WO1998033632A1 - Procede pour comprimer des articles ondules en fibrociment - Google Patents

Procede pour comprimer des articles ondules en fibrociment Download PDF

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Publication number
WO1998033632A1
WO1998033632A1 PCT/BE1998/000012 BE9800012W WO9833632A1 WO 1998033632 A1 WO1998033632 A1 WO 1998033632A1 BE 9800012 W BE9800012 W BE 9800012W WO 9833632 A1 WO9833632 A1 WO 9833632A1
Authority
WO
WIPO (PCT)
Prior art keywords
curvature
platens
fiber
stack
cement sheets
Prior art date
Application number
PCT/BE1998/000012
Other languages
English (en)
Inventor
Patricio Rogat Verdugo
Original Assignee
Redco S.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Redco S.A. filed Critical Redco S.A.
Priority to AU57426/98A priority Critical patent/AU5742698A/en
Priority to BR9807530-6A priority patent/BR9807530A/pt
Publication of WO1998033632A1 publication Critical patent/WO1998033632A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B1/00—Producing shaped prefabricated articles from the material
    • B28B1/52—Producing shaped prefabricated articles from the material specially adapted for producing articles from mixtures containing fibres, e.g. asbestos cement
    • B28B1/528—Producing shaped prefabricated articles from the material specially adapted for producing articles from mixtures containing fibres, e.g. asbestos cement for producing corrugated sheets

