CA2178197C

CA2178197C - Device for processing thermoplastic materials

Info

Publication number: CA2178197C
Application number: CA 2178197
Authority: CA
Inventors: Helmut Bacher; Helmuth Schulz; Georg Wendelin
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-12-21
Filing date: 1994-12-20
Publication date: 1999-08-24
Anticipated expiration: 2014-12-20
Also published as: ATE151010T1; JP2750954B2; EP0735945A1; DE59402323D1; JPH09501623A; KR100207175B1; AU676108B2; WO1995017293A1; AU1266995A; EP0735945B1; DK0735945T3; ES2102912T3; BR9408385A; CA2178197A1

Abstract

A device for plasticising thermoplastic materials has a revolving feed screw for plasticising the plastic materials within a housing. The plastic materials to be plasticised are supplied to the feed screw by a feeding device through a feeding hole in the housing. The housing of the feed screw is provided on its inner wall with at least two broad pockets. These pockets extend in the longitudinal direction of the feed screw and are mutually separated by narrow ribs, when compared to the width of the pocket. One pocket is open towards the feeding hole, the other pockets are sealed against the feeding hole by at least one rib of the housing of the feed screw. In order to improve filling of the feed screw, a feeding device for the plastic materials to be processed is associated with the feed screw. This feeding device stuffs the plastic materials into the feeding hole of the housing of the feed screw with a component of motion normal to the longitudinal axis of the feed screw. The depth of the pocket open towards the feeding hole is at least constant, seen in the direction of rotation of the feed screw. Alternatively or in association therewith, one of the ribs may be adjustable, to allow the feeding capacity of the feed screw to be modified according to the plastic materials to be processed.

