Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D37/00—Tools as parts of machines covered by this subclass
  • B21D37/20—Making tools by operations not covered by a single other subclass

Definitions

• the present invention relates to a tool for shaping of articles from a basic material , especially from a sample of plate or sheet material, by applying compressive forces thereto, such as tools or molds for vacuum shaping and press tools .
• Press tools normally include a female part or die as well as a male part, and when the article to be shaped is of a complicated shape, the tool parts are of a correspondingly complicated shape. Further- more, the tool parts must be made from a material with mechanical properties which al low transfer of the necessary pressu re to the sample with retention of the geometric shapes of the tool parts, often within narrow limits or tolerances .
• press tools are made from steel , and the shaping su rface parts of the tool are subjected to a finishing treatment by various kinds of machining, such as milling, grinding, polishing, etc .
• DSP materials may be shaped in an extraordinarily easy manner, as they show far better casting performance than normal cement-based materials . I n spite of this, the DSP materials may attain compressive strengths which are up to 4 - 6 times the compressive strength of normal cement-based products, in special embodiments even as high as the yield stress of iron (about 260 MPa) , and they show far better castability than normal cement-based materials .
• the DSP materials permit, in a very simple way, casting of other components into the mass of the cement-based material , e.g . , components in the form of bars or fibers and the like, to impart toughness to the material . Also, it is possible with great ease to incorporate fine piping or small channels in the material in order to permit liquid and gas transport from or to the shaping zone, and futhermore, components of particularly high hardness such as steel or hard metal bodies may be incorporated at zones where extremely high loads are incurred du ring the compression shaping process .
• DSP materials (DSP designates Densified Systems containing homogeneously arranged ultrafine Particles) are characterized by comprising a matrix which comprises
• the particles A or the coherent structure formed therefrom being homogeneously distributed in the void volume between the particles B,
• the dense packing being substantially a packing corresponding to the one obtainable by gentle mechanical influence on a system of geometrically equally shaped large particles in which locking surface forces do not have any significant effect
• said pa rticles having a size of 100 ⁇ m - 0. 1 m
• bodies A, B, C, and D appear from the above-mentioned patent applications (in I nternational Patent Application No . PCT/DK79/00047, Publication No. WO 80/00959, the bodies D of the present application are termed bodies C) .
• the bodies B are typically particles which cu re by partial dissolution in a liquid, chemical reaction in the dissolved phase, and p recipitation of a reaction product.
• the bodies B are of an inorganic binder such as cement.
• at least 20% by weight of the bodies B are Portland Cement; it is preferred that at least 50% by weight of the bodies B are Portland cement, and in particu lar, it is preferred that the particles B essentially consist of Portland cement particles .
• the bodies B may, in addition , comprise particles selected from fine sand, fly ash , and fine chalk.
• the bodies A are also particu larly particles which cu re by partial dissolution in a liquid, chemical reaction in the solution , and precipitation of a reaction product, especially particles which show a substantially lower reactivity than the particles B, or substantially no reactivity.
• the bodies A are inorganic bodies of the types disclosed in the above-mentioned patent applications , in particular, e. g .
• silica dust normally has a particle size in the range of from about 50 A to about 0.5 ⁇ m, typically from about 200 A to about 0.5 ⁇ m, and is an SiO 2 - rich material p roduced as a by-product in the production of silicium metal or ferros ilicium in electrical fu rnaces .
• the specific su rface area of silica dust is about 50, 000 - 2, 000, 000 cm ⁇ /g, in particular about 250, 000 cm 2 /g .
• the bodies A may also, e. g . , comprise fly ash , in particular fly ash which has been finely ground, in particular to a specific su rface area ( Blaine) of at least 5000 cm 2 /g, in particular at least 7000 cm 2 /g, and often at least 10,000 cm 2 /g .
• fly ash in particular fly ash which has been finely ground, in particular to a specific su rface area ( Blaine) of at least 5000 cm 2 /g, in particular at least 7000 cm 2 /g, and often at least 10,000 cm 2 /g .
• the bodies A are normally present in a vol ume of 0. 1 - 50% by volume, preferably 5 - 50% by volume, and in particular 10 - 30% by volume, of the total volume of bodies A + B . I n most cases , the most valuable strength properties are obtainable when both the bodies A and the bodies B are densely packed.
• the amount of silica dust to secu re a dense packing of the silica dust particles depends on the grain size distribution of the silica dust and, to a large extent, on the void available between the densely packed particles B .
• a well-graded Portland cement containing additionally 30% of fine spherically shaped fly ash particles will leave a much smaller available void for the silica dust when densely packed than correspondingly densely packed cement in wh ich the grains are of equal size.
