GB1560927A

GB1560927A - Agglomerating apparatus for thermoplastic plastics films

Info

Publication number: GB1560927A
Application number: GB11398/77A
Authority: GB
Original assignee: Pallmann Maschinenfabrik GmbH and Co KG
Current assignee: Pallmann Maschinenfabrik GmbH and Co KG
Priority date: 1976-04-06
Filing date: 1977-03-17
Publication date: 1980-02-13
Also published as: IT1077754B; DE2614730C2; JPS52123448A; FR2347169A1; JPS6235884B2; DE2614730A1

Description

(54) AGGLOMERATING APPARATUS FOR THERMOPLASTIC PLASTICS FILMS (71) We, PALLMANN KG., Maschinenfabrik, a Kommanditgesellschaft of the Federal Republic of Germany, of Wolfslochstrasse 51, 6660 Zweibriiken, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to apparatus for the continuous agglomeration of thermoplastic plastics films.

Known apparatus of this type ("Kunststoff Berater" Plastic Adviser May 1961, page 370) consists essentially of a rotating hollowing cylinder with radial perforations. In this hollow cylinder, pressure members in the form of a pair of rollers and two distributors blades separated constructionally from the rollers rotate in a common direction of rotation. On the periphery of the hollow cylinder are arranged stationary knives. With this known continuously operating agglomerating apparatus thermoplastic plastics films or plastic film wastes, preferably of polyvinylchloride, polyethylene or polypropylene, after previous crushing in a cutting mill, are fed in the form of so-called tinsels by means of a blower with a conveying pipe and an air separator to a worm dosing device connected with the agglomerating apparatus.The plastics film particles arrive via the worm dosing device into the actual agglomerating apparatus, that is, in the rotating hollow cylinder provided with radial perforations. In this hollow cylinder the film tinsels are distributed by the distributor blades on the inner casing surface and the rollers roll the film tinsels into the radial perforations until these emerge, more or less greatly compressed, at the periphery of the hollow cylinder and are cut to a predetermined length by the stationary knives. The rotating rollers have no drive of their own. They are on the contrary set in rotation by friction with the material.

The granulate leaving the agglomerating apparatus is led pneumatically to a cooler from which the finished granulate emerges.

Particles which are below a certain size are returned to the agglomerating device pneumatically via a cyclone and are thus exposed again to the agglomerating operation.

This known agglomerating apparatus is disadvantageous due to the fact that a comparatively non-uniform granulate is obtained.

This granulate may, for example, consist only of tinsel particles folded together and/or portions irregularly fused together. The nonuniformity of this granulate results from the fact that it is left more or less to chance when an individual film particle is taken up by the pressure members defined by the rollers and is rolled into one of the radial perforations of the rotating hollow cylinder. This may take place on the first rolling or only after several rollings. Plastics particles which are thus rolled several times undergo a greater degree of compression and agglomeration than the film particles which on the first rolling are pressed into one of the radial holes.The consequence of this difference in compression is the said non-uniformity of the granulate which, in the case where the granulate is used for subsequent processing in automatic injection moulding machines or blowing machines is very disadvantageous. With the known arrangements which are also designated as tableting machines it is furthermore difficult to adapt to one another a material feeding time which is independent of the passage of the material and on the other hand a dwell time for the material in the machine which is dependent thereon. Furthermore, the energy expenditure with these known arrangements may be unduly large due to the unavoidably non-uniform granulate particles which are processed therewith and also due to the fact that particles may emerge from the apparatus in the raw state.

In order to obviate these drawbacks, instead of the known apparatus, so-called disc mills (see German Patent Specification No.

1,454,873 and German Patent Specification No. 1,454,875) with discs lying in horizontal or vertical planes have been developed.

