IL33099A - Process and apparatus for the mechanical manufacture of raw blocks - Google Patents

Description

Process and apparatus for the mechanical manufacture of raw blocks from granular thermoplastic material NOBEL A 31180 2 The present invention relates to the production from chips or granules of a thermoplastic of manufacture for the ultimate manufacture of sheets and the like final By some known chips or granules of thermo plastic material are moulded in the heat to f orm a block and the after is mechanically sliced or peeled to form It is not in this to achieve a uniform distribution of the chips in the mould if the starting materials are well but it becomes substantially more difficult to distribute the chips formly in the form if they have a for of 60 x 60 x 3 In that case one has to rely on the skill of the particularly when materials of several different colours axe Heating the block from the outside has the disadvantage that in the process of moulding the outwardly hot the pressure acts inwardly towards the centre of the block and as a result the pattern varies over the of the By other known plastic materials in comminuted form are calendered to form these are cut into rods or blocks and the latter are subjected to a second calendering whereby a variegated sheet material is produced as a final All these known whose last process step is a calendering produce patterns which have a tudinal orientation and are and not 3 The invention has the object to provide a process for the production of a form which final products such as sheets or the like can be made by a mechanical operation other than In the case of patterned products it is an object of the invention to make it possible to avoid longitudinal ation of the patterns and to achieve a repetitive and reproducible The invention consists in a process f or the facture of raw blocks serving as for the production of sheets and the a granular thermoplastic material is calendered to form a raw web whose width approximately corresponds to one dimension of the block to be the web is cut transversely into the strips are cut into substantially rectangular then the chips are disposed in regular rows and the stack is heated without pressure to sinter to form a coherent the is placed in a form or mould and pacted under pressure and in the heat to form the raw This process achieves the uniform distribution of the chips over the length and thickness of the raw and consequently a uniform and ible pattern in the plates or other final products made from the 4 On their way to the stacking station the chips are preferably turned into a transverse position so that the original longitudinal orientation of the veining is no longer visible in the raw For achieving special two or more raw webs made from the granular starting material may be laminated into a compound Electrically conductive floorings are presently manufactured by coating the granular starting material with a conductive layer before moulding it in the box Such coated granules cannot be prior to the in a furnace since there exists electric contact between their conductive outer layers and the electrodes of the In order to overcome this the conductive layer has been coated with a which is a cumbersome and expensive The present invention eliminates this drawback in that an electrically conductive paste is sandwiched between at least two raw webs in the course of the laminating and the compound web is subjected to a heat Where the ultimate product consists of plates or panels of comparative small dimensions the raw block may have a substantially It can then simply be cut or In that case the chips are so stacked that the stack as well a s the sintered product have a similar Such raw blocks be peeled by a circumferentially proceeding cutting operation to form continuous sheets such as are advantageously used for some as because they can readily be laid in an economical a second embodiment of the invention provides a process for the manufacture of round raw blocks which can thus be in which process the chips are stacked in a comparatively thin layer and preferably to form a the latter is wound into a substantially cylindrical and this is moulded into the raw block by radially applied The compacting especially the magnitude of the pressure and the moulding should be so chosen that the round block is sintered throughout its It can then readily be The continuous sheets thus produced can be wound to form bolts which occupy a minimum of storage space and are easy to pack and Such or any panels or lengths cut have or none of those internal stresses which are apt to make conventional floor coverings warp or or to detach them the By this process any desired marbling pattern can be produced since the patterns are not distorted by the radial compression of the round and the same marbling can always be the amount of recycle material is smaller by about to than it has been up to now in conventional which means a substantial saving of Similarly as the first embodiment of the this second embodiment enables the manufacture of products having an electrically conductive For the of the s d forms raw web be sound into a round it is tageous to the layer of chips about 2 to mm preferably about 4 to 20 the sintering preferably before entering the zones of higher the web may be submitted to a preliminary compression whic accelerates If the operation of compacting the wound web is applied to marbled w ith view to producing patterned sheets by peeling the pressure cannot be exerted on the ends