• dense packing of silica dust would most likely correspond to silica dust volumes from 15 to 50% by volume of particles A + particles B . Similar considerations apply to systems comprising other types of particles A and B .
• Quartz sand may typically be used as particles D.
• sand materials are used which are stronger (bodies C) than the sand materials used in ordinary concrete.
• concrete sand used in ordinary concrete consists of ordinary rock such as granite, gneiss, sandstone, flint and limestone comprising minerals such as quartz, felspar, mica, calcium carbonate, silicic acid, etc.
• Examples of bodies C with high strength and hardness are refractory grade bauxite containing 85% Al 2 O 3 , (corundum) and silicon carbide. Both materials have considerably higher hardness than the minerals in ordinary sand and stone. Thus, both corundum and silicon carbide are reported to have a hardness of 9 according to Moh's hardness scale, and the Knoop indentor hardness is reported to be 1635 - 1680 for aluminum oxide (corundum) and 2130 - 2140 for silicon carbide, while quartz, which is one of the hardest minerals in ordinary con crete sand and stone, has a Moh's hardness of 7 and a Knoop indentor hardness of 710 - 790 (George S. Brady and Henry R. Clauser, Materials Handbook, 11th ed., McGraw - Hill Book Company).
• materials may, of course, be used as strong sand and stone materials (bodies C).
• materials with a Moh's hardness exceeding 7 may be used, e.g. topaz, lawso ⁇ ite, diamond, corundum, phenacite, spinel, beryl, chrysoberyl, tourmoiine, granite, andalusite, staurolite, zircone, boron carbide, tungsten carbide.
• the hardness criterion could, of course, also be stated as Knoop indentor hardness where minerals having values above the value of quartz (710 - 790) must be considered strong materials compared with the minerals constituting ordinary concrete sand and stone.
• the bodies C are typically bodies of materials containing strong natural minerals, strong artificial minerals, and strong metals and alloys, in particular of such materials that the strength of the particles corresponding to at least one of tne following criteria:
• the bodies C increase the strength of tools made of DSP materials in that, contrary to normal sand and stone used in connection with cement matrices, they have strengths which are of the same level as the DSP matrix proper, such as discussed in detail in I nternational Patent Application No. PCT/DK81/00048, Publication No. WO 81/03170, European Patent Application No. 81103363.8 and Danish Patent Application No. 1957/81.
• the bodies C are typically present in a volume which is about 10 - 90% by volume, preferably 30 - 80% by volume, and in particular 50 - 70% by volume, of the total volume of the bodies A, B, and C. It is often preferred that the bodies C are also substantially densely packed .
• the DSP matrix may further contain , embedded therein , propertyimproving bodies which are typically fibers and/or plates selected from the group consisting of metal fibers, including steel fibers, mineral fibers, glass fibers, asbestos fibers , high temperature fibers , carbon fibers and organic fibers , including plastics fibers, such as polypropylene fibers , polyethylene fibers , nylon fibers, Kevlar fibers and other aromatic fibers , whiskers , including inorganic non-metallic whis kers such as graphite and AL 2 O 3 , whiskers , wollastonite, asbestos, and other inorganic synthetic or natu rally occu ring inorganic fibers, metallic wh iskers, such as iron whiskers , and mica .
• metal fibers including steel fibers, mineral fibers, glass fibers, asbestos fibers , high temperature fibers , carbon fibers and organic fibers , including plastics fibers, such as polypropylene fibers , polyethylene fibers , nylon fibers,
• the fibers are normally chopped fibers (or yarns or rovings) and are typical ly present in an amount ot 1 - 5% by volume when they have an aspect ratio of more than 100 or up to 5 - 10% by volume when they have an aspect ratio of 10 to 100. Larger amounts of chopped fibers may be incorporated in these techniques by combining large and small fibers , e. g . by use of an 0. 1 - 1 mm thick steel fiber in combination with a 10 ⁇ m glass fiber.
• the 'steel fibers may also have a particular geometric configu ration en hancing their fixation or anchoring in the material ; for example, they may show indentations at their su rfaces or may be shaped with hooks or other p rotrusions secu ring a maximum anchoring in the matrix .
• additional bodies D which are advantageously incorporated in the articles of the invention are metal bars, including reinforcing steel bars or rods, which may be pre-stressed .
• additional bodies D When the materials comprise additional bodies D, it may be attractive for optimum str ength and rigidity or for other pu rposes to obtain dense packing of the additional bodies .
• the easily deformable (easily flowable) m ⁇ trix permits a considerably denser arrangement of additional bodies than was obtainable in the known a rt.
