Stranggranulierer

Abstract

The present invention relates to a strand granulator for granulating strands such as plastic strands into pellets, comprising a cutting unit having a rotationally driven cutting rotor and a counter-blade cooperating therewith, as well as a feed device having a pair of counter-rotating feed rollers for feeding the strands to the cutting unit, wherein at least one of the feed rollers is movably mounted transversely to its longitudinal axis by means of a movable roller suspension, and a gap between the feed rollers is variable, wherein an actuating actuator is provided which is articulated to the movable roller suspension for adjusting the gap and / or the pressure force between the feed rollers, wherein the actuating actuator has, on the one hand, a pivot point on the movable roller suspension and, on the other hand, a pivot point on a cutting unit support on which the cutting rotor is mounted.so that the movable roller suspension and the cutting unit carrier are directly connected by the actuator.

Description

[0001] The present invention relates to a strand granulator for granulating strands such as plastic strands into pellets, comprising a cutting unit having a rotationally drivable cutting rotor and a counter knife cooperating therewith, and a feed device having a pair of counter-rotating feed rollers for feeding the strands to the cutting unit, wherein at least one of the feed rollers is movably mounted transversely to its longitudinal axis by means of a movable roller suspension and thereby a gap between the feed rollers can be changed, wherein an actuating actuator articulated on the movable roller suspension is provided for adjusting the gap and / or the pressing force between the feed rollers.

[0002] Such strand granulators are typically used to granulate plastic strands produced by a caster and an associated die plate and fed to the strand granulator via a conveyor chute, see, for example, DE 31 45 613 A1, EP 0 079 609 A1, or US 4,528,157 B1. Such strand granulators, which also have the capability of dry cutting, can also be used to granulate other materials, such as food products in the form of pasta strands or pharmaceutically active material strands into tablets. By feeding several strands parallel to one another to the cutting unit, high throughput rates can be achieved.

[0003] The cutting unit comprises a rotary-driven cutting rotor, which may have rib- or strip-shaped cutting projections on its peripheral surface that interact with a stationary counter-blade. The counter-blade may essentially consist of a blade bar positioned adjacent to the circumference of the cutting rotor, so that the passing, strip-shaped projections of the cutting rotor can cut off the plastic strands at the counter-blade.

[0004] In order to be able to feed the strands in a controlled orientation and speed to the working area of ​​the cutting unit, i.e. the area between the counter knife and the cutting rotor, a feeding device is installed upstream of the cutting unit, which has counter-rotating feed rollers, between which the strands are conveyed to be fed onto the cutting unit.

[0005] Such cutting units with a pair of upstream feed or intake rollers are known, for example, from the documents DE 101 06 677 C1, DE 34 26 316 A1, DE 31 45 613 A1 and DE 26 00 078 A1.

[0006] These feed or intake rollers are usually designed in such a way that they can form a feed gap with a variable gap size in order to adapt to different material strands or even to irregularities in the material strands. For example, the feed gap can be variable from 0 to 5 mm and can also increase significantly for a short time, for example to up to 20 mm. In order to make the gap between the feed rollers variable in this way, at least one of the feed rollers can be displaceably or movably suspended transversely to its longitudinal axis by means of a movable roller suspension. A control actuator is usually assigned to the movable suspension in order to be able to adjust the gap between the feed rollers and / or the pressing force between the feed rollers. Such a control actuator can, for example, be a pneumatic cylinder in order to elastically and movably pretension or release the movably suspended feed roller.The gap can be adjusted as desired. Elastic preload can also be achieved using a hydraulic cylinder with a connected pressure accumulator, or even a mechanical spring device, such as a spring strut.

[0007] The movable suspension of the feed roller can also be advantageously used to move the feed roller further away for maintenance or repair purposes, allowing access to the cutting unit, which is usually blocked by the feed rollers in front of it. Since the feed rollers must guide the often unstable strands precisely into the cutting unit gap between the cutting rotor and the counter blade, the feed rollers are often located directly in front of the cutting unit or in close proximity to it, obscuring the working area of ​​the cutting unit, including the counter blade and cutting unit rotor.

