not allow a continuous flow of steam from a remote source through a plate, which passes through a prescribed area of the conglomerate. located inside the molding cavity, and that leaves the conglomerate through it plate. Because both the steam injection and the ventilation of moisture / vapor share the same system of ducts, passages and openings located within the lower press plate of the system of US Patent No. 4,188,877, this press system must alternate between the application of steam in the molding cavity a Through all the openings and the removal of steam (and moisture) from the cavity through all the openings. It is an object of the invention to provide a press for forming reliefs in fiber sheets that overcomes the deficiencies of the prior art. It is another object of the invention to provide said relief press that allows steam to flow continuously through a fibrous conglomerate located within a press mold cavity and simultaneously vent steam and moisture from the mold cavity at the same time as the press. ue maintains a surface for relief inside the cavity. According to a preferred realization of the present invention, a distribution plate for use in a fiberboard press has a mold cavity and includes a steam injection conduit that provides fluid communication in the mold cavity from a supply. remote steam. The distribution plate also includes a steam vent line that provides fluid communication from the die cavity to a remote location. The press plate allows continuous flow of steam into the molding cavity through the dedicated injection duct, and the continuous flow of steam and moisture from the t, A ..fe. ^. ^ *. »M the molding cavity through the dedicated ventilation ducts.

BRIEF DESCRIPTION OF THE DIAMETERS Figure 1 is a cross-sectional view taken essentially along the line 1 -1 of Figure 2 showing a fiberboard press according to the invention including an upper plate for relief, a lower distribution plate, internal distribution conduits, and fluid flow arrows. Figure 2 is a view of a partial plane of a distribution plate according to the invention showing the flow of vapor through the material located between the steam channels of the surface of the lower distribution plate. Figure 3 is a view of a partial plane of the distribution plate according to a second embodiment of the invention which shows details of the injection nozzles, the venting doors, the channels of the surface of the ventilation and supply plate; and Figure 4 is a cross-sectional view taken essentially along line 4-4 of Figure 3 showing details of the injection nozzles, the ventilation doors, the supply and ventilation con ducts.

DETAILED DISCUSSION OF THE PREFERRED EMBODIMENT With reference to Figure 1, there is shown a fiberboard press 1 0 (partially) including a top plate for relief 1 2, having a relief surface 14 and a plate lower distribution 1 6 defining a cavity defines a mold cavity 1 7, a longitudinal axis 1 8 and a pressing axis 20. As mentioned above, a binder is used to give the conglomerate or compressed fibrous material 22 , structural integrity and keep it in the newly molded form. These binders are usually thermosetting resins such as urea-formaldehyde, phenol-formaldehyde, resorcinol-formaldehyde, condensed furfuryl alcohol resins or organic polyisocyanates. The binder is added to the noncellulosic lig starting materials or fibers and the mixture or "material" becomes a fibrous conglomerate that is compressed between the previously described press plates while heat (usually in the form of steam) is applied to the conglomerate located inside the cavity. Steam is injected through material 22 either before, during or after or some combination, of which the compression of the conglomerate is made depending on eg the type of resin material and the properties desired for the product. finished. For a product of an embossed decorative board, the steam is preferably injected once the conglomerate is fully compressed or consolidated, usually until the binder of the material 22 is cured. The plates 1 2, 1 6 are opened and removed the product of cured and molded fiber board. As shown in Fig. 1, a perimeter dam 1 9 known in the art can be used to minimize edge losses and to otherwise stabilize material 22 during pressing. An important feature of this invention is that the surface U ^^^^ t * * - - for relief 14 is "clean" of any door, nozzle, opening or any other type of hole that could ruin or stain the surface of the material in which the relief is made. The pressing press allows to make the relief of the surface of the material 22 with a more pronounced detail. To ensure that all the material 22 is uniformly and completely cured in the fastest possible manner, a lower distribution plate 16 is provided with one or more supply conduits 26 to provide steam through the material 22 and one or more ventilation ducts. 