Wire material granulator

Abstract

The invention relates to a wire granulator for granulating a wire, such as a plastic wire, into granules, comprising a cutting mechanism having a rotationally drivable cutting rotor and a counter-tool which interacts therewith, a cutting gap being formed between the cutting edge of the counter-tool and the rotor tooth tip of the cutting rotor. According to the invention, a cutting gap adjustment device with a cutting gap adjustment actuator is provided for adjusting the gap size of the cutting gap during operation of the cutting mechanism.

Description

Technical Field

[0001] The invention relates to a strand pelletizer for pelletizing strands, such as plastic strands, into pellets, comprising a cutting mechanism having a rotatably driven cutting rotor and a counter-knife interacting therewith, wherein a cutting gap is formed between the blade of the counter-knife and the rotor tooth tips of the cutting rotor, wherein the cutting rotor and / or the counter-knife are adjustably mounted so that the gap size of the cutting gap can be adjusted. Background Art

[0002] Such strand pelletizers are typically used to pelletize plastic strands produced by a continuous casting machine and associated nozzle plates and fed to the strand pelletizer via a conveyor trough (see, for example, DE 31 45 613 A1, EP 0 079 609 A1, or US 4,528,157 B1). However, strand pelletizers with dry cutting capabilities can also pelletize other materials, such as strands of food or pharmaceutically active materials in the form of pasta strands. By feeding multiple adjacent strands in parallel to the cutting mechanism, higher production rates can be achieved.

[0003] In this case, the cutting mechanism comprises a rotatably driven cutting rotor, which may have rib-like or strip-like cutting projections or rotor teeth on its circumferential surface, which interact with a fixed counter-knife. The counter-knife may essentially consist of blades positioned adjacent to the circumference of the cutting rotor, so that the passing strip-like projections or rotor teeth of the cutting rotor can sever the plastic strand at the counter-knife.

[0004] In order to be able to supply the wire material to the working area of ​​the cutting mechanism (i.e. to the area between the counter knife and the cutting rotor) in a controlled direction and speed, a supply device is connected upstream of the cutting mechanism, which supply device has counter-rotating supply rollers, between which the wire material is conveyed to be fed to the cutting mechanism.

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

[0006] To achieve high-quality cutting of the plastic strands and an efficient cutting process, the cutting gap between the rotor teeth of the cutting rotor and the blade of the counter-knife must be set very small and precisely. The cutting gap should also be as uniform as possible over the length of the cutting rotor and counter-knife. If the cutting gap is too large, the strands, which are often viscoplastic or sticky, will not be sheared cleanly, and a clean cut edge cannot be achieved. Furthermore, since the strand material can be sheared between the rotor tooth tips and the blade of the counter-knife, the load on the cutting mechanism increases significantly, which can lead to increased bearing loads, vibrations, and increased power requirements.

[0007] If, on the other hand, the cutting gap is set too small, there is a risk of direct mechanical contact between the rotor tooth tip and the counter-tool, for example when the initially very small cutting gap is further reduced due to thermal loads and the resulting deformations.

[0008] As mentioned above, since the cutting gap should be very small but not too small, setting the cutting gap of a strand pelletizer is very difficult and cannot be done perfectly even with extensive experience, because it is difficult to estimate the influences on the cutting gap that occur during operation (for example, thermal expansion processes and different strand materials), especially difficult to estimate during the start-up of the strand pelletizer.

[0009] The cutting gap on a strand pelletizer is usually measured manually when the machine is stationary using a so-called sight glass with very fine gradations (e.g., hundredths of a millimeter thickness), so that the cutting gap between the cutting rotor and the counter-knife can be set precisely within a range of 1 / 100 of a millimeter.

[0010] However, the dynamics of the startup process make it difficult to correctly set the cutting gap. Due to the influence of hot wire material and / or the temperature of the process water used, the cutting gap can change during machine startup, negatively impacting the cutting process. Depending on the process, for example, when using cold or hot process water, the gap can become larger or smaller, a dynamic process. This variation persists until a steady state is reached. In extreme cases, the cutting rotor can strike the counter-tool, causing damage.

[0011] If the cutting gap increases during the startup process, the cutting gap may not be set optimally, because it may not be possible to set the cutting gap small enough at the beginning of the startup process to reliably prevent the cutting rotor from hitting the counter knife on the one hand and to take into account the gap increase that occurs during the startup process on the other hand.

