EP0115957A1 - Dispositif et procédé pour la fabrication de produits de contruction cimenteux - Google Patents

Dispositif et procédé pour la fabrication de produits de contruction cimenteux Download PDF

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Publication number
EP0115957A1
EP0115957A1 EP84300608A EP84300608A EP0115957A1 EP 0115957 A1 EP0115957 A1 EP 0115957A1 EP 84300608 A EP84300608 A EP 84300608A EP 84300608 A EP84300608 A EP 84300608A EP 0115957 A1 EP0115957 A1 EP 0115957A1
Authority
EP
European Patent Office
Prior art keywords
rolls
band
roll
cementitious
twin
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP84300608A
Other languages
German (de)
English (en)
Inventor
Howard Anthony Barker
Stephen Holt
Denise Margaret Hoys
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Redland Technology Ltd
Monier Braas Research and Development Ltd
Original Assignee
Redland Technology Ltd
Redland Technologies Ltd
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 Redland Technology Ltd, Redland Technologies Ltd filed Critical Redland Technology Ltd
Publication of EP0115957A1 publication Critical patent/EP0115957A1/fr
Withdrawn legal-status Critical Current

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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
    • B28B1/30—Producing shaped prefabricated articles from the material by applying the material on to a core or other moulding surface to form a layer thereon
    • 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
    • B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
    • B28B3/12—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein one or more rollers exert pressure on the material