Definitions

  • the present invention concerns a process for the production of pressed fiber-cement shaped articles, more specifically corrugated sheets.
  • the invention also provides an assembly and novel platens for stack-pressing corrugated sheets.
  • Fiber-cement articles are obtained from an aqueous suspension of a mixture of hydraulic binder, reinforcing fibers and optional additives, said suspension being dewatered and allowed to set. Before curing, the said articles are appropriately shaped, for example in the form of flat or corrugated sheets.
  • Fiber-cement products for roofing and cladding are subjected to continuous and sometimes intense weathering conditions. Such products must therefore exhibit adequate mechanical resistance and durability.
  • a generally applicable method for improving the fiber-matrix bond in a fiber-cement sheet is to densify the sheet by compressing the fresh product after forming and shaping but before curing and hardening. This so-called post-compression step improves the fiber-matrix bond in the fiber-cement product in addition to increasing its density and decreasing its porosity. Post-compression can be applied regardless of the fiber-cement composition.
  • freshness or green mean the same and refer to the condition of a fiber-cement article during manufacturing, whereby the article has reached a level of consistency so as no longer to be fluid but rather coherent, while still being readily deformable such as through corrugation on a corrugation bench.
  • Such single-sheet presses generally present a short stroke (i.e. an opening of a few decimeters) and operate with a short cycle during which a pressure of 20 to 250 kgf/cm 2 (1.96 MPa to 24.52 MPa) is applied to the shaped article.
  • single-sheet presses consume much energy and, contrary to conventional slower running stack presses, their maintenance costs are very high.
  • the compression step of fiber-cement articles by means of a single-sheet press is also a limiting factor in the production cycle. Depending on the format of the sheets, a compression cycle can take between 10 and 30 seconds. One single press can therefore only handle about 2 to 6 sheets per minute.
  • the currently available single-sheet presses can handle the output of only one fiber-cement production unit.Their operation must thus be carefully synchronised with upstream equipment.
  • known stack presses are fitted with a rigid top die and a rigid bottom die. On top of the bottom die is piled a succession of fiber-cement sheets, separated by intermediate metal platens. The entire stack is compressed simultaneously at a maximum pressure of generally between 20 and 250 kgf/cm 2 (1.96 MPa to 24.52 MPa) . After compression, the stack is disassembled and the platens are cleaned for reuse.
  • stack presses For the same production capacity, stack presses have lower investment costs and are less expensive to operate than are single-sheet presses. As stack presses operate in batch (off-line), they can, in one go, compress sheets produced by several production units.
  • the longer compression cycle of a stack press allows the surplus water to be expelled more gradually from the fresh sheets which is beneficial to the mechanical properties of the pressed fiber-cement products.
  • the entire sheet must have been compressed. This requires: I) that during compression, both surfaces of the fiber-cement sheet are in full contact with the platen or die and that ii) every part of the fiber-cement sheet is subjected to a, preferably 5 homogeneous, compression force perpendicular to the surfaces of the sheet.
  • corrugated fiber- 5 cement sheets present a top-surface curvature which may be different from their bottom- surface curvature.
  • the metal platens will not be in full contact with the lower surface of the corrugated fiber-cement sheet immediately above. Gaps will appear adjacent the 0 furrow and ridge area of the said fiber-cement sheet. A similar phenomenon is observed with metal platens having curvatures corresponding to the bottom-surface curvature of the fiber-cement sheets.
  • metal platens having a higher thickness 5 in the furrow and ridge area as compared to in the slope areas of the platen. This can be achieved by covering the upper surface of the metal platen with a polymer layer which is thicker in the furrow and ridge areas than in the slope areas, by glueing strips of such polymeric material into the furrow and ridge areas of the platen or through a platen consisting of two corrugated outer metal sheets which are more spaced apart in their furrow and ridge areas than in their slope areas, and whereby the space between the two sheets is filled with a rigid, self-hardening polymer.
  • a compact stack of alternating corrugated fiber-cement sheets and metal platens can be realized, i.e. a stack substantially without voids between subsequent fiber-cement sheets and platens.
  • the process according to the invention enables the production by means of stack-pressing of corrugated fiber-cement sheets suitable for use as cladding and/or roofing.
  • the invention concerns a process using undulated platens with special mechanical characteristics and design wherein said platens undergo a controlled elastic, i.e. reversible, deformation during stack pressing.
  • the present invention consists in a process for producing compressed corrugated fiber-cement sheets.
  • corrugated fiber-cement sheets having a bottom surface with a given bottom-surface curvature and a top surface with a given top- surface curvature can be obtained by pressing a compact stack built up of an aligned vertical arrangement of alternating undulated platens and fresh fiber-cement sheets.
  • the said platens are made of an elastomeric material which deforms resiliently during pressing.
  • a compact stack is a stack with substantially no voids between subsequent sheets and platens.
  • the lowermost and the uppermost elements of the stack both are platens.
  • Each platen of the stack has a top surface, the curvature of which corresponds substantially to the curvature of the bottom surface of the fiber-cement sheets to be produced.