Machines of this type with vertically disposed discs have tooth-like projections which on operation are partly or competely cooled for the purpose of leading away resulting agglomeration heat. Either both or only one of the discs may be arranged rotatable. These agglomeration devices require apart from their own relatively high expenditure of energy a very careful disc width adjustment to be ascertained empirically and dependent on the material. Furthermore it is necessary for the speed of the apparatus and that of the connected material-depositing worm or a corresponding unit to be carefully adjusted relative to one another. In practice, therefore, automatic regulating means for both ranges of speed for the achieving of optimum outputs are indispensable.

The object of the present invention is to design an apparatus of the above mentioned type such that independently of the type of plastics films to be agglomerated a constant uniform granulate capable of being percolated with the lowest expenditure of energy and with smaller constructional expenditure than hitherto can be achieved.

According to the invention therefore there is provided apparatus for the continuous agglomeration of thermoplastic plastics films, in particular polyvinylchloride, polyethylene, polypropylene films, in which for compressing the material as supplied by a worm there is provided a rotatable multi-blade (preferably two-bladed) compressor arranged to be driven by a driving shaft with a respective pressure member arranged on each compression blade, said pressure member being arranged to rotate against the inner wall of a cylinder provided with radial passage openings, and on the outer peripheral face of the cylinder there is provided at least one cutting knife which is mounted so as to be movable relative to the cylinder, the material supply worm and the multi-blade compressor and the driving shaft being connected in a rotationally fixed manner to one another.

The invention will now be described further by way of example only and with reference to the accompanying drawings in which: Fig. 1 is a diagram of an agglomerating installation of a generally known type but incorporating one form of an agglomerator according to the invention; Fig. 2 is a part-longitudinal section of the agglomerator on the line II-II of Fig. 1 to a larger scale than Fig. 1; Fig. 3 is an axial section of the agglomerator on the line III-III of Fig. 2 showing only essential parts thereof and to a larger scale than Fig. 2; and Fig. 4 is a part-section on the line IV-IV of Fig. 3 showing essential parts of the agglomerator in a view similar to the view of Fig. 2 but to a scale twice as large as Fig. 2.

With the agglomerating installation shown diagrammatically in Fig. 1 there is provided instead of the known tableting machine an agglomerator 9. Plastics material to be crushed is led, as shown by arrow I, through a material inlet to a cutting mill 2 from which it is fed in crushed form via a suction pipe 3 to a first blower 4. This blower 4 conveys the material via a pressure pipe 5 to an air separator 6.

The material separated by this air separator then falls into a collecting receptacle 7 from where it is fed via a depositing apparatus 8 to the inlet of the agglomerator 9.

The material agglomerated in the agglomerator 9 then falls from this downwards in the direction of the arrow 9a and is led along a suction pipe 10 to a special container 11 which serves as a cooling and cleaning apparatus and in construction is known per se.

In so far as the agglomerted material running into the container 11 still contains undesired particles of dust these are substantially led off from the special container 11 via a suction pipe 14 and are returned by a main blower 15 via an air exhaust and dust pipe 16 to the air separator 6 and thus to the agglomerator 9 for reprocessing.

The cleaned, dust-free and agglomerated finished material in the form of granulate capable of being percolated is removed from the special container 11, via a delivery apparatus 12, in the direction of arrow 13.

In Fig 2 essential parts of the agglomerator are shown in longitudinal section. In an agglomerator housing 23 (only partly shown) there is located a main shaft 20 which rotates in the direction of the arrow 47 when driven by a geared motor (not shown) or a motor with a connected set of toothed wheels. On a section of the shaft 201 which is of reduced diameter there is rotationally fixed a hub 21 on which are connected agglomerating blades 19 and a pressure supply worm 18.

The hub 21 is firmly connected to the agglomerating blades 19 and the worm 18 is likewise firmly connected to the agglomerating blades 19 by means of threaded bolts (not shown in detail in Fig. 2). The agglomerating blades 19 are in their turn firmly connected to the main shaft 20 and likewise the worm 18 is firmly connected to the main shaft 20 by means of a inner shaft bolt (not shown).