Definitions

  • cementitious building products where used herein, is intended to include roofing slates,tiles, panels or the like and particularly such cementitious products of relatively thin cross-section and high flexural strength.
  • the invention provides a method of manufacturing a cementitious building product comprising the steps of mixing together cement, water and a processing aid, subjecting the mixture so formed to high shear mixing in a twin-roll mill, the rolls of which are rotated at controlled speeds and thereby causing the mixture to plasticise and then to adhere to only one of the rolls to form a band of material thereon; removing the band of material from the said roll; forming the material into blanks, and curing the blanks to form a building product.
  • the invention also provides apparatus for manufacturing a cementitious building product comprising means for mixing together cement, water and a processing aid; a twin-roll mill comprising a pair of contra-rotating rolls; means for rotating the rolls at controlled speeds to effect high-shear mixing of the cementitious mixture and thereby form a band of material on one of the rolls; means for removing the band of material from the said roll, and means for forming and curing the band of material to form a building product.
  • the distance between the rolls of the twin-roll mill is varied between a first position in which the distance is small to prevent the mixture from passing through the rolls before it plasticises and a second position in which the remainder of the mixing takes place.
  • the material is formed into blanks by cutting the material into separate pieces and pressing the pieces to form the blanks.
  • the rolls of the mill are preferably rotated at unequal speeds, for example, in the ratio 10:11.
  • the distance between the rolls of the mill may be varied by rams (for example, hydraulic) extended and retracted by an appropriate control circuit.
  • rams for example, hydraulic
  • a doctor blade may be provided for running the band of material from the faster-moving roll, the band falling onto a conveyor which may transfer the band to cutting, pressing and curing stations.
  • Edge trimming means may also be provided for trimming the band of material to a predetermined width
  • One aspect of the invention is the provision of high shear mixing apparatus comprising
  • the said apparatus may comprise part of a processing plant for producing, when the plant is in use, cured cementitious products from the band of material removed from the said roll, the plant also comprising:-
  • the relative speeds of the two rolls of the apparatus are in a ratio of at least 10:11 however, in other convenient arrangement the speeds of the rolls may be in a ratio of up to 1:4.
  • the distance between the rolls may be opened at a controlled rate, as the cementitious composition fed thereto becomes plastised, from a zero nip to that distance apart which defines the final thickness of the band of material to be produced.thereby.
  • the size of the nip may be altered in stages with a short dwell time between each stage in order to optimise the high shear mixing action of the contra-rotating rolls.
  • the present invention also conveniently provides an improved method of manufacturing roofing slates comprising the steps of:-
  • the apparatus described below overcomes or mitigates these drawbacks by providing apparatus with which cementitious products of acceptable flexural strength and durability can be readily produced from low water/cement ratio compositions.
  • the apparatus or plant comprises a mixer 10, a feed conveyor 12, a twin-roll mill 14, a transfer conveyor 16, a cutting device 18,a press 20 and a curing chamber 22.
  • the mixture 10 is of conventional design and is utilized, when the plant is in use, to form a homogeneous mixture from the constituents placed therein. While the mixer shown may be tipped about a fulcrum 24 to deposit its contents onto an upper run 26 of the conveyor 12, any other suitable transfer arrangement may be used.
  • the conveyor 12 is arranged with its upstream end 28 adjacent the mixer 10 and a downstream end 30 overlying the nip of the twin-roll mill 14.
  • the mill 14 has a pair of contra-rotating rolls 32 and 34 the distance between adjacent surface portions of which is defined as the nip between the rolls.
  • the rolls 32 and 34 are arranged in side-by-side relationship and have an operative width defined by edge cutters not shown in Figure 1 but which are described below with reference to Figure 3.
  • the rolls are of equal diameter and are arranged with their axes parallel and horizontal.
  • the rolls 32 and 34 are arranged to run at unequal speeds and a suitable motor and gears are provided for this purpose.
  • the slower moving roll 32 has a peripheral speed of 20m per minute in one example, while a differential gear ratio of 10:11 ensures that the faster moving roll 34 has a peripheral speed of approximately 22m per minute.
  • the rolls 32 and 34 rotate in the direction of the arrows 32a and 34a respectively and the roll 32 is arranged to be moved relative to, the roll 34 to vary the size of the nip formed therebetween.
  • the means for effecting the said movement of the roll 32 comprises a pair of hydraulic rams 35(one of which is shown in Figure l) and an appropriate control circuit which is shown in Figure 2.
  • Each ram 35 is connected between an end of the roller 32 and a fixed part of a frame 37 of the twin-roll mill 14.
  • the control circuit allows an operative to cause a progressive spacing of the rolls 32 and 34 or a stage by stage spacing thereof with appropriate dwell periods between each stage.
  • the hydraulic circuit 50 for operating the rams 35 comprises a pump 51 for supplying pressure fluid via a directional control valve 52 to supply lines 53, 54 for the respective rams.
  • Each supply line 53, 54 includes, connected in series to the supply side of the ram, a flow control valve 56 and two check valves 57, 58 arranged to operate in opposite directions.
  • a preset relief valve 59 and a pressure transducer 49 is also provided in each supply line.
  • the return side of the rams is connected via return line 4 3 to the directional control valve 52 and thence to a tank 45.
  • a main circuit relief valve 41 and on/off control 44 are connected between the pump 51 and tank 45.
  • the circuit 50 is designed to allow the rams 35 to be extended very quickly to a position in which the nip between the rolls 32, 34 is a zero gap and to retract the rams at a controlled rate, keeping the rolls parallel, to a position in which the gap is approximately 4mm.
  • the flow control valves 56 control this basic movement.
  • the relief valves 59 ensure that neither piston is overloaded at any time while the pressure in the hydraulic circuit is controlled by valve 41 .
  • the solenoid operated check valves 57, 58 allow both rams to be extended or retracted independently.
  • the apparatus 14 also includes a return conveyor 36 which is located beneath the nip of the rolls 32 and 34 and which, when the apparatus is in use, returns cementitious material dropping through the nip of the rolls 32 and 34, and not being processed thereby, to the feed conveyor 12.