  • each platen of the stack has a bottom surface, the curvature of which corresponds substantially to the curvature of the top surface of the corrugated fiber-cement sheets to be produced.
  • the said stack is pressed in a vertical press having rigid bottom die and a rigid top die.
  • the curvature of the top surface of the bottom die corresponds substantially to the curvature of the top surface of the corrugated fiber-cement sheets to be produced.
  • the curvature of the bottom surface of the top die corresponds substantially to the curvature of the bottom surface of the corrugated fiber-cement sheets to be produced.
  • the shape of the platens enables the piling of a compact stack before pressing, i.e. one presenting few or no voids.
  • the shape of the top and bottom dies permits maximum contact between the dies and the stack during pressing.
  • the stack is positioned between the bottom and top die in aligned relationship with same. During pressing, pressure is applied and released in a controlled manner.
  • the minimum distance between the top surface and the bottom surface of each platen is at least once or more preferably at least twice the thickness of the corrugated fiber-cement sheets to be produced.
  • the thickness of the corresponding platen should preferably be at least 4.5 or even at least 9mm.
  • the Shore A hardness of the platens is comprised between 50° and 100°, or more specifically between 75° and 85°.
  • the platens present a tensile stress at 300 % elongation of between 30 and 90 kg/cm 2 , whereby 300 % elongation refers to the condition of the test sample three times its original length, the said tensile strength being measured according to ASTM D-412).
  • Said platens consist substantially of a material selected from the group comprising silicone, polybutadiene, polyurethane, synthetic rubber, nitrile rubber and EPDM (Ethylene Propylene Diene Modified) rubber.
  • the surfaces of the platens which come into contact with the green fiber-cement sheets may be coated with a platen oil before piling the stack, so as to keep the sheets from adhering to the platens.
  • the thickness of the platens, and the material out of which they are made will depend on the process conditions, such as the composition of the hydraulically setting mixture and the pressure applied.
  • the pressure applied to the fresh fiber-cement sheets in the stack can be between 20 kgf/cm 2 (1.96 MPa) and 100 kgf/cm 2 (9.81 MPa) and is preferably between 30 kgf/cm 2 (2.94 MPa) and 80 kgf/cm 2 (7.85 MPa).
  • the pressure to be applied will generally depend on process conditions such as the height of the stack, the desired degree of compaction (density of the sheets) etc.
  • the fresh fiber-cement sheets are corrugated to substantially the desired corrugated end-shape before being placed in the stack. If the bottom die is removably connected to the press, the stack may be piled onto the bottom die away from the press before pressing. The stack, resting on the bottom die in aligned relationship therewith, is then placed in the press beneath and in aligned relationship with the top die. In that case the stack may be removed from the press together with the bottom die after pressing and before depiling.
  • the compressed fresh fiber-cement can be handled as are conventionally pressed fresh fiber-cement sheets.
  • the compressed fresh fiber-cement sheets may be steam-cured or air- cured depending on the type of composition used.
  • the platens can be moulded between a first and a second steel mould member, the first mould member having a surface curvature corresponding substantially to the curvature of the top surface of the corrugated fiber-cement sheets to be produced, the second mould member having a surface curvature corresponding substantially to the curvature of the bottom surface of said corrugated fiber-cement sheets.
  • first mould member may be used as the bottom die, the second mould member being suitable for use as the top die.
  • the present invention equally covers an assembly for producing compressed corrugated fiber-cement sheets as described above, said assembly comprising a vertical press and at least 3 undulated platens.
  • the platens are made of a resiliently deforming elastomeric material.
  • the vertical press has a rigid bottom die and a rigid top die.
  • the top surface of the bottom die has a curvature corresponding substantially to the curvature of the top surface of the corrugated fiber-cement sheets to be produced.
  • the bottom surface of the top die has a curvature corresponding substantially to the curvature of the bottom surface of the corrugated fiber-cement sheets to be produced.
  • the curvature of the bottom surface of each platen corresponds substantially to the curvature of the top surface of the corrugated fiber-cement sheets to be produced.
  • the curvature of the top surface of each platen corresponds substantially to the curvature of the bottom surface of said sheets.
  • the Shore A hardness of the platens can be comprised between 50° and 100°, preferably between 75° and 85°.
  • the tensile stress at 300 % elongation of the platens is preferably between 30 and 90 kg/cm 2 .
  • the platens consist substantially of a material selected from the group comprising silicone, polybutadiene, polyurethane, synthetic rubber, nitrile rubber and EPDM (Ethylene Propylene Diene Modified) rubber.
  • the bottom die is preferably removably attached to the press.
  • the invention also covers the above-described platens for use in the production of compressed corrugated fiber-cement sheets by means of stack-pressing.
  • Figure 1 represents a partial cross section of a corrugated fiber-cement sheet to be produced.
  • Figure 2 is a schematic cross sectional view of a stack with alternating platens and cement sheets.
  • Figure 3 is a schematic representation in elevation view of a stack press having a stack of platens and sheets between its bottom and top die.
  • the following abbreviations have systematically been used:
  • bottom die BDt top surface of bottom die BD
  • CBDt curvature of the top surface of bottom die BD W: Wagon onto which bottom die BD is mounted TD: top die
  • TDb bottom surface of top die
  • CTDb curvature of the bottom surface of top die