[0012] To understand these dynamic changes, attempts are made to measure the cutting gap over short time intervals in order to identify how the cutting gap changes under given process conditions. However, this is both time-consuming and relatively inaccurate, as the machine cools down quickly after being shut down or the temperature changes again, necessitating rapid measurements. Indeed, the gap changes again as soon as the machine stops and the cutting head is opened. Summary of the Invention

[0013] The object of the present invention is therefore to provide an improved strand pelletizer of the aforementioned type, which avoids the disadvantages of the prior art and further develops it in an advantageous manner. In particular, an improved cutting gap setting should be achieved, so that dynamic changes due to, for example, temperature changes can be better taken into account.

[0014] Therefore, it is proposed to appropriately set or readjust the cutting gap during ongoing machine operation, and to do so, to move the cutting rotor and / or the counter-knife transversely to the longitudinal axis of the cutting rotor. According to the present invention, a cutting gap adjustment device having a cutting gap adjustment actuator is provided for adjusting the gap size of the cutting gap during operation of the cutting mechanism. This online adjustment of the cutting rotor and, if applicable, the counter-knife makes it possible to react to changes in the gap size, for example, during startup, and to optimally adjust the gap size for the operation of the cutting mechanism even under changing conditions.

[0015] Preferably, the cutting rotor is mobile, while the counter-tool is held in a fixed position. This allows for a more stable design of the cutting mechanism and avoids undesirable deformation of the counter-tool, which is typically less rigid. Furthermore, the scraper gap, once set, relative to the supply roller of the feed device upstream of the cutting mechanism can be kept constant and does not need to be readjusted when adjusting or readjusting the cutting gap between the cutting rotor and the counter-tool.

[0016] In an improved example of the invention, the cutting gap adjustment device can have a feed device for feeding the cutting rotor toward and away from the counter tool, wherein a fixed-position holder can be provided for the counter tool, which can fixedly mount the counter tool even when the cutting rotor is adjusted.

[0017] The feed device can translate the cutting rotor transversely to its rotor axis towards and away from the counter-knife in order to set the gap size of the cutting gap.

[0018] In a further development of the invention, the feed device can be designed to move the two ends of the cutting rotor synchronously with one another, so that the cutting rotor moves completely or only in translation without a rotational component, in particular completely perpendicularly to its rotor axis. As a result, the gap size increases or decreases uniformly over the length of the cutting gap.

[0019] However, in another refinement of the invention, the feed device can also be designed to selectively move the cutting rotor only translationally in the manner described, i.e., with a translational displacement occurring synchronously at both ends, or to superimpose a rotational movement on the translational displacement, i.e., a rotational movement about a rotational axis substantially perpendicular to the translational displacement and the rotor axis, so that the two ends of the cutting rotor are moved toward or away from the counter-tool to different degrees. Thus, for example, the cutting gap at the right end portion can be reduced or increased to a greater extent than at the opposite left edge portion of the cutting rotor. This asymmetric feed allows for a corresponding thermal expansion to react to possible asymmetric wear or asymmetric temperature loads, in particular to enable the cutting gap to be set to the same size at the right and left edge portions of the cutting rotor despite such asymmetric influences.

[0020] In an advantageous refinement of the invention, the adjustment actuator of the cutting gap adjustment device can have an electric stepping motor which allows a precise adjustment of the cutting gap and which can also control the adjustment easily and precisely.

[0021] In order to allow a fine conversion of the drive movement of the adjusting actuator into the desired displacement of the cutting rotor or a corresponding cutting mechanism element, the cutting gap adjustment device can have one or more worm gear stages, which are particularly capable of converting the rotational movement of the adjusting actuator into a translational displacement of the cutting rotor with sufficient precision to enable the cutting gap to be set precisely within a range of 1 / 100 mm. In particular, such a worm gear stage can operate without backlash.

[0022] For further fine adjustment or to achieve very fine adjustment while stably mounting the cutting rotor, the cutting gap adjustment device can include a cutting rotor bearing having an eccentrically designed bearing shell. The cutting rotor bearing supports the cutting rotor itself so that it can rotate about its longitudinal axis or rotor axis, wherein the bearing shell is designed eccentrically and can rotate about the rotor axis, so that a rotation of the bearing shell about the rotor axis results in a translational displacement of the rotor axis toward or away from the counter-tool.