30 to simultaneously vent or remove the vapor and any trapped and / or condensed air from the material l 22 in a continuous and free-flowing manner. The lower distribution plate 1 6 has a surface 1 5 which includes a plurality of injection nozzles 24 each of which is preferably aligned along the length of one of several steam supply conduits 26 as shown in Figure 4. The supply ducts Steam 26 according to the example of the present invention are shown in Figures 1 and 4 are shown oriented along a line substantially parallel with the longitudinal axis 1 8. The steam supply conduits 26 are joined and in fluid communication with a main steam supply conduit 28. Located adjacently and substantially parallel to the steam supply conduit 26 is a ventilation duct 30., and in flow communication with the ventilation duct 30 there is at least one and preferably several ventilation doors 32. Each ventilation door 32 provides fluid communication between the molding cavity 1 7 and the ventilation duct 30. Each vent 30 is attached and in fluid communication with a main vent pipe 34. The previously described conduits, pipes, nozzles and doors arrangement allows a dedicated supply of steam from a remote supply point through the supply conduit main 28, the steam supply ducts 26 and finally through each injection nozzle 24 so that the steam is injected together with the material 22 located inside the molding cavity 1 7. By injecting the vapor through the material 22, it is also extracted from the material 22 through the ventilation doors 32 the ventilation ducts 30 and finally through the tube Main Vent 34 Because steam can be continuously applied to the material 22 and simultaneously removed continuously from the material 22, the injected steam is forced to flow through the material 22 in a "cross-flow" manner without deteriorating or smearing the surface of the pressed product against the relief-forming surface 14 of the upper relief plate 1 2. As shown in Figure 1, when steam is injected (represented by the arrows) through the material 22 of the supply conduit 26 and the injection nozzles 24, flows through the material 22 in the direction of the nearest vent door 32, effectively heating a large area of the material 22 in the process. The embodiment of the distribution plate 1 6 shown in Figures 1 and 2 includes stepped injection nozzles with respect to »? .,you"?. Mt-? Fa-, M- > to ventilation doors 32. In an alternative embodiment (not shown). The ventilation doors can be located in coordinated alignment with the injection nozzles. The exact size and position of each injection nozzle 24 and vent port 32 can vary according to the specific characteristics of the material 22, the binder and the desired dimensions or properties of the article being manufactured. For example, the injection nozzles 24 located in thicker areas of the material 22, are preferably sized so that the steam injected from these nozzles 24 is injected deeper into the thicker material 22. To further facilitate steam distribution to all the areas of the conglomerate, the pressing surface 1 5 of the distribution plate 16 can also have surface channels 27 for the steam distribution of surface channels 31 for steam ventilation. Each surface vapor distribution channel 27 opens into the molding cavity 1 7 and is arranged in fluid connection with at least one steam injection nozzle 24. Preferably, a plurality of steam injection nozzles 24 they are located in the lower part of each surface steam distribution channel. Similarly, each surface steam vent channel 31 is opened to the mold cavity 1 7 and is arranged to remain in fluid communication with at least one steam vent door 32. Preferably, a plurality of vent doors are provided. steam 32 are located at the bottom of each surface steam ventilation channel 31 e ^ a »rafees * In another embodiment shown in Figures 3 and 4, a slit 29 is provided in the pressing surface 1 5 of the lower distribution plate 1 6. The slit 29 is suitably sized to receive a slotted thin plate (not shown) that further facilitates steam distribution and ventilation, and that acts as a support for the conglomerate on the steam distribution and ventilation channels, 27 and 31 respectively, and the steam injection nozzles and steam doors. ventilation 24 and 32 respectively. Any suitable conduit and tube arrangement 10 can be used to provide steam to the injection nozzles 24 and vent the vapor from the molding cavity 1 7 as described above and in accordance with the invention. The ventilation ducts 30 and the supply ducts 26 can be formed integrally within the lower distribution plate 1 6 by drilling or can be supplied through tubes separate and determined, attached outside the plate 1 6. The steam injection system described above includes the steam injection nozzles 24, the surface steam distribution channels 27, the steam supply conduits 26 and the spout of steam main 28, and the steam ventilation system including the doors of steam ventilation 32, the surface steam ventilation channels 31, the steam ventilation ducts 30 and the steam ventilation duct 34 that do not communicate with each other except through interstitial spaces or "channels" that exist in the interior of the fibrous conglomerate. The distribution plate according to the invention allows inject steam through the steam injection system, so that «Ai) 8 &e. .. *« fa «. «. t, 4 »-. * > - i