Description

~'; J, -~ ~ ` 21~197 The invention relates to an apparatus for processin3 ~ O~JId:~liC synthetic plasUcs material, in particular in fomm of foils, such as foil rests, sacks, pouches, bags, 5 and the like, comprisin~q an intake opening in Uhe wall of Uhe housing of a screw which at least conveys the syntheUc plasUcs matenal introduced into Uhe housing, and preferably also plasUcises this material, into which intake opening the synthetic plastics material is supplied by means of a supply means, Uhe housing of the screw being provided on its inner wall with wide pockets extending in longitudinal direcUon of Uhe 10 screw or curved at least over the major part of the axial region of the intake openin~
and, when seen in a section perpendicularly to the screw axis, surround Uhe screw along circular ring segments and are separated from each oUher by ribs that are nan-ower, when compared wiUh the width of the pockets, one of which pockets being open towards the intake opening, whereas another pocket is closed towards the intake 15 opening by a further rib of the housing wall, which rib jl,.,~lr " ' ~y neighbours Uhe intake opening.
Apparatus for processing ~lltllllu,ul~l~liu synthetic plasUcs material having such pockets on the inner wall of a screw housing are known (GB~A 1,3~8,488, DE-A
1,729,198, DE-A 3,401,817) These known apparatus, however, have con~ ,dl,l~
20 problems in connecUon wiUh hlling the screw, in particular if the lI~ , synthetic plasUcs material to be processed is in fomm of sheetings on foils, even if these foils are comminuted. The foil elements, namely, consUtute a co~,u.al~ti.~l~ Ioose mass, which is not sufhcienUy reliable taken along by the screw or even consUtutes a brjdge in Uhe region of Uhe intake opening of the screw housing As a consequence Uhereof, Uhe 25 output of the screw becomes irregular, and there is even the danger of a breakdown of Uhe output, what is of .li ,ddvcll ,Idge in particu~ar at such screws which convey towards ~ ~ ` 2~781~7 an extruder head. Further, by e..u,~u,,,i~,dl reasons, there is a~ways the requirement to have the efficiency of the screw as high as possible, at a given outer diameter of the screw. If one bies to meet this requirement by reducing the core diameter of the screw, experience has shown that this is limited by the co,~sid~,dl,le moment applied to the 5 screw in order to convey the synthetic plastics material taken along by the screw and to plasticize this material so that it can be extnuded.
These problems are sbll increased by the fact that the synthetic plasbcs material to be processed as a nule is not hu,,,uy~,leous, in particular not over a longer period of time. SyntheUc plasbcs material of the iniUally described kind is frequently supplied as 10 waste material which should be subjected to a recycling process. Within this, experience has shown that as well the kind of the supplied synthetic plastics material (chemical cu,,,r ~ of the synthet~c plastics material) as also the shape of the material to be treated varies ~.ù~ id~:ldlJly. Cull~,uolldillyl~, also the efficiency of the conveyance of the screw, that is the amount at which Uhe screw takes along the 15 syntheUc plastics material and conveys it away from the intake opening, varies <,ul l:,ideldlJly in dt ,ue l Ide l lcy from the kind of the matenal to be treated.
Further it must be ull~ d, that by reasons of keeping the rate of utilizaUon of existent plants, an apparatus of the iniUally described kind should also be able to be utilized for such kinds of syntheUc plasbcs material which are already cu, ,~ide,d~ly pre-20 condensed or, ":~,ue~ ly, are relatively compact, such as dy!J~Ulllald~ orgranulates. For such kinds of synthetic plastics material there is the danger that the efficiency of co,~ .J...,ce of the screw becomes too great so that the screw, as to say, is overfed. Further, the admissible efficiency of conveyance of the screw can also exceeded by processing synthetic plastics material which requires a high amount of 25 energy in order to be bansferred into the plasbcized condition. An efficiency of the screw that is too high, or o~,.r~e.li"y thereof can be noticed by the fact that the driving ` 21~8:197 motor of the screw operates in the region of limiting overload currdnt, whereby Ille~hd~ ,d~ elements can be overloaded In critical cases, this may lead td a rupture of the machine.
The invention has at its object to overcome the described disad~/a"~d~t:s and 5 problems and to make the filling of the screw more reliable and il1d~ Iddl ,I from the kind of the ~ d:.liC synthetic plasbcs material to be trdated. Further, the output of the apparatus for a given screw diameter should be kept as great as possib~e whithout that the driving moment of the screw reaches ~,)a-l",issdl,le regions. The invention solves this task by the features that- starting from an apparatus of an initially described 10 kind - the supply means stuffs the synthetic plastics material into the intake opening of the screw with a c~"",o,~"~ of moUon directed perpendicularly to the longitudinal axis of the screw, and that at least the rib illlllledid~ neighbouring the intake opening is adjustable. Both described features serve for the same purpose, namely to keep taking up of the synthetic plastics material by the screw as optimally as possible. The stuffing 15 action of the supply means ensures that always sufficient material is at disposal in order to suffficiently fill the screw. This, in parb'cular, is of importance if the synthetic plastics material to be treated has the initially described loose condition, for example has the shape of sheeting particles, and, therefore, tends to bridge in front of the intake opening. Such brid3es are avoided by the stuffing action oF the supply means, Further, 20 however, it is ensured by the sufficient volume of the pockets that the synthebc plastics mass stufled by the supply means into the pocket which is open towards the intake opening, is also reliably taken along by the screw and is conveyed by the screw. The wall of this pocket which is constituted by the rib following the pocket, when seen in peripheral direction of the screw, has namely the effect that the synthetic plastics 25 material disposed within this pocket cannot rotate together with the screw and the synthetic plastics material mass being positioned within this pocket is pressed between - ~ ` 2178~97 the volutions of the screw when engagino the rib which conhnes this pocket, and therefore, is reliably conveyed by these Yolutions. The situation is simi~ar at the at ~east one further pocket, into which, indeed, the synthetic plastics material can escape during notation of the screw, however, by again supplied synthetic plastics material is 5 always pressed forwardly ( when seen in conveying direction of the screw), so that the material at the end of the pocket, at the latest, enters again between the volutions of the screw. Therefore, the pockets constitute an additional hlling space in the region of the intake opening for the synthetlc plastics material which is supplied under pressure and, therefore, is pre-co"",.~ased to a oertain degree. This has as a consequence that 10 the core diameter of the screw can be made greater as this was possible heretofore. A
greater core diameter of the screw, however, means that a greater moment can be applied to the screw, as this was possible heretofore, so that the maximum output per time unit at a given screw diameter can be increased when compared with known O~ a.
The ~ ' ' b/ of at least that rib that closes the neighbouring pocket with respect to the intake opening, ensures the possibility to adjust the efhciency of cu"/~,Jd"..e of the screw to the respective requirements without that the screw itself must be changed, so that no time-consuming ,~:pla-,~",~."l of the screw must be made and without that the moment applied to the screw must reach ;~ ",;cc~ ,= regions.
20 The change of the additional filling space conhned by the respective rib, namely, has as a consequence that the ability of the screw to take up material, therefore its efficiency of conveyance, is changed, since the volume of the hlling space conhned by the nespective rib is changed. Each adjustable rib is in its action dependent from the degree of the respective .lia,UldCe",~.,l, whereby in a surprising manner there is the 25 possibility to cullaid~ bly influence the conveyance efhciency of a screw in a simple manner. Thereby, this eflhciency can be so controlled that the output of the apparatus which in the most cases conveys the plasticized synthetic plastics material towards an extnuder head, can be adjusted to the present maximum driving moment ~f the screw, in d~:~,el~d~ .y from the respective syntheUc plastics material to be breated. Thereby, namely, the addiUonal effect is obtained that - in dt~ "denc~ from the degree of 5 ~ "l - a smaller or greater amount of the synthetic plasbcs material disposed within that pocket which is confined by this rib, is conveyed back into the intake opening, and, therefore, is not taken along by the screw in its direction of conveyance.
In such a manner, the efficiency of conveyance of the screw can be changed in a simple and effective manner and an over~oad of the suew can be avoided, when 10 keeping the take up volume of the screw constant. With such an apparatus, therefore, the efficiency of the supply at the intake zone can so be controlled that the oubput of the apparatus is adjusted to the given maximum tuming movement applied to the screw. Suitably this is made so that before starting the apparatus, the ~ ribs are retracted outwardly (with respect to the screw) into the screw housing, and during 15 operation the adjustable ribs are advanced towards the screw to such an extent as Uhis is admissible for the machine or its drive means"e:",ecth~ly Thereby it is possible to process as well loose synthebc plastics material parUcles (generally having the shape of flakes or chips) as also already highly pre-condensed synthetic plastics material particles (in the extreme case: granulates) with the same exbruder screw efficiently and 20 always keeping the oubput at the maximum. As already mentioned, the efficiency of cu, . ~ u,- .. ,ce of the screw is increased when the ribs confining the pockets are displaced inwardly, because the ribs avoid that the synthetic plastics material rotates together with the screw and the last rib (that is the rib neighbouring the intake opening) avoids bhat Uhe syntheUc plastics material disposed within this pocket reaches the 25 intake opening again, and this to a degree which is the higher, the more this rib is advanced towards the screw. The retraction of each adjustable rib into the screw 2 1 ~ 7 housing, to the contrary, means that the eHiciency of conveyance of the screw isdecreased, because a partial amount of the synthetic plastics material is no more taken along and conveyed by the screw so efficiently, and/or an amount of the synthetic plastics material is supplied back into the intake opening.
It is most favourable, if according to a further tllllbO.lil,le"l of the invenUon Uhe depth measured in radial direction of the screw of at least the pocket which is open towards the intake opening, is constant or increases, when seen in direcUon of revolution of the screw. In such a manner Uhe maximum possible take-up volume of the screw can be utilized, i~ d~ from Uhe kind and properties of the synthebc plastioe material to be treated and without the danger of an overload of the screw or its drive means, It:,,ue~,6.~1y.
Ribs which are adjustable in radial direction of the screw are known (DE-A-3,233,841, DE-A-2,112,306). However, none of these ribs is disposed in theinvenbve sense, so that the adjustment of these nbs cannot be made effective in the inventive sense, inasmuch within the known apparatus no stuffng action onto Uhe material introduced into the intake opening takes place. Also the two iniUally described known apparatus cannot operate in the invenbve manner, because on the one hand there is no stuffing action of the supply means and on the other hand the ribs cannot be displaced. Further, within some of the known apparatus the volume of the pockets is not sufficiently great because the pockets show a sickle-shaped cross section, the depth thereof decreases in direction of rotation of the screw.
According to a preferred ~:IllL,Odil,le:lll of the invenbon, at least one rib isdisposed at the side of the screw opposing the intake opening and consUtutes a bearing abutment for the screw in that axial region of the screw that is disposed in the 2s zone of the intake opening, for the purpose to take up the stuffing pressure exerted by the supply means. Thereby, the screw ist securely bearingly supported also within the region of the intake opening. This is of advantage not only in connecUon with taking up . 217~197 the stuffing pressure of the supply means, but also in case of the intake of rigid foreign matter into the pocket which is open towards the intake opening, because such foreign matter, for example metal parb'cles, stones or the like, ~,OII:>idt:ld~ load the screw in the region of the intake opening. By these reasons it is suitabie bhat at least one further s rib is disposed in that region which opposes the pocket that is open towards the intake opening.
Within the spirit of the invenUon, the ribs between the pockets may extend parallely with respect to the axial direction of the saew, what is the most simple constnuction seen from the standpoint of production. However, within bhe spirit of bhe 10 invention it is also possible to provide nbs between the pockets which extend curved in direction of rotation of the suew, preferably with a constant curvature, so that these ribs extend like the twist of a rifle. A particular faYounable take-up of the synthetic plastics material by the screw is obtained within the spirit of bhe invention if the direcb'on of rotabon of the screw at the intake opening is directed to the open pocket. In order to 15 ensure a filling space of the pocket that is as great as possible, it is suitable according to a further t7111L,u.li",~,llL of the inventl'on if the pockets e%tend in axial direction of the screw beyond the axial zone of bhe intake opening on both sides. Therefore, synthetic plastics material enters also the zone before the intake opening of the screw housing, when seen in direction of conveying of the screw, however, this material is always 20 tranported by the cu,~ J...,~æ action of the screw in direction towards the extnuder head or the like.
In order to enhance that the syntheb'c plastics material is fed back from the pockets between the volutions of the screw, according to a further er"bo~li",~"l of the invention, the depth of at least one pocket may continuously deaease in direction of 2s COII~J~ Ct: of the screw, preferably to zero. Thereby, the synthetic plastics material disposed within the pockets is by and by taken along again by the screw. However, .` 2173197 according to an other e",~o-li",e"L of the invention, the depth of at least one pocket can at first remain constant and can decrease to zero only at the end of Uhe axial length of Uhe pocket.
The podkets that are dosed wiUh respect to the intake opening, suitably are of 5 equal width, however, the pocket which is open on its side towards the intake opening, as a nule, has a greater width. The nbs confining the podkets with respect to each other may be UUlll,Udl `hc'y nanrow. Preferably, within the spirit of the invention, there are at least two wide pockets, eadh one of which extending over an angle of at least 35, when seen from the axis of the screw. Particularly favourable results are obtained if the 10 ratiû of the widUh of the pockets to that of the ribs is 3 to 6, preferably 4 to 5, when measured in peripheral direction of the screw.
The invention is applicable wiUh a particular advantage to such construcUons in which the screw is an extnuder screw the core diameter thereof increases towards the extruder head. This increase of the inner screw diameter means a ~ l , of the 15 material and thereby plastizicing thereof. This can be made with a very high output because - as already mentioned - the filling space at the intake opening is increased by the pockets wiUhout that the core diameter of the screw must be unduly reduced.
However, the screw can also be a mere conveyor screw. The direction of the screw, when seen frûm the intake opening, is of no importance. In the most cases, the screw 2û will be disposed h~ u, ,'..:'y~ however~ also an d~ nJc ~ bein9 different therefrom is possible. Further it is possible to make this direction variable by making the housing of the screw tiltable with respect to the supply means.
Particular favourable results are obtained by an apparatus in which the supply means comprises a receptacle in the bottom region thereof at least one tool is 25 disposed that can be rotated around a vertical axis and is provided with working ed~es, which tûol comminutes the synthetic plastics material introduced into the receptacle .` 2~7~1~7 and/or mixes it and conveys it through an opening out of the receptacle, which opening is in connection with the intake opening of the screw housin3, the opening of the receptacle wall preferably being disposed at least substantially at the level of the tool.
Thereby the most favourable results are obtained if the upstream side of the pocket 5 which is open with respect to the intake opening is disposed at least substantially at the level of the tools or of a rotor disk carryin9 the tools. Thereby, the centrifugal force c~""polle"l exerted onto the synthetic plastics material is utilized in an opUmal manner in the sense of a stuffing action forfilling the pocket. This centrifugal force ~,u,,-~,.,,,,,,l can be.assisted by providing the tools with working ed~es that are bc,~vvcll-lly 10 displaced - when seen in peripheral direction - so that the tools press the synthetic plastics material in the manner of a spatula into the intake opening and therefore also into the pocket, in addition to the action of the centrifugal force. Filling of the screw can be further improved within the spirit of the invention by inclining the bottom of the open pocket in direction to the tools or to a rotor disk canying the tools. Thereby, a funnel-15 like shape of the intake opening is obtained what enhances taking up of the syntheticplastics material from the receptacle.
A particular favourable tll,boli",t"~ of the invention consists in that Uhe rib confining the pocket which is open with respect to the intake opening, is disposed at that side of the screw that opposes the intake opening. In case of a receptacle of the 20 above descnbed kind serving as a supply means, this rib is disposed at least substantially at the level of the axis of the screw. The pocket being open to the intake opening, therefore, is ccll~ t; ~l~ broad and extends - when measured from the axis of the screw - over an aperture angle of about 90.
As a rule, it is suitable to make the direction of rotation of the tools at the intake 25 opening in direction of transport of the screw, although the inverse allclllg~ l could be used.