[0008] In order to move at least one of the feed rollers for maintenance or repair, it is practical if the feed roller or both feed rollers are mounted on a protective hood. In the operating position, this hood covers the feed rollers and, if necessary, part of the cutting unit. This hood can be pivoted into a maintenance position, where the hood exposes the feed device and the cutting unit. If the feed roller is mounted on the hood, it is automatically moved along when the lid or hood is opened and pivoted away from the cutting unit.

[0009] In order to achieve the previously described desired variability of the gap size in the closed operating position, the actuator mentioned can act between the cover hood and the feed roller, whereby the movable roller suspension allows corresponding movements between the feed roller and the cover hood.

[0010] However, these previous cover hood solutions are disadvantageous in several respects. Firstly, the cover hood or the cutting chamber flap must be sufficiently robust to absorb the pressure forces from the actuator, especially if the actuator is supported on a ceiling surface of the cover hood rather than on one of the side flanks. At the same time, the cover hood must also be sufficiently securely locked to the lower housing or machine frame of the strand pelletizer in the closed operating position, or held there to do so, in order to be able to transmit the operating forces occurring on the feed rollers and ensure the flow of force. However, such sufficiently robust cover hoods are difficult to handle, or additional opening aids such as relief springs are necessary to allow comfortable operation.

[0011] Above all, such existing covers are relatively bulky and require sufficient space not only to reliably support the actuator mentioned above, but also to accommodate any handling aids such as relief springs, so the cutting head of the strand pelletizer is usually relatively high. Due to the relatively large size of the cover, it also forms a relatively large resonance chamber, which is detrimental to the desired sound insulation.

[0012] Based on this, the present invention is based on the object of creating an improved strand pelletizer of the aforementioned type that avoids the disadvantages of the prior art and advantageously develops them further. In particular, a compact feed device with counter-rotating feed rollers is to be created, which allows a variable gap between the feed rollers during operation and allows easy access to the cutting unit for maintenance purposes without the need for a heavy, bulky cover.

[0013] According to the invention, the stated object is achieved by a strand pelletizer according to claim 1. Preferred embodiments of the invention are the subject of the dependent claims.

[0014] It is therefore proposed that the actuating actuator for adjusting the contact pressure or the gap between the feed rollers is no longer supported on the cover hood, but rather that it is linked to the cutting unit carrier, which also supports the cutting rotor, so that the cover hood no longer has to absorb the actuating forces of the actuating actuator or the reaction forces of the feed rollers. According to the invention, it is proposed that the actuating actuator has, on the one hand, a linkage point on the movable roller suspension and, on the other hand, a linkage point on a cutting unit carrier on which the cutting rotor is mounted, so that the movable roller suspension is directly connected to the cutting unit carrier by the actuating actuator. By directly linking the actuating actuator to the cutting unit carrier, a direct flow of force into the stable cutting unit carrier can be achieved without the operating forces orPre-tensioning forces of the feed rollers would have to be redirected via a cover hood, so that a light and also significantly smaller cover hood design is possible.

[0015] To enable easy and sufficiently long movement of the at least one feed roller for maintenance purposes or, for example, for repairs to the cutting unit, an advantageous development of the invention can provide a detachable coupling for uncoupling the actuating actuator. Said coupling preferably uncouples the actuating actuator from the movable roller suspension, so that the actuating actuator does not have to be moved when the movable roller suspension is moved to move the feed roller into the maintenance position. If necessary, the coupling can also uncouple the actuating actuator from the cutting unit support.

[0016] The aforementioned detachable coupling can be designed as a manually detachable quick-release coupling, allowing tool-free uncoupling of the actuator. For example, such a quick-release coupling can have a detachable locking pin with a manually detachable locking device, which, when locked, attaches the actuator to the roller suspension or another linkage element in an articulated manner.

[0017] If necessary, a non-manual operation of the clutch may also be considered in order to prevent unintentional or unauthorized release of the clutch.

[0018] In a further development of the invention, the roller suspension can have a rocker for pivotally mounting the adjustable feed roller, wherein said rocker can be pivotally mounted about a pivot axis parallel to the longitudinal axis of the feed roller in order to be able to move the feed roller mounted on the rocker away from the other feed roller and / or from the cutting unit or back into the operating position by pivoting the rocker and to carry out the compensating movements mentioned above in order to vary the gap size in the operating position.

