GB2174034A

GB2174034A - Apparatus for manufacturing a building block

Info

Publication number: GB2174034A
Application number: GB08528414A
Authority: GB
Inventors: Dennis Henry Ogden
Original assignee: Bip Chemicals Ltd
Current assignee: Bip Chemicals Ltd
Priority date: 1984-11-22
Filing date: 1985-11-19
Publication date: 1986-10-29
Also published as: GB8528414D0; EP0182619A2; GB2174034B; EP0182619A3

Abstract

The apparatus is of the type having a mould box (1), and at least one core (3) rigidly mounted in the mould box by means of a spacer bar (4). At least a portion of the moulding surface of the core and/or the mould box is formed from a rubbery polymer. The polymer may be used as a coating (8 Figure 2) and/or the core (3) may be a moulding of the polymer. An undercut may be made in a block by providing a core (10, 16 Figures 3 and 4) with an expandable resilient portion. The polymer may also be used to provide a cushion (7 Figure 2) under the lower edge of the mould box. In the process using the apparatus the mould box and core are removed from uncured mould blocks after a very short time e.g. 1 to 60 seconds. <IMAGE>

Description

1 GB 2 174 034 A 1

SPECIFICATION being to produce a cavity in the moulded block, wherein at least a portion of the moulding surfaces Improvements in or relating to manufacture of of the core and/or the mould box is formed from building blocks an rubbery polymer, such as a rubbery pol,,,ure-

70 thane.

This invention relates to the manufacture of build- The rubbery polymer may be incorporated into ing blocks and particularly such blocks which con- the apparatus as inserts or coatings on the surlace tain cavities. of the mould box and/or the core but preferably Building blocks of this type are conventionally the core is itself a resilient core which consists esmade in an apparatus which includes a mould box 75 sentially of the rubbery polymer.

and at least one core. The mould box is to mould The resilient core may for example be a hollow, the outer side walls of the block and typically con- shaped core made of a rubbery polymer, such as a sists of four sides but no top or bottom. In use the rubbery polyurethane.

box is placed on a flat surface or on a purpose- The natural resilience of the material is benefi- built baseplate which then forms the base of the 80 cial, when a block is being moulded, in promoting mould. Cavities are formed in the block by the compaction of the mix in the mould as the appara presence of cores. The cores used to mould cavi- tus is vibrated in the usual manner.

ties in the block are attached rigidly to the mould Particularly suitable rubbery polymers are polyu box by means of spacer bars. To make a block a rethanes but other rubbery polymers may be used.

predetermined amount of damp particulate con- 85 The preferred rubbers have the following range of crete mix is poured into the mould defined by properties:

mould box, flat surface and core a stripper plate is a) high abrasion resistance to avoid rapid wear brought down onto the mix to function also as a b) good elasticity to ensure accurate shape re top plate, and then the assembly is vibrated to tention consolidate the mix. Where a purpose-built base- 90 c) lack of creep plate is used the whole assembly is normally vi- d) rapid recovery to original shape brated but if there is no baseplate, only the mould e) sufficient rigidity to maintain shape under the box is vibrated. The mould box and core are then loads imposed during block formation.

lifted vertically away from the consolidated mix f) capable of good adhesion to the metal compo- forming an uncured block which is subsequently 95 nents of the mould box either directly or by use of cured. To facilitate its extraction from the uncured adhesives block the core may have a slight taper. The apparatus may also be adapted to enable a There are several areas where problems arise block to be manufactured wherein a recess is pro- with the apparatus for making blocks in this way vided in the walls of the cavity which, when the eg cores and walls tend to wear very rapidly and 100 cavity is filled with insulating foam, will assist in the vibration step generates a lot of noise. preventing dislodgement of the foam. In this em- Also, in our UK Patent Number 1 563 394 we bodiment of the invention the apparatus comprises have described a method for filling the cavity or a core to generate the cavity, said core including a cavities in a building block with an insulating plas- resilient portion which when expanded will form a tics foam. Whilst such foam-filled blocks are now 105 recess in a wall of said cavity and when retracted in widespread use and have excellent insulating will permit removal of the core from the cavity properties we have found that in certain circum- with the block in a green state.

stances foam which has been injected into the The resilient portion of the core may for example block cavity can become loosened or dislodge par- be a portion, such as an end portion, made of a ticularly when the cavity has a taper. 110 rubbery abrasion resistant polymer, such as a rubUnexpectedly we have now found that in the bery polyurethane, which in its expanded position manufacture of building blocks with cavities, the includes a portion which extends laterally out use of a resilient core in the moulding apparatus wardly from the core to form the necessary recess.

gives advantages which lead to improved block A positive expansion and retraction of the resili- production. Such a core may further be adapted to 115 ent portion may be achieved if desired by using a produce'blocks having cavities with undercut por- hollow cross section core and a movable core tions. spreader or bladder-like construction which can be We have now also found that a major reduction expanded by application of fluid pressure and con in the level of noise generated in use of the appatracted either by virtue of natural resilience on re ratus can be achieved by judicious positioning of 120 moval of such pressure, or by evacuation.