- 21~ 97 The most favourable alldl,ge",t:"I is to dispose the screw substantially tangential with respect to the wall of the receptacle, however, the screw could also be disposed obliquely or even in direction of Uhe axis of the receptade. Further, of course also at a supply means of the above described kind, the screw housing could also be s swive~lably connected to the receptacle.
Such a receptacle, however, is not the only possibility for the supply means. To the contrary, within the spirit of Uhe invention, there are numerous other F - ' "" for the construcUon of the supply means. Thus, for example, it is possible to constitute the supply means by a funnel connected to the intake opening of the screw housing, in 10 which funnel a stuh'ing scnew is disposed. Also in connection with such a supply means, there are the above described ~ ' "'i~ for the direction of the sGrew housing.
In order to provide for an adjustment effect of the ribs which is as great as possible, it is suitable within Uhe spirit of the invenUon, to make all or the majority of the 15 ribs ~ o i"depe,~dt:"t'~ fnom each other. However, it would also be possible to make only the outemmost rib .I;~I,I,.r~l,lr. oradjustable, that is that nb that i"-",adidl-:ly neighbours the intake opening and in its advanced posiUon closes the neighbouring pocket with respect to the intake opening, and to make the other ribs ngid.
For adjustment of the ribs it is suitable if according to the invention eadh 20 adjustable rib is guided wiUhin a longitudinal slot of Uhe housing and is coupled with adjustment means. As a nule, this longitudinal slot exfends in the screw housing in axial direction thereof, however also curvings are possible, which, as a nule, have a small degree of the bend and may extend along a helical line. A favourable ,:"~bo~i",~"I
consisfs also in that at least one of the ribs extends obliquely with respect to the 25 longitudinal axis of the screw, the surface of this rib facing the screw being shaped according to the periphery of the screw. For longer ribs (seen in axial direction of the - ~ ~17~197 screw) which in the whole extend along a helical line, the respective rib should be subdivided, when seen over its length, the several portions may be adjustable i~,di,uP,~de,.t'~ from each other. In each case, the longitudinal slot of the housing ensures a reliable guiding of the rib. The adjustment means may, within the spirit of the 5 invenb'on, be consUtuted by pressure screws and tension screws which are abubted against the housing of the screw. However, also hydraulic adjustment means may be used and it would even be possible to make the hydraulic adjustment dependent from reaching the maximal admissible tuming moment of the screw. Suitable control means for this are at disposal. When the adjusbment is made by means of screws, it is to be 10 , ~cu. ", . ,~:. Ided - in case of a substanb'ally radial adjustment of the rib with respect to the screw - to provide at least two tension screws and at least two pressure screws per rib, always a pair of these screws engaging the nb in the end zone thereof. To dispose the screws at the rib ends avoids a tilting moment for the ribs and enables a parb'cular fine adjusbment. By the tension screws, the respecb've rib is retracted into bhe screw 15 housing, by the pressure screws it is advanced in direction towards the screw.
In the accompanying drawings, e,~d"-~,l. ';~e ~."Lo.li".~.,t~, of bhe invention are s.,l,e, '' 'l~ shown. Fig.1 shows a vertical section through a hrst e..~o~i",~"l of the apparabus. Fig.2 is a honzontal section taken along the line ll - ll of Fig.1. Fig.3 shows in an enlarged scale the screw and the pockets or ribs surrounding it. Fig.4 shows a 20 vertical section through a second t:"lL,odi",~"~ and Fig.5 is a section taken along the line V - V of Fig.4. Fig.6 shows a variant to Fig.5. Fig.7 shows a variant to Fig.3. Fig.8 shows a further elllbO~ ,clll in a vertical section and Fig.9 is a section taken along the line IX - IX of Fig.8. Fig.1û shows a further ~",I,odi",e"~ in a vertical section and Fig.11 is a section taken along the line Xl - Xl of Fig.10. Fig.12 shows still a further 25 e",bodi",e"l in a top view, partially in section, and Fig.13 shows a section taken along the line Xlll - Xlll of Fig.12 through a ~ -lP rib.

