DE10106677C1 - Granulator especially suitable for plastic strands, has roller stripper fixed resiliently to counter-blade carrier - Google Patents

Abstract

The roller stripper (25) is fixed to the counter-blade (58) carrier (23), the connection being flexible. Preferred features: Strands are granulated simultaneously. The cutting tool (59) is a cylindrical rotor (61) with external cutters (62), the minimum clearance gap between the fixed counter blade carrier (58) cutter (60) and the cutting edge (66) of the cutting tool (59) being less than 1.0 mm. The gap is adjustable. The roller (8) is cylindrical, with a smooth outer surface. A further roller (9) of the feeder, is axi-parallel to the rotating roller (8), with the strand fed between them. One roller is driven, preferably both, in counter-rotation. The stripper defines a gap over the whole length of the rotating roller. The stripper blade (26) is fastened to the carrier, with an edge parallel to the roller. It is constructed and held resiliently. The stripper has a joint holding the stripper blade, permitting flexure and resilient displacement. The joint, a weakened region, intervenes between fastening section and stripper. The stripper is triangular in cross section. One side is concave towards the roller. Its construction defines a lip projecting at an angle to the roller circumference.

Description

The invention relates to a granulating device for granulating lieren of strands of material, especially plastic strands.

Granulating devices can be used for waxes, special Pharmaceuticals, natural vegetable fibers, food or Plastics are used for the production of granules. Plastic granules or pellets serve as the starting material for plastic processing processes such. B. injection molding or injection molding or extrusion process to form molded articles or to be processed into composite materials. For high high-quality applications, the granules must have sufficient homogeneity nity and a defined shape.  

The plastic is used to produce the granulate melted in a special extruder and through nozzles of the Extruder pressed. This creates thin plastic strands ge, which is then used to shred the pelletizer be performed.

In a pelletizer known from DE 198 16 611 A1 The plastic strands are set up immediately after they have gone out emerge from perforated plate openings using a rotating knife cut off. The cutting surfaces of the knives lie directly on the perforated disc.

Another granulation known from practice Plastic strands are set up by means of a feeder direction fed to a cutting device. The cutting a rotating multi-tooth cutting tool points in the direction whose cutting edges are attached to a stationary counter knife pass a small gap. Belongs to the feeder a cylinder roller. This is a fixed squeegee assigned, which serves to haf if necessary on the roller detachable plastic strands.

DE 42 36 451 C1 describes a granulating device known, which is a feeder with an upper feeder roller and a lower feed roller and one against the zu Direction of the strand material rotating shear knife roller includes, which against a fixed anvil knife (counter knife) works. The counter knife is together with one of the lower feed roller assigned scraper on a between the lower feed roller and the shear blade roller arranged carrier fixed. Is in operation lower feed roller held locked in one position, where there is only a small distance between the lower one Feed roller and the doctor blade remains. Out of order  the lower feed roller can be placed in one of the counter swivel this distant position to clean the Roller enables.

Both in the granulation known from practice direction as well as that according to DE 42 36 451 C1 is the Scraper bar or the scraper knife on a carrier brought, who also carries the fixed counter knife. Point the strands thickened or, especially when starting the Machine, initially thick teardrop-shaped heads on that too can be glued together, these thickenings lead, when they arrive at the cylinder roller, to a slight against elastic deformation of the same. Touches the cylinders roll the squeegee or the doctor blade, this can lead to the displacement of the carrier, which is also the counter knife wearing. A collision between the teeth of the cutting knife or the shear knife roller and the counter knife due to the for a high-quality granulate requires a narrow cutting gap should be avoided.

Based on this, it is an object of the invention to provide a Gra To create the nulator, which is used to produce qualitatively high quality granules is suitable and at the risk the damage to the cutting tools, especially at the driving process is reduced.

This task is done with a pelletizer solved the features of claim 1.

The granulating device according to the invention has a Cutting device and a feed device. The Cutting device is by a cutting tool and a stationary counter knife formed, on or in operation several cutting elements of the cutting tool with little Pass the gap to the granulate from the strand of material cut off defined size. A circulating in operation Feeder roller enables precise alignment of the material strand in relation to a cutting edge of the counter knife sers. For wiping any material sticking to the roller as a fixedly arranged stripping element is provided.