• the incorporation of fibers is of great interest due to the unique capability of the DS P matrix with respect to anchoring fibers .
• the particular type and configu ration of fiber will depend upon the particular field of use of the tool , the general principle being that the larger the dimensions of the tool , the longer and coarser a re the preferred fibers .
• the tools of the invention are of large sizes, they are preferably reinforced with reinforcing steel such as bars or rods or steel wires or fibers . Due to the very gentle conditions under which the material can be shaped, the reinforcing bodies can retain their geometric identity during the casting process .
• the DSP matrix (in particular adjacent to the active surface part of the shaping tool) comprises an additional solid substance in the voids of the structure formed from the particles A and B .
• This additional solid substance may, e. g . , be selected from the group consisting of organic polymers such as polymethyl methacryIate or polystyrene, low-melting metals, and inorganic metalloid solids such as sulfur.
• the DSP material may be cast by combining
• the stress field will be due to oscillating forces with a frequency between 0.1 Hz and 10 6 Hz, the oscillating forces being of the type stated above, or a combination of such oscillating forces with non-oscillating forces of the type stated above.
• the liquid is water
• the dispersing agent is typically a concrete superplasticizer of the kind discussed in I nternational Patent Application No. PCT/DK79/00047, Publication No. WO 80/00959, or I nternational Patent Application No. PCT/DK31/00048, Publication No. WO 81/03170, Eu ropean Patent Application No. 81103363.8 and Danish Patent Application No. 1957/81.
• the surface-active dispersing agent is normally present in an amount sufficient to allow a fluid to plastic consistency of the material in a low stress field of less than 5 kg/cm 2 , preferably less than 100 g/cm 2 , and the ideal amount of the dispersing agent is one which substantially corresponds to the amount which will fully occupy the surface of the particles A of Fig . 2 in I nternational Patent Application No.
• the concrete superplasticiser type which has been used in the examples is of the type comprising alkali or alkaline earth metal salts, in particular a sodium or calcium salt, of a highly condensed naphthalene sulphonic acid/formaldehyde condensate, of which typically more than 70% by weight consist of molecules containing 7 or more naphthalene nuclei .
• a commercial product of this type is called "Mighty" and is manufactured by Kao Soap Company, Ltd. , Tokyo, Japan .
• this type of concrete superplasticiser is used in the high amount of 1 - 4% by weight, in particular 2 - 4% by weight, calculated on the total weight of the Portland cement and the silica dust.
• the DSP material for producing the tools of the invention may be packed and shipped as a dry powder, the addition of the liquid, typically water, taking place on the job. In this case, the dispersing agent is present in dry state in the composite material.
• This type of composite material offers the advantage that it can be accurately weighed out and mixed by the producer, the end user just adding the prescribed amount of liquid and performing the remaining mixing in accordance with the prescription, e.g., in the manner described in Example 11 in International Patent Application No. PCT/DK79/00047 and in International Patent Application No. PCT/DK81/00048, Publication No. WO 81/03170, European Patent Application No. 81103363.8 and Danish Patent Application No. 1957/81.
• the weight ratio between water and Portland cement plus any other bodies B plus silica dust in cement-silica-dust-based DSP materials is typically between 0.12 and 0.30, preferably 0.12 - 0.20.
• the abovementioned patent applications also disclose several important variations and embodiments for making valuable DSP materials, including embodiments where the composite material is pre-mixed or shaped in a higher stress field, in which case the water/powder ratio may be as low as, e.g., 0.08 - 0.13.
• the casting may also be performed by extrusion or rolling at a shaping pressure of up to 100 kg/cm 2 , and in special cases at even higher shaping pressures.
• the casting may also be performed by spraying, painting or brushing, injection or application of a layer of the mass on a supporting surface and shaping the mass so as to obtain at least part of said shaped surface part.
• the casting may also be performed as centrifugal casting.
• this solid may be introduced by partially or completely infiltrating the solidified DSP material with a liquid and thereafter solidifying the liquid , such as by cooling or polymerisation, to form the solidified substance.
• the liquid will usually show at least one of the following characteristics: it is capable of wetting the internal surface of the structure formed from the particles A and B,
• the efficiency of the infiltration with the liquid may be enhanced by one or more of the following measu res :
• cement-polymer based materials CP materials and DSPP materials
• UK Patent Application No. 7905965, publication No. 2 018 737 A, European Patent Application No. 80301908, publication No. 0 021 681 , and European Patent Application No. 80301909, publication No. 0 021 682 A1 disclose production of specimens of a substantially higher quality than usual cement-based products based on the use of far more concentrated polymer solutions than those conventionally combined with Portland cement in very high concentrations and based on very intensive mixing of the components, typically in a high stress field. Such materials are valuable materials for use as concrete-like materials according to the present invention .