The main shaft 20, hub 21, agglomerating blades 19 and pressure worm 18 thus form a stable combined unit rotating with the main shaft 20.

The main shaft 20 is mounted on a bearing 22 in a tubular part 24 of the housing at the end of the shaft carrying this combined unit 21, 19 18.

A solid pivotable housing cover 28 lies opposite this combined unit 21, 19, 18 as seen in the direction of the shaft 20, which housing cover 28 has a connection flange 29 which carries a housing of the worm 18 as well as also the material inlet 17. On the housing cover 28 there is disposed a water cooling part 27 which at the same time is fixed by the connecting flange 29 which carries the worm housing.

On the side of the main shaft bearing 22 a special intermediate ring 25 is firmly connected to the tubular housing part 24 on which in its turn the water cooling part 27 is likewise firmly connected.

Between the combined unit 21, 19, 18 arranged on the mainshaft 20 and the housing cover there is located a disc-like space, designated as "disc space", in which the agglomerating blades 19 located on the shaft 20 rotate.

The outer one of this disc space is surrounded by a ring 34 which has radially directed passage openings 48. On the side of the housing cover 28 this disc space is sealed by the central connection of the worm 18 and by the water cooling part 27. On the other side turned towards the shaft 20 the disc space is sealed by a water cooling part 26 and in its central region by the hub 21.

In order to prevent agglomerating material being able to escape through the narrow annular sealing gap 32 between the hub 21 and the cooling part 26, the annular face of the hub 21, which rotates in operation in the sealing gap 32, is provided with continuous spiral sealing ribs which are arranged to deflect agglomerating material towards the disc space for the agglomerating blades 19.

Due to this seal, penetration of agglomerating material can be substantially prevented.

Between the hub 21 and the special intermediate ring 25 there is built in a sealing ring 33 with square cross-section which likewise prevents a penetration of agglomerating material. Cooling water is fed to the cooling part 26 via a bore 30 in the tubular housing part 24. The water cooling part 27 located on the other side, adjacent the housing cover, receives cooling water via a pipe 31 to which is connected a water hose.

Opposite the ring 34 and radially outwardly thereof are two cutting knives 35 which are adjustably mounted in a holder 36. The holder 36 is located on an annular body 37 which is mounted in its turn on the tubular housing part 24 via a bearing 38.

The annular body 37 furthermore has a chain wheel 39 over which a driving chain (not shown) runs which is driven via a further chain wheel which is associated with a gear (also not shown).

Fig. 3 shows the agglomerating blades 19 rotating in operation as well as the ring 34 surrounding these blades 19. The passage bores directed radially indicated at 48 are arranged around the full periphery of the ring 34. The agglomerating blades 19 rotate in the direction of the arrow 47 and are located with their hub firmly on the shaft 20.

The hub 21 is fixed behind the blades 19 at the places indicated by reference numeral 40.

The material pressed into the so-called disc space by the worm 18 in the direction of the arrow 1 8a (Fig. 2) is guided in the direction of the arrows 46 into the free space by the agglomerating blades 19 whereby it strikes the free faces of the agglomerating blades 19.

Recesses 41 are provided in the agglomerating blades 19 to facilitate distribution of the material. The material is then pressed by pressure pieces 44 of the blades 19 through the radial passage openings 48 of the sievelike ring 34.

The pressure pieces 44 are arranged adjustable in the direction of the ring 34 so that they may be subsequently adjusted against this ring on becoming worn.

The ring 34 is non-rotatably mounted between the two cooling parts 26, 27 lying axially opposite one another.

In the apparatus shown there are provided two agglomerating blades 19 displaced in respect of one another by 1800. The outer peripheral faces of these agglomerating blades 19 turned towards the ring 34 run in a curve such that there peripheries, which are provided with channels 43, together with the circular ring 34 form a closed space which progressively narrows counter to the direction of rotation 47. The adjustable pressure piece 44 provided on the radial outer end of each blade 19 and adjustable in the direction of the ring 34 has a pressure surface 441 which during the rotation of the blades 19 contacts on the inner face of the ring 34 and presses the compressed material uniformly and completely through the passage openings 48 of the ring.