[0019] The pivot axis of the rocker arm can preferably be arranged on a side of the cutting unit facing away from the strand inlet or the feed rollers, so that, for example, the cutting rotor of the cutting unit is located between the rocker arm axis and the feed roller mounted on it, possibly with a transverse offset. This gives the rocker arm a relatively high lever arm, so that, on the one hand, adjustment movements during operation relative to the other feed roller follow a trajectory that is not too curved, and, when moving into the maintenance position, a trajectory that favorably encompasses the cutting unit can be achieved.

[0020] Advantageously, the swing axis can be positioned such that a movement of the feed roller mounted thereon out of the operating position includes both a component that leads away from the other feed roller and a component that leads away from the cutting rotor.

[0021] The cutting device carrier mentioned can form a housing of the cutting head or the strand pelletizer, or can also form a different machine support frame which can be enclosed by the housing.

[0022] Independently of this, the said cutting unit carrier can have two carrier legs which extend approximately upright and can be arranged at opposite end sections of the cutting unit rotor in order to be able to rotatably mount the cutting rotor at opposite end sections on the carrier legs of the cutting unit carrier, for example by means of roller bearings or plain bearings.

[0023] The counter blade, with which the cutting rotor interacts, can also be mounted on the two support legs, so that the support legs of the cutting unit carrier can hold the cutting unit between them, for example, can guide it past the cutting unit to the right and left.

[0024] If the cutting device carrier has such carrier legs that accommodate the cutting device between them, the aforementioned actuator can be arranged on an outer side of the aforementioned carrier legs and can extend with its effective axis at least approximately parallel to the aforementioned outer side.

[0025] In particular, the actuating actuator can be arranged adjacent to the outer side of a support leg and can be hinged to this support leg in order to introduce the actuating forces directly into the support leg.

[0026] Preferably, two actuators can be provided, which can be provided on the right and left on the outer sides of the said support legs, in order to be able to pretension or move the movable feed roller on both sides and without tilting in the desired manner.

[0027] Advantageously, a pressure cylinder in the form of a tandem cylinder can be provided as the actuator in order to be able to apply sufficient actuating forces in a compact design. Advantageously, one such tandem cylinder can be provided on each side.

[0028] The at least one actuator can be articulated, in particular, to an end section of the aforementioned rocker arm, preferably by means of the aforementioned releasable coupling means, which end section is opposite the rocker arm axis. This allows the movable feed roller to be held stably in the desired working or operating position, and the lever on the rocker arm can be utilized.

[0029] In particular, the pivot point of the actuator on the roller suspension can be positioned in the immediate vicinity of the movable feed roller in order to achieve the most direct possible force flow into the actuator in the swing arm.

[0030] If the two feed rollers define an at least approximately horizontal feed gap for the strands, the actuator can extend upright or have an approximately upright line of action. Irrespective of this, a force line of action of the actuator can be arranged approximately perpendicular or transverse to a virtual connecting line connecting the rocker arm axis to the pivot point of the actuator on the rocker arm.

[0031] The feed device and / or the cutting unit can advantageously be enclosed by a cover hood that can span an upper side of the feed device and / or the cutting unit. Said cover hood can be pivotally mounted on the machine frame and / or a lower housing half, preferably about a horizontal hood pivot axis that can extend parallel to the longitudinal axis of the movable feed roller. For example, the hood pivot axis can coincide with the pivot axis of the aforementioned rocker arm of the roller suspension or be positioned in close proximity to it and extend at least approximately parallel thereto.

[0032] Said cover can form a sound-damping hood and enclose the feed device and / or the cutting unit on five sides. Preferably, said cover can be connected to a lower housing part on at least three sides without a gap, although depending on the design, a gap can also remain between the lower housing part and the machine.

[0033] The invention is explained in more detail below using a preferred embodiment and the accompanying drawings. In the drawings: Fig. 1: a perspective side / front view of the cutting head of a strand pelletizer according to an advantageous embodiment of the invention, wherein the two feed rollers of the feed device are shown in their operating position in which the actuators are coupled to the roller suspension, Fig. 2: a partial perspective view of the actuator for adjusting the gap and / or the pressure forces between the feed rollers, wherein the actuator is shown in its position on the outside of the cutting unit carrier and is uncoupled from the roller suspension to allow the feed roller to be moved away into a maintenance position, and Fig. 3: a sectional view of the cutting head of the strand pelletizer from the previous figures, illustrating the position of the feed rollers relative to the cutting unit in the operating position and the low overall height of the cutting head made possible by the roller suspension.