~ 7 The apparatus according to Figs.1 to 3 comprises a receptacle 1 for the treatment of the ~ Jkl~lic synthetic plastics material, which as a nule consists of U,e""opla~Ik, synthetic plasbcs scrap material of all kind, used or not used, which material may be delivered in form of foils or sheetings or also in a more compact form.
s The receptacle 1 has a bottom 2 and side walls 3. The synthetic plastics material to be treated is introduced into the receptacle 1 from above by means of a loading means (not shown), if desired after a pre-treatment, for example a cleaning step or a separation step by means of which the matenal is freed from cores foreign bodies, as stones or metal elements. The synthetic plasUcs material within the receptacle 1 is 10 treated by at least one rotating tool 4 provided with sharp working edges 5 acb'ng on the syntheh'c plastics material and suitably being bent. These tools as a nule comminute and/or mix bhe synthetic plasboe material. A comminutation takes place if the synthetic plastics material is introduced into the receptacle in fomm of bigger elements (foils, bottles or the like), substantially a mere mixing effect takes place when the synthetic plastics material has been previously already worked up (for example a granulate). In the most cases, during this mixing and/or comminutation, the synthetic plastics material is also heated what facilitates to plasticize the synthetic plastics material later on. The tools 4 are mounted on a rotor disk 6 which is disposed within the region of the bottom 2 and is driven for rotab'on in direction of the arrow 9 20 (Fig.2) by a motor 8 and a shaft 7 which intersects the bottom 2.
An opening is provided in the side wall 3 of bhe receptacle 1 which consUtutes the intake opening 10 in the wall 11 of the housing 12 of a screw 13. The screw is driven for rotation around its longitudinal axis 15 in direction of bhe arrow 14 by means of a drive means (not shown) and conveys the synthetic plastics material in direction of 2s the arrow 16. If the screw 13 is no mere conveyor screw but an extruder screw, the synthetic plastics material is plasticized so that this material can be fed by the screw 13 ~ 217~97 towards an extruder head (not shown) conneded to the housing 12. The volutions 17 of the screw 13 extend, when seen against the anow 16, beyond the intake opening 10 and merge there into screw threads 18 acting as a sealing, the pitch thereof being directed in the same sense as that of the screw threads. The screw 13 or its housing 5 12 may be provided with a heating and/or with a cooling means.
The substantially rectangular intake opening 10 is of col~pdl~.';icly large size and extends in axial direction of the screw 13 at least over substantially a half volution of the screw 13. The height of the intake opening 10, measured in axial direction of the receptacle 3, amounts to at least substantially three quarters of the diameter of the 10 screw threads 17. This ensures that the screw can take up great masses of the synthetic plashcs material from the reseptacle 1. The housing 12 of the screw 13 is connected laterally substantially tangential to the side wall 3 of the receptacle 1, so that - when seen in direction of the axis 15 of the screw 13 - the periphery of the screw 13 is substantially flush with the inner surface of the side wall 3 of the receptacle 1 (Fig.1).
The wall 11 of the screw housing 12 merges at the lower edge of the intake opening 10 into the transiUon section 20 between side wall 3 and bottom 2 of the receptacle 1 by a substanbally l)c,i~u,,t..:'y disposed section 19. The bottom 21 of this horizontal section 21 is substanhally disposed at the same level as the top surface 22 of the rotor disk 6.
This ensures the optimal position for the rotor disk, however, deviabons therefrom are 20 not too cribcal as long as they are too great. Preferably, the bottom 21, as Fi~.1 shows, is slightly inclined towards the rotor disk 6 or its tools 4, so that the intake opening 1û
shows a funnel-like shape.
The receptacle 1 with its rotating tools 4 constitutes a supply means 27 that presses the synthetic plastics material breated by it into the intake opening 1û. This 25 action, on the one hand, is created by the centrifugal force of the syntheUc plastics material rotated by the rotating tools 4, on the other hand by the spatula-like acbon of ` ~ 21~ 7 the tools 4. Thereby, a stuffing action is exerted onto the synthetic plastics material in the region of the intake opening 10, the direcbon of this pressure or the stuffing action is substanbally perpendicular to the longitudinal axis of the screw 13. Thereby, on the one hand, it is avoided that bridges of the synthetic plastics material can occur in the S region of the intake opening 10, on the other hand, always sufficient synthetic plastics material is pressed in the region of the intake opening 10 beetwen the sin31e volutions of the screw 13, so that the screw is always suffficiently supplied with synthetic plastics material, even if this matenal has a very loose configuration, for example is fomled of flakes, small foil elements or the like. In order to still improve the take-up of the synthetic plasUcs material which is supplied into Uhe intake opening 10 by the tools 4 which suitably constitute knives, and in order to provide for at least one additional filling space in the region of the intake opening 10, in addition to the spaces confined by the screw threads 17, pockets 23,24 are provided in the inner wall 1~ of the screw housing 12. These pockets extend in ~ongitudinal direction of Uhe screw 13 in the region and in the neighbourhood of the intake opening 10 over at least one volution of the screw, in the example shown over about 2.5 screw threads (Fig.2). Each pocket 23,24 is fommed by a wide groove in the wall 11 of the housing 12, the width of which, when measured in peripheral direction of the screw 13, remains preferably constant over the length of the pocket. However, the depth of the pockets 23,24, measured in radial direction of the screw 13, decreases in conveyance direction (arrow 16) of the screw 13 continuously, preferably ,r,,~,,uu,~iù~ y However. the constnuction may also be so that this depth of each pocket 23,24 at first remains constant in directlon of transport of the screw 13 and smoothly decreases only towards the end of the respective pocket 23,24 neighbourin3 the outlet opening of the screw housing 12. Thus, the pockets 23,24 have their greatest depth always at the end of the pockets which neighbours the driven end of the screw 13. As Fig.2 shows, this pocket end suitably is flush with the sealing ~ 2~ 781~7 ~s threads 18. At the other end neighbouring the output end of the screw 13, the pockets 23,24 merge smoothly into the cylinder-shaped inner surface of the wal! 11. In each cross section of the screw 13, the depth of the pocket, measured in radial direction of the screw 13 remains constant over the width of the pocket (Fig.1) or increases in 5 direction of rotation (arrow 14) of the screw 13. In the eAd~ ,I,odi",~"~ shown, the greatest pocket depth amounts to about 5 to 10 % of the diameter of the suew 13.
The several pockets 23,24 are separated from each other by ribs 25 and a further rib 26 closes the row of pockets 23 at the upper end of the intake opening 10 with respect to the interior of the receptacle. At the lower end of the intake opening 10, the first 10 pocket 24 (counted in directlon of rotaUon of the screw 13), however, is open towards the interior of the receptacle 1, so that there the synthetic plastics material comminuted and/or mixed by the tools 4 is pressed into the pocket 24 when the rotor disk 6 rotates.
Within this, also the above described stuffing action is effective, that means that the synthet~c plasUcs material is pressed in by the centrifugal action of the synthetic 1s plastics material circulating within the receptacle 1 as well as by the spatula-like action of the circulatin~ tools 4. The synthetic plastics material pressed through the intake opening into the interior of the screw housing 12, enters not only the pocket 24 and the spaces between the several threads 17 of the screw 13, but from there fills also the two pockets 23. Since the ribs 25,26 extend in axial direction of the screw 13 and also the 20 pockets 23,24 extend in this direction, the synthetic plastics material positioned within these pockets 23,24 cannot rotate together with the screw 13. However, by the always newly supplied synthetic plastics material and by the rotatjon of the screw 13, the synthetic plastics material positioned within the pockets 23,24 is advanced, also substantially in direction of the arrow 16, until the pockets 23,24 at their ends merge 25 into the cylindrical shape of the wall 11 of the suew housing 12. During this transport of the synthetic plastics material within the pockets 23,24, the synthetic plastics 21~197 .~