As shown in the drawings the blades 19 in the region below the pressure pieces 44 have side recesses 42 therein which act to reduce the axial cross-sections of the blades 19 and thereby reduce heating of the blades during the operation.

As mentioned the peripheral faces of the agglomerating blades 19 have channel-like recesses 43. These recesses 43 are provided in the radial outer region of the blades 19 and in front of the pressure pieces 44 and give rise to an effective and uniform distribution of the material in the free space continually becoming smaller in radial direction between the ring 34 and the channel-like peripheral recesses 43 of the blades 19.

Fig. 4 which is a section on line IV-IV of Fig. 3 shows the limitation of the so-called disc space therefore of the space in which the agglomerating blades 19 rotate. On the side of this disc space turned towards the shaft 20 this space is sealed by the shaft 20 itself with the hub 21 placed thereon and the water cooling part 26 whereby between this and the hub is provided the helical sealing gap ring 32.

The side turned towards the material inlet 17 (on the right side in Fig. 4) is bounded by the central section of the worm 18 and by the water part 27. In the peripheral direction the disc spade is surrounded by the ring 34. The material conveyed by the worm 18 in this disc space surrounded on all sides may thus in operation only escape via the passage openings of the ring 34 with simultaneous agglomeration.

The manner of operation of the agglomerator 9 is as follows: The plastics material to be agglomerated is fed to the agglomerator via the inlet 17 and in fact via a depositing apparatus correspondingly adjusted (not shown). It is then conveyed by the pressure worm 18 in the direction of the arrow 1 8a with increasing pressure unyieldingly into the so-called disc space and thus to the rotating agglomerating blades 19.

The shaft 20, worm 18, blades 19, hub 21 are firmly connected to one another and have accordingly a common speed and direction of rotation.

Subsequently, the material fed by the pressure worm 18 into the disc space and further compressed by the agglomerating blades 19 rotating in this space arrives in the region of the pressure pieces 44 at the outer end of the blades 19 and is pressed radially outward by these through the passage openings of the sieve ring 34.

With this pressing and agglomerating procedure which takes place during the pressing of the material through the openings of the sieve ring 34, in consequence of the strong rubbing, the material is greatly heated so that the plastics material is pressed together homogenously in the openings of the sieve ring upon pressing through so as to become agglomerated and agglomerated round rod-like parts emerge from the sieve ring. Upon the emerging of these agglomerated particles from the sieve ring 34 these are cut up into short rod particles by the cutting knives continuously rotating around the sieve ring counter to the direction of the arrow 47. The agglomerted material produced in this manner is a desirable plastics granulate capable of being percolated and which can be added to starting material for different plastics manufacturing processes.It is obvious that the granulate thus obtained can only be added to such further processing procedures in which the material in its chemical composition corresponds to the chemical composition of the granulate. The high degree of heat produced during this agglomerating procedure is substantially led off by the cooling parts 26 and 27.

On the side of the shaft 20 this cooling serves in particular for the cooling of the closure parts provided on this side of the disc space and likewise for the cooling of the agglomerating blades 19.

On the side of the housing cover 28 the cooling part 27 serves likewise for the cooling of the disc space closure parts provided there in particular a part of the worm housing running out to the disc space as well as for the cooling of the introduced material to be agglomerated. A cooling of the material is necessary in order to avoid over-heating which would endanger the desired final structure of the material.

It has already been mentioned that for avoiding an unnecessary heating of the agglomerating blades the axial cross-sectional thickness of the agglomerating blades in the region of the inner section of the agglomerating blade is reduced by provision of the recesses 42. Accordingly on both sides of each blade 19 there are gaps which can accommodate the material to be agglomerated and in which at the same time a cooling takes place.