• a particutariy valuable embodiment of such materials is one in which they are combined with fibers of the above-mentioned types, and/or when their viscosity has been lowered to a suitable value for casting or molding by a pretreatment such as dilution with polymer solution or water prior to their casting, in particular during high stress field mixing.
• Especially interesting polymer-containing materials are DSP materials which correspond to the above-described DSP materials, but in which a polymer binder is also present (such materials can be designated DSPP materials: Densified Systems containing Polymer and homogeneously arranged ultrafine Particles).
• the organic polymers contemplated for use in CP or DSPP materials comprise, e.g., the same polymers as those mentioned in the abovementioned UK Patent Application No. 7905965, Publication No. 2 018 737 A, that is, water-dispersible polymers more or less pertaining to the following groups (or mixtures of polymers pertaining to one or several of the groups):
• Latexes colloidal aqueous emulsions of elastomers as defined in 1) Kirk-Othmer, Encyclopedia of Chemical Technology, 7, pages 676/7I6) .
• the polymer may be of a special group:
• cement dispersing agents known as concrete superplasticizers, e.g., medium molecular weight polymers such as alkali or alkaline earth metal salts of sulphonated naphathalene or melamine formaldehyde condensates or their parent acids or higher molecular weight polymers thereof. Also amide derivatives of these polymers may be used. It is a characteristic feature of all of the above-mentioned polymer classes that the polymers thereof are capable of forming film from an aqueous dispersion through dewatering and/or cross-lin king.
• Typical concentrations of polymer in the aqueous phase used for making the cement-polymer-containing matrices are in the range of 1 - 60%.
• the amount of aqueous phase (water + polymer) used in preparing the materials is in the range of from about 10 to about 70% by volume, in particular in the range of from about 20 to about 50% by volume, calculated on the total composition .
• the ratio between polymer (solid) and cement will depend upon several factors such as the desired strength of the material, the exact character of the polymer, the type and particle size of the cement, the presence of any other bodies which fill voids between the cement particles , etc.
• the volume ratio between polymer and cement in the matrix used in the materials according to the invention will normally be in the range between 0.1 and 35 per cent by volume (but may be between 0 and 40% by volume) , and will in many cases be between 2 and 10 per cent by volume.
• a very special type of matrix of high strength and especially also high tensile strength in bending suitable for the tools of the present invention although it will often not contain any polymer is a matrix comprising, as its substantial binder component, cement, the materials forming the matrix having been subjected to a particular treatment, that is, intense grinding and shear influence du ring early stages of the hydration of the cement, resulting in the formation of extremely well-distributed colloid of cement hydration products in a very homogeneous material .
• Such material may be produced by h igh shear treatment and grinding of cement with added water u ntil some hydration of the cement has ta ken place.
• the cement used in these matrices of the present invention is normally Portland cement, including any modifications of Portland cement such as low heat cement, low al kali sulphate resistent cement, gypsum, plaster of Paris, calcium sulphate, h igh alumina cement, magnesium oxide cement, zinc oxide cement, and, for various special pu rposes cements of the silicon oxide cement type (as specified in e. g . US Patent No . 4, 154, 717, of May 15, 1979) and fluoroaluminosilicate glass and other types used in dental tech nology, e. g . glass ionomer cement types and other cements of types wh ich may deliver ions capable of cross-lin king the polymer.
• Portland cement including any modifications of Portland cement such as low heat cement, low al kali sulphate resistent cement, gypsum, plaster of Paris, calcium sulphate, h igh alumina cement, magnesium oxide cement, zinc oxide cement, and, for various special pu
• part of the cu ring mechanism in these matrices used according to the present invention may be said to consist in ion ic "cross-lin king" of negative sites on polymers th rough di- , tri- or other polyvalent positive ions (cations) such as calcium ions or silicon ions , of . , e. g . , L. Holiday, Chemistry and I ndustry, 2nd December, 1972, pages 921 - 929.
• one particularly interesting group of polymers is polymers based on acrylic acids and other polymers having carboxylic acid groups or derivatives thereof lin ked to a polymer backbone. Examples of such materials are listed on page 1 15 - 145 in "New Dental Materials” edited by Paul G . Stecher, Noyes Data Corporation , Park Ridge, New Jersey, USA, 1980. Most of these polymers are classified in the above-mentioned group I I , that is , as water-soluble resins. Particularly interesting materials of this type comprise materials in which the carboxy group has been modified into an amide group .