of the wound the direction of the since this would a flow of in the axial direction and the marbling would become uneven over the the we in order to make the end faces of the round block the latter is upset to such an extent only that its remains about equal to the width of the ra sheet from the block by peeling is obtained with a uni width and withou distortion of the The actual compactio of the wound web is per hydraulically or radially outwards When a determined compacting pressure has been the round block should preferably be cooled its inner It has been found advantageous to apply the radial pressure from outside as soon as it has reached the predetermined ma to cool the compacted block from the inside and maintain the until the turns have become completely welded eooling of the round block from within can be effected by the cooling of a core of steel or the like on which the web has been wound to form the round his has the advantage that the material shrinks s re d he eednot s eciall cho ed course the pressurizing fluid may also be out is not particularly advantageous since there arises the danger that cracks are created in the block since the solidified peripheral material ca no longer flow and follow the similar reasons it is not advantageous to make the compacting pressure ac the inside the less so since in that case the core required fo holding the block in the peeling operation has to be introduced and anchored the block after the compacting invention also provides apparatus carrying ou processes Embodiments of the invention are by way of example in accompanying drawings in 1 is a diagrammatic side of a plan for manufacture raw blocks from chips of thermoplastic material according a first embodiment the invention the sake of convenience this Figure has been divided and the parts marked appear 2 is a plan view of the plant according to 3 to 5 are side views of variants of some parts o the plant 1 and 6 is diagram illustrating the theoretical the width of the and that of the compacted 7 is a fragmentary side view of a plant according to another embodiment of the 8 an axial section of a cylindrical mould fo the radial compaction of a ound raw and 10 show different and 11 shows an electrically conductive between two The shown in 1 and 2 comprises three worm extruders 1 each a feed hopper Each extruder can be fed with a mixture of granulated thermoplastic material of different or each extruder may be charged with a different The material is plasticized in the extruders and discharged onto cutters 2 where it is again shreds 3 drop onto a conveyor belt 4 which fers the material to a second belt 5 located at an angle to the The conveyor 5 distributes the hot shredded material 3 evenly in a gap 6 between two rollers 7 it is calendered into a web 8 whose width is approximately equal to that of the block which is to be made by The raw web 8 is transversely cut by a cutter 10 into strips which are delivered by further eonveyor belt to a tudinal The latter divides the transversal strips 11 of the raw web into substantially chips 1 which drop onto a belt This is mounted on a carriage 16 reclprocable on a base and the belt 15 is movable at a higher speed than the carriage As the carriage advances in the direction in which the work proceeds the in into position above a further conveyor the conveyor belt 15 is at rest relative to the carriage and the chips 14 as they drop from the cutter of belt with the chips starts at the front end of the and ends at rear end when the carriage 16 has completed its forward As the carriage 16 returns to the the belt 15 runs a a larger speed than the the direction of movement of the upper stretch belt being whereby the chips 14 are dropped from the belt on carriage 16 has returned into a position in which end is located above the rear end of the conveyor By varying the relative speeds of the belt d carriage the chips can deposited in stacks 20 of various patterns on veyor suc patterns are schematically represented in 9 and the pattern according to 9 is obtained when the speed of the carriage is rather relative to that of the than With a what higher speed of the carriage relative the belt about a pattern like that according to 10 is In any ease the stacking proceeds i a substantially uniform and regular The transfer of the chips from the cutter to the conveyor belt and from the latter on to the belt turns the chips 1 out of the original orientation of the web so that the longitudinal veining of the web produced by the rollers 7 is broken f e conveyor 18 carries th stack 20 into a frequency heated tunnel where the chips are and owing to their uniform distribution the conveyor their sintering is also sintered 20 is heated from the outside in a tunnel furnace 21 and then trimmed by a cutter 22 to the dimensions of a raw block The hot raw block 9 is in a covered with a spiked lid compacted in a press 25 and The spiked lid 24 serves a holder for the moulded block 26 in the cess of slicing the latter into illustrates an arrangement for the creation of certain marbling Two or more pairs of calender rollers 27 produce each a raw web 28 and these are laminated by a pair of rollers The com ound web asses between rollers 2 and further processed as above with reference to and 4 illustrates the manufacture of an electrically conductive flooring by an arrangement which corresponds su tially to that of except that the laminating rollers 29 are replaced by a pair of rollers 30 by means of which a ive paste or powder 31 is sandwiched between two raw webs