[0023] Preferably, the cutting rotor is supported at its opposite ends by two such cutting rotor bearings having bearing shells of eccentric design, so that a translational displacement can be provided at both rotor ends by a corresponding rotation of the eccentric bearing shells.

[0024] Advantageously, the adjustment actuator can be designed to adjust the two eccentric bearing shells on opposite ends of the cutting rotor synchronously with each other in order to achieve an equal increase or decrease in the gap size at both ends.

[0025] In particular, the eccentric bearing shells of the cutting rotor bearings can be rotated by means of the aforementioned worm gear stage, wherein advantageously each rotatable bearing shell can have an external toothing that meshes with the toothing of the adjusting actuator worm, so that a rotational movement of the worm shaft can cause the bearing shells to rotate about the rotor axis of the cutting rotor. Due to the eccentricity, the rotational movement of the bearing shells is converted into a displacement of the cutting rotor.

[0026] To facilitate maintenance of the cutting mechanism, the eccentric bearing housing can be designed as a half-shell, which essentially surrounds or fits snugly into the bearing housing with which it interacts, essentially only over an angular range of approximately 180°. This is sufficient to move the cutting rotor by rotating the eccentric bearing housing, while on the other hand the cutting rotor can be removed from the half-shell or half-bearing housing, thus simplifying maintenance.

[0027] In particular, the eccentric half-bearing shell can have a zero position in which the bearing shell is open toward the top, so that the cutting rotor is situated, as it were, in the eccentric bearing shell and can be removed upwards.

[0028] During operation of the cutting mechanism, the relative position of the cutting rotor and the counter-knife can advantageously be adjusted semi-automatically or fully automatically. For example, one or more feed steps useful for optimally setting the cutting gap can be displayed to the machine operator on a display device, such as a monitor, so that the machine operator can then initiate the corresponding feed under his control, for example by activating an input device, such as a touchscreen button on a touchscreen display, on which prompts can also be displayed. For example, such semi-automatic control operation can be provided during the startup process, so as to initiate a predetermined readjustment of the cutting gap, for example, near the end of the startup process or when a stable operating state is achieved.

[0029] However, in an advantageous refinement of the invention, the cutting gap can also be set automatically without intervention by the machine operator. To this end, a sensor system for detecting at least one machine operating and / or particle parameter related to the cutting gap, and a control device for controlling the adjustment actuator of the cutting gap adjustment device based on the signal from the sensor system can be provided.

[0030] The sensor system can advantageously detect machine operation and / or particle parameters during machine operation or when the cutting mechanism is running, and continuously or periodically provide signals for currently characterizing the machine operation and / or particle parameters during machine operation, so that the control device can readjust the cutting gap based on the current sensor system signal.

[0031] In particular, the control device may control the stepper motor if the machine operation and / or particle parameters detected by the sensor cause the stepper motor to be activated.

[0032] Sensors can, in principle, monitor various variables as machine operating parameters or pellet parameters and use them to set the cutting gap. For example, the sensor system can use one or more temperature sensors to sense one or more relevant machine or process temperatures, such as the water temperature in the feed and / or return of a strand pelletizer, and / or the melt temperature of the feed material and / or the pellet temperature of the pellets. The control device can then readjust the cutting gap based on the temperature.

[0033] Alternatively or additionally, the sensor system may also comprise, for example, one or more vibration sensors to detect vibrations on granulator components (eg, cutting mechanism) in order to initiate adjustments based on sensor signals that are indicative of the vibration intensity.

[0034] In particular, however, the sensor system can firstly detect the cutting gap itself in relation to the current gap size and provide a signal indicating the gap size and / or characterizing a change in the gap size.

[0035] In particular, in a modified embodiment of the present invention, the cutting gap between the cutting rotor and the counter-knife can be measured as an operating parameter of the strand pelletizer during operation (i.e., while the cutting rotor is running and / or while cutting strands), and a sensor system suitable for this purpose can be used. Advantageously, at least one sensor for determining the cutting gap during operation of the cutting mechanism is provided on the fixed counter-knife. By means of the at least one sensor operating during the cutting operation, changes in the cutting gap during operation, in particular also dynamic changes in the cutting gap during the startup process, can be detected or monitored. Knowledge of the dynamic characteristics of the cutting gap allows the gap size to be set to an optimal value, which, on the one hand, ensures high-quality cutting while, on the other hand, avoids the risk of the cutting rotor striking the counter-knife.