[0034] As the figures show, the strand granulator 1 comprises a cutting unit 2 which has a rotationally driven cutting rotor 3 to which a counter knife 4 is assigned, so that strands entering the cutting unit 2, such as thermoplastic plastic strands, can be sheared off by the cutting knife 2 on the counter rotor 4.

[0035] In a manner known per se, the cutting rotor 3 can have circumferential cutting projections 5, which can be strip-shaped and extend essentially over the entire length of the cutting rotor 3. The cutting projections 5 can be arranged essentially parallel to the longitudinal roller axis of the cutting rotor 3, but can also extend at an angle or in a slightly helical manner along the cylindrical envelope surface of the cutting rotor 3.

[0036] The said counter knife 4 is attached to the said envelope surface of the cutting rotor 3 and can be strip-shaped or form a web-shaped blade, past which the cutting knife 2 sweeps with its cutting projections 5, cf. Fig. 3.

[0037] The cutting unit 2 is mounted on a cutting unit support 6, which may have two upright support legs 7 and 8, between which the cutting unit 2 is arranged. The cutting rotor 3 can be mounted on the support legs 7, 8 so as to be rotatable about its longitudinal roller axis, for example by means of roller or plain bearings, by which the cutting rotor 3 is attached or mounted to the support legs 7, 8. The aforementioned counter knife 4 can be fixedly mounted, for example, also mounted on the aforementioned support legs 7, 8.

[0038] In order to feed the strands 9 to the cutting unit 2 at a controlled speed and in a controlled direction, a feeding device 10 is arranged upstream of the cutting unit 2, which comprises two counter-rotating feed rollers 11, 12, which are advantageously driven in rotation, for example by an electric motor.

[0039] The cutting rotor 3 of the cutting unit 2 can also be driven in rotation by an electric motor, wherein the cutting unit 2 and the feed device 10 can have separate rotary drives, but alternatively can also be coupled to one another, so that the cutting rotor 3 and the feed rollers 11, 12 are driven by a rotary drive if necessary.

[0040] Of the feed rollers 11, 12 mentioned, one feed roller 12 can have a smooth circumferential contour and the other feed roller 11 can have a relief-like circumferential contour with depressions and elevations. As the Fig. 1 and Fig. 2, for example, the upper feed roller 12 can have strip-shaped circumferential projections which extend parallel to the longitudinal axis of the roller, but can also be slightly inclined thereto or can extend helically over the length of the feed roller 11, cf. Fig. 1 and Fig. 2.

[0041] In order to be able to vary the gap between the two feed rollers 11, 12 during granulation, for example, within a range of 0-5 mm or, for short periods, significantly more, for example, up to 20 mm, one of the two feed rollers, preferably the upper feed roller 11, can be mounted so that it can move transversely to its longitudinal axis. Such transverse mobility can compensate for irregularities in the plastic strands, but in particular, it can also process strands of different thicknesses.

[0042] The transverse mobility of the movable feed roller 11 is oriented such that the said feed roller 11 can move away from the other feed roller 12 and move towards it, preferably at least approximately perpendicular to the envelope contour of the other feed roller 12.

[0043] To enable transverse mobility of the feed roller 11, a movable roller suspension 13 is provided, which may comprise a pivotally mounted rocker arm 14 on which the transversely movable feed roller 11 is rotatably mounted. Said rocker arm 14 may be pivotally mounted about a rocker pivoting shaft 15, which may extend at least approximately parallel to the longitudinal axis of the feed roller 11 and / or parallel to the longitudinal axis of the cutting rotor 3.

[0044] As the figures show, the said swing arm pivot axis 15 can be arranged on a side of the cutting unit 2 which is opposite or facing away from the inlet side or the side on which the feed device 10 is arranged. Fig. 1 and Fig. 3, the swing arm pivot axis 15 can be arranged such that the cutting rotor 3 is arranged between the swing arm pivot axis 15 and the movable feed roller 11, wherein the cutting rotor can have a transverse offset with respect to a virtual connecting line between the swing arm pivot axis 15 and the longitudinal axis of the feed roller 11, cf. Fig. 3.