The compound web passes through a series of heaters or red radiators 32 where the paste is homogeneously then the web is further processed as described 5 illustrates the arrangement of two transverse cutters 33 instead of the single cutter 10 of the for producing two sets of strips 34 of different These strips 34 may either be taken up in common by a single belt 35 in order jointly to be cut or the plant may comprise two separate conveyor belts coordinated to two separate longitudinal which makes for a greater variability of the The processes described with reference to 1 to 5 produce a raw web having approximately the width of the compacted The 20 for this block has a somewhat greater bulk width since the are not tightly shows theoretical relationship between the bulk width of the and the width of the compacted The difference of width between the two amounts to about half the width of a In that case the chips tightly packed in not only in the centre but also at the and there will be no flow of material from the centre towards the walls in course of the compacting In the direction of its the is cut into lengths corresponding to the block to be Since in these cutting planes the chips are cam occur the edges in the moulding Such flowing movements as occur within the block during the moulding are actually desirable for creating special marbling mechanical production of the ensures the producibility of the process of each chosen 7 illustrates a plant for the production compacte round parts of the plant of 1 and which are in those 1 to are cable to this plant as well and been omitted from addition the plan of 7 a conveyor arrangement corresponding to the 17 of except that 7 shows a pair of drive rollers 38 for the belt two aligned tunnel furnaces 41 of which the latter is preferably heated to a highe temperature than the forme a pair rollers 44 between the two furnaces for the sintered web on its way from the first to the second a conveyor belt 39 running through both furnaces and between the rollers winding 44 and driven by a chain 4 i and 46 on which the web emerging from the tunnel 41 is wound to form a which is subjected to a certain in the by a taut endless belt spool is preferably hollow and designed to be cooled from inside by means of any suitable cooling flanges may ably be disposed at its ends for upsetting the wound web to the desired they are secured to the spool by collars nuts following for may be made in the plant according to there may be a furnace instead of the two furnaces and this may be designed different rising from the inle to outlet Several conveyors may be disposed in parallel in order to increase the in while a web 45 carried by the conveyor 59 is being wound on a spool a second conveyor 59 is charged with a fresh feed and a third conveyor carries its web through the furnaces and gets ready to discharge the web on to a It is preferable that the or conveyors 59 move through the furnaces not at a uniform speed but slower at the beginning and more quickly at the The arrangement of the calender rollers 44 is optional but With the plant in the work proceeds as A charge chips is stacked by the eonveyor then arrangement on a conveyor belt 5 the latter runs at a uniform speed through the tunnel furnace The charge has the weight required for the production of a round In the furnace 40 the charge sintered into a wha coherent structure which is by the roller then i passes into the furnace 41 where the speed of the conveyor is by a change of and the temperature is higher than in the furnace preferably 170 and and the sintering is The raw web 45 emerging from the furnace 41 is allowed to cool to the desired temperature and then wound on the spool on to which it is tightened by the belt The radial compaction of wound web 45 is effected by means of a substantially cylindrical Figure 8 trates an embodiment such a mould in which the compacting ressure is exerted radiall i mould comprises a cylindrical casing 48 within which tubular 49 casing has an inlet wit pressur gauge and for a pressurizing fluid The flanges fit the ends of the casing When the spool with the wound has been placed in the pressurizing is admitted and presses the membrane on to the wound When pressure has been it is maintained fo time while a cooling fluid is introduced into the holloa spool or in the round blook may be cooled from the which is achieved by the cooling of the pressurizing As variant the pressurising membrane may be disposed on spool and the latter be designed for the introduction of pressurizing fluid whereby the compacting pressure is made to aet radially production of an electrically conductive a electrically conductive a paste or may be sandwiched between two webs similarly aa described above wit reference to a web may be coated the conductive material on one face nly but there arises the danger that chips so coated are toppled over while being discharged on to the belt 59 and the conductive face of two or more chips contact one whereby the conductivity of the final product becomes danger can be avoided by the pattern stacking ing to 9J in this when the finished is peeled parallel to planes represented by the line in ther always exist unbroken conductive layers traversing the flooring Sheet from the top the bottom fhe mutual spacing of the conductive layers the flooring can be varied These conductive layers are subsequently b the application of a conductive or by ducing in the side a conductive whereby any electrostatic charges are discharged to the insufficientOCRQuality