The invention is based on the concept, a common one seed carrier for both the stripping element and the Ge to use counter knife. This results in a simple compact Construction. According to the wiping element is after extensively connected to the common carrier. this makes possible in the event of a bending or relocation of the rotating Rolling out the squeegee without misalignment or Shifting the counter knife. The risk of cutting tool is damaged, is excluded or at least significantly reduced.

The measure according to the invention also makes it possible If necessary, the cutting gap is smaller (with a smaller safety margin)  set. The precision of the cutting factory can be improved.

The granulating device according to the invention is suitable for the production of granules from strand-like material, such as B. plastic strands. There can be several in a group pe arranged strands simultaneously the cutting device be fed. The strands can be delivered ready or in be continuously produced in an extrusion process.

The cutting tool is preferably a concentric one Cutting rotor with an essentially cylindrical movement tool body and several arranged on its outer circumference Cutting elements formed. The cutting elements can e.g. B. are made of ceramic.

The width of the cutting gap between the counter knife and the cutting edges of the cutting elements is preferably each adjustable as required. For this purpose, at least the cutting rotor but preferably also the carrier for the counter knife be adjustable (adjustable). The minimum gap width is generally between 0.04 mm and 0.1 mm and is usually chosen to be less than 0.1 mm. The gap width can also be smaller than 0.04 mm with high operational reliability be set to create fine granules.

The rotating roller of the feed device is preferred as a cylindrical roller with a substantially smooth jacket area. The scraper can with a bar be formed sharp edge.

In one embodiment of the invention is another Roll provided that parallel to the rotating roller is ordered. The plastic strands are between the two  Rolls picked up and the cutting edge of the counter knife guided. The outer surface of the additional roller can be smooth or be profiled. In support of Strand conveying is at least on the smooth cylinder roller driven.

The stripping device has, in addition to the stripping element (lip), a fastening part which serves for connection to the carrier. The stripping device is adjustably attached to the carrier and has elongated holes for this purpose. The adjustment is as follows:

• 1. The cutting gap between counter knife bar and The cutting rotor is stopped. (Moving the beam).
• 2. The scraper is attached to the roller (through the elongated holes in the stripping device).

The stripping element can lie against the rotating roller or at a short distance from this, a wiping gap be arranged forming. Because of the possible deflection of the Roller, especially in the middle, should actually be a wiping gap widening towards the center of the roll will be. The flexible holder of the wiper element but allows the stripping gap over the entire length the roller is uniform, i.e. with a constant width train. Plastic strands sticking to the roller effectively detached at every point along the roller.

The stripping element is preferably simply through a strip with a straight, toothless scraper edge forms.

The squeegee is preferably resilient trained and kept to evade if necessary  can. For example, it can be configured such that it when the rotating roller runs against it, on the ver binding point to the fastening part of the scraper tion deformed. Thus, the transition between the Ab squeegee and the fastening part a kind of joint (spring joint), which effectively decouples the stripping element and counter knife.

The joint can be formed by a web, the one elastic connection between the squeegee and the Fastening area creates. The web is, for example, over the ge Entire length of the squeegee formed and essentially chen parallel to the rotating roller. The elastic egg properties of a joint formed in this way co-determined by the shape of the web. Alternatively, the Squeegee be resilient throughout.

In one embodiment of the invention, the wiper is form by a triangular body in cross section det. In a side surface of the body facing the roller a groove is provided around a narrow, flexible connection manure and thus the bridge, d. H. to create the elastic joint fen.

In an alternative embodiment, the wiper is strip in the form of one of the fastening part of the wiper device from lip to protrude towards the roller educated. In relation to the width of the attachment sometimes the lip is relatively narrow and long. The lip can thus when touched, for example, by the rotating roller elas dodge the table. The root of the squeegee, which the ver binding point between the fastening area and the Ab forms a lip, is at the same time the resilient Joint.  

Further advantageous details of embodiments the invention result from subclaims of the drawing and the associated description.