material is by and by pressed between the threads 17 of the saew 13. As soon as this happens, the transport of the material by the screw 13 is in the usual. mannsr, for example towards an extruder head or towards a fur~her saew leadin~ to an extruder head.
However, the constnuction can also be such that the ribs 25 which are positioned between two pockets 23,24 each, extend t~vist-like curved in longitudinal direction of the screw housing 12, and this with a curvature which follows the revolution motion of the screw 13 (arrow 14) Up to a certain extent, this may also be the case for the rib 26 positioned at the upper end of the intake opening 10. The inclination of the 10 direction of the ribs relative to the axial dinection of the saew 13, however, as a nule is small, in the most cases it does not exceed 5. By such a twist-like configuration of the ribs 25,26 confining the pockets 23,24, the take-up of the synthetic plastics material is enhanced and a cleaning effect ist obtained, because the synthetic plastics material slides alon3 the ribs.
Suitably, the direcUon of rotation (arrow 9) of the rotor disk 6 is so chosen, that the periphery of the rotor disk 6 moves along the intake opening 10 in direction of transport of the screw 13 (arrow 16). However, also the opposite direction of rotation of the rotor disk 6 is possible, because then the material pressed into the intake opening 10 by the rotor disk 6 or its tools 4, ,~: ,,ue-,ti~,ly, engages the saew threads 17 nunning 20 in the opposite directlon and thereby is guided in a particular effective manner into the pockets 23,24.
The saew 13 or its housing 12 must not exactly be posiUoned ~ca~ y with respect to the receptacle 1. Thus, the screw housing 12, seen from above, may be so positioned that, when seen from above, it intersects the periphery of the rotor disk 6 25 like a secant, so that the screw 13 is positioned nearer to the circulating tools 4.
The tangential or secant-like positioning of the saew housing 12 with respect to ~17~197 the receptacle 1 has the advantage, that the drive means for the screw 13 and the outlet opening of the screw 13, for example an extnuder head, can be disposed at the two front ends of the screw 13, so that the synthetic plasb'cs material is conveyed by the screw to the extruder head or the like without any defledion. The diredion of the screw 13 is suitably so chosen that the screw threads 17 at the intake opening 10 nun in diredb'on towards the bottom 21 of that pocket 24 which is open towards the interior of bhe receptacle 1.
The inventl've dlldllyelllelll is also applicable on le~æ~ es in which more than one circulating tool set is disposed. For example, the receptacle may comprise two star 10 wheels havin~ vertical axes disposed adjacent each other, which star wheels carry the tools 4, the orbits of the tools 4 i, llel~e~,LI ~y each other like the teeth of a gear, however do not hinder each other. It is only of importance that at least one of these tool sets stuffs the treated synthetic plastics material into the intake opening 10 with a direcbon of transport substanbally perpendicular to the axis of the screw 13.
Fig.3 shows that the two pockets 23 which are closed on their sides, are of equal width and each extend over an angle of at least 35, when seen from the axis of the screw 13. It is favourable to provide wide pockets because thereby more pre-c~""~.,e:.sed synthetic plastics matenal, in parb'cular in form of flakes, can be l The ribs 25,26 however are cu"",~ `y nanrow, in any case substantially nan ower than the pockets. It has been shown that it is suitable to choose the ratio between the width of the pockets, when measured in peripheral diredion of the screw~ and the width of the ribs by substantially 3 to 6~ preferably by 4 to 5.
Particularly favourable results have been obtained in the interval of 4.4 to 4.8 for this ratio The ribs must not have equal width.
Fur~her~ it is possible to provide the pockets with a widbh thàt decreases in tranport direction of the screw 13 (arrow 16), so that the pocket cross section is 2~78197 decreased not only by the decreasing pocket depth. When seen in a cross section, the pockets 23,24 always sunound the screw cross section by sedions of a circular ring.
For the pocket 24 this holds in that region that nei3hbours Uhe wedge-shaped intake gap confined by Uhe bottom 21. The width of the lowemmost pocket 24 Uhat is open with 5 respect to the intake opening 10, is suitably greater than that of Uhe other pockets 23.
ParLIculatly favourable is an I~ LJodillle:lll in which at least one tib 25 is disposed at that side of the screw 13 that opposes Uhe intake openins 10 (Fig.1,3). As it is shown in Fig.1,3, this tib 25 confining the pocket 24 is disposed substantially at the Isvel of the axis of Uhe screw 13. AltemaUvely thereto, a second tib 25 may disposed mintor-invetted with respect to a lowenmost rib 25 with respect to Uhe axis 15 of the sctew 13.
Since the tibs 2~ engage Uhe petiphery of the screw threads 17, a good abutment for the screw 13 is obtained by this tib 25 or by the desctibed pair of ribs, with respect to the stuffing pressure exetted by the inttoduced synthetic plasUcs material on the screw 13, which pressure may be relatively high for cvll~a~ Idillyly shaped tools 4. A futthet 15 pressure is exerted onto the sctew 13 if a compact foteign body, for example a woodenor metal piece, for example a screw, or a synthetic plastic element that was not sufficiently comminuted, is inttoduced. If such a foreign body enters the pocket 24, Uhis results in a pressure <,ulll,uullt:llL acting on the sctew 13, which pressure cull,,oolle,,L is directed away from the intake opening 10 and is abutted by the desctibed positioning 20 of the ribs. Thereby, the sctew 13 is bearingly supported and teliably abutted also in the tegion of the intake opening 10.
In order to be able to adapt oneself to different kinds of synthetic plastics material to be tteated, at least one of the nbs 25,26, in particular the rib 26, is æ,~ For this, the respective rib is guided within a longitudinal slot 30 (Fig.2) of 2'i the housing 12 of the screw 13. This longitudinal slot 30 extends in axial direction of the screw 13. The respecUve rib 25 or 26 is formed by a ledge which fits into the 21~
longitudinal slot 30 and is guided along the side walls thereof, which slot intersects the wall of the housing 12 (Fig.2). Di~ means 31 are provided for ~ , f~
of the rib 25 or 26 in the slot 30, the rib 25 or 26 being coupled with these means.
Wlthin the e~ odilll~l~l shown, the .liapld~ ll means 31 are fonmed by tension s screw bolts 32 and pressure screw bolts 33. The pressure screw bolts 33 engage the outer edge of the ledge of the respective rib 25 or 26 and can be screwed into screw threads of a cover member 34 which Ughtly closes the opening formed by the longitudinal slot 30, however leaves sufficient space for the movement of the respective rib 25 or 26. The tension screw bolts 32 can be screwed into saew threads 10 of the ledge of the respective rib 25,26 and are abutted with their heads on the cover member 34. In the Figs.1 and 2, the ribs 25,26 are shown in their innermost position in which the ribs close the pockets 23,24 agalnst each other and engage the threads of the saew 13 or at least are posiboned very dose to them. If the pressure screw bolts 33 are saewed back, the respectlve rib 25 or 26 can be retracted by the tenslon screw 15 bolts 32 Into the hollow space ~.. ~.. ~.I.. l.-d by the cover member 34. This means that the pockets 23,24 which are confined by the ribs 25, are more or less brou3ht into connection with each other, what means that the volume of the pocket is increased.
This, however, causes not an increase of the efficiency of the conveyance of the screw 13, but a decrease thereof, because now the respedive rib 25 cannot more so 20 effectively press the synthetic plastics material positioned withln the podket 24 or 23, confined by thls nb, into the volutions of the screw. The retraction of the rib 26 has as a consequence that the synthetic plastics material posltloned within the pocket 23 confined by this rib 26 is partially conveyed back Into the intake opening 10, the amount of this synthetic plastlcs material being conveyed back into the opening 10 25 being dependent from the distance for which the rib 23 was retracted.