  • Figure 1 shows a partial cross-section of a possible corrugated sheet- having a constant thickness Sd.
  • Each type of corrugated fiber-cement sheet has a particular top surface
  • a partial cross-section of a compact, vertically aligned stack of 6 platens P and 5 fresh fiber-cement sheets F is represented in figure 2.
  • the platens P are made of a resilient elastomeric material such as polyurethane.
  • the minimum thickness Pd of the platens is in excess of twice the thickness Sd of the corrugated sheets S to be produced.
  • the surface area of the platens P is greater than the surface area of the fresh sheets F.
  • the stack is assembled so that when the fresh sheet F is placed onto platen P, there remains all around the border of the fresh sheet F, an edge E of platen P which is not covered by fresh sheet F.
  • the stack is placed between rigid bottom die BD and rigid top die TD in aligned relationship therewith.
  • the bottom surface TDb of top die TD has a curvature CTDb which corresponds substantially to the curvature CSb of the bottom surface Sb of the corrugated fiber-cement sheet S which one wishes to produce.
  • the top surface BDt of bottom die BD has a curvature CBDt which corresponds substantially to the curvature CSt of the top surface St of corrugated fiber- cement sheet S to be produced.
  • the press is closed by means of a hydraulic control system (not shown) so as to apply the required compression force to the stack.
  • the press is opened by said hydraulic system, so as to allow the stack to be removed from the press.
  • Bottom die BD is mounted on a wagon W which can be rolled from under the press.
  • the number of sheets that can be pressed simultaneously depends on the material used for the platens and the thickness of the sheets. Fifteen to thirty sheets have been stacked and pressed with good results.
  • the method can be applied to press any kind of conventional fiber-cement corrugated sheet regardless its profile and thickness.
  • step 2) to 4) are performed during the Magnani fabrication stage.
  • the pressing process can proceed directly from step 2) to step 5) and following, whereby the fresh sheets F are the corrugated fresh sheets leaving the Magnani forming Machine.
  • the pressing process of the invention may be effected with a conventional hydraulic press or with a press having more than one opening for introducing a corresponding number of mixed stacks to be pressed.
  • Fiber-cement sheets having a profile generally known as profile no. 7 were pressed using the method according to the present invention.
  • the fiber-cement sheets having profile n° 7 short had the following dimensions: Length (along the ridges and furrows): 1080 mm, Width (along the ridges and furrows): 1050 mm.
  • the fiber-cement sheets having profile n° 7 long had the following dimensions: Length (accross the ridges and furrows): 2400 mm, Width (accross the ridges and furrows): 1050 mm.
  • the nominal thickness of the sheets was 4.5 mm before pressing and 4.0 mm after pressing.
  • the deformable platens used were about 20 cm longer and wider than the sheets to be pressed.
  • the thickness of the platens varied between 4 and 8 mm.
  • the platens were made of polyurethane having a Shore A hardness of 80° , a modulus at 300% elongation according to ASTM D-412 of 50 kgf/cm 2 (4.90 MPa) and an elongation at break according to ASTM D412 of 760 %.
  • the platens had been manufactured in a mould (not represented in the figures).
  • the mould was made of a pair of two steel pieces, each piece having one side mechanically machined to obtain a curvature corresponding to the curvature of respectively the top and bottom surface of the profile 7 fibre-cement sheets.
  • Said steel pieces were spaced apart in parallel position in order to form the lateral walls of the mould into which the resin was poured to produce the deformable platen. This operation was repeated to make the required number of platens.
  • the hydraullically setting fiber-cement mixture used for the manufacture of the sheets had the following composition (expressed in percentage by weight on dry weight basis):
  • the platens were coated with a a silicone lubricant as a demoulding oil.
  • Corrugated green fiber-cement sheets were stack-pressed in one batch.
  • the stack thus also comprised 16 platens.
  • the stack was pressed in a standard press equipped for pressing flat sheets, but provided with the upper and lower dies according to the invention.
  • the mould which had been used for moulding the platens were more used as the two dies.
  • the respective corrugated die surfaces were parallelly adjusted by electronic means.
  • the maximum pressure applied to the sheets was 25 kg/cm 2 (2.45 MPa). Pressure was applied during a cycle of 3 minutes. The holding time at maximum pressure was 2 minutes. A lateral deformation of the stack under load was observed of no more than 1 % of the width of the sheets. Said deformation was entirely reversible.
  • the compressed sheets were steam-cured in a conventional manner during 10 bar (0.1 MPa) steam pressure.
  • the present invention presents numerous advantages.
  • the main advantage of the invention is, that is now possible to stack- press corrugated fiber-cement sheets and, in doing so, to obtain products of sufficient quality.
  • the process according to the invention can advantageously be applied to any type of hydraulically setting fiber-cement mixture.
  • Known additives may be used in the process according to the invention provided one chooses a platen material which is compatible with those additives at the occuring temperatures and pressures.
  • the process can be performed with a whole range of known stack- presses, once they have been provided with the correctly profiled top die and bottom die.
  • the process according to the present invention can be realized with small or rudimentary stack-presses, provided they can exert the minimum pressure required for post-compression.
  • process according to the present invention can equally be incorporated in advanced installations, such as fully automated fabrication units.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)
  • Sealing Battery Cases Or Jackets (AREA)
  • Secondary Cells (AREA)