• the amide group will be split off due to al kaline hydrolysis and the carboxy group will be available for cross-linking with cations, notably ions released from the inorganic parts of the matrix material .
• Polymers which are acids and which cross-lin k in the presence of bases are known in dental technology.
• such polymers will normally be too reactive in than they react too fast to allow shaping or molding of the composition after mixing .
• Such materials may be plaster of Paris or fluoroaluminosilicate glasses .
• Portland cement leaches ions of several types , including calcium ions (predominantly) , aluminium ions, silicon ions, manganese ions , magnesium ions , and iron ions .
• CP or DSPP materials may be used in the tools of the invention in the same manner as DSP materials, or the CP or DSPP materials may be applied as, e.g . , strips or sheets on su rface areas of the tools which will be exposed to maximum stresses .
• DSP materials in the following, it should be understood as also referring to CP or DSPP materials adapted to suit the same pu rposes .
• the cement-based casting material for the tool is designed, with respect t ⁇ its particular composition, in accordance with the requirements associated with the particular use and desired performance of the tool in question .
• bodies or fibers of good heat conductivity such as metal bodies or metal fibers .
• the required strength of the material for the male and female tool depends upon these parameters according to an expression which states that the strength of the tool material , divided by the strength of the sheet or panel to be shaped, is proportional to a constant multiplied by the thickness of the sheet or panel material divided by the radius of curvatu re, the constant being dependent on the direction of the pressu re forces and on the friction coefficient between the plate shaped and the male and female tools (the properties in the expression above referring to the conditions prevailing during the shaping operation , i . e. , shaping temperature, shaping speed, etc. ) .
• a model may be provided either as an authentic model of the article to be shaped, or as a casting in a suitable material , such as glass fiber/polyester.
• the male tool may be cast di rectly on the model . After hardening, the model is demounted, and the male tool is supplied with a thickness layer corresponding to the thickness of the plates to be pressed . (Typically, wax sheets are used as thickness layers) . Thereafter, the female tool is cast over the male tool covered with the thickness layer. After hardening, the female and male tools are separated and the thickness layer is removed (in this technique, only a model of one side of the desired product is used) .
• the male pa rt may be cast as explained above under 1 )
• the mode! remains on the male part du ring the harden ing, and thereafter, the female tool is cast as described under 1 ) , but di rectly on the model .
• this technique a model provided with an exact copy of both faces of the article to be made is used.
• a releasing agent such as graphite, is preferably sprayed on the surface of the mode! prior to casting against it.
• the material comprising the DSP matrix may be reinforced according to normal reinforcement principles where steel bars and the like may be arranged in configurations suitable for resisting tensile stress .
• Micro- reinforcement against micro-cracks etc. and local stresses may be obtained by means of various types of fibers, such as the ones mentioned above
• Such reinforcing fibers need not be uniformly distributed in the matrix, but may in some cases with advantage be concentrated in tool surface parts or other tool parts which are exposed to especially high stresses when the tool is used .
• the tool of the invention may be reinforced according to normal reinforcement principles.
• the character and extent of the reinforcement may be pre-calculated on the basis of considerations relating to whichever portions or sections of the tool of the invention that will be particularly exposed to stresses .
• the reinforcement may comprise one or more members of steel or another metal positioned in the tool so that at least one surface part thereof is exposed and forms part of the shaped surface part of the final tool .
• Such exposed reinforcing metal members are with advantage positioned so as to form protruding edge portions or other protruding parts of the final tool which are excessively stressed du ring use of the tool .
• the su rface part of the reinforcing tool members to be exposed is shaped so as to be exactly complementary to the respective corresponding su rface part of the mold .
• These metal su rface parts to be exposed are preferably also finished by grinding and/or polishing .
• the reinforcing metal members are thereafter placed in the mold , which is partly defined by the mode!, so that the surface part of the reinforcing members to be exposed are in contact with the corresponding su rface part of the model .
• DSP material will also permit very easy repai r or post-strengthen i ng of pa rts wh ich , d u ring use of the tool , prove to be exposed to too high stresses .
• one may, e. g. , incorporate DS P material of the particular type, or this may be combined with incorporation of particularly hard bodies such as hard metal or steel bodies or bodies or strips of CP or DSPP material, especially at the sites where the maximum stresses occur during use of the tool .
• the material used according to the invention shows optimum properties with respect to easy casting to obtain economic tools even for small quantity productions, the material is also optimal with respect to its su rface properties .
• the material used according to the invention may obtain a su rface li ke polished metal or smooth plastic, in other words a su rface which is ideal for a shaping tool and which minimizes the friction with the article shaped . It was most su rprising that these particular su rface requi rements were found in practice to be fulfilled by a material based on cement.