[0036] In a refinement of the invention, the at least one sensor is positioned in the immediate vicinity or close to the cutting edge of the counter-tool in order to be able to detect changes in the cutting gap as directly as possible.

[0037] In particular, the at least one sensor can be rigidly fastened to the counter-tool, so that the sensor follows or experiences changes in the distance of the counter-tool from the cutting rotor in the same way as the counter-tool.

[0038] In particular, the at least one sensor can be arranged at least partially embedded in the counter-cutter and, with respect to the direction of rotation of the cutting rotor, behind or downstream of the cutting edge of the counter-cutter and thus facing a rotor tooth passing the counter-cutter. Preferably, the at least one sensor can be located directly below the cutting edge of the counter-cutter, wherein "below" means that the cutting edge itself protrudes slightly above the sensor towards the cutting rotor, for example in the manner of an eave, and that a passing rotor tooth first passes over the cutting edge itself and then over the sensor.

[0039] The sensor can be arranged on the counter-tool, for example so that the sensor is directly opposite the rotor tooth when the rotation angle of the rotor tooth of the cutting rotor is less than 20°, less than 10° or less than 5° relative to the following cutting rotor position, in which the rotor tooth tip of the rotor tooth is exactly at the cutting edge of the counter-tool.

[0040] Advantageously, the at least one sensor can be designed to detect a passing rotor tooth tip of the cutting rotor, in particular to detect the distance thereto.

[0041] Advantageously, the at least one sensor is a contactless distance sensor. In particular, the sensor can be designed in the form of an eddy current sensor.

[0042] Such eddy current sensors can determine the distance to electrically conductive rotor tooth tips, which can be made, for example, of steel or other electrically conductive alloys. Advantageously, in such eddy current sensors, non-conductive media such as water or coolant, as well as materials such as thermoplastic strands, do not influence the measurement results.

[0043] In order to be able to detect the rotor tooth tips, which usually pass by very quickly, with sufficient accuracy, the at least one sensor can be operated with a relatively high sampling frequency, which in an improved example of the invention can be greater than 2 kHz, greater than 5 kHz, greater than 10 kHz, even greater than 20 kHz or greater than 50 kHz, or even greater than 100 kHz.

[0044] In an advantageous refinement of the invention, a plurality of sensors are distributed along the cutting gap so that the cutting gap can be measured in different parts of the cutting mechanism. This allows for precise detection of uneven dynamic variations in the cutting gap across the entire width, such as those that may experience greater variations in the center due to a greater feed volume than at the left and right edges of the cutting mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention will be explained in more detail below based on preferred exemplary embodiments and related drawings.

[0046] Figure 1A partially cutaway side perspective view of a strand pelletizer according to an advantageous embodiment of the invention is shown, in which its cutting mechanism comprising a cutting rotor and counter knives and its supply device comprising a pair of counter-rotating supply rollers upstream of the cutting mechanism can be seen.

[0047] Figure 2 A partial cross-sectional view of the cutting mechanism and the upstream supply roller is shown, showing a distance sensor disposed below the blade of the counter knife for detecting the size of the cutting gap.

[0048] Figure 3 Shown Figure 2 A partial enlarged cross-sectional view of a sensor embedded in a counter cutter in FIG, showing the position of the sensor in the counter cutter and relative to the rotor tooth tip cutting the rotor.

[0049] FIG. 4 shows a perspective view of a cutting rotor bearing with an eccentric bearing shell which can be adjusted by an adjusting actuator via a worm gear stage in order to be able to move the cutting rotor towards or away from the counter-knife. DETAILED DESCRIPTION

[0050] As shown in the figure, the strand pelletizer 1 includes a cutting mechanism 2, which has a rotatably driven cutting rotor 3, which is assigned a counter knife 4, so that the cutting rotor 3 can cut or shear strands such as thermoplastic plastic strands entering the cutting mechanism 2 at the counter knife 4.