  • the edge trimming means 60 comprises two circular blades 61, arranged one adjacent each end of the roll 34 and in contact therewith. To ensure that the blades 61 remain in contact with roll 34, each blade 61 is mounted on an adjustment screw 63 and is spring urged towards the roll 34. The screw 63 are in turn fixed to a bar 64 attached to the support frame 37 of the mill. The cutting blades 61 are effective to cut a band of material on the roll 34 and scrapers 65,then remove the excess material from the roll 34.
  • Each scaper 65 comprises a curved blade which is fixed to a bracket 66 fixed to the frame 37 and one end of which is in close proximity to the roll 34.
  • the material thus removed from the roll 34 falls into a collecting trough 68 arranged below the blades 61 where it is collected.
  • the excess material thus collected may simply be removed or may be recycled to the mill by suitable means.
  • the trimmed band of material remaining on the roll 34 is removed by a cut-off device 70 in the nature of a doctor-blade.
  • the cut-off device 70 comprises a doctor blade 72 extending the full width of roll 34 and slidable in a housing 73 into and out of engagement with the roll 34.
  • a pair of double-acting pneumatic rams 75 are connected between a bracket 76 fixed to the edge of the doctor blade 72 remote from the roll 34 and brackets 77 fixed to the frame 37 and are operable to move the doctor-blade 72.
  • the housing 73 comprises two metal plates 78 having brackets 79 at their ends by means of which the housing is fixed to the support frame 37. Clamped between the plates 78 are two pairs of retaining strips 81 and two felt pads 82 therebetween, the blade 72 slides between the pads 82 which are effective to clean the blade as it is retracted.
  • the blade 72 is effective to slit a band of cementitious material from the faster moving roll 34, and allow the band to fall by gravity onto the transfer conveyor 16.
  • the transfer conveyor 16 of the processing plant comprises an upstream end 38 located beneath the roll 34 and a downstream end 40 located adjacent to the press 20.
  • the cutting device 18 overlies an upper run 42 of the conveyor 16 and comprises a die-sett which, when the plant is in use, cuts a series of green state blanks from the laid out band of cementitious material.
  • the plant includes a transfer device, not shown, but of known type, for transferring the green state blanks to the press 20.
  • the press 20 is a conventional press used in the manufacture of building products capable of exerting a pressure of 6Mpa on the blanks to compact them.
  • the curing chamber 22 of the plant is one which operates under 100% relative humidity and at temperatures between 30° and 90°C.
  • the blanks are transferred from the press to the curing chamber in known manner.
  • Appropriate packaging means may also be provided in the processing plant for stacking and packaging the finished products.
  • An operative mixes a cementitious composition in the mixture 10 the composition being a, cementitious composition of low water/cement ratio and containing a processing aid.
  • the composition is mixed until a high degree of homogeneity is achieved.
  • the mixer 10 is then rotated about its fulcrum 24 to deposit the composition, which at this stage has a crumbly quality, onto the upper run 26 of the conveyor 12.
  • the composition is carried by the upper run of the conveyor 12 and thence falls into the nip of the rolls 32 and 34.
  • the conveyor speed is 15m per minute and the composition is fed at a constant rate over 10 to 20 seconds.
  • the crumbly cementitious composition is thus carried by the upper run of the conveyor and passes from the end 30 of the conveyor into the nip of the rolls 32 and 34.
  • the nip between the rolls 32 and 34 is initially set by rams 35 to zero gap and the peripheral spee of the rolls 32 and 34 are, as stated above, twenty and twenty-two meters per minute respectively.
  • the cementitious composition falls into the nip of the rolls they are progressively spaced apart by operation o rams 35 to widen the nip.
  • the rate of movement of the roll 32 as it wiè the nip is controlled to ensure that as little as possible of the composition falls straight through onto the conveyor
  • the composition is subjected to high shear mixing and, initially, the composition sometimes adheres to both rolls.
  • the nip opening rate and speed of rotation of the rolls should ensure that the cementitious material adheres to only the faster moving roll; however, under any circumstances the unequal speed of the rolls ensures tha the degree of high shear mixing reduces the composition eventually to a state approaching high plasticity and any material on the slower moving roll 32 will then transfer to the faster moving roll 34 and forms a single band thereon with a thickness defined by the final spacing of the nip between the rolls, for example 4mm.
  • the width of the band is determined by the edge cutters 6 defining the operative width of the rolls 32 and 34.
  • the operative then operates the cut-off device to slit the band of highly plastic cementitious material which then passes onto a steel platen (not shown) which is carried by the upper run 43 of the conveyor 16.
  • the laid out band of cementitious material from a typical mix is about 152cm x 86cm x 0.4cm and has a consistency similar to putty.
  • the conveyor 16 is arrested with the platen and material under the cutting device 18 which is operated to cut the material into green state blanks.
  • the platen and blanks are thereafter conveyed to the press 20 where they are arranged in a stack for pressing at a pressure of 6MPa for two hours.
  • the stacks of blanks are conveyed to a curing chamber where they are subjected to 100% relative humidity at a temperature of 60%C for 8 hours.
  • the roofing slates may then be ready for use or may be subjected to further ageing prior to use.
  • a modified plant provision may be made for applying an organic polymer or other suitable coating material to at least one surface of the cememtitious products prior to or after the curing operation.
  • the operation of the apparatus is not limited to the process discribed above.
  • the relative speeds of the rolls of the mill may be varied and one or other of the rolls may be heated or cooled to assist in plasticising the cementitious composition as described above.
  • cementitious products manufactured in a plant utilising a high shear mixing apparatus as hereinbefore disclosed and having a composition as described have been found to have an enhanced flexural strength and modulus of elasticity.
  • the apparatus is not limited to that described above and may be modified.
  • a motorised system may replace the rams 35 for adjusting the nip between the rolls 32, 34 and such a system may be advantageous for continuous operation of the plant.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Devices For Post-Treatments, Processing, Supply, Discharge, And Other Processes (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)
EP84300608A 1983-01-31 1984-01-31 Dispositif et procédé pour la fabrication de produits de contruction cimenteux Withdrawn EP0115957A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB838302584A GB8302584D0 (en) 1983-01-31 1983-01-31 Manufacture of cementitious building products
GB8302584 1983-01-31

