US3705778A - Plastifying apparatus - Google Patents

Abstract

A plastifying apparatus is disclosed. A rotatable roller has arranged angularly spaced with reference to its periphery a plurality of gap-forming elements each of which defines with the periphery a wedge-shaped gap which tapers in direction of rotation of the roller. Feed means feeds material to be plastified into the first one of the gaps for successive movement through this and the following gaps as the roller rotates, whereby the material undergoes successive plastification steps.

Description

mite tates atent (Collin [54] PLASTIFYING APPARATUS [72] Inventor: Heinrich Collin, Munich, Germany [73] Assignee: Krauss-Maffei Aktiengesellschait, Munich, Germany [22] Filed: March 12, 1970 [21] Appl. No.: 18,903

[30] Foreign Application Priority Data March 13, 1969 Germany ..P 19 12 779.8

[52] US. Cl ..425/224, 264/212 [51] Int. Cl. ..B29d 7/02 [58] Field of Search "1 8/9, l0, l5, 2 C; 264/349, 264/212, 216, 175; 425/224 [56] References Cited UNITED STATES PATENTS 3,158,670 11/1964 Camras ..1s/15Rx' 1 1 Dec.12,1972

2,014,937 9/1935 Kratz et al. .Q.....264/212 2,546,342 3/1951 Jurgensen et al. ..264/2l2 X 3,098,262 7/1963 Wisotzky ..264/2l2 UX Primary Examiner-J. Spencer Overholser Assistant Examiner-Norman E. Lehrer Att0rneyMichael S. Striker [5 7 ABSTRACT A plastifying apparatus is disclosed. A rotatable roller has arranged angularly spaced with reference to its periphery a plurality of gap-forming elements each of which defines with the periphery a wedge-shaped gap which tapers in direction of rotation of the roller. Feed means feeds material to be plastified into the first one of the gaps for successive movement through this and the following gaps as the roller rotates, whereby the material undergoes successive plastification steps.

20 Claims, 7 Drawing Figures PATENIEU DEC 12 1912 SHEET 1 OF 5 INVENTOR [lawman 066! h ma Shh ATTORNEY FIG. 2

INVENTOR Hewuc I Crab/u adedJv ATTORNEY PATENTEnuzc 12 972 3.705.778

sum 3 or s INVENTOR UN-I60 6 66/ N 22 0/5- sh-a ATTORNEY INVENTOR I'm/me Con/41 BY 4M ATTORNEY PATENTEDDEB 12 I972 3' 705. 778

SHEET 5 0r 5 INVENTOR l! C064! ATTORNEY PLASTIFYING APPARATUS BACKGROUND OF THE INVENTION The present invention relates generally to the plastification of materials, and more particularly to an apparatus for plastification of materials. Still more specifically the invention relates to an apparatus for plastifying tenacious materials, particularly masses of synthetic plastics.

An apparatus for plastifying tenacious masses is known from German Pat. No. 1,256,401. Here the masses are supplied by means of a feed screw onto one end of a rotatable roller. Means is provided which defines tapered gaps with the periphery of the roller and the mass to be plastified is repeatedly passed through these tapered gaps and advanced helically with reference to the axis of rotation of the roller. At the other end of the roller an outlet is provided at which the mass leaves. The material or mass to be plastified is supplied in form of a narrow ribbon so that the width of the roller is not properly utilized. It is not possible with this construction to produce foils or sheets of material, particularly in view of the fact that the rollers utilized in the aforementioned patent are self-adjusting and not stationarily mounted.

It is, however, of particular interest that foils be capable of production in accordance with this general approach, because heretofore the production of foilsespecially those of polyvinylchlorideis generally carried out on multiple-roller calenders which are expensive in their initial investment cost and rather large so that they require significant space availability. Evidently, high investment expenses and large space requirements are disadvantages which have been sought to be overcome heretofore by utilizing tworoller calendars in which a predetermined quantity of synthetic plastic material is plastified by repeatedly passing through. the gap defined between the two rollers so as to be convertedinto a foil. However, this approach has not been found practical because even calendars constructed in this manner are expensive, aside from the fact that the production of foils in this manner is possible only discontinuously because, as just pointed out, the material to be plastified must be supplied in batches.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to overcome the aforementioned disadvantages.

More particularly it is an object of the present invention to provide an apparatus for plastifying materials and converting the plastified materials into foils or sheets, which not only requires smaller investment expenses but which also permits a continuous production.

