Patent Publication Number: US-5628955-A

Title: Method of manufacture of structural products

Description:
This invention relates to manufacture of fibrous, cementitious and clay products; a related invention, titled &#34;Construction Components and Assembly System&#34;, as U.S. Application Ser. No. 08/438,806 makes use of this technology to obtain a very small tolerance necessary for that invention. 
     Casting, pressure molding and extruding have long been necessary for forming cementitious products. A very small tolerance is not possible using these methods without loss of other desirable attributes. Without sufficient plasticity, voids within the product result and an acceptable finish can not be accomplished with today&#39;s molding, casting and extrusion technology. Use of flammable resinous materials is not a viable alternative even though an insulated, fire resistant cover is applied, due to resulting bonding and insurance problems. 
     However, reduction in strength and loss of accuracy resulting from excess moisture or molding pressure can be overcome by the sapient use of electrical and magnetic forces. An acceptable finish, fiber alignment and a dimensionally accurate, stable and strong product can be fabricated from nonplastic cementitious materials by use of this technology. Other problems such as equipment wear due to abrasion, and adhesion of cementitious material to the mixing container can also be avoided. 
     Unrestrained rod shapes such as fibers, and elongated fragmented particle, and filaments containing graphite, carbon and, or iron will readily align with iron rods when passing through a weak magnetic field. Other moisture coated rod shapes of materials will also react in the same manner. Aggregates in fragment form will form clusters with sharp edges in contact and nearly parallel peripheral surfaces. Moreover, when attracted to magnetized surfaces, these rod and fragmented shapes will remain aligned and will adhere closely to the magnetic surface; thereby allowing spaces and voids to be eliminated. Cement and color filaments will also be attracted to a magnetized surface to provide an acceptable finish. Consolidation may follow for successive layers of fibrous and fragmented media. The resulting nonplastic matrix will set and cure to form a dimensionally accurate, stable and strong product. 
     The process begins by moving materials from storage vats. Controlled weights, electrical charge and magnetic force must be maintained throughout all processes and steps. A supervisory control center is required for not only these processes but also for coating, flow, alignment and depositing of fibers, as well as movement of a shaping device and shaping tools. Fibers must be separated and impressed with a charge prior to coating in order to assure that cement is in contact with all surfaces. By adding a wetting agent to control the surface tension of the setting agent, and by controlling the amount of setting agent, sufficient agent can be applied to cause the cement to set while excessive setting material can be avoided which would result in a poor quality product. If flammable cements and catalysts are used, inert gasses should be used to purge oxygen from the environment in order to prevent ignition. Premixed cement and fibers, now readily available in most markets, may be used, but coating and aligning are more difficult. Aqueous solutions, when used as a catalytic agent, will facilitate alignment due to electrical flow along surfaces. Although the setting agent may be added to the fibers after alignment, the preferred method is to insert it before alignment to prevent fiber displacement during the coating action. Coating of fibers with a setting material containing a wetting agent prior to adding cement is a convenient way to ensure against excessive setting material. Other agents such as those effecting air entrainment, hardening and bonding may be added to the setting material to improve product characteristics. An air blower of the squirrel cage type is used to force cement toward fibers and into a thin sheet in the coating step. Providing an electrical charge to the mixing and aligning device will enhance the process to prevent premature adherence of the cementitious material to the container since the repelling magnetic force is very small. 
     After the coating step, the cement, a setting and solidifying agent, (aqueous or resin materials), and fibers, will be directed in a thin sheet, flowing through a magnetic field modified by a grid of parallel magnetized rods carrying an electrical current (supervised by the control center) to align fibers and filaments in direction and plane. The grid should be controllable to allow rotation around a vertical as well as horizontal axis. The magnetic field may be created by permanent magnets and/or electromagnets. Fiber direction may be rotated or otherwise changed by moving the aligning rods about vertical as well as horizontal axes. The electrical flow and magnetic field may be very small during this alignment step. Excessive current will result in small holes in the shaped product. The controlled, aligned and coated fibers should then be passed to a shaping device containing attracting magnetized iron surfaces. A pushing magnetic force field will be required at the discharge with the field directed parallel with the media flow for nonmagnetic fibers and cement. However, it should be noted that most hydraulic cements, other than white cement, contain sufficient iron oxides to be considered magnetic for this invention, while resinous cements may, or may not, contain sufficient iron oxides. 
     After the fibers are aligned in a thin sheet, either parallel or perpendicular or angular relative to a primary face of the product, fibers are attracted to surfaces defining the product. Multiple layers are deposited and consolidated until the desired shape is reached. Products having undercuts made by shaping tools where the attracting surfaces are not facing the flow of fibers, must be shaped by increasing the magnetic attracting force of that surface until all cavities are filled. The fiber and cement mixture is not plastic, therefore present technologies are not applicable. However, all cavities are now filled; voids have been avoided; and contact with the shaping surfaces assures satisfactory finish surfaces. When the shaping stage is completed, the shaping device is moved to accomplish initial set. 
     When initial set is completed, poles of the attracting magnetized tool surfaces shall be changed, obstructing shaping tools shall be removed, and the product shall be released and moved to final curing. All processes, movements, weights, electrical circuits, and magnetic fields must be supervised by a central control from bulk storage vats to final curing. In summary, by sequence, from storage vat to product storage; the following steps apply: moving and weighing material, impressing electrical charge and magnetic field, separating fibers, coating fibers with setting agent and cement, aligning fibers, depositing fibers on shaping tool surfaces, application of layers until the shape is completed, accomplishing initial set, reversing poles, removing tools, removing product. 
     Materials used for the various components of this invention will be selected from available commercial products. Selection of specific materials must be flexible to adjust for market conditions, availability of new fiber products, and local codes. Some high strength fibers are damaged by caustic cements. When the alkalinity of the cement is within the acceptable range for the fiber to avoid permanent damage, and bonding between the fiber and the cement occurs, fibers and cements are referred to as being compatible. 
     Materials are described by generic nomenclature; since commercially available products differ in physical characteristics, each product must be tested to ensure alkalinity and bonding compatibility with other products. 
     Cementitious materials in particulate form include hydraulic cements such as low alkalinity Portland, pozzolana, and calcium aluminate cements; resinous cements such as heat, moisture and catalytic curing cements; fireclays, kaolin, low alumina clays, gypsum; aggregate materials contained within referenced cementitious materials include basalt, volcanic, other igneous, terra-cotta, and hard clay materials. Resinous cementitious material should be enclosed in hydraulic cementitious or gypsum covers. Catalyists to effect solidifying and bonding include chemical additives and agents to effect desired wetting characteristics, improve bonding and elasticity, air entrainment. Additives and agents will be in aqueous, resinous, and latex forms. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of alignment and consolidation elements. 
     FIG. 2 is a detail sectional view from FIG. 3 to show movement of shaping tools necessary for product release. The release of the product from the shaping device is a major constraint. 
     FIG. 3 shows a more detailed view of the shaping device in FIG. 1 and FIG. 5 ready for placing fibrous media upon attracting magnetic surfaces. 
     FIG. 4 shows a partial sectional view of magnetic surfaces to form shapes on the surfaces of the shaping device. 
     FIG. 5 shows a schematic view of a rotating assembly to move the shaping device. 
     FIG. 6 is a corner detail from FIG. 3 with elevated rotors after discharging material showing shaping tools. 
     FIG. 7 is a corner detail of FIG. 10 showing shaping tools. 
     FIG. 8 is a sectional view of the shaping tools detailed in FIG. 6. 
     FIG. 9 details a sectional view of shaping tools shown in FIG. 7. 
     FIG. 10 contains a view of a second shaping device. 
    