[0051] In a manner known per se, the cutting rotor 3 can have circumferential cutting projections or rotor teeth 5, which can be designed in the form of strips and extend substantially over the entire length of the cutting rotor 3. In this case, the cutting projections or rotor teeth 5 can be arranged substantially parallel to the longitudinal roller axis of the cutting rotor 3, but can also extend at an angle to this longitudinal roller axis or extend slightly helically along the cylindrical envelope surface of the cutting rotor 3. See Figure 2 and 3 When viewed in cross section, the rotor teeth may be tapered overall and / or arranged obliquely relative to the radial direction so that the tooth tips are slightly inclined forward relative to the direction of rotation 7 of the cutting rotor 3 in order to be able to "bite" into the wire.

[0052] The counter cutter is arranged on the envelope surface of the cutting rotor 3 and can be designed as a strip or a plate. The counter-tool 4 can have a blade 8 which runs along the envelope surface of the cutting rotor 3, in particular parallel to the axis of rotation of the cutting rotor 3, and see Figure 2 , the blade may be undercut or "sharpened" at a slightly acute edge angle.

[0053] A cutting gap is defined between the cutting edge 8 of the counter-knife 4 and the tooth tip 6 of the rotor tooth 5 of the cutting rotor 3 , the gap size of which can be in the range of a few hundredths of a millimeter.

[0054] In order to feed the strand to be cut (e.g., thermoplastic strand or food strand) to the cutting mechanism 2 at a controlled speed and direction, a feeding device 10 is connected upstream of the cutting mechanism 2. The feeding device 10 comprises two counter-rotating feeding rollers 11, 12, so as to transport the strand between them and deliver it to the cutting mechanism 2. Figure 2 As shown, the counter knife 4 is located in the transport region of the supply rollers 11 , 12 and is arranged between said supply rollers 11 , 12 and the cutting rotor 3 .

[0055] As is known, see Figure 1 The strands to be granulated from the continuous casting machine can reach the supply device 2 via a conveying device such as a conveying trough 9 .

[0056] See also Figure 2 and 3 In order to be able to determine the gap size of the cutting gap between the blade 8 of the counter-knife 4 and the tooth tip 6 of the cutting rotor 3 even during operation of the cutting mechanism 2, the cutting mechanism 2 is assigned a sensor system having at least one sensor 13, which is arranged on the fixed counter-knife 4. Advantageously, a plurality of sensors 13 can be arranged distributed along the length of the cutting gap, so that the gap size can be determined in different parts of the cutting mechanism 2.

[0057] like Figure 2 and 3 As shown, the sensor 13 is advantageously mounted on the counter-knife 4 directly adjacent to the cutting edge 8, so that the sensor 13 follows the variations in the distance of the counter-knife 4 from the cutting rotor 3. In particular, the at least one sensor 13 is situated directly behind or downstream of the cutting edge 8 with respect to the direction of rotation 7 of the cutting rotor 3 and is positioned at the portion of the counter-knife 4 that each rotor tooth 5 reaches after passing the cutting edge 8.

[0058] like Figure 2 and 3 As shown, the sensor 13 can advantageously be arranged at least partially embedded in the counter-tool 4 , wherein the counter-tool 4 can, for example, have a hole (e.g., in the form of a blind hole) open toward the cutting rotor 3 , into which the sensor can be arranged to be embedded. If the sensor is equipped with a data cable, a through-hole or transverse hole can also be provided in the counter-tool for leading the data cable out. However, the sensor can also have a wireless data transmission module, such as a Bluetooth or radio interface.

[0059] The sensor head of the sensor 13 can be directed toward the rotor tooth 5 being passed, wherein see Figure 2 and 3 , the sensor head can be arranged to be exposed to the side of the counter cutter facing the cutting rotor 3 or flush therewith.

[0060] The sensor 13 is advantageously designed as a contactless distance sensor, in particular in the form of an eddy current sensor, which can detect the distance between the sensor head and the tooth tip 6 of the passing rotor tooth 5, and therefore the distance between the counter-tool 4 and the tooth tip 6 of the passing rotor tooth 5. The sensor head of the sensor 13 generates an eddy current field directed toward the rotor tooth 5, which is influenced by the ferromagnetic rotor tooth according to its distance from the sensor head, so that the sensor 13 can provide a sensor signal that is representative of the distance.

[0061] Advantageously, the sensor 13 operates with a sufficiently high sampling frequency, for example greater than 2 kHz or greater than 5 kHz or greater than 10 kHz, in order to be able to accurately detect very rapidly passing tooth tips 6 .

