Underwater pelletizer

Abstract

To provide an underwater pelletizer that achieves cutting molten strands without adhesion even at high throughput of a pellet through a cutting chamber, ensures that the pellets are removed from the cutting chamber without residue, and achieves short pellet residence time in the cutting chamber.SOLUTION: Processed water can be introduced into a cutting chamber 4 and can be discharged from the cutting chamber through an outlet 8 together with cut pellets. A cutting chamber housing 3 is provided with multiple flow channels and / or chambers for producing different processed water flows. At least two separate inlets for separately feeding co-rotating and non-rotating flow passages are led from an end face of the cutting chamber opposite a die plate 2 into the cutting chamber. The cutting chamber housing is provided with at least one fixed annular distribution chamber 12. The distribution chamber has at least one outlet port 13 opening forward into the die plate and into the cutting chamber for feeding the non-rotating flow passage.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an underwater pelletizer for pelletizing a molten material such as a polymer melt, comprising a die plate, a cutting chamber housing including a cutting chamber, and a rotatably drivable cutter head disposed in the cutting chamber for dividing the molten strand output from the die plate into pellets, wherein the cutting chamber is capable of passing a processing liquid which can be introduced into the cutting chamber through at least one inlet and can be discharged from the cutting chamber together with the pellets through an outlet, and the cutting chamber housing is provided with a plurality of flow channels for generating different processing liquid flows, the plurality of flow channels including a flow passage which rotates together with the cutting chamber and passes through at least one cutter head channel of the cutter head, and at least one flow passage to the cutting chamber which does not rotate together with the cutter head. [Background technology]

[0002] During underwater pelletizing, a cutterhead fitted with blades or shear plates for splitting or shearing the molten strand output from the holes in the die plate operates within a cutting chamber surrounded by a cutting chamber housing and flushed with process water, so that the cutterhead operates "underwater" and the molten strand is pelletized in a water bath. This not only facilitates the discharge of pellets, which are swept away by the process water exiting the cutting chamber and carried in the form of a water-pellet mixture, but also, among other things, prevents the cut pellets from adhering or solidifying on equipment surfaces, because the temperature-controlled process water quenches or cools the usually hotter plastic strand output from the die plate or the cut pellets on the surface, thereby reducing adhesion.

[0003] It should be made clear in this context that the process water does not have to be pure water, but should be understood in the sense of a process liquid, which may contain water, but may also contain or consist of other liquids, and that water containing additives is often used as the process liquid.

[0004] In addition to the desired reduction in adhesion tendency, the flow of process water through the cutting chamber should also perform or support other tasks and avoid negative effects. For example, in certain applications, the pellets should not be overcooled so that they have sufficient residual heat that can, for example, cause or support subsequent crystallization. In addition to proper temperature control of the process water, the goal is to have a shorter residence time of the pellets in the process water, which itself entails rapid removal of the cut pellets from the cutting chamber.

[0005] The problem of removing chopped pellets from the cutting chamber becomes more pronounced in pelletizers with high throughputs. In large-scale industrial installations, the throughput of the melt through the die plate, and therefore the throughput of chopped pellets through the cutting chamber, can be several orders of magnitude greater than 20 t / h, or 30 t / h, or even 40 t / h. To be able to remove such large quantities of pellets from the cutting chamber, an effective flow of process water through the cutting chamber is necessary to prevent, as far as possible, the accumulation of pellets in dead zones or vortices in the flow, which could lead to clogging of the cutting chamber in the worst case scenario.

[0006] An area where such pellets tend to accumulate is sometimes the front center gap between the cutter head and the die plate. Typically, the holes in the die plate are arranged in an annular area around the center of the die plate or cutter head where the cutter head blade or cut-off plate sweeps over the die plate at a predetermined cutting speed to desired sever or cut off the strands exiting the die plate holes. Pellets can accumulate in the annular area swept by the blade if process water is not constantly flowing through this area.

[0007] In addition to the rinsing effect described above, the process water is also intended to provide cooling, particularly in the annular region described above where the cutting blade sweeps over the holes in the die plate, thereby cooling or superficially quenching the molten material emerging therefrom and being cut, as well as cooling the cutting blade and die plate.