• the conditions reported in Example 1 permitted drawing of a steel plate of a thickness of 0.9 mm with a radius of cu rvature of 3 mm without any special measu res .
• important types of articles made by using the tools of the present invention are articles made from metal sheet or panei materials, e. g . , body or hull parts for ships, agricultural machinery, aircraft and other transport or traffic vessels, in particular also body parts for automobiles, and especially repair components corresponding to body parts or sections of body parts for automobiles, such as hoods or fenders or parts thereof, doors or parts thereof, bottom panels or parts thereof, front parts or parts thereof, etc.
• the sheet or panel materials used for making such articles may suitably be blanks cut from continuos sheet or panel materials by mechanical means, electric means, acoustic means, or electromagnetic means, e. g. , cutting, sawing, punching, wire cutting by means of a wire cutting machine, laser cutting, etc.
• the present invention makes the precision drawing/bending technique available to new fields of application , such as the preparation of large structu res for ship hulls, buildings, large containers and parts thereof, reaction vessels, etc.
• the tools of the invention may be made completely from the new cement-based materials, or they may be made by applying more or less thick surface domains of these materials to other structures showing sufficient strength for the purpose, including old drawing/bending tools made for the shaping of articles which have become obsolete.
• FIG. 1 and 2 diagrammatically illustrate a method of casting a male too! part
• Fig. 3 is a diagrammatic sectional view showing the tool part made by the method of Figs. 1 and 2
• Fig. 4 diagrammatically illustrates casting of a female tool part or die corresponding to the male tool part shown in Fig. 3,
• Figs. 5 and 6 diagrammatically illustrate a pressing or drawing tool comprising a male and a female part in two different operational positions
• Figs. 7 and 8 are perspective views further illustrating the process of casting a male tool part
• Fig. 9 is a perspective view of a male tool part cast by the method illustrated in Figs. 7 and 8,
• Fig. 10 is a sectional view of a mold in which cooperating male and female tool parts may be cast simultaneously
• Figs. 11 and 12 are perspective and partially sectional views of a vacuum shaping mold made by the method according to the invention, .
• Figs. 13 and 14 illustrate a method of forming a lower tool part for use in making corrugated plates,
• Fig. 15. is the lower tool part with a perforated, corrugated steel plate being placed thereon, and
• F)y. 16 is a side view and partially a cross sectional view in a completed tool for pressing a corrugated plate made from a fiber cement material.
• Fig. 1 shows containiner 10 open at the top, which may be made from any sufficiently rigid material, such as, e.g. wood or steel.
• a moldable material 11, such as moldable resin, e.g. a moldabie composition for making cellular polyurethane or polystyrene, is placed in the container 10 in a plastic condition, and a model 12 of the articles to be shaped is placed in the moldable composition 11 with its concavesurface facing upwards as shown in Fig. 1.
• a supporting frame 13 is placed on the upper edge of the container 10 as shown in Fig .
• a reinforcing structu re 14, e. g . of steel rods, is provided in the frame 13.
• a cement-based DSP casting material 15 of the type identified above is pou red into the upwardly open mold, while vibration of the mold, if desired, until the upper su rface of the casting material is substantially on level with the upper edge of the frame 13.
• the frame 13 with the resulting male tool 16 is removed from the mold, as shown in Fig . 3.
• the male tool 16 is then covered with a layer 17 of a plastic material , e.g. , a wax sheet of a thickness corresponding to the thickness of the plate or sheet material to be shaped by means of the tool .
• a frame 18 with a reinforcing structu re 14 is placed on the upper edge of the frame 13, thereby again providing a open mold open at the top, the bottom surface of the mold being constituted by the wax-covered surface of the male part 16.
• a female part 19 is now cast in this mold . Any edge portion of the casting mold extending outside the model contour is plastered with a suitable material such as wax to a thickness which is preferably greater than the thickness of the blank to be shaped in the final tool assembly.
• the male and female tool parts are mounted in a press, e. g . a hydraulic press , and a blank 20 is introduced therebetween and is shaped into the configuration of the model 12 by drawing .
• a press e. g . a hydraulic press
• a blank 20 is introduced therebetween and is shaped into the configuration of the model 12 by drawing .
• the model 12 is suspended between two frames (13 and 18) arranged substantially vertically between vertical walls 21 , thus establishing a dual mold in which the casting material can be introduced, through inlets 22 and 23, into two mold chambers 24 and 25 for simultaneous casting of the male and the female tool parts against opposite sides of the model 12.