In the drawing is an embodiment of the counter state of the invention. Show it:

Fig. 1 is a side view of a Granu liereinrichtung according to the invention, in a partial and schemati lized representation,

Fig. 2 shows the granulating device according to Fig. 1, in a scale and

Fig. 3 shows another embodiment of the Granuliereinrich device, in a fragmentary and schematic Dar position.

Fig. 1 shows in a simplified representation of a section of a granulating device 1 according to the invention, which is for the production of granules of plastic lines 2. The granulating device 1 includes a conveying and feeding device 3 , a stripping device 4 and a cutting device 5 .

The plastic strands 2 are extru dated from the melt and fed to the granulating device 1 . Alternatively, previously manufactured plastic strands are used. In the figures, the plastic strands of the granulating device 1 are fed from above. The parts of the granulation device 1 can also be arranged in such a way that the plastic strands 2 are guided obliquely or horizontally.

The feed device 3 is essentially formed by two rotatably mounted rollers 8 , 9 , which are arranged at a distance and parallel to one another, so that the plastic strands 2 pass between the rollers 8 , 9 and are conveyed by them. A first roller 8 is designed as a cylinder roller with an approximately smooth lateral surface 10 . Your man telfläche 10 is in contact with the plastic strands 2 . The second roller 9 here has a profiled outer peripheral surface 11 . The profile is formed by ribs 12 which extend in the axial direction of the roller 9 and are trapezoidal in cross section. Their radial outer sides 14 can be curved in accordance with a circle concentric with the axis 13 . Alternatively, a smooth roller can be used.

Between the roller 8 and the roller 9 , a passage gap 17 is set for the plastic strands 2 . To adjust the gap width depending on the strand thickness, the roller 9 is preferably adjustable before. In operation, the ribbed roller 9 in Fig. 1 is driven counterclockwise (arrow 18 ) and in the opposite direction to the cylinder roller 8 rotating. Accordingly, the cylinder roller 8 can be driven (arrow 21 ).

Following the gap 17 , the stripping device 4 is adjustably arranged on a carrier 23 . The stripping device 4 , shown enlarged in FIG. 2, has a fastening part 24 set up for connection to the carrier 23 and a stripping part or a stripping element 25 . It is preferably in one piece and made of metal or plastic.

The stripping element 25 is formed by a strip with a substantially triangular cross-section that tapers towards a stripping edge 27 . The straight scraper edge 27 is arranged in the vicinity of the cylinder roller 8 , parallel to the axis 20 thereof. Between the outer surface 10 and the stripping edge 27 , a narrow stripping gap 28 defined along the roller 8 is defined. The scraper edge 27 is fixed between a side of the roller 8 facing concavely formed 30 and a side 31 facing the plastic strand 2 . The page 31 is essentially flat and only slightly rounded in the immediate vicinity of the scraper edge 27 . It includes an acute angle with the side surface 30.

In the stripping device 4 between the fastening supply part 24 and the stripping element a cross-sectionally rectangular groove 32 is provided which extends through the side surface 30 and extends transversely to the side 31 into the stripping device 4 . The groove 32 defines the stripping element 25 from the fastening part 24 . Between the straight in Fig. 1, but any bottom 33 of the groove 32 and the side 31, a narrow section or web 34 is defined, which creates an elastic connection between the parts 24 and 25 . The width of the groove 32 corresponds approximately to the thickness of the web 34 . The length of the scraper element is at least three times the groove width. This gives the desired compliance.

On the fastening part 24 , a flat surface 37 is formed as a seat, which extends in the radial direction to the axis of rotation 20 . A step 38 adjoins the plane surface 37 . The fastening part 24 then runs out with a V-shaped end region 40 .

As a seat for the fastening part, the carrier 23 has a recess 42 with a rectangular cross section. The end region 40 of the fastening means 24 is supported on a bevel 43 provided in connection with the recess 42 . The stripping device 4 is secured by bolts 44 adjustable bar on the support 23 . To this end mounting part 24 steps through bores 45 and corresponding threaded bores 23 in the carrier 47 are provided in the Fixed To. The bolt 44 is seated with radial play in the bore 45 in order to be able to adjust the wiping device 4 radially to the roller 8 .