In such a manner, the effect whldh Is obtained by the stumng action of the ' 217gl~7 supply means 27 formed by the circulabng tools 4 and by the pockets 23,24, can be adjusted at choice. This adjustment is of advantage if the synthetic plastics material to be treated changes with respect to c ., " ~, density or power required for pla~liui~i"g, or is subject to ~"~ ,aL,le variations thereof. Any overload of the 5 apparatus can be avoided thereby. Within this, the procedure suitably is so that the operahon of the apparatus is started with ribs 25,26 which âre retracted into the housin3 12 or into the cover members 34. If it shows within this thât the admissible maximum driving moment for the drive of the screw 13 is not reached, the ribs 25,26 confining the pockets 23,24 are displaced individually or in cu,,~l,i,, ", to such an 10 extent in direction towards the screw 13 as this is admissible for the âpparatus or its drive means ,c::" e-,...~Iy. Thus, the co,~ ,e efficiency of the screw 13 is incneased if the ribs 25,26 are moved towards the screw 13, and is decreased if the ribs 23,24 are displaced outwardly.
The ribs 25,26 can also be displaced by means of hydraulic ~
15 means. Such a hydraulic ~ ,l has the advantage, when compared wiUh a "1 by means of screws, that, if desired, a plurality or all ribs 25,26 can be displaced in common. As a nule, however, It is more favourable to make the ribs 25,26 læ i,~depe"dt~ from each other This holds in particular for the outermost rib (rib 26), since this rib gives the already mentioned addiUonal effect of back-20 conveyance of the taken-up synthetic plastics material into the intake opening 10. If always a sufficient abutment for the screw 13 must be given also within the region of the intake opening 10, then it is suitable to make those ribs 25 rigid which fomm the abutment within the region of the intake opening 10, and to have only the rib 28 , which neighbours Uhe intake opening 10 This ensures that the stuffing 2s pressure exerted by the supply means 27 and also Uhe pressure exerted by a rigid foreign body which was taken-in into the pocket 24, can always reliably be abuhted. As ` 21~8~g~
already mentioned, a rib pair can be provided instead of one single rib 25 disposed at Ihe level of the axis 15 of the screw 13, one nb of this pair being disposed somewhat below the axis 15, the other somewhat above thereof. If desired, also more than two ribs 25 may be provided, however the width of the pockets 23,24 should not be too smail.
Within the e",bo ii",e"~ according to Figs.4 and 5, the supply means 27 comprises a funnel 28 connected from above to the intake opening 10, a supply screw 29 being positioned within this funnel. The screw 29 conveys the synthetic plasUcs material which was introduced into the funnel 28 from above, towards the intake opening 10 and stuffs it into this opening, the direct~on of this stuffing action being substantially perpendicular to the direction of the longitudinal axis of the screw 13. With respect to the adjustment of the ribs 25,26, the elllbu iilllellI according to Figs.4 and 5 is similar to that of Figs.1 to 3. Within the elllbOdi"lellI according to Figs.4 and 5, however, the ribs 23,24 are longer, when compared with Uhe intake opening 10, and these ribs extend over the entire region of the intake opening 10 as well as over the neighbouring areas, whereas within the elllbO iilllellI according to Figs1,2 and 3, the ribs 25,26 are only somewhat longer Uhan the greatest dimension of the intake opening 10, which is rectangular in this case.
The variant according to Fig.ô is similar to that of Figs.4 and 5, however, the two ribs 25 or their guide slots 30 in the housing 12, leD,Ue~ y, are not disposed radially with respect to the axis of the screw 13, but obliquely, in the elllbO iilllellI shown substantially tangenUal with respect to the core of the screw 13, the inclination being directed towards Uhe leaving side of the screw 13. This has the advantage that by the obliquely directed walls of the ribs 25 which are engaged by the synthetic plastics material during rotation of the screw 13, the synthetic plastics material is pressed particulariy effective into the volutions 17 of the screw 13. Simultaneously, a cleaning . `-- 2~ 7 effect for the ribs 25 is obtained, so that no dead comers are fommed on these ribs 25, in which synthetic plastics material may remain for a longer period and may be themmically damaged thereby. A similar effect is also obtained for the rib 26 within the ~"~L,od",l~"~ according to Figs. 1 to 5.
Within the ~IllI,Odil~ ,,I according to Figs.7, which is similar to that of Figs.1 to 3, a similar effect as described above is obtained by the feature that the front surfaces 35 of the ribs 25,26 facing the screw 13 extend obliquely, so that these front surfaces fomm a wedge together with the outer penphery with the screw threads 17.
The ~ Lu~il,,_"~ according to Figs.8 and 9 differs from that according to Figs.1 to 3 by the feature that the ribs 25,26 conhning the pockets 23 or 24 can be shifted along an obliquely disposed p~ane, for example within T-grooves 36 or guide means having a dove-tail cross section. These T-grooves extend in axial direction of the screw 13. By an axial ~ ,L of the respective rib 25,26, its front surface 35 can be adjusted with respect to the screw 13 in radial direction thereof. The effect is the same 15 as this has been described in connection with the above described ~:,,ILudi,,,~lllb. The adjustment is made by di:,~,lac~",~"~ means 31, for example by tension screw bolts 32 and pressure screw bolts 33, as described above.
The t:lllbu~illle:ll~ according to Rgs.10 and 11 shows similar wedge-fommed ribs 25,26 which are guided within T-grooves 36, however in connection with a supply 20 means 27, the c~, fi" ~ ~ thereof c~"~:;",u"d~ substantially to that according to Figs.4 to 6. When the ribs 25 or 26 are displaced, the take-in behaviour for the synthetic plastics material at the intake openin3 10 within this ~,,,L,udi,,,~,,L is also changed by the fact that, in addition to the inward or outward movement of the ribs 25 or 26, these ribs are also axially displaced so that, in particular for the rib 26, the intake 25 ûpening 10 is more or less freed. In the position shown, in which the ribs are completely projected, the rib 26, for example, does not extend over the entire axial - ~ ~1781~7 region of the intake opening 10, however, it does when the rib 26 is retracted. The effect obtained by the axial shift of the rib 26, therefore, opposes the effed obtained by the radial adjustment of the rib (with respect to the screw 13) or decreases this effect. If Uhe contrary should be obtained, that means, if the two effects should assist 5 each oUher, Uhen only the direction of the wedge of bhe rib 26 must be positioned inversely, so that the bp of the wedge of the rib 26 faces the sealing threads 18.
Vvithin the ~",I,odi."~"l according to Fiss.12 and 13, the seneral construction of the supply means 27 and of the screw 13 is similar to that of Figs.1 to 3. However, at least one of Uhe ribs 25,20 does not extend in axial direction of the screw 13, but 10 obliquely thereto, in Uhe t:,~d~ "l~udilll~,ll shown, Uhe inclination amounts to about 30. The front surface 35 (Fig.13) facing the screw 13 of Uhe respective rib 25 or 26 is shaped co",::,po"di"~l~ to the periphery of the screw threads 17, so Uhat this front surface 35 ei;r~,y..'~e,~ engages the screw threads 17 (the rib displaced in its innemmost posiUon) and therefore abuts the screw 13, the ribs 27 being cleaned by the screw Uhreads. The said ob~ique posiUon of the respective rib is so chosen that, when Uhe screw 13 is rotated, the synthetic plasb'cs material is pressed into the volubons of the screw.
Within all e,,ll,v.li,,,_.l~, the opening, through which the treated synthetic plasUcs material is delivered out of the receptacle 1 by the tools 4, coincides with the intake opening 10 of the screw housing 12. This must not necessariy be so, however, Uhese two openings may also be i"l~ ,.,u,~,~eul~:d by a tube (not shown) As a rule, however, the direct connection is more favourable. In such a bube or also within the intake opening 10, a gate valve may be positioned by which the receptacle 1 can be closed with respect to the screw housing 12, if this is desired.
The screw 13 must not necessarily be huricu"~ positioned, however, it can be also disposed obliquely with respect to the horicontal direction, or even vertically.