In pursuance of the above objects, and others which will become apparent hereafter, one feature of the invention resides in an apparatus which comprises a rotatable roller having a periphery and a plurality of stationary gap-forming elements arranged angularly spaced about the periphery and defining with the same respective wedge-shaped gaps which taper in direction of rotation of the roller. Feed means is provided for feeding material to be plastified into a first one of the gaps for successive movement of such material through all the gaps in response to rotation of the roller.

Utilization of the novel apparatus according to the present invention makes it possible to produce foil continuously and of excellent quality by means of a single rotatable roller, and to do so under full utilization of the axial length of the roller. It is an important aspect of the invention that the mass being plastified passes successively through the respective gaps, and that the plastification is completed when the mass has passed once through each of the gaps, so that a second pass through any of the gaps is not necessary.

By mounting the roller stationarily-except for its ability to rotate-the foil produced with the arrangement according to the present invention can be made of a predetermined precise thickness because the position of the roller in space does not vary so that it is a simple matter to provide for exact adjustment of the width of the gaps which is determinative-particularly the ultimate or terminal gapof the thickness of the finished foil. By arranging the gaps so that they are positioned downstream of one another, with each gap receiving the foil from the respective preceding gap, certain advantages with respect to operation and economy are obtained. A change in the mass between any two successive gaps-which follow closely on one another and in which the mass undergoes kneading or plastification-is precluded and the available heat is utilized to maximum extent because cooling of the surface of the material as it moves from one gap to the next successive gap by radiation of heat and heat exchange with the ambient air is substantially avoided.

The configuration of the gaps is important with respect to the period of time for which the mass is in contact with the wall of the gap-forming element, and at the core or center of the pocket of material which undergoes at any given moment plastification in any one of the gaps, the so-called dwell time. This dwell time is important particularly in working of materials whose characteristics vary with time, for instance deterioration of polyvinyl chloride during long dwell time at high working temperatures. This strictly limited dwell time is achieved by the particular configuration of the gaps which, according to an advantageous embodiment of the invention, are bounded between the circumference of the roller and straight surfaces on the gap-forming elements which define with the roller circumference a tangential angle of between 0 and approximately 45. Optimum-that is shortest-dwell time is obtained if the angle is between substantially l5 and 30. This minimum dwell time which is required for sufficient homogenization of a plastic mass, can be obtained by utilizing a requisite number of gap-forming elements in conjunction with a roller having the necessary diameter of corresponding size.

In accordance with a further advantageous feature of the invention the gap-forming elements may be united-or at least some of them may be united-in form of a single member. Thus, at least two and advantageously between four and six of these gap-forming elements may be united in a single member provided with grooves whose inner boundary surfaces constitute the surfaces which define with the circumference of the roller the respective gaps. This provides for a very simple construction and eliminates any necessity for individually mounting, adjusting and heating the gapforming elements. It is particularly advantageous that with this construction only a single member need be adjusted for permitting a variation in the configuration or width of several different successive gaps. Clearly, such member can be mounted so that the width of all of the gaps can be varied simultaneously, or that for instance only the width of the ultimate gap can be varied. Of course, the ultimate or terminal gap is the most important because its width defines the thickness of the foil which issues from it. Also, it is of course advantageous that with this type of construction a single heating unit can be provided for heating the member instead of requiring individual heating units for the individual gap-forming members. Finally, such a member can be readily mounted and can accordingly be connected with and disconnected from the apparatus according to the present invention in a most simple manner.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawmg.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic side view illustrating an apparatus according to the present invention which utilizes individual gap-forming elements;

FIG. 2 is a fragmentary section, on an enlarged scale, illustrating a further embodiment of the invention in a section normal to the axis of rotation of the roller;

FIG. 3 is a view similar to FIG. 2, on a smaller scale, illustrating a further embodiment;

FIG. 4 is a diagrammatic view analogous to the embodiment of FIG. 2 but illustrating one possible adjusting means for adjusting the gap width;

FIG. 5 is a fragmentary view analogous to FIG. 4 butt illustrating a further possibile adjusting means for ad justing the gap width;

FIG. 6 is a diagrammatic end view illustrating a further embodiment of the invention; and