The side 49 of the carrier 23 facing the roller 8 is designed to be cylindrically concave in accordance with the side 30 of the scraper strip 4 , the radius of curvature being greater than the radius of the roller 8 . As a result, between the roller 8 and the sides 30, 49, a crescent-shaped gap 50, which widens continuously starting from the stripping gap 28 in the circumferential direction 21 of the roller 8, is defined.

The cutting device 5 is formed in the present example by a stationary counter knife bar 58 and a circular cutting tool 59 . The counter knife bar 58 made , for example, of steel, a hard metal, a metal alloy or ceramic has a rectangular cross section and a sharp cutting edge 60 and is connected to the carrier 23 .

The rotating cutting tool 59 has a tool body by 61 , which carries on its peripheral side a plurality of spaced cutting elements 62 made of steel or hard metal or ceramic. Each cutting element 62 has a rake surface 64 with a positive rake angle and a free surface 65 which borders on the rake surface 64 at a cutting edge 66 . The cutting edges 66 which run past the counter knife 58 in operation on a common flight circle define a cutting gap 67 with the cutting edge 60 .

The granulating device 1 works as follows:
In operation, the plastic strands 2 are conveyed from the extruder 6 or a corresponding strand supply to the feed device 3 . Here they are taken up between rollers 8 , 9 and fed through the passage gap 17 and past the flat side 31 of the stripping device 4 to the cutting device 5 . The strands 2 pass through the counter knife 58 and are cut between this and the cutting elements 62 .

If necessary, plastic strands 2 adhering to the cylinder roller 8 are detached by the stripping element 25 , so that they continue to run on the flat side 31 of the cutting device 5 . The wiping gap 28 between the wiping edge 28 and the lateral surface 10 of the cylinder roller 8 is selected along this uniform and smaller than the strand thickness so that all strands can be effectively stripped NEN.

If initially, during the start-up process, the strands 2 have teardrop-shaped heads which may be glued to one another and these heads arrive at the cylinder roller 8 , they can lead to a slight elastic bending of the same. The cylinder roller 8 may start on the scraper strip. In such a case, the stripping element 25 is displaced elastically by the roller 8 on the web 34 . The stripping element 25 can also be elastically bent and / or compressed starting from the web 34 over its entire height. From the roller 8 or the plastic strands immediately outgoing load forces are only weakened transferred to the carrier 23 . A displacement of the carrier 23 for the counter knife bar 58 and a collision of the cutting tools 58 , 59 can be largely avoided.

The crescent-like widening gap 50 between the roller 8 and the concave sides 30, 49 facing it ensures that the roller 8 touches only the squeegee and not the carrier 23 when bent.

When the roller 8 returns to its initial state, relieving the squeegee, the stripping element 25 automatically returns to its original position, in which a uniform stripping gap 28 is formed. The web 34 acts here as a flexurally elastic joint or spring joint. This elastic joint also makes it possible to set the width of the cutting gap very small, for example below 0.04 mm.

In Fig. 3, a modified embodiment of the invention is illustrated. Insofar as there are similarities in construction and / or function with the granulating device described above, reference is made to the above description using the same reference signs.

The granulating device of FIG. 3 differs from the preceding by the stripping 25th It is designed here as a squeegee that det a lip bil. This extends away from the fastening part 24 in the direction of the cylinder roller 8 and at an acute angle to the circumference thereof. The lip is narrow, approximately as thick as the web 34 according to FIGS. 1 and 2. In the immediate vicinity of the wiping edge, the lip tapers and forms the wiping edge 27 there .

The root 71 (connection between the fastening part 24 and the lip) forms the elastically flexible joint corresponding to the web 34 in the embodiment according to FIGS. 1 and 2. The lip can thus be elastically deformed by the roller 8 in the event of a load and resiliently springs after relief who returned to the starting position. Favorable elastic properties are obtained if the length of the lip is at least as large as its thickness, preferably much greater than this.