    
     DETAIL DESCRIPTION OF THE DRAWINGS 
     Fibers and filaments must be prepared for mixing by separating and coating each with a setting agent to attract cement introduced in a mixing chamber and forced into a thin sheet. The flow of the thin sheet may be traced from the stack throat at 133 in FIG. 1 past magnetizable rods 107 between opposing magnets 106 with like poles in close proximity. The magnet flux may be small from the two surfaces of similar charge. The rods will be attached to the repelling poles and to like electrical poles. Since the rods are in close proximity, media fibers will be forced into a line parallel to the rods and into a plane midway between them. Premature adherence to the containing chute may be avoided by electrical fields. After passing this step the media is deposited upon attracting magnetic surfaces of the shaping device indicated at 143 in FIG. 1 also shown in FIG. 3 and FIG. 5. The attracting flux is generated by magnets at 117. Consolidation is enhanced by the magnet at 135 which provides the greatest flux generated. The field should be directed parallel with the flow. In FIG. 5, the shaping device detailed in FIG. 3 is continuously cycled through the material deposit and shaping, initial cure, separation, and return. Fibers and filaments are piped into the top of the aligning device at 132; and cement (or clay) dust coat the fibers and filaments. They are forced through the stack throat in a thin sheet at 133 into the alignment stack at 134. The repelling magnet, 135, is located at the end of each stack. A diagonal alignment stack is indicated at 136; longitudinal stacks, parallel to shaping device movement, are at 137 and transverse stacks are at 138. The empty shaping device is returned for use at 139; initial set is accomplished at 140 and the shaped product has been separated from the shaping apparatus at 141 and is being moved into final curing ovens. 
     The multiple stacks shown at 138 carry various mixtures of cements, fibers, filaments, clays, and aggregates depending on the use, market price and location. Repelling electromagnets 135 will be located at the downstream side of each stack discharge. Electromagnets schematically indicated at 117 are attracting magnets, while those at 106, and 135 are repelling magnets. The drive wheel is shown at 142. While equipment in differing rotated alignments at 132 through 138 is always connected to a positive electrical pole, the negative pole for attracting surfaces must change after initial set. 
     Shaping tools represented at 105 and 144 in FIG. 2 are moved by hydraulic rotors, 109 and 110. Pistons 118 through 123 are also necessary in order to release the product after initial set. All tools are made up of two parts; anodes (connected to repelling pole and electrical current) are illustrated at 102 and cathodes (connected to attracting pole and electrical current) at 104, separated by electric insulators at 103. All tools and connectors are comprised of anodes, cathodes, and insulators; even though not specifically illustrated or called out hereafter. Cathodes will change poles and electrical charge while the anode will always be the same. Space has been provided to avoid conflicts between tools and product parts. Tool 108 with its attached leg must be moved to the left by piston 120 without rotation until it is under the base, 116, at the position 113. It can then be moved downward along with tools 111 and connectors 112, 115, 126 and 146 to position 114. Tools at 124 shape ventilation holes. A small indentation in the base 116 is at the position 125. Fiber alignment is shown at 145. 
     Sheet Two shows additional details from Sheet One along with the shaping device for another product. A transverse section through tools 107 (this sheet only) is also indicated in FIG. 8. End blocks are necessary at corners shown at 200. Position 201 indicates the rotor tools elevated in the manufacturing sequence after product separation. Shaping tools are best viewed at this point. In FIG. 9 the anode 202, the magnetized surfacing material also carrying an electrical current, is separated from cathode 204, carrying opposite charge and pole, by insulation 203; while 205 connects the tools to the pistons 206 in FIG. 10. Holes are formed by 207 and 208 penetrating the base cathode 209. 
     Any part of this Specification and claim found objectionable may be severed and the remainder shall remain intact. I declare that my intended application is valid without such severed part.