FIG. 7 is a fragmentary sectional view taken in direction normal to the axis of rotation of the roller and illustrating a further adjusting device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing firstly the embodiment illustrated in FIG. ll it will be seen that reference numeral 1 identifies a roller rotatable about its axis but otherwise stationarily mounted. The circumference or periphery of this roller cooperates with a plurality of gap-forming elements 2-7 and defines with the same a corresponding plurality of wedge-shaped gaps 3-13 each of which tapers in the direction of rotation 23 of the roller 1. Roller l is mounted in stationary bearings by means of its shafts or pins 14, and each of the elements 2-7 is pivotable about a stationary shaft 16. A bolt 17 and nut 1% is provided in conjunction with each of the elements 2-7, being arranged between a respective stationary support 20 and the freely tiltable or pivotable portion of the respective element 2-7, as illustrated. Heating channel 23 is provided in the elements 2-7 through which a heating medium may flow, or which may accommodate heating wires or the like. Of course, it may be generally said that the channels 21 are heatexchange channels, because it is conceivable that under certain circumstances heat exchange in general may be desirable, that is that a cooling fluid rather than a heating fluid, or both in alternating relationship, are to pass through these channels.

Each of the elements 2-7 is provided with a surface 27 which is planar and which can be positioned so as to define a predetermined angle with respect to the tangent of the periphery of the roller 1. According to FIG. 1 this angle is approximately 15 but it may vary between 0 and 45 and is at its optimum when it is between substantially 15 and 30.

The material to be plastified, for instance synthetic plastic granulate, agglommerate or melt, is introduced into the first gap 8 in the direction of the arrow 22 by any suitable feed means, for instance a chute C (see FIG. 6). The roller 1 turns in the direction of the arrow 23 and the material to be plastified, hereafter identified as the granulate for the sake of convenience, undergoes kneading in the first gap. The heating which occurs during this kneading process, in conjunction with the heat supplied through the heating channels 21, initiates the plastification of the material. At the same time the material undergoes excellent admixture and homogenization and then issues at 19 from the narrowest section of the gap 8 in form of a lightly plastified skin or sheet which is transported by the continued rotation of the roller 1 to the next gap 9 wherein the next plastification step takes place. From the gap 9 the material is again transported to the gap 10, from there to the gap 11 and from there to the gap 12. Finally, in the embodiment illustrated in FIG. 1 there is a terminal gap l3, and this receives the material from the gap 12. The gap 13 is of particular importance because the width of the narrowest section 19 of the gap 13 determines the thickness of the sheet or foil which issues from the gap 13. This foil may either be removed from the roller ll immediately downstream of the gap 13 as suggested by the arrow 24, or only after it passes between the roller 1 and a second roller 26 as suggested by the arrow 25, and the second roller 26 may for instance be constructed as an embossing roller or the like.

Resort to the novel invention, that is the novel method and apparatus as illustrated by way of example in FlG. 1, produces foil continuously from sufficiently kneaded and admixed plastified mass. One highly advantageous aspect of the invention is that with it the entire axial length or width of the roller 1 can be utilized. Evidently, this results in more economical manufacturing conditions.

FIG. 2 shows a further embodiment of the invention. Like reference numerals identify like elements as in FIG. 1. Here, however, the individual gap-forming elements 2-7 of FIG. 1 have been replaced with a single member 30 whose width corresponds to the axial length of the roller 1. It is also provided with the heating channels 22., but in addition it is provided with four- -or more or fewer-grooves 31-34 extending in parallelism with the axis of rotation of the roller 1. Each of the grooves 34 has the illustrated cross-sectional configuration in that its downstream portion -as seen with respect to the rotation of the roller 1 as identified by concavely curved surface portion 36. The maximum depth of the grooves is approximately 3-10 mm and may be identical in all grooves, or may be decreasing in the direction of rotation of the roller 1. In the latter case the volumetric content of each succeeding gap will of course decrease whereby the median dwell time of the mass is similarly decreased, a concept which is advantageous with respect to the temperature of the mass and the attendant danger of deterioration thereof.