Abstract

L'invention concerne un procédé permettant de produire des plaques de fibrociment ondulées comprimées (S), présentant une surface inférieure (Sb) avec une courbure de surface inférieure (CSb) et une surface supérieure (St) avec une courbure de surface supérieure (CSt). Selon le procédé, on presse une pile compacte constituée d'une structure verticale alignée dans laquelle alternent des plaques ondulées (P) présentant une surface supérieure (Pt) et une surface inférieure (Pb), et des plaques de fibrociment frais (F), les plaques (P) étant constituées d'un matériau élastomère qui se déforme de manière résiliente durant le pressage. L'invention concerne également un ensemble qui permet de produire des plaques de fibrociment ondulées comprimées (S) présentant une surface inférieure (Sb) avec une courbure de surface inférieure (CSb) et une surface supérieure (St) avec une courbure de surface supérieure (CSt). Ledit ensemble comprend une presse verticale et au moins trois plaques ondulées (P) constituées d'un matériau élastomère qui se déforme de manière résiliente.
PCT/BE1998/000012 1997-01-30 1998-01-27 Procede pour comprimer des articles ondules en fibrociment WO1998033632A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU57426/98A AU5742698A (en) 1997-01-30 1998-01-27 Process for pressing corrugated fiber-cement articles
BR9807530-6A BR9807530A (pt) 1997-01-30 1998-01-27 Processo para prensar artigos de fibra-cimento corrugados.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CL1997000170 1997-01-30
CL170-97 1997-01-30

Publications (1)

Publication Number Publication Date
WO1998033632A1 true WO1998033632A1 (fr) 1998-08-06

Family

ID=4574490

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/BE1998/000012 WO1998033632A1 (fr) 1997-01-30 1998-01-27 Procede pour comprimer des articles ondules en fibrociment

Country Status (6)

Country Link
AR (1) AR008557A1 (fr)
AU (1) AU5742698A (fr)
BR (1) BR9807530A (fr)
PE (1) PE29099A1 (fr)
WO (1) WO1998033632A1 (fr)
ZA (1) ZA98733B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3523262B1 (fr) 2016-10-06 2021-06-16 Etex Services NV Procédés de production de produits en fibrociment à partir de débris de fibrociment

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1794435A (en) * 1929-09-20 1931-03-03 Ambler Asbestos Shingle & Shea Apparatus and method for making corrugated sheets
FR1051294A (fr) * 1950-09-20 1954-01-14 Procédé et machine pour la production de plaques ondulées en fibro-ciment
GB769739A (en) * 1955-04-01 1957-03-13 James D Argaville Clark Improvements in platen-type presses
GB2036635A (en) * 1978-11-25 1980-07-02 Emi Ltd Moulding video discs

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1794435A (en) * 1929-09-20 1931-03-03 Ambler Asbestos Shingle & Shea Apparatus and method for making corrugated sheets
FR1051294A (fr) * 1950-09-20 1954-01-14 Procédé et machine pour la production de plaques ondulées en fibro-ciment
GB769739A (en) * 1955-04-01 1957-03-13 James D Argaville Clark Improvements in platen-type presses
GB2036635A (en) * 1978-11-25 1980-07-02 Emi Ltd Moulding video discs

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3523262B1 (fr) 2016-10-06 2021-06-16 Etex Services NV Procédés de production de produits en fibrociment à partir de débris de fibrociment
US11554987B2 (en) 2016-10-06 2023-01-17 Etex Services Nv Methods for producing fiber cement products with fiber cement waste

Also Published As

Publication number Publication date
ZA98733B (en) 1999-02-19
BR9807530A (pt) 2000-03-14
PE29099A1 (es) 1999-04-01
AR008557A1 (es) 2000-01-19
AU5742698A (en) 1998-08-25

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