• the mode! 12 should conform, with respect to both of its surfaces, with the desired article to be produced.
• the reinforcing structure 14 may comprise reinforcing steel members 14a having su rface parts placed in contact with the model 12. These su rface parts are shaped so that the inter-engaging su rface parts of the model 12 and the steel members 14a are exactly complementa ry.
• the steel members 14a are advantageously connected to the other part of the reinforcing structu re 14 by wi res or rods (not shown ) which may, for example, be welded to the steel members 14a .
• the exposed surface pa rts of the steel members 14a will form part of the shaped tool su rfaces at locations where the tool parts will be exposed to exceptionally high stresses du ring use, namely at protruding edge portions of the tool parts .
• the incorporation of such reinforcing members 14a of steel or another metal at excessively stressed su rface areas of the tool parts may result in a substantial prolongation of the useful life of the tool .
• Figs . 11 and 12 diagrammatically illustrate vacuum forming of a dishshaped article 26 such as a lamp body for an automobile, from a thermoplastic piane sheet or plate 27 by means of a moid or die 28 which may be cast from a cement-based casting material of the type identified above.
• the mold 28 may be made by casting the cementbased material against the outer su rface of a model in the manner described above.
• the mold 28 has a cavity 29 open at the top wh ich may be brought into communication with a vacuum sou rce, not shown , th rough suction passages 30 defined within the bottom wall of the mold 28 and th rough a vacuum conduit 31 which is provided with a valve 32.
• the thermoplastic sheet or plate 27 may be clamped between a flange 33 formed at the upper end of the mold 28, and a clamping member 34 which contains electrical heating means 35 to which power may be supplied th rough a cable 36.
• the cavity 29 may be connected to the vacuum sou rce by opening the valve 32, whereby the heated thermoplastic plate will be sucked into tight engagement with the inner walls of the cavity 29 so as to form the article 26.
• the mold 28 may be provided with inner passages , not shown, for circulating a cooling medium, such as water.
• Figs . 13 and 14 illustrate the production of a lower tool part 37 of a pressing tool to be used for pressing corrugated plates 38 made from a fiber cement material .
• the tool part 37 is cast from a cement-based casting material 15 of the type identified above in a mold formed by a bottom part 39 and a surrounding frame part 40.
• the bottom part 39 may consist of a lower layer 41 made from a moldable material, such as resin, with a corrugated upper surface, and a corrugated steel plate 42 with a shape which is complementary to the upper surface of the layer 41 .
• a number of closely spaced strips or bands 43 of rubber are affixed to the upper surface of the steel plate 42 by means of a suitable adhesive, so that the strips extend transversely and preferably at right angles to the direction of the corrugations of the plate 42.
• the frame part 40 When the rubber strips 43 have been arranged in mutually spaced relationship over the total upper surface of the steel plate 42, the frame part 40 is placed on top of the bottom part 39 as shown in Fig. 14.
• This frame part 40 is provided with a number of suction tubes 44 each extending along a respective corrugation top of the corrugated steel plate 42. These suction tubes are supported by means of transversely extending supporting bars 45, the ends of which are fastened to the frame part 40.
• the casting material 15 is now poured into the upwardly open mold, while vibrating of the mold, if desired, until the upper su rface of the casting material is substantially on level with the upper edge of the frame part 40.
• the frame 40 with the resulting lower tool part 37 is removed from the bottom part 39.
• the tool part 37 will form a corrugated upper surface with a number of closely spaced, transversely extending grooves 46 formed by the rubber strips 43, and these grooves are intended to serve as draining grooves .
• the upper surface of the lower tool part 37 is covered with a perforated, corrugated steel plate 47 with a shape which is complementary to the corrugated shape of the upper surface of the tool part 37 and the steel plate 47 is preferably covered by a corrugated wi re gauze (not shown) , for example made from bronze.
• Fig . 16 shows a complete pressing tool mounted in a mechan ical or hydraulic press .
• the tool comprises the lower tool part 37, which may be stationary, and an upper tool part 48, which is fastened to a vertically movable part 49 of the press .
• the upper tool pa rt 48 may be made in a manner similar to that described above in connection with the lower tool part.
• the upper too! part may be made without the transversely extending draining grooves 46, and the perforated, corrugated steel plate 47 may be replaced by a solid corrugated steel plate 50. I n the lower position of the upper tool part 48; a corrugated closed space is defined between the corrugated plates 47 and 50.
• suction tubes 44 a re connected to these groove sections th rough connecting bores or tubes 51 , and the suction tubes 44 are connected to a pump or vacuum sou rce, not shown , so that water is sucked out from the cavity defined between the upper and lower tool parts while the fiber cement material is being compressed .