Claims (29)

1. A process for the manufacture Of raw blocks serving as semi-manufactures for the production of plates, panels, sheets and the like, wherein: (a) a granular thermoplastic material is calendered to form a raw web whose width approximately corresponds to one dimension of the block to be made; (b) the web is cut transversely into strips, the strips are cut into substantially rectangular chips, then the chips are disposed in regular rows and stacked; (c) the stack is heated without pressure to sinter to form a coherent pre-product; (d) the pre-product is placed in a form or mould and compacted under pressure and in the heat to form the raw block.

2. A process according to Claim 1, wherein in the course of the operations beginning with the cutting of the raw web and the stacking of the chips, the chips are turned into a transverse position so as to disturb the longitudinal veining pattern of the raw web.

3. A process according to Claim 1 or 2, wherein a laminated raw web is made from two or more raw webs produced Individually from the granular raw material, and the laminated web is cut into chipso

4. · A process according to Claim 5, wherein an electrically conductive material is sandwiched between at least two layers constituting the laminated web.

5. A modification of the process according to Claim 1 or 2, wherein two or more webs are separately made from the granular starting material and individually cut into transverse strips, and -15- 33099/2

6. A process according to Claim 5, wherein the strips produced from different webs have different widths.

7. A process according to any of the preceding Claims, wherein the width of the stack from which the pre-product block is made is larger, preferably by half the width of one chip, than the corresponding dimension of the block to be made.

8. · A process according to any of the preceding Claims, wherein the chips are stacked substantially horizontally.

9. A process according to any of Claims 1 to 7, wherein the chips are stacked slopingly in roof-tile manner.

10. A process according to any of the preceding Claims, for the production of a substantially reetangular-prismatic raw block, wherein the chips are so stacked that the sintered pre-product approximates the shape of the raw block to be made, and the pre-product is compacted under pressure and in the heat in a box-mould.

11. A process according to any of Claims 1 to 9 for the production of a substantially cylindrical pre-product, wherein the chips are stacked in a comparatively thin layer and heat-sinte ed, preferably in steps, to form a web, the latter is wound into a substantially cylindrical pre-product, and this is moulded into the raw block by radially applied pressure*

12. A process according to Claim 11, wherein the stack of chips is converted into the sintered pre-product by being conducted through at least one furnace where it is subjected to heating at rising temperatures.

13. A process according to Claim 12, wherein the stack is pre-sintered in a first furnace at a lower temperature, and finally sintered in a second furnace at a higher temperature.

14. A process according to Claim 13, wherein on its way from the first to the second furnace the pre^sintered web is calendered*,.

15. A process according to Claim 11, wherein the stack, before being sintered, is laid at a height of 2 to 30 mm, preferably 4 to 20 mm.

16. Λ process according to Claims 11 to 15, wherein at the end of the compacting operation the compacted block is cooled from inside and or outside while the compacting pressure is maintained.

17. A plant for carrying out the process according to Claim 1, comprising at least one calender for the formation of the raw web; means for cutting the web into strips, and means for cutting the strips into ehipsj a conveyor for stacking the chips on a second conveyorj at least one furnace for sintering the stack while on the second conveyor to form a pre-productj and means for transforming the pre-product into the raw block.

18. A plant according to Claim 17, wherein the second conveyor is designed to transport the stack of chips through the furnace in the process of sintering.

19. A plant according to Claim IS, wherein the furnace comprises at least three conveyors for the staggered processing of three separate stacks of which one is being loaded on the conveyor, one is in or after the sintering process, and one is being tr&nsfered to bloek-forming means.

20. A plant according to Claim 17 or 13, wherein the stacking conveyor, comprises a belt mounted on a reciprocable carriage and designed to be intermittently moved forwards at a speed higher than the moving speed of the carriage.

21. A plant according to any of Claims 17 to 20, comprising two furnaces, so disposed that the stack of chips passes through them successively, of which the second one is adapted to be heated to a higher temperature than the first one.

22. A plant according to Claim 21 for the performance of the process according to Claim 10, wherein a cutter for severing the sintered we¾ into pieces corresponding to the box-form is disposed in the second furnace.

23. A plant according to Claim 21 for the performance of the process according to Claims 11, 12 and 13, wherein the conveyor passing through both furnaces is adapted to be run through the second furnace at a higher speed than through the first furnace.

24. A plant according to Claim 23, wherein a calender is disposed between the two furnaces.

25. A plant according to Claim 17 for carrying out the process according to Claim 11, comprising a winding spool with detachable flanges at its ends, and a cylindrical mould into whose ends the flanges of the spool fit tightly 5 a tubular membrane inside the cylindrical mould; and an inlet for a pressurizing fluid a&apted to press the membrane onto one cylindrical surface of the wound bolt of the pre-product.

26. A plant according to Claim 25, wherein the tubular membrane is disposed near the wall of the cylindrical mould and adapted to be pressed on the outer surface of the bolt. —IB—

27. A plant according to Glaim 25» wherein the membrane is disposed near the spool surface and adapted to be pressed against the inner surface of the bolt.

28. A plant according to Claim 25, wherein the spool is hollow and adapted to receive a cooling fluid.

29. Processes for the manufacture, from chipa of a thermoplastic material, of raw blocks serving as semimanufactures for the production of plates, panels, sheets and the like, and apparatus for carrying out these processes, substantially as described herein with reference to the accompanying drawings. For the Applicants DR. REINH COHN AKD PARTHSHS βL