It will be appreciated that the grooves 31-34 replace and have the same purpose as the gaps 8-13 shown in FIG. ll. However, the grooves 31-34 in FIG. 2 are directly successive and are connected by short shear surfaces 37-41 which have a small spacing from the surface of the roller 1 and extend approximately parallel thereto. The length of the shear surfaces 37-41 with respect to the rotation of the roller l is approximately 2-10 mm; their distance from the surface of the roller 1 decreases in direction from the shear surface 37 to the shear surface M, with the distance between the roller 1 and the shear surface 41 being one of the determinative factors which govern the thickness of the finally produced foil. However, it is clearly possible to leave the distance of the shear surfaces 37-41 from the surface of the roller 1 identical if desired. I

The surface portions 35 are of particular importance because the quality of the foil obtained with the apparatus according to the present invention is largely determined by the kneading and mixing process in the gaps 42 and 43 during rotation of the roller 1 in the direction of the arrow 23, and on entry of the mass into the uppermost gap 42, that is the leading gap. It is necessary that materials which are susceptible to damage are subjected to a dwell time which is as short as possible, and that overheating and deterioration or decomposition of the mass with formation of bubbles and decolorations is avoided. If the cross-section of the grooves 31-34 is that illustrated in FIG. 2, it has been found that a positive angle a, between the respective surface portion 35 and the tangent to the roller periphery is of advantage, and the angle (1 should be in the region between 0 and 40. An angle a, on the order between approximately and is particularly advantageous because despite the succession of several of the gaps it reduces to a minimum any conditions of overheating, particularly also in the case of soft and hard polyvinyl chloride.

In the embodiment of FIG. 3 the member as takes the place of the member 39 in FIG. 2. Reference numeral identifies the heat-exchange conduits, whereas reference numerals 47, 48 and 49 identify the gap-forming grooves. The gap-forming surfaces 56 converge upwardly analogous to FIG. 2 into concavely curved surface portions 51, whereas the downstream portions of the surfaces 50 are significantly shortened-with respect to the configuration shown in FIG. 2-in order to obtain a further concavely curved surface portion 52 which terminates the grooves M49 at an angle on the order of between 90 and ISO, preferably less than approximately l35, with reference to the upwardly directed tangent to the roller surface. The radius r, of the curved surface portion 52 is smaller than the radius r, of the curved surface portion 51; in

fact, it is approximately one third to two thirds of the radius r,. The purpose of this is to achieve a further reduction in the dwell time of the material at the surface portion and in the interior of the respective gap, as well as to facilitate the flow of the material which takes place within the respective gap during the kneading of the material. This construction is particularly advantageous for highly delicate materials, that is materials which are especially susceptible to damage under the aforementioned conditions. In addition, it will bee seen in FIG. 3 that the depth of the grooves 47-49 decreases in the direction of rotation of the roller 1 as signified by the arrow 23, with the groove 49 having the smallest depth. Furthermore, a shear surface 54 follows each groove 47-49, that is arranged downstream of the respective groove.

FIGS. 4 and 5 illustrate how the respectively terminal gap can be adjusted. In FIG. 4 this terminal gap which, as has already been pointed out before, is of importance for the thickness and also for the surface quality of the foil produced-is identified with reference numeral 67. The lower portion 57 of the member 55-which is again provided with the heatexchange channels or conduits 56is formed with a slot 58 whose width is adjustable by means of a screw 59. A further screw 59a is shown in broken lines and suggests a further possibility for obtaining the desired effect. Reference numeral 69 identifies the shear surface at the downstream end of the gap 67.

In the embodiment of FIG. 5 a wedge-shaped member 61 is pressed into a slot with non-parallel side faces by means of a screw 62 which in turn is mounted in a member 64 which is connected with the member 63 replacing the member 55 of the embodiment in FIG. 4. The terminal gap is here identified with reference numeral 68 and the associated shear surface with reference numeral 70. With the constructions according to FIGS. 4 and 5 the width of the respective terminal gap 67 in FIG. 4 and 68 in FIG. 5, and the distance between the roller surface and the respectively associated shear surface 69 or 70 (associated with the respective terminal gap) can be varied in a simple and effective manner.

In the embodiment illustrated in FIG. 6 like reference numerals again identify like elements. I-Iere,

- however, there are provided two members and 76 located at opposite sides of the roller 1. With this construction the pressures which act upon the roller 1 as a result of the hydrodynamic pressure increases in the gaps 77 at least in part negate one another so that there is a much smaller bending pressure exerted upon the roller 1 than would normally be expected from the pressures which develop in the gaps 77 and act upon the roller 1. The result is a significantly decreased load upon the (non-illustrated) bearings for the roller 1. It is hardly necessary to emphasize that this is highly advantageous in that the avoidance of bending or flexing of the roller l transversely of its elongation is of significant importance in the production of foils of constant thickness.