rubbery polymer in such apparatus. In any embodiment of the apparatus the mould We have also found that the use of a resilient box may have, on that edge which is to abut polymer in the apparatus can give rise to a block against a flat surface onto which a block is to be mould whose interior surface has improved abra- moulded, a cushion of rubbery polymer.

sion resistance over the -conventional steel mould. 125 The cushion of rubbery polymer reduces the According to the present invention there is pro- noise generated during vibration of the apparatus vided an apparatus for moulding a building block during moulding of a block. Preferably the cushion of the type comprising a mould box having sides is at least 3mm thick and it is particularly preferred but no base or top and at least one core rigidly at- that the cushion is 5 to 10mm thick.

tached thereto by means of a spacer bar, the core 130 The invention will now be particularly described, 2 GB 2 174 034 A 2 by way of example only, with reference to the ac- is placed on a transfer plate and pressed on to it, companying drawings in which - the cushion 7 comes into contact with the transfer Figure I is an exploded diagram of the principal plate. As the mould box and transfer plate are con components of a block mould. ventionally made of steel, this prevents metal to Figure 2 is a series of cross-sectioned views of a 70 metal contact and reduces noise.

core on line A-A showing a mould core in accord- The coating 8 of polymer on the walls of the ance with one embodiment of the invention. mould box also reduces noise and improves the Figure 3 is a series of similar cross-sectional life of the mould box. The preferred polymer for views illustrating a second embodiment of the in- cushion, coating and core is a rubbery polyure- vention. 75 thane; for example one made from a polyether po Figure 4 is a series of similar Gross-sectional Iyol of mol.wt 1000 such as Terathane 1000 views illustrating a third embodiment of the inven(commercially available from Du Pont) and methyl tion. ene diphenyl isocyanate (IVIDI).

With reference to Figure 1 a block mould con- The coating 8 may be cast onto the metal walls sists of a mould box 1, transfer plate 2, cores 3 80 of the mould box at 900C to 100'C using a mixture mounted on a spacer bar 4 and a pair of stripper of 918 parts by weight of the polyol and 282 parts plates 5. of IVIDL In use to shape a block the mould box 1 and coIn the second embodiment of the invention res 3 are placed on the transfer plate 2, thus defin- shown in Figure 3 the cores are modified to faciliing with the transfer plate an open-topped mould 85 tate their expansion inside the mould box and ena cavity. A metered amount of damp concrete mix is ble a block to be moulded with a cavity which is poured into the cavity, the top is closed by means better adapted subsequently to retain a foam fill of the stripper plates and the whole assembly is vi- ing.

brated to ensure proper compaction of the mix to Referring now to Figure 3, diagram A illustrates form a moulded block of correct dimensions. The 90 a mould box 1 and conventional core 9 in position mould box and cores can now be removed to on a transfer plate 2 forming a cavity ready for leave the moulded block 6 on the transfer plate. concrete to be poured in.

The stripper plates 5 are used to hold down the Diagram B illustrates a modified core 10 which is moulded block on the transfer plate whilst the made of a flexible material such as a rubbery po mould box and cores are lifted off the moulded 95 Iyurethane, and which is provided with a core block 6, leaving the latter on the transfer plate 3 on spreader 11 of a rigid material such as steel.

which it is removed for curing. The time taken As shown in diagram C when the modified core from the filling of the mould cavity to removal of 10 is placed with a mould box 1 on a transfer plate the mould box and cores is in the range I to 60 2 and pressed on to it, the core spreader is first to seconds, for example 3 to 20 seconds. It will thus 100 come into contact with the transfer plate. As the be appreciated that the concrete mix can not be mould box and core 10 are lowered on to the sloppy since there is no appreciable cure taking transfer plate 2 the core spreader 11 slides up into place before the mould box is removed and the the hollow interior of the core 7 and is maintained uncured block must then be free-standing. in alignment within it by engagement of a guide Referring now to Figure 2, the diagram illustrates 105 rod 12 in a hole in an internal web 13 in the core in cross-section a mould box 1 and core 3 in posi- 10. The effect of the core spreader is to force apart tion to be lowered on to a transfer plate 2 to form the lower portions of the core 10 so that when in a cavity ready for concrete mix to be poured in. position in the mould box the widened core de The cores 3 are of conventional external shape, fines an undercut in the mould cavity shape.

optionally tapered to facilitate their removal from 110 After a block has been moulded using the modi inside a moulded block but they each are made fied core, removal of the core and mould box from from a rubbery polyurethane polymer which is the transfer plate is accomplished as usual since highly abrasion resistant. the upward movement of the core 10 will initially Each core is a hollow shape, which has been serve to lift it off the core spreader 11 and so the formed on the spacer bar 4. 115 core 10 will contract and slide out of the moulded The mould box 1 is provided with a cushion 7 on block.