i;,. *, _. »*****. *. * .., '**. ._ *. . . -. , «_- t ... s, t« t > fejfe »i (<» feit «-. flow through the "channels" of the material or conglomerate, and then out through the steam ventilation system as described above. This "cross-flow" action of the steam purges the air from the conglomerate. Once this is achieved, both the injection system and the ventilation system can be used to draw the high pressure steam through the conglomerate to speed up the curing process. At the end of the steam cycle when the binder is cured, both the injection system and the ventilation system can be used to vent the pressure inside the mold cavity and the conglomerate, ie Depressurize the mold cavity and the conglomerate. Although preferred embodiments of the invention have been described for illustrative purposes, those skilled in the art will appreciate that many additions, modifications and substitutions are possible without departing from the scope and spirit of the invention defined by the claims that are accompanied. ^ & amp;? $ ^ & amp;

Claims (23)

1. REVIVAL NAME IS 1. A distribution plate for use in a press for the manufacture of fiberboard products from a material, said distribution plate comprising: a generally flat contact surface for receiving and pressing said material; at least one steam injection nozzle located in said contact surface and adapted to be coupled to a steam source, whereby steam can be injected into said material, and at least one steam vent door located in said surface of contact and adapted to be coupled to a source of negative pressure to eliminate the steam injected from said material, the steam injection nozzle and the steam vent door being operable simultaneously during the operation of said press. The distribution plate according to claim 1, wherein said contact surface defines a first coordinated axis and a second coordinated axis, and further comprises means located within said distribution plate for a fluid communication between said at minus a steam injection nozzle and said steam source. 3. The distribution plate according to claim 1, wherein said contact surface defines a first coordinated axis and a second coordinated axis and further comprises means located within said distribution plate for fluid communication between d isha so less a ventilation door and said source of negative pressure. ., a *; »« .- a 4. The distribution plate according to claim 2, wherein said contact surface includes a plurality of steam injection nozzles that are uniformly spaced from each other and distributed over said entire contact surface. 5. The distribution plate according to claim 2, wherein said contact surface includes a plurality of ventilation doors that are uniformly spaced from each other and distributed throughout said contact surface. The dispensing plate according to claim 2, wherein said contact surface includes a plurality of ventilation doors and a plurality of steam injection nozzles that are uniformly spaced from each other and distributed throughout their contact surface, so that each steam injection nozzle is adjacent to at least one ventilation door. 7. The distribution plate according to claim 6, wherein the distance between two adjacent steam injection nozzles is approximately equal to the distance between any of said plurality of steam injection nozzles and at least one of said plurality of ventilation doors so that steam injected into said material from any one of said plurality of steam injection nozzles is locally ventilated by at least one adjacent ventilation door. 8. The dispensing plate according to claim 2, wherein said contact surface includes a plurality of steam injection nozzles that are uniformly spaced along each of the several inlet bellows. steam, said steam injection nozzle heads being generally parallel to each other and to said first coordinate axis, and said steam entering lines being disposed through said contact surface. The distribution plate according to claim 8, wherein said contact surface further includes a plurality of ventilation doors that are uniformly distributed along each of several rows of ventilation doors, said rows of doors being of ventilation generally parallel to each other and to each one of said rows of steam injection nozzles, said ventilation doors being arranged through said contact surface, and each of said rows of ventilation doors being located between two adjacent vapor injection blades. 