Coming now to the embodiment of FIG. 7 it will be seen that this is concerned with the adjustability of the member 80 which corresponds to one of the previously described members, for instance is analogous to one of the members 75 or 76 of FIG. 6. Such adjustability is of l060l0 040i importance because the members-such as the member 8 lihas a plurality of grooves which define with the circumference of the roller l gaps which are fixed with respect to one another-that is with respect to their position on the member 841-; because of this, and because in some embodiments it is desired that the terminal gap be adjustable separately, the adjusting arrangements must be capable of affording adjustment of the member 8llor an analogous memberin several directions. This is accomplished in FIG. 7 by providing the member 8ft, which is again provided with the heatexchange channels 21, with a mounting on a traverse till by means of a wedge-shaped member 82 which is vertically shiftable via a screw 83 and thus permits simultaneous adjustment of all gap widths between the member $63 and the circumference of the roller 1. There are further provided additional screws 84 which serve to permit shifting movement of the member 80 in a plane which is in parallelism with the axis of rotation of the roller 11, so that the gap widths are varied not identically but differently. The screws 84 and 85 serve to arrest the member 80 with reference to the traverse bl when tightened. The latter is further pivotable about a shaft 556 which is stationary and extends in parallelism with the axes of rotation of the roller 1. This makes it possible for the member 80 to be tilted towards the right in FIG. 7 so that access can always be had readily for cleaning purposes, inspection purposes and for removal if necessary. Such pivot action is accomplished by means of a worm gear drive 87, 88 when a handwheel $9 is rotated. The kneading forces in the gaps are resisted by a ram 9ft which is mounted stationarily, for instance by being supported on the housing of the apparatus.

it is one of the particular advantages of using members such as the member 80, or the analogous members which have been described and illustrated in the preceding embodiments, that aside from the initial or first gap into which the material to be plasticized originally passes-the intrusion of air into the mass undergoing plastificationand more particularly into the space between the downstream ends of the respective gaps and the upstream ends of the next-following gaps where the mass passes in form of a foil over the circumference of the roller, or into the space between the circurnference of the roller and the mass, is avoided. Furthermore, the material leaving the first or initial gap, and in fact the first several gaps, is still only partially plastitied and therefore has the tendency to move away from the roller circumference and to curl about the edge of the respective gap-forming element, thereby very possibly forming at the same time an airinclusion within the material. This is avoided with the type of element under discussion in the embodiments 2-7, such as the element 8b, where several of the individual gap-forming elements are united in a single member bid, or an analogous member. Of course, there is also the advantage that with this particular construction the space requirements are significantly decreased over those which would prevail if individual gap-forming elements were used as in the embodiment of FIG. 1, so that a significantly greater number of gaps can be provided as seen with respect to the circumference of the roller, whereby a greater degree of admixture and plastification is achieved. Also, mounting space, measuring space and other space requirements which would be necessary if the gap-forming elements were individual as in FIG. l, are avoided.

A further advantage of utilizing the member 80 or an analogous member is the fact that the kneading processes which take place in the gaps formed between this member and the circumference of the roller 1 can be more readily controlled. While the terminal or final gap is determinative of the thickness of the foil produced, the preceding gaps control the kneading steps. With the exception of the initial gap all others between the initial and the terminal gap are completely filled with material undergoing the kneading process. Only the initial gap requires a certain adjustment with respect to the supply of material to it. Normally the inlet end of the initial gap will face upwardly and the material will be introduced in downward direction into this initial gap, and it is a simple matter to control the supply of material to it.

in an embodiment such as that shown in FIG. 6 it is of course possible not only to use two of the members, such as the members '75 and 76, but also to use three or more. The number of gaps can be distributed among these members, and it is advantageous if there is a total of twelve or even more such gaps. If two members, such as the members and 76 are provided, they are arranged to be located oppositely one another. If more than two members are provided they are equi-angularly distributed with reference to the circumference of the roller ll. In all instances it is then possible, as already suggested in the discussion of the embodiment of FIG. 6, to so arrange the members that the pressures originating in the respective gaps thereof will negate or at least substantially negate one another to avoid bending stresses upon the roller 1. It is essential in this connection that the terminal or final gap, from which the finished foil issues, exert upon the roller 1 a pressure which is higher than that exerted by the other gaps of the same member so that floating of the roller in view of the unavoidable bearing play is avoided and the thickness of the foil can be maintained constant. Otherwise, that is if the roller 1 could yield in the bearings, variations in the width of the outlet end of the terminal gap would result in variations of the thickness of the foil produced.