[0045] In particular, the said rocker 14 can be arranged on an end section of the cutting unit carrier 6 which is opposite the inlet-side end of the cutting unit carrier 6 or the inlet of the cutting head, cf. Fig. 1 and Fig. 3.

[0046] The aforementioned rocker arm 14 can have two rocker arms between which the feed roller 11 is received or arranged, wherein the aforementioned rocker arms can be rigidly connected to one another by the rocker pivot axis 15. However, the rocker arms could also be formed separately and mounted separately on the rocker pivot axis 15.

[0047] In order to adjust the gap between the two feed rollers 11, 12 and / or to variably adjust the pressure force between the two feed rollers 11, 12, a control actuator 16 is assigned to the roller hanger 13. This actuator can be designed, for example, in the form of a pressure medium actuator, in particular a pneumatic cylinder. To enable torsion-free or tilt-free actuation, two control actuators 16 can be provided, which can be arranged on opposite end sections or sides of the feed device 10.

[0048] Such a pressure medium actuator, especially a pneumatic cylinder, can advantageously be designed as a tandem cylinder in order to provide sufficiently high actuating forces while maintaining a compact design. Such a tandem cylinder can provide correspondingly higher forces thanks to an additional pressure chamber without requiring an oversized design.

[0049] In particular, the two actuators 16 can engage the two mentioned rocker arms of the rocker 14 and extend to the right and left on the outside of the support arms 7, 8 of the cutting unit support 6.

[0050] The actuators 16 are each pivoted on the one hand to the aforementioned rocker arm 14 and on the other hand to the cutting unit carrier 6, in particular one of the carrier legs 7, 8. Due to the direct pivot points 17, 18 on the roller suspension 13, in particular the rocker arm 14 on the one hand, and on the cutting unit carrier 6 on the other hand, the roller suspension 13 and the cutting unit carrier 6 are directly connected to one another by the actuators 16. This achieves a direct force flow, which transmits the operating or reaction forces of the feed device 10 acting on the rocker arm 14 directly into the cutting unit carrier 6 via the actuators 16, without the force flow having to take a detour via a cover or other attachments.

[0051] In order to remove the feed roller 11 for maintenance purposes and to release the cutting unit 2, which is normally blocked by the feed device 10, the actuators 16 can advantageously be uncoupled from the roller suspension 13. A detachable coupling 19 can be assigned to the pivot points 17 of the actuators 16 on the rocker arm 14.

[0052] Irrespective of this, the said coupling 19 can advantageously be designed as a quick coupling, which can preferably be operated manually or without tools in order to allow easy uncoupling.

[0053] In order to be able to easily pivot the rocker 14 with the relatively heavy feed roller 11 mounted thereon upwards into a maintenance position, the rocker 14 can be assigned a further actuating actuator 20 which is activated for the movement into the maintenance position and can be inactive in the operating position, wherein this additional actuator 20 can also be articulated on the one hand to the cutting unit carrier 6, in particular its carrier leg 7, and on the other hand acts on the rocker 14, cf. Fig. 1. The actuator 20 can, for example, be a relief spring to relieve the weight of the pivoting unit consisting of the rocker arm 14 and the feed roller 11. However, to enable motorized movement into the maintenance position, the actuator 20 can also be a hydraulic or pneumatic cylinder or, for example, comprise a spindle motor.

[0054] As in particular Fig.As shown in Figure 3, the cutting unit 2 and the feed device 10 can be covered during operation by a cover hood 21, which can span the top side of the cutting unit 2 and the feed device 10. Due to the described articulation of the actuators 16 not to the aforementioned cover hood 21, but rather to the support legs 7, 8 of the cutting unit support 6, the aforementioned cover hood 21 can be designed to be lightweight and compact, in particular spanning the cutting unit and / or feed rollers at only a small distance. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 31 45 613 A1 [0002, 0005] EP 0 079 609 A1

[0002] US 4,528,157 B1

[0002] DE 101 06 677 C1

[0005] DE 34 26 316 A1

[0005] DE 26 00 078 A1

[0005]