1 0. A distribution plate for use in a press for the manufacture of fiberboard products from a conglomerate, said distribution plate comprising: a substantially flat contact surface for receiving and pressing against said material; at least one steam injection nozzle located on said contact surface and adapted to be coupled to a steam source, whereby vapor can be injected into said material; and at least one steam venting door located in said contact surface and adapted to be coupled to the atmosphere to remove the steam injected from said material, said boiler being the steam injection and said steam ventilation door. operable simultaneously during the operation of said press. eleven . The distribution plate according to claim 10, wherein said contact surface defines a first coordinate axis and a second coordinate axis and further comprises means for fluid communication 5 between said at least one steam injection nozzle. and said steam source. The distribution plate according to claim 10, wherein said contact surface comprises means for a fluid communication between said at least one ventilation door 10 and said atmosphere. The distribution plate according to claim 1, wherein said contact surface includes a plurality of steam injection nozzles that are uniformly spaced from each other and are distributed through said entire contact surface. The distribution plate according to claim 1, wherein said contact surface includes a plurality of ventilation doors that are uniformly spaced from each other and distributed throughout said contact surface. The distribution plate according to claim 1, wherein said contact surface includes a plurality of ventilation doors and a plurality of steam injection nozzles that are uniformly spaced apart from each other and distributed throughout the entire contact surface, so that each steam injection nozzle is adjacent to at least one ventilation door. 25 1 6. The distribution plate according to claim 1 5, - ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^? ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^ where the distance between two adjacent steam injection nozzles is approximately equal to the distance between any one of said plurality of steam injection nozzles and at least one of said plurality of ventilation ports so that the Value added between any of said plurality of steam injection nozzles is locally ventilated by at least one adjacent ventilation door. 1 7. The distribution plate according to claim 1, wherein said contact surface includes a plurality of nozzles of 10 steam injections are uniformly spaced along each of several steam inlet cells, said rows of steam injection nozzles being generally parallel to each other and uniformly spaced over said entire contact surface. The distribution plate according to claim 1, wherein said contact surface further includes a plurality of ventilation doors that are disposed equitably along each of several rows of ventilation doors, said rows of ventilation doors generally parallel to each other and to each of said rows of steam injection nozzles and being uniformly spaced across said contact surface, each of said vent door holders being located between two adjacent rows of steam injection nozzles. 1 9. The distribution plate according to claim 1, wherein said first and second coordinated axes are arranged in 25 orthogonal sense to each other and said means of fluid communication include at least one steam injection nozzle and said steam source at least one vapor passage formed integrally, and said vapor passage is connected to each of said at least one steam injection nozzle and said source of steam so that steam can be selectively displaced from said steam source through said vapor passage and said at least one steam injection nozzle to be distributed through said material. 20. The distribution plate according to claim 1, wherein said first and second coordinated axes are disposed orthogonally to each other and said fluid communication means between said at least one vent door and the atmosphere include at least one less an integrally formed vent passage, and said vent passage is connected to each of said at least one vent door and said atmosphere so that the water vapor located within said material can be selectively moved from said exhaust doors. ventilation to said atmosphere through said at least one ventilation passage. twenty-one . The distribution plate according to claim 2, wherein said first and second coordinated axes are disposed orthogonally to each other and said fluid communication means, between said at least one steam injection nozzle and the steam source. , include at least one vapor passage formed integrally, and said vapor passage is connected with each of said at least one steam injection nozzle and said steam source so that the vapor can be selectively moved from the vapor to the vapor. The source of steam goes through a steam passage and said at least one steam injection nozzle to be distributed through all said material. 22. The distribution plate according to claim 2, wherein said first and second coordinate axes are disposed orthogonally to each other and said fluid communication means, said at least one vent door and the source of negative pressure, they include at least one integrally formed vent passage, and said vent passage is connected to each of said at least one vent door and said negative pressure source so that the water vapor located within said vent can be entrained through said ventilation doors to said source of negative pressure through said at least one ventilation pad. 23. The distribution plate according to claim 9, wherein said first and second coordinate axes are orthogonal to each other and where each of said rows of steam injection nozzles is located generally parallel to said first axis. ¡, MÍ <--*."to,. -