217~97 The screw 13 must not be an extruder screw, however, it is possible to construct this screw as a mere conveyor screw which transports the material, if desired by pre-plasUckin3, to a proper plasticizing screw of an extnJder.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for processing thermoplastic synthetic plastic material, the apparatus comprising:
an elongate housing defined by a wall having an inner surface and an outer surface;
a screw extending along a longitudinal axis and conveying thermoplastic synthetic material within said housing;
an intake opening formed in said wall through which said thermoplastic material is introduced into said housing;
a receptacle for receiving the material to be processed, said receptacle being defined by walls connected to said intake opening;
supply means for stuffing said plastic material into said intake opening with a component of motion of the plastics material directed perpendicularly to the longitudinal axis of said screw, said supply means having at least one tool driven for rotation around an axis so that the tool moves relative to said walls of said receptacle near the intake opening and within said receptacle;
at least two wide pockets positioned on the inner surface of the wall of said housing, said pockets extending at least over a major part of said intake opening when viewed in a direction of the axis of the screw, and surrounding said screw along circular ring segments when viewed in a section perpendicular to the axis of the screw, one of said pockets being open adjacent said intake opening so that the material stuffed into the intake opening by the supply means can freely enter said open pocket;
ribs confining said pockets, said ribs being narrower than the width of said pockets when measured in a peripheral direction of the inner surface of the wall of said housing, one of said ribs being adjustably positioned adjacent said intake opening for closing said open pocket adjacent said intake opening, said rib being adjustable to and from the screw, said adjustable rib being disposed at an edge of the intake opening at which the periphery of the screw during its rotation leaves the housing and enters the intake opening.