• the materials used in this example were as fol lows
• Cement Low al kali sulphate resistant Portland cement.
• Silica dust Fine spherical SiO 2 -rich dust. Specific surface (determined by BET technique) about 250,000 cm 2 /g, corresponding to an average particle diameter of 0.1 ⁇ . Density 2.22 g/cm .
• Bauxite Refractory grade calcined bauxite, 85%
• a so-called concrete superplasticiser sodium salt of a highly condensed naphthalene sulphonic acid/formaldehyde condensate, of which typically more than 70% consist of molecules containing 7 or more naphthalene nuclei. Density about 1.6 g/cm . Available either as a solid powder or as an aqueous solution (42% by weight of Mighty, 58% by weight of water). (Available under the trademark CemMix® from Aalborg Portiand ⁇
• Steel fibers Diameter 0.4 mm, lengths 12 mm and 24 mm, respectively. Cut by means of a blunt tool so that the ends of the fibers show a slight deformation enhancing the anchoring of the cement-based matrix.
• a cement-based casting material was made from the following composition :
• the resulting soft fluid mixture was cast into a mold as shown in Figs . 2 and 8 in which a glass fiber-epoxy model 12 of the fender part, depth about 5 cm, arranged in polyu rethane foam in a box 10 of dimensions of approximately 80 cm by 60 cm, constituted the bottom su rface, and in which the reinforcement in the frame 13 consisted of 1 cm steel rods .
• the mold was vibrated by means of a pneumatic hammer.
• the moid was filled with the casting material to the highest level possible, up to or just above the edge of the steel frame 13. Thereafter, the exposed su rface of the casting material was covered with plastic film to avoid evaporation of water therefrom.
• the casting mass was allowed to solidify at room temperature for about 24 hou rs and was thereafter kept at about 30 - 35°C for about 48 hou rs .
• the frame was then tu rned upside down , and the polyu rethane and the glass fiber-epoxy model were removed , th us exposing the s u rface of the cu red cement-bonded material .
• a 0.9 mm wax film was placed and adapted to conform exactly to the configu ration of the su rface. I n the same manner as il lustrated in Fig .
• the male and female tool parts were mounted in a 200 tons hyd raulic press , and fender parts corresponding to the model were made from blan ks of cold-rolled 1403 steel of a thickness of 0.9 mm.
• the drawing pressure was 50 tons .
• the compression time was about 30 seconds per blank, but using a faster hydraulic press , it would be possible to obtain compression times of about 2 - 3 seconds.
• the minimum radius of curvature obtained in this case was 3 mm. In this manner, about 1000 units were shaped without any deterioration of the tool .
• Corrugated plates or paneis produced by conventional methods were exposed to a compression treatment by means of a tool of the type shown in Fig . 16.
• the overall dimensions of the lower tool part were 735 x 1100 x 140 mm.
• the lower tool part was provided with four suction tubes 44 with a diameter of 25 mm, while the diameter of the connecting bores 51 were 10 mm.
• the tool parts 37 and 48 were cast from the same DSP material as described in Example 1 and in the same manner as described in Example 1 .
• the width and depth of the draining grooves were 10 mm and 8 mm, respectively, and the spacing of the grooves was 15 mm .
• the lower tool part 37 was covered by a perforated, corrugated steel plate with a thickness of 2 mm, and the diameter of the perforations were 2 mm, and the mutual spacing of the perforations was about 8 - 10 mm.
• This perforated steel plate was covered by a corrugated wire gauze made from bronze, and the upper tool part 48 was covered by a non -perforated, corrugated steel piate 50.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Mounting, Exchange, And Manufacturing Of Dies (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Pens And Brushes (AREA)
• Control And Other Processes For Unpacking Of Materials (AREA)
• Nonmetallic Welding Materials (AREA)
• Cutting Tools, Boring Holders, And Turrets (AREA)

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Cited By (5)

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Citations (11)

• 1981
  • 1981-11-19 WO PCT/DK1981/000103 patent/WO1982001674A1/en active Application Filing
  • 1981-11-19 AU AU78064/81A patent/AU7806481A/en not_active Abandoned
  • 1981-11-19 EP EP81109785A patent/EP0052380A3/en not_active Withdrawn
  • 1981-11-19 JP JP56503645A patent/JPH0470097B2/ja not_active Expired - Lifetime
  • 1981-11-19 BR BR8108879A patent/BR8108879A/pt not_active IP Right Cessation
• 1982
  • 1982-07-16 NO NO822468A patent/NO822468L/no unknown

Patent Citations (11)

Non-Patent Citations (1)

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