its lower edge and a coating 8 of the same poly- A head 14 on the guide rod 12 will eventually ar mer on its interior walls. rest relative movement of the core 10 and core In use the resilience of the cores aids the com- spreader 11 and cause the core spreader to lift paction of the mix during the vibration stage re- 120 away from the moulded block with the core.

ferred to above. - In the third embodiment of the invention illus The rubbery polyurethane from which the cores trated in Figure 4 the cores are of a similar kind to are made may for example be derived from a polythose of Figure 3 but have an alternative spreader ether polyol of 1000 mol.wt, such as Terathane mechanism. Figure 4 also illustrates use of an ap- 1000 commercially available from Du Pont, and 125 paratus with no baseplate.

methylene diphenyl isocyanate (MDI). Referring now to Figure 4, diagram A shows a Thus the cores may be cast onto the spacer bar mould box 1 and a core 16 mounted on a spacer in moulds at 90'C to 100'C using a mixture of 918 bar 4. The mould box is suspended above a flat parts by wt of the polyol and 292 parts of IVIDL base 15 which could be, for example, a smooth As shown in diagram 2B when the mould box 1, 130 concrete floor.

3 GB 2 174 034 A 3 The core 16 is a hollow moulding of rubbery pol- that edge which is to abut against a flat surface ymer having the conventional, slightly tapered, ex- onto which a block is to be moulded a cushion of ternal shape but ledges 17 are moulded into its rubbery polymer.

internal walls adjacent to the bottom of the core. 12. An apparatus according to claim 11 in The spreader mechanism is very simple and conwhich the cushion has a thickness of 5 to 1Omm.

sists only of a thick section 18 of a stiff rubbery 13. An apparatus according to claim 11 or 12 in polymer (which could be the same material as the which said rubbery polymer is a rubbery polyure core 16) which is V-shaped in cross-section with thane.

the apex of the 'Y' extending below the bottom of 14. An apparatus substantially as described the core and the ends of the arms of the "V" being 75 herein with reference to Figures 1 and 2 of the ac- adhered to the ledges 17 on the inner side of the companying drawings.

walls of the core. 15. An apparatus substantially as described When in use the mould box and core assembly herein with reference to Figure 3 of the accompa- is lowered on to a flat surface the apex of the "V" nying drawings.

shaped sheet 18 contacts the surface first then as 80 16. An apparatus substantially as described the core 16 is lowered further the effect is to flatten herein with reference to Figure 4 of the accompa the "V", and thus force outwardly the lower por- nying drawings.

tions of the sides of the core. It will be appreciated 17. A process for the manufacture of a building that in this embodiment the sheet 18 functions as a block in an apparatus as claimed in any one of the simple hinge and could be replaced by a metal 85 preceding claims wherein the mould box and core hinged spreader to perform the same function. assembly is lowered onto a flat surface, a damp concrete mix is poured into the mould cavity so

Claims

CLAIMS formed, the top of said cavity is closed by means of one or more

stripper plates, the apparatus is vi 1. An apparatus for moulding a building block 90 brated and then the mould box and core assembly of the type comprising a mould box having sides is lifted away using the stripper plates to hold but no base or top and at least one core rigidly at- down the uncured block on the flat surface.

tached thereto by means of spacer bar, the core 18. A process according to claim 17 wherein being to produce a cavity in the moulded block the time taken from the filling of the mould cavity wherein at least a portion of the moulding surfaces 95 to removal of the mould box and core assembly is of the core and/or the mould box is formed from a in the range 1 to 60 seconds.

rubbery polymer. 19. A process according to claim 18 wherein
2. An apparatus according to claim 1 in which said time is in the range
3 to 20 seconds.

said polymer is a rubbery polyurethane. 20. A process for moulding a building block 3. An apparatus according to claim 1 or 2 in 100 substantially as described herein with reference to which the core is a resilient core which consists es- the accompanying drawings.

sentially of a rubbery polymer.
4. An apparatus according to claim 1, 2 or 3 in Printed in the UK for HMSO, D8818935, 9186, 7102.

which the core is moulded from said polymer. Published by The Patent Office, 25 Southampton Buildings, London,
5. An apparatus according to claim 4 in which WC2A lAY, from which copies may be obtained.

the core is formed on a metal spacer bar.
6. An apparatus according to any preceding claim in which the core is a hollow moulding of said polymer.
7. An apparatus according to any of the preced ing claims wherein said core includes a resilient portion which when expanded will form a recess in a wall of said cavity and when retracted will permit removal of the core from the cavity with the block in a green state.
8. An apparatus according to claim 7 in which said resilient portion of the core member is made of a rubbery polymer.
9. An apparatus according to claim 7 or 8 which includes means for expanding the core member to form a portion which expands laterally outwardly when in position inside a mould to form a cavity having an undercut portion.
10. An apparatus according to claim 9 in which the core member is moulded from a rubbery poly mer and the means to expand the core is a core spreader which will force apart resilient portions of said core member when in use.
11. An apparatus according to any one of the preceding claims wherein the mould box has on