it will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in an apparatus for plastification of plastifiable materials, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning of the following claims.

lOOlO 0402 What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

11. An apparatus for plastifying of materials, particularly of synthetic plastics, and for making foils from such materials, comprising in combination a roller having a periphery; a plurality of stationary elements angularly spaced about said roller and having respective surfaces spaced from and defining with the periphery of said roller respective wedge-shaped gaps which taper in direction of rotation of said roller and which have downstream ends extending with slight spacing in at least substantial parallelism with the axis of said roller, said gaps including an initial and a terminal gap; heating means associated with said stationary elements for heating the same; and feed means for feeding plastifiable material into the initial one of said gaps over the entire length thereof, for successive movement of such material through all of said gaps in response to rotation of said roller so that such material becomes plastified in said gaps by heating by said stationary elements heated by said heating means associated with said stationary elements and converted into a foil which is discharged from the terminal one of said gaps.

2. An apparatus as defined in claim 1, said gaps having respective upstream and downstream end regions which are each concavely curved inwardly towards said periphery.

3. An apparatus as defined in claim ll; further comprising adjusting means for adjusting the taper of the respective gaps.

An apparatus as defined in claim 1, said plurality of elements comprising between four and six of said elements.

5. An apparatus as defined in claim 1, said surfaces each being a flat surface.

6. An apparatus for plastifying of materials, particularly of synthetic plastics, and for making foils from such materials, comprising a rotatable roller having a periphery; a plurality of stationary elements substantially longitudinally coextensive with said roller angularly spaced thereabout, at least two of said elements being unitary with one another in form of a member having a face directed towards said roller and provided with a plurality of grooves extending in axial parallelism with said roller and being bounded by groove surfaces which define with the periphery of said roller respective wedge-shaped gaps which taper in direction of rotation of the roller and include an initial and a terminal gap; and feed means for feeding material into the initial one of said gaps over the entire length thereof, for successive movement of such material through and processing in all of said gaps in response to rotation of said roller, and for discharge of the processed material from the terminal one of said gaps.

7. An apparatus as defined in claim 5, wherein the respective flat surface includes with a tangent to the periphery of said roller an angle of between and 45.

8. An apparatus as defined in claim 7, wherein said angle is between substantially 15 and 30.

9. An apparatus as defined in claim 6, said plurality of elements comprising at least one additional member similar to the first-mentioned member and being angularly spaced with reference to the latter and to said periphery.

ll An apparatus as defined in claim 6, said groove faces including with respective tangents to said periphery angles of between 0 and 30.

111. An apparatus as defined in claim 10, wherein said angles are on the order of between 10 and 20.

12. An apparatus as defined in claim 10, said gaps having respective upstream and downstream ends, and wherein said upstream ends have upstream end regions which are concavely curved inwardly towards said periphery of said roller.

13. An apparatus as defined in claim 6; further comprising adjusting means for adjusting the taper of at least said terminal one of said gaps.

14. An apparatus as defined in claim 6; further com prising adjustable mounting means mounting said member for tilting movement with reference to said periphery of said roller.

15. An apparatus as defined in claim 2, wherein said downstream end regions are curved so as to include with a tangent opposite to the direction of rotation of said roller an included angle of between substantially and 150.

11.6. An apparatus as defined in claim 15, wherein said included angle is below substantially 17. An apparatus as defined in claim 15, wherein said upstream end regions are curved on a first radius, and said downstream end regions are curved on a smaller second radius.

18. An apparatus as defined in claim 17, wherein said first radius is greater than said second radius by between one-half and twice the amount of said second radius.

19. An apparatus for plastifying of materials, particularly of synthetic plastics, and for making foils from such materials, comprising a rotatable roller having a periphery; a plurality of stationary elements substantially longitudinally coextensive with said roller-angularly spaced thereabout and defining with the periphery of said roller respective wedge-shaped gaps which taper in direction of rotation of the roller and which include an initial-and a terminal gap; feed means for feeding material into the initial one of said gaps over the entire length thereof, for successive movement of such material through and processing in all of said gaps in response to rotation of said roller, and for discharge of the processed material from the terminal one of said gaps; and shear surfaces downstream of the respective gaps and extending with slight spacing in at least substantial parallelism with said periphery of said roller.