A granulating device 1 for granulating plastic strands 2 has a cutting device 5 provided for this purpose with a rotating cutting tool 59 and a fixed counter knife 58 and a feed device 3 . This has at least one revolving cylinder roller 8 for feeding the plastic strands 2 to the cutting device 5 . The cylinder roller 8 is a squeegee 25 assigned to detach strands 2 adhering to the cylinder roller 8 . The squeegee 25 is resiliently connected to the carrier 23 . The carrier 23 supports both the counter knife 58 and the squeegee 25 . The resilient connection between rule's carrier 23 and squeegee 25 enables a limited evasive movement of the squeegee 25 without misalignment or displacement of the counter knife. This will surely prevent the counter knife from being pressed into the rotating knife roller by the scraper bar.

Claims (15)

1. granulating device ( 1 ) for granulating material strands, in particular plastic strands,
with a cutting device ( 5 ), which has a cutting device ( 59 ) with at least one moving cutting element ( 62 ) and a counter knife ( 58 ) for separating granulate from the supplied material strand, and has a fixed knife on a support ( 23 ) at a distance from it Cutting tool ( 59 ) is arranged,
with a device for supplying the strand provided for material to be granulated to the cutting means (5) Zuführein (3), one of the at least one circulating in the operating cylinder (8), and
with a scraper element ( 25 ) assigned to the roller, which is connected in a stationary manner to the support ( 23 ) for the counter knife ( 58 ),
wherein the stripping element ( 25 ) is flexibly connected to the carrier ( 23 ). 2. Granulating device according to claim 1, characterized ge indicates that it has more to granulate at the same time rer material strands is set up. 3. Granulating device according to claim 1, characterized in that the cutting tool ( 59 ) is designed as a rotating cutting rotor with a substantially cylindrical tool body ( 61 ) and a plurality of cutting elements arranged on its outer circumference ( 62 ). 4. Granulating device according to one of claims 1 to 3, characterized in that the minimum gap distance between a cutting edge ( 60 ) of the fixed counter knife ( 58 ) and a cutting edge ( 66 ) of the cutting tool ( 59 ) is less than 0.1 mm. 5. Granulating device according to claim 4, characterized ge indicates that means for adjusting the gap distance are provided. 6. Granulating device according to claim 1, characterized in that the rotating roller ( 8 ) is a cylinder roller with a substantially smooth outer surface. 7. Granulating device according to claim 1 or 6, characterized in that the feed device ( 3 ) has a further roller ( 9 ) which is arranged axially parallel to the rotating roller ( 8 ), the strand of material between the two rollers ( 8th , 9 ) is promoted. 8. Granulating device according to claim 7, characterized in that at least one of the rollers ( 8 , 9 ) is driven in rotation, preferably both rollers are driven in opposite directions rotating. 9. Granulating device according to claim 1, characterized in that the stripping element ( 25 ) with the rotating roller ( 8 ) defines a uniform stripping gap ( 28 ) over its entire length. 10. Granulating device according to claim 1 or 9, characterized in that a squeegee ( 26 ) is provided as the stripping element ( 25 ), which is connected to a fastening part ( 24 ) for attachment to the carrier ( 23 ), and that the squeegee ( 26 ) has a wiping edge ( 27 ) aligned parallel to the rotating roller ( 8 ). 11. Granulating device according to claim 10, characterized ge indicates that the squeegee is resilient is formed and held. In that the stripper (4) to 12. granulator according to claim 11, characterized a hinge (34, 71), which holds the wiping element (25) and the sen elastic bending displacement of the Abstreifele member (25) and that the Joint ( 34 , 71 ) on the transition between the fastening part ( 24 ) and the Abstreifmit tel ( 25 ) of the stripping device ( 4 ) is provided. 13. Granulating device according to claim 12, characterized in that a weakened area ( 34 ) is provided as a joint in the stripping element ( 25 ). 14. Pelletizer according to claim 13, characterized in that the stripping element ( 25 ) has a substantially Liche triangular cross-section and that from the scraper edge ( 27 ) by a preferably concave surface ( 30 ) in the direction of the roller ( 8 ), and a generally flat side (31) is defined. 15. Granulating device according to claim 12, characterized in that the stripping element ( 25 ) in the form of a protruding from the fastening part ( 24 ) of the stripping device ( 4 ) in the direction of the roller ( 8 ) and at an acute angle to the circumference of the lip is trained.