Claims

[1] Strand granulator for granulating strands such as plastic strands into pellets, with a cutting unit (2) which has a rotationally driven cutting rotor (3) and a counter knife (4) cooperating therewith, and with a feeding device (10) which has a pair of counter-rotating feed rollers (11, 12) for feeding the strands to the cutting unit (2), wherein at least one of the feed rollers (11, 12) is movably mounted transversely to its longitudinal axis by means of a movable roller suspension (13) and a gap between the feed rollers (11, 12) is variable, wherein an actuator (16) articulated on the movable roller suspension (13) is provided for adjusting the gap and / or the pressure force between the feed rollers (11, 12), characterized bythat the actuator (16) has, on the one hand, a pivot point (17) on the movable roller suspension (13) and, on the other hand, a pivot point (18) on a cutting unit carrier (6) on which the cutting rotor (3) is mounted, so that the movable roller suspension (13) and the cutting unit carrier (6) are directly connected by the actuator (16). [2] Strand pelletizer according to the preceding claim, wherein a releasable coupling (19) is provided for uncoupling the actuating actuator (16) for moving the movable feed roller (11) into a maintenance position. [3] Strand pelletizer according to the preceding claim, wherein the releasable coupling (19) is designed to uncouple the actuating actuator (19) from the movable roller suspension (13), wherein the coupling (19) is associated with the articulation point (17) of the actuating actuator (16) on the movable roller suspension (13) in order to separate said articulation point. [4] Strand pelletizer according to one of the two preceding claims, wherein the releasable coupling (19) is designed as a quick coupling that can be operated manually and without tools. [5] Strand pelletizer according to one of the preceding claims, wherein the actuator (16) is designed as a pressure medium cylinder, in particular a pneumatic cylinder, and is acted upon by a pressure source whose pressure level is adjustable. [6] Strand pelletizer according to the preceding claim, wherein the pressure center cylinder is designed as a tandem cylinder. [7] Strand granulator according to one of the preceding claims, wherein the cutting mechanism support (6) has two upright support legs (7, 8) between which the cutting mechanism (2) is arranged and on which the cutting rotor (3) is rotatably mounted, wherein said actuator (16) is articulated on one of said support legs (7). [8] Strand pelletizer according to the preceding claim, wherein the actuator (16) extends on an outer side of the support leg (7), in particular extends substantially parallel thereto. [9] Strand granulator according to one of the preceding claims, wherein the movable roller suspension (13) comprises a rocker (14) on which the movable feed roller (11) is rotatably mounted, wherein said rocker (14) is pivotally mounted about a rocker pivot axis (15) which extends at least approximately parallel to the longitudinal axis of said feed roller (11). [10] Strand granulator according to the preceding claim, wherein said rocker pivot axis (15) is arranged on a side of the cutting unit (2) facing away from the feeding device (10). [11] Strand granulator according to the preceding claim, wherein the cutting rotor (3) is arranged between said rocker pivot axis (15) and the movable feed roller (11), in particular with a transverse offset to a virtual connecting line between the rocker pivot axis (15) and the longitudinal axis of the feed roller (11). [12] Strand pelletizer according to one of the two preceding claims, wherein the actuator (16) is articulated on an end portion of the rocker (14) which is opposite the rocker pivot axis (15). [13] Strand granulator according to one of the preceding claims, wherein the cutting unit (2) and the feeding device (10) are covered on the top by a cover hood (21), wherein said cover hood (21) is pivotally mounted on the cutting unit carrier (6) about a pivot axis parallel to the longitudinal roller axis of the cutting rotor (3). [14] Strand pelletizer according to the preceding claim, wherein the cover hood (21) is decoupled from the supporting forces for supporting the feed device (10) and lies outside a force flow which diverts operating and / or reaction forces of the feed device (10) into the cutting device carrier (6). [15] Strand granulator according to one of the two preceding claims, wherein the covering hood (21) has a hood cover which has a clear distance from the feeding device (10) and / or from the cutting device (2) which is smaller than the diameter of the movable feeding roller (11) and / or than the diameter of the cutting rotor (3). [16] Strand pelletizer according to one of claims 13 to 15 in conjunction with one of claims 8 to 11, wherein the cover hood (21) is formed separately from the rocker arm (14) and is pivotable independently of the rocker arm (14).

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