[0062] Advantageously, the gap size of the cutting gap measured online can be used to appropriately set the gap size by adjusting the position of the cutting rotor 3 and / or the counter-tool 4, which can also advantageously be carried out during operation of the cutting mechanism, but can also be carried out in a stopped state, wherein the feed device with an adjustment actuator can be controlled by the control device based on the signal from the sensor 13 in order to move the cutting rotor 3 closer to or further away from the counter-tool 4, wherein, if necessary, the counter-tool 4 can also be moved accordingly.

[0063] As shown in FIG4 , the cutting rotor 3 can be rotatably placed on a cutting mechanism or mounted on a machine frame at its opposite ends via two cutting rotor bearings 19 , wherein FIG4( a) shows only one rotor bearing 19 on one end of the cutting rotor 3 .

[0064] As shown in FIG4 , the cutting rotor bearing 19 comprises an eccentrically designed bearing shell 20, which is eccentrically designed relative to the rotor axis of the cutting rotor and is rotatable about a rotation axis parallel to the rotor rotation axis, so that due to the eccentric profile of the bearing shell 20, the cutting rotor 3 is translated toward or away from the counter-tool 4. More precisely, each cutting rotor bearing 19, when its eccentric bearing shell 20 is rotated, causes “its” end of the cutting rotor 3 to move toward or away from the counter-tool 4.

[0065] In this case, the eccentric bearing shell 20 can be rotatably mounted on the cutting mechanism frame or the machine frame.

[0066] As further shown in FIG. 4 , the eccentric bearing shell 20 can advantageously be rotated via a worm gear stage 21 , wherein such a worm gear stage 21 can be provided for each of the cutting rotor bearings 19 .

[0067] 4( b) and 4( c), the worm gear stage 21 may advantageously have an external toothing on the rotatable bearing housing 20 that meshes with the worm drive shaft, such that rotation of the worm drive shaft causes a corresponding rotation of the bearing housing 20. Referring to FIG4( b), the worm drive shaft may preferably extend parallel to a wall and / or an outer side of a cutting mechanism frame supporting the cutting mechanism 2, and / or extend transversely to the longitudinal axis of the cutting rotor.

[0068] The worm gear stage 21 at the opposite end of the cutting rotor 3 can be driven by a stepper motor 22 which rotatably drives the worm gear shaft, possibly via an intermediate gear stage.

[0069] The stepper motor 22 is controlled by a control device 17, which can be designed as an electronic control device, for example in the form of a control computer, which can process a control program or multiple control programs stored in a memory via a processor in order to set the gap size of the cutting gap according to relevant machine operation and / or particle parameters, or readjust it during operation.

[0070] As shown in Figure 4(c), the control device 17 is connected to a sensor system 18, which may include the cutting gap sensor 13 and / or other sensors so as to move the cutting rotor 3 towards or away from the counter tool 4 based on sensor signals used to characterize corresponding machine operating parameters and / or particle parameters.

Claims

1. A strand pelletizer for pelletizing strands, such as plastic strands, into pellets, the strand pelletizer comprising a cutting mechanism (2) comprising a rotatably driven cutting rotor (3) and a counter-knife (4) interacting with the cutting rotor, wherein: A cutting gap is formed between the blade (8) of the counter cutter (4) and the rotor tooth tip (6) of the cutting rotor (3), and is characterized in that a cutting gap adjustment device (14) having a cutting gap adjustment actuator (15) is provided, and the cutting gap adjustment device is used to adjust the gap size of the cutting gap during the operation of the cutting mechanism.

2. Strand granulator according to the preceding claim, wherein The cutting gap adjustment device (14) comprises a sensor system (18) for detecting at least one machine operation and / or particle parameter during operation of the cutting mechanism (2) and a control device (17) for controlling the cutting gap adjustment actuator (15) based on the machine operation and / or particle parameter detected by the sensor.

3. Strand granulator according to the preceding claim, wherein The control device (17) is designed to automatically drive the cutting gap adjustment actuator (15) during operation of the cutting mechanism (2) without requiring intervention by a machine operator.

4. A strand granulator according to any one of the preceding claims, wherein The cutting gap adjustment device has a feed device (16) for feeding the cutting rotor (3) toward and away from the counter-knife (4), wherein the counter-knife is fixedly mounted.

5. Strand granulator according to the preceding claim, wherein The feed device (16) has at least one cutting rotor bearing (19) which rotatably supports the cutting rotor (3) and is designed to be adjustable transversely to the longitudinal axis of the cutting rotor, wherein preferably at least two of the adjustable cutting rotor bearings (19) are arranged at opposite ends of the cutting rotor (3).