The agglomerating apparatus so far described is suitable apart from the compressing and agglomeration of thermoplastic plastics films also for the treatment of fibres or for the compressing and agglomeration of other plastics, for example, foam wastes. It is characterised particularly by a compact construction which is insensitive and robust in operation and at the same time is spacesaving. Material is compressed in a relatively small space which is accurately geometrically determined and sealed on all side. By means of the two blades 19 rotating in this space the material is led continuously to the stationary sieve ring 34, through which it is pressed by the pressure pieces 44 which are adjustably fixed on the ends of the blades 19 directly through the openings 48 of the sieve ring with thz necessary pressure.

WHAT WE CLAIM IS 1. Apparatus for the continuous agglomeration of thermoplastic plastics films, in particular polyvinylchloride, polyethylene, polypropylene films, in which for compressing the material as supplied by a worm there is provided a rotatable multi-blade (preferably two-bladed) compressor arranged to be driven by a driving shaft with a respective pressure member arranged on each compression blade, said pressure member being arranged to rotate against the inner wall of a cylinder provided with radial passage openings, and on the outer peripheral face of the cylinder there is provided at least one cutting knife which is mounted so as to be movable relative to the cylinder, the material supply worm and the multi-blade compressor and the driving shaft being connected in a rotationally fixed manner to one another.

2. Apparatus according to claim 1, characterised in that the supply worm is at one side of the agglomerating blades and on the other side thereof there is arranged a hub rotationally fixed on the driving shaft which hub has a radially extending face which is connected and sealed to a counter-face of the blades.

3. Apparatus according to claim 2,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. material conveyed by the worm 18 in this disc space surrounded on all sides may thus in operation only escape via the passage openings of the ring 34 with simultaneous agglomeration. The manner of operation of the agglomerator 9 is as follows: The plastics material to be agglomerated is fed to the agglomerator via the inlet 17 and in fact via a depositing apparatus correspondingly adjusted (not shown). It is then conveyed by the pressure worm 18 in the direction of the arrow 1 8a with increasing pressure unyieldingly into the so-called disc space and thus to the rotating agglomerating blades 19. The shaft 20, worm 18, blades 19, hub 21 are firmly connected to one another and have accordingly a common speed and direction of rotation. Subsequently, the material fed by the pressure worm 18 into the disc space and further compressed by the agglomerating blades 19 rotating in this space arrives in the region of the pressure pieces 44 at the outer end of the blades 19 and is pressed radially outward by these through the passage openings of the sieve ring 34. With this pressing and agglomerating procedure which takes place during the pressing of the material through the openings of the sieve ring 34, in consequence of the strong rubbing, the material is greatly heated so that the plastics material is pressed together homogenously in the openings of the sieve ring upon pressing through so as to become agglomerated and agglomerated round rod-like parts emerge from the sieve ring. Upon the emerging of these agglomerated particles from the sieve ring 34 these are cut up into short rod particles by the cutting knives continuously rotating around the sieve ring counter to the direction of the arrow 47. The agglomerted material produced in this manner is a desirable plastics granulate capable of being percolated and which can be added to starting material for different plastics manufacturing processes.It is obvious that the granulate thus obtained can only be added to such further processing procedures in which the material in its chemical composition corresponds to the chemical composition of the granulate. The high degree of heat produced during this agglomerating procedure is substantially led off by the cooling parts 26 and 27. On the side of the shaft 20 this cooling serves in particular for the cooling of the closure parts provided on this side of the disc space and likewise for the cooling of the agglomerating blades 19. On the side of the housing cover 28 the cooling part 27 serves likewise for the cooling of the disc space closure parts provided there in particular a part of the worm housing running out to the disc space as well as for the cooling of the introduced material to be agglomerated. A cooling of the material is necessary in order to avoid over-heating which would endanger the desired final structure of the material. It has already been mentioned that for avoiding an unnecessary heating of the agglomerating blades the axial cross-sectional thickness of the agglomerating blades in the region of the inner section of the agglomerating blade is reduced by provision of the recesses 42. Accordingly on both sides of each blade 19 there are gaps which can accommodate the material to be agglomerated and in which at the same time a cooling takes place. The agglomerating apparatus so far described is suitable apart from the compressing and agglomeration of thermoplastic plastics films also for the treatment of fibres or for the compressing and agglomeration of other plastics, for example, foam wastes. It is characterised particularly by a compact construction which is insensitive and robust in operation and at the same time is spacesaving. Material is compressed in a relatively small space which is accurately geometrically determined and sealed on all side. By means of the two blades 19 rotating in this space the material is led continuously to the stationary sieve ring 34, through which it is pressed by the pressure pieces 44 which are adjustably fixed on the ends of the blades 19 directly through the openings 48 of the sieve ring with thz necessary pressure. WHAT WE CLAIM IS