Publications (1)

Publication Number Publication Date
EP0115957A1 true EP0115957A1 (fr) 1984-08-15

Family

ID=10537218

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84300608A Withdrawn EP0115957A1 (fr) 1983-01-31 1984-01-31 Dispositif et procédé pour la fabrication de produits de contruction cimenteux

Country Status (3)

Country Link
EP (1) EP0115957A1 (fr)
AU (2) AU2390484A (fr)
GB (1) GB8302584D0 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0332984A2 (fr) * 1988-03-12 1989-09-20 Hoechst CeramTec Aktiengesellschaft Pièces façonnées et procédé pour leur production

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3316586A (en) * 1963-12-19 1967-05-02 S E T E P Soc D Etudes De Rech Devices for feeding uncured plastic sheet to a movable sheet-receiving device
US3429959A (en) * 1961-07-11 1969-02-25 Kleinewefers Soehne J Method of making foils of thermoplastic synthetic materials
FR1564693A (fr) * 1968-02-19 1969-04-25
GB1228798A (fr) * 1968-07-31 1971-04-21

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3429959A (en) * 1961-07-11 1969-02-25 Kleinewefers Soehne J Method of making foils of thermoplastic synthetic materials
US3316586A (en) * 1963-12-19 1967-05-02 S E T E P Soc D Etudes De Rech Devices for feeding uncured plastic sheet to a movable sheet-receiving device
FR1564693A (fr) * 1968-02-19 1969-04-25
GB1228798A (fr) * 1968-07-31 1971-04-21

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0332984A2 (fr) * 1988-03-12 1989-09-20 Hoechst CeramTec Aktiengesellschaft Pièces façonnées et procédé pour leur production
EP0332984A3 (fr) * 1988-03-12 1991-07-24 Hoechst CeramTec Aktiengesellschaft Pièces façonnées et procédé pour leur production

Also Published As

Publication number Publication date
AU2390384A (en) 1984-08-02
AU2390484A (en) 1984-08-02
GB8302584D0 (en) 1983-03-02

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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AK Designated contracting states

Designated state(s): AT BE CH DE FR GB IT LI LU NL SE

17P Request for examination filed

Effective date: 19850211

17Q First examination report despatched

Effective date: 19860224

STAA Information on the status of an ep patent application or granted ep patent

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18W Application withdrawn

Withdrawal date: 19860516

RIN1 Information on inventor provided before grant (corrected)

Inventor name: HOYS, DENISE MARGARET

Inventor name: BARKER, HOWARD ANTHONY

Inventor name: HOLT, STEPHEN