6. Strand granulator according to the preceding claim, wherein The at least one cutting rotor bearing (19) has an eccentrically designed bearing shell (20), which is rotatable about an axis of rotation parallel to the longitudinal axis of the cutting rotor and, during rotation, causes the cutting rotor (3) to move towards or away from the counter-knife (4) due to the eccentricity of the bearing shell.

7. Strand granulator according to the preceding claim, wherein The eccentric bearing shell (20) is designed as a half shell and is designed to be opened toward one side, in particular toward the upper side, for removing the cutting rotor (3).

8. The strand granulator according to claim 5 or 6, wherein: The cutting gap adjustment device (14) has a worm gear stage (21) for moving the cutting rotor (3) toward and away from the counter-tool (4), in particular for moving the cutting rotor bearing (19) toward and away from the counter-tool (4).

9. The strand granulator according to any one of claims 1 to 3, wherein The cutting gap adjustment actuator (15) has an electric stepping motor (22).

10. Strand granulator according to the preceding claim, wherein The cutting gap adjustment actuator (15) has a plurality of stepper motors (22) arranged to adjust the cutting gap at different portions along the cutting rotor (3).

11. The strand granulator according to claim 10, wherein: Synchronization devices for synchronizing the adjustment of the cutting rotor (3) are provided on different cutting rotor parts, wherein the synchronization devices are advantageously configured electronically and / or are provided with an electronic synchronization control module for synchronously controlling a plurality of stepper motors (22).

12. The strand granulator according to any one of claims 1 to 3, wherein At least one sensor (13) is provided on the fixed counter-tool (4), for determining the gap size of the cutting gap during operation of the cutting mechanism (2), wherein the at least one sensor (13) is particularly designed as a non-contact distance sensor.

13. Strand granulator according to the preceding claim, wherein The at least one sensor (13) is designed as an eddy current sensor.

14. The strand pelletizer according to claim 12, wherein The cutting gap adjustment device (14) has a sensor system (18) and a control device (17), wherein the sensor system is used to detect at least one machine operation and / or particle parameter during the operation of the cutting mechanism (2), and the control device is used to control the cutting gap adjustment actuator (15) according to the machine operation and / or particle parameter detected by the sensor, wherein the control device (17) has a controller, which is used to drive the cutting gap adjustment actuator (15) according to the gap size of the cutting gap determined by the sensor (13) and adjust the gap size to a target value.

15. The strand granulator according to claim 13 or 14, wherein: The at least one sensor (13) is arranged on the counter-knife (4) in close proximity to the cutting edge (8) of the counter-knife (4).

16. The strand granulator according to claim 13 or 14, wherein: The at least one sensor (13) is directed toward a passing rotor tooth tip (6) of the cutting rotor (3) and / or detects the distance of the passing rotor tooth tip (6) from the sensor head of the sensor (13) and / or from the counter-tool (4).

17. The strand granulator according to claim 13 or 14, wherein: The at least one sensor (13) is arranged to be at least partially embedded in the counter-knife (4) and, with respect to the direction of rotation (7) of the cutting rotor (3), to be arranged behind the cutting edge (8) of the counter-knife (4) and to face the cutting rotor (3).

18. The strand granulator according to claim 13 or 14, wherein The at least one sensor (13) is arranged on a side portion of the counter-tool (4), which side portion is reached by a rotor tooth (5) at a rotation angle of less than 20°, less than 10° or less than 5° relative to a cutting rotor position in which the rotor tooth tip (6) of the rotor tooth (5) is located exactly at the blade (8) of the counter-tool (4).

19. The strand granulator according to claim 13 or 14, wherein The at least one sensor (13) and / or a controller connected to the sensor (13) and processing the sensor's signal has a sampling frequency greater than 2 kHz, greater than 5 kHz, greater than 10 kHz or greater than 30 kHz.

20. The strand granulator according to claim 13 or 14, wherein A plurality of sensors (13) are distributed over the length of the cutting gap and mounted on the counter-tool (4).

21. Strand granulator according to the preceding claim, wherein The cutting gap adjustment device (14) is designed to move the cutting rotor (3) individually and possibly to different extents at different cutting rotor sections depending on sensor signals from a plurality of sensors (13).

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