1. Apparatus for the continuous agglomeration of thermoplastic plastics films, in particular polyvinylchloride, polyethylene, polypropylene films, in which for compressing the material as supplied by a worm there is provided a rotatable multi-blade (preferably two-bladed) compressor arranged to be driven by a driving shaft with a respective pressure member arranged on each compression blade, said pressure member being arranged to rotate against the inner wall of a cylinder provided with radial passage openings, and on the outer peripheral face of the cylinder there is provided at least one cutting knife which is mounted so as to be movable relative to the cylinder, the material supply worm and the multi-blade compressor and the driving shaft being connected in a rotationally fixed manner to one another.

3. Apparatus according to claim 2,

characterised in that the hub forms on its outer cylindrical face a sealing ring formed preferably helically which seals against a corresponding counterface of a water cooling part disposed between the hub and the cylinder.

4. Apparatus according to claim 2, chaacterised in that a compression space is defined within the cylinder for the agglomerating blades said space being bounded radially outwardly by the said cylinder, at one side axially by the hub and by the radial annular face of a cooling part, and at the other side axially by a central part of the worm and by a radial annular face of a cooling part surrounding the worm.

5. Apparatus according to any one of the claims 1 to 4, characterised in that the worm is surrounded partly by a material inlet which is open upwards which is supported on a cover of a housing of the apparatus preferably via the intermediary of a connection flange.

6. Apparatus according to any one of the claims 1 to 5, characterised in that the said cylinder is mounted non-rotatably between two cooling parts lying axially opposite one another.

7. Apparatus according to any one of the claims 1 to 6, characterised in that there are two cutting knives mounted adjustably in holders, said knives being displaced relative to one another by 1800 and together with the holders being capable of being driven via a chain wheel from a gear motor or the like.

8. Apparatus according to claim 7, characterised in that the chain wheel is connected to an annular body which is arranged co-axially to the axis of the shaft and is rotatable counter to the direction of rotation of the shaft, a bearing being interposed between the annular body and the shaft

9. Apparatus according to claim 6, characterised by separate cooling water supply pipes in the cooling parts.

10. Apparatus according to claims 2 or any claim dependent on claim 2, characterised in that the hub with the agglomerating blades are connected to the supply worm and these parts in their turn are connected positively to the shaft.

11. Apparatus according to any one of the claims 1 to 10, characterised in that the agglomerating blades are provided in their middle region with recesses forming an outlet and distribution space.

12. Apparatus according to any one of the claims 1 to 11, characterised in that the periphery of the agglomerating blades turned towards the cylinder runs in a curve such that this blade periphery together with the cylinder forms a continually narrowing compression space opposite the direction of rotation of the agglomerating blades.

13. Apparatus according to any one of the claims 1 to 12, characterised in that each said pressure member is on the radial outer end of the reflective blade and is adjustable in the direction of the cylinder and contacts with a pressure face on an inner face of the cylinder.

14. Apparatus according to claims 4 or any claim dependent on claim 4, characterised in that the axial cross-section of the agglomerating blades in a region lying opposite the cooling parts is kept smaller than in the central and/or the outer peripheral region of the agglomerating blades.

15. Agglomerating apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.