20. An apparatus as defined in claim 19, said shear surface having in direction of rotation of said roller a length between substantially 2 and 10 mm.

Claims (20)

1. An apparatus for plastifying of materials, particularly of synthetic plastics, and for making foils from such materials, comprising in combination a roller having a periphery; a plurality of stationary elements angularly spaced about said roller and having respective surfaces spaced from and defining with the periphery of said roller respective wedge-shaped gaps which taper in direction of rotation of said roller and which have downstream ends extending with slight spacing in at least substantial parallelism with the axis of said roller, said gaps including an initial and a terminal gap; heating means associated with said stationary elements for heating the same; and feed means for feeding plastifiable material into the initial one of said gaps over the entire length thereof, for successive movement of such material through all of said gaps in response to rotation of said roller so that such material becomes plastified in said gaps by heating by said stationary elements heated by said heating means associated with said stationary elements and converted into a foil which is discharged from the terminal one of said gaps.

2. An apparatus as defined in claim 1, said gaps having respective upstream and downstream end regions which are each concavely curved inwardly towards said periphery.

3. An apparatus as defined in claim 1; further comprising adjusting means for adjusting the taper of the respective gaps.

4. An apparatus as defined in claim 1, said plurality of elements comprising between four and six of said elements.

5. An apparatus as defined in claim 1, said surfaces each being a flat surface.

6. An apparatus for plastifying of materials, particularly of synthetic plastics, and for making foils from such materials, comprising a rotatable roller having a periphery; a plurality of stationary elements substantially longitudinally coextensive with said roller angularly spaced thereabout, at least two of said elements being unitary with one another in form of a member having a face directed towards said roller and provided with a plurality of grooves extending in axial parallelism with said roller and being bounded by groove surfaces which define with the periphery of said roller respective wedge-shaped gaps which taper in direction of rotation of the roller and include an initial and a terminal gap; and feed means for feeding material into the initial one of said gaps over the entire length thereof, for successive movement of such material through and processing in all of said gaps in response to rotation of said roller, and for discharge of the processed material from the terminal one of said gaps.

7. An apparatus as defined in claim 5, wherein the respective flat surface includes with a tangent to the periphery of said roller an angle of between 0* and 45*.

8. An apparatus as defined in claim 7, wherein said angle is between substantially 15* and 30*.

9. An apparatus as defined in claim 6, said plurality of elements comprising at least one additional member similar to the first-mentioned member and being angularly spaced with reference to the latter and to said periphery.

10. An apparatus as defined in claim 6, said groove faces including with respective tangents to said periphery angles of between 0* and 30*.

11. An apparatus as defined in claim 10, wherein said angles are on the order of between 10* and 20*.

12. An apparatus as defined in claim 10, said gaps having respective upstream and downstream ends, and wherein said upstream ends have upstream end regions which are concavely curved inwardly towards said periphery of said roller.

13. An apparatus as defined in claim 6; further comprising adjusting means for adjusting the taper of at least said terminal one of said gaps.

14. An apparatus as defined in claim 6; further comprising adjustable mounting means mounting said member for tilting movement with reference to said periphery of said roller.

15. An apparatus as defined in claim 2, wherein said downstream end regions are curved so as to include with a tangent opposite to the direction of rotation of said roller an included angle of between substantially 90* and 150*.

16. An apparatus as defined in claim 15, wherein said included angle is below substantially 135*.

17. An apparatus as defined in claim 15, wherein said upstream end regions are curved on a first radius, and said downstream end regions are curved on a smaller second radius.

18. An apparatus as defined in claim 17, wherein said first radius is greater than said second radius by between one-half and twice the amount of said second radius.

19. An apparatus for plastifying of materials, particularly of synthetic plastics, and for making foils from such materials, comprising a rotatable roller having a periphery; a plurality of stationary elements substantially longitudinally coextensive with said roller angularly spaced thereabout and defining with the periphery of said roller respective wedge-shaped gaps which taper in direction of rotation of the roller and which include an initial and a terminal gap; feed means for feeding material into the initial one of said gaps over the entire length thereof, for successive movement of such material through and processing in all of said gaps in response to rotation of said roller, and for discharge of the processed material from the terminal one of said gaps; and shear surfaces downstream of the respective gaps and extending with slight spacing in at least substantial parallelism with said periphery of said roller.

20. An apparatus as defined in claim 19, said shear surface having in direction of rotation of said roller a length between substantially 2 and 10 mm.

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