2. An apparatus as set forth in claim 1, wherein the depth of at least the open pocket adjacent the intake opening is substantially constant when seen in direction of revolution of the screw.

3. An apparatus as set forth in claim 1 or 2, wherein at least one rib is disposed upon the screw opposite the intake opening and constitutes a bearing abutment for the screw at least in the axial region of the screw disposed in the area of the intake opening, for relieving pressure exerted by the supply means.

4. An apparatus as set forth in claim 1, 2 or 3, wherein the ribs extend between the pockets curved in direction of revolution of the screw.

5. An apparatus as set forth in claim 4, wherein the ribs extend along a constant curvature.

6. An apparatus as set forth in any one of claims 1 to 5, wherein the direction of revolution of the screw at the intake opening is directed towards the open pocket.

7. An apparatus as set forth in any one of claims 1 to 6, wherein the pockets extend in axial direction of the screw to both sides beyond the region of the intake opening.

8. An apparatus as set forth in any one of claims 1 to 7, wherein the depth of at least one pocket continuously decreases in direction of transport of the screw.

9. An apparatus as set forth in claim 8, wherein the depth of at least one pocket remains constant in transport direction of the screw and decreases at the end of the axial length of the pocket to zero only.

10. An apparatus as set forth in any one of claims 1 to 9, wherein the pockets which are closed with respect to the intake opening are of equal width.

11. An apparatus as set forth in any one of claims 1 to 10, wherein at least two wide pockets, each of which extends over an aperture angle of at least thirty five degrees, are measured from the axis of the screw.

12. An apparatus as set forth in any one of claims 1 to 11, wherein when measured in peripheral direction of the screw, the ratio between the width of the pockets and the width of the ribs is three to six.

13. An apparatus as set forth in claim 12, wherein when measured in peripheral direction of the screw, the ratio between the width of the pockets and the width of the ribs is four to five.

14. An apparatus as set forth in any one of claims 1 to 13, wherein the rib which limits the pocket which is open towards the intake opening is disposed at the side of the screw that opposes the intake opening.

15. An apparatus as set forth in any one of claims 1 to 14, wherein the screw is an extruder screw having a core diameter which increases towards a head of the extruder screw.

16. An apparatus as set forth in any one of claims 1 to 15, said at least one tool being rotatable around a vertical axis and provided with working edges, said tool comminuting synthetic plastics material introduced into the receptacle and pressing the comminuted material into an opening formed in the side wall of the receptacle, which opening is in communication with the intake opening in the wall of the housing of the screw.

17. An apparatus as set forth in claim 16, wherein said tool heats the plastics material.

18. An apparatus as set forth in claim 16 or 17, wherein the open pocket is disposed at least substantially at the level of the tool.

19. An apparatus as set forth in claim 16, 17 or 18, wherein the open pocket has a bottom that is inclined in a direction towards the tool.

20. An apparatus as set forth in any one of claims 16 to 19, wherein the direction of rotation of the tool at the intake opening is in the direction of transport of the screw.

21. An apparatus as set forth in any one of claims 16 to 20, wherein the screw is disposed at least substantially tangential with respect to the side wall of the receptacle.

22. An apparatus as set forth in any one of claims 1 to 21, wherein at least two ribs are adjustable independently from each other.

23. An apparatus as set forth in claim 22, wherein each adjustable rib is guided within a longitudinal slot formed in the housing and is coupled to displacement means.

24. An apparatus as set forth in claim 23, wherein said displacement means comprises tension screws and pressure screws which are abutted on the housing.

25. An apparatus as set forth in claim 24, wherein at least two tension screws and at least two pressure screws are provided per rib.

26. An apparatus as set forth in any one of claims 1 to 25, wherein the adjustable rib has a body in the shape of a wedge and is guided in a longitudinal direction of the wedge adjustable within the housing of the screw.

27. An apparatus as set forth in claim 26, said body of the adjustable rib having a surface facing the screw, said surface being obliquely shaped.

28. An apparatus as set forth in any one of claims 1 to 27, wherein at least one of the ribs extends obliquely with respect to the longitudinal axis of the screw and is shaped at its surface facing the screw in a manner corresponding to the periphery of the screw.

29. An apparatus as set forth in any one of claims 1 to 28, wherein the adjustable rib is disposed at a level of the longitudinal axis of the screw.

30. An apparatus as set forth in any one of claims 1 to 29, wherein the depth of at least one pocket, measured in a radial direction of the screw, increases when viewed in the direction of the rotation of the screw.

31. An apparatus for processing thermoplastic synthetic plastic material, the apparatus comprising:
an elongate housing defined by a wall having an inner surface and an outer surface;
a screw extending along a longitudinal axis and conveying thermoplastic synthetic material within said housing;
an intake opening formed in said wall through which said thermoplastic material is introduced into said housing;
supply means for introducing said plastic material into said intake opening with a component of motion of the plastics material directed perpendicularly to the longitudinal axis of said screw, said supply means comprising a receptacle having a side wall, and at least one tool disposed within said receptacle, said tool being rotatable around a vertical axis and provided with working edges, said tool comminuting synthetic plastics material introduced into the receptacle and pressing the comminuted material into an opening formed in the side wall of the receptacle, which opening is in communication with the intake opening in the wall of the housing of the screw;
at least two wide pockets positioned on the inner surface of the wall of said housing, said pockets extending at least over a major part of said intake opening when viewed in a direction of the axis of the screw, and surrounding said screw along circular ring segments when viewed in a section perpendicular to the axis of the screw, one of said pockets being open adjacent said intake opening;
ribs separating said pockets from each other, said ribs being narrower than the width of said pockets when measured in a peripheral direction of the inner surface of the wall of said housing; and an adjustable rib positioned adjacent said intake opening and capable of closing said open pocket adjacent said intake opening, said rib being adjustable to and from the screw, said adjustable rib being disposed at an edge of the intake opening at which the periphery of the screw during its rotation leaves the housing and enters the intake opening.

32. An apparatus for processing thermoplastic synthetic plastic material, the apparatus comprising:
an elongate housing defined by a wall having an inner surface and an outer surface;
a screw extending along a longitudinal axis and conveying thermoplastic synthetic material within said housing;

an intake opening formed in said wall through which said thermoplastic material is introduced into said housing;
supply means for introducing said plastic material into said intake opening with a component of motion of the plastics material directed perpendicularly to the longitudinal axis of said screw, said supply means comprising a funnel in connection with the intake opening, and a screw for moving synthetic plastics material disposed in the funnel towards the intake opening;
at least two wide pockets positioned on the inner surface of the wall of said housing, said pockets extending at least over a major part of said intake opening when viewed in a direction of the axis of the screw, and surrounding said screw along circular ring segments when viewed in a section perpendicular to the axis of the screw, one of said pockets being open adjacent said intake opening;
ribs separating said pockets from each other, said ribs being narrower than the width of said pockets when measured in a peripheral direction of the inner surface of the wall of said housing; and an adjustable rib positioned adjacent said intake opening and capable of closing said open pocket adjacent said intake opening, said rib being adjustable to and from the screw, said adjustable rib being disposed at an edge of the intake opening at which the periphery of the screw during its rotation leaves the housing and enters the intake opening.