[0008] To meet the sometimes conflicting requirements for treated water flowing through the cutting chamber, it has been proposed to supply treated water to the cutting chamber along a specific flow path and to discharge the mixture of granules and treated water in a specific direction to facilitate discharge. For example, it has been proposed that the inlet for supplying treated water to the cutting chamber and the outlet for discharging the treated water together with pellets from the cutting chamber must be arranged tangentially to the generally cylindrical outer surface of the cutting chamber housing, so that the treated water flows in a spiral pattern through the cutting chamber or along the outer surface of the housing when flowing through the approximately cylindrical cutting chamber. For example, WO 2019 / 063123 proposes arranging the treated water inlet and outlet axially spaced apart from each other at a tangential angle, if necessary, at the top of the cutting chamber housing, to achieve a spiral flow in the cutting chamber. At the same time, by arranging the inlet and outlet on the upper side of the cutting chamber housing, the cutting chamber housing can be opened through the bottom cover, and after removing the bottom housing cover, access to the cutter head can be obtained, for example, for maintenance or cleaning of the cutting chamber.

[0009] Furthermore, it has been proposed to introduce process water into the cutting chamber through several separate inlets or flow channels, allowing for individual control of various process water rinsing requirements in a targeted manner. For example, European Patent No. 3062978 proposes supplying a portion of the process water through a first flow channel coaxial with the drive shaft of the cutter head, flowing forward through flow channels in the cutter head to the central region of the die plate, where the flow channels rotate together with the cutter head. This portion of the process water is primarily intended to cool the dissolved strands as they are cut off. Another portion of the process water is introduced into the cutting chamber from the periphery of the cutting chamber housing through a second process water inlet, and this circumferentially introduced process water flow primarily functions to carry the pellets to the opposite outlet for the process water / granule mixture. The two process water flows can be controlled separately in terms of quantity, so as to induce a cooling effect when cutting the pellets on the one hand and a rinsing effect through the cutting chamber on the other hand.

[0010] However, such a multi-passage flow control system may require a complicated cutting chamber housing structure, which impairs the ease of maintenance and cleaning of the cutting chamber. In particular, in such a multi-passage flow system, it is often difficult to open the cutting chamber housing to gain access to the cutting blade or the interior of the cutting chamber. Meanwhile, the flow effect has not yet been optimally resolved, as pellets tend to accumulate inside the rotating blade, especially in the central region between the cutter head and the die plate. Summary of the Invention

[0011] It is therefore the object underlying the present invention to provide an improved underwater pelletizer of the above-mentioned kind, thus avoiding the disadvantages of the prior art and developing the latter in an advantageous way. In particular, non-adhesive cutting of the molten strand into pellets, even at high pellet throughputs through the cutting chamber, reliable residue-free removal of the pellets from the cutting chamber and a short residence time of the pellets in the cutting chamber are achieved by a clever flow of process water through the cutting chamber, in such a way that the remaining residual heat allows the desired post-processing steps.

[0012] According to the present invention, the above-mentioned problem is solved by an underwater pelletizer according to claim 1. Preferred embodiments of the invention are the subject matter of the dependent claims.

[0013] It is therefore proposed to feed treated water from the end face of the cutting chamber opposite the die plate through at least two inlets, one of the aforementioned front inlets feeding fresh treated water to the cutter head and its at least one cutting blade channel insofar as they provide a flow path that rotates together, and the other of the aforementioned front inlets feeding a stationary flow path that leads directly to the cutting chamber without bypassing the cutter head and that does not rotate with the cutter head and is led outside the cutter head in a forward direction to the die plate.In the present invention, at least one stationary annular distribution chamber is provided in the cutting chamber housing and has an outlet port located on the end face of the cutting chamber opposite the die plate, which outlet port opens forward to the die plate and directly into the cutting chamber.

[0014] The feed stream guided by the rotating cutter head and therefore rotating therewith, and the feed stream not guided by the rotating blades and flowing from the fixed outlet into the cutting chamber and therefore not rotating therewith, complement each other to flow the cut pellets away from the die plate, with the rotating feed stream and the non-co-rotating feed stream both being directed from opposite ends of the cutting chamber towards the die plate, but corresponding to different regions therein. The co-rotating feed stream is directed more centrally, particularly within the annular region swept by the blades on the die plate, while the non-co-rotating feed stream or the feed stream coming from the fixed outlet may be directed less centrally or further out, particularly beyond the cutter head and / or into the region of the rotating blades on the die plate. The fixed outlet ports, which provide non-rotating flow passages, may be located, in particular, radially outside the diameter of the cutterhead and / or spaced apart from the cutterhead and / or aligned with it so that the treated water flow from said outlet ports does not contact the cutterhead at the end face, but passes through the cutterhead channels provided therein, but flows laterally or circumferentially beyond the cutterhead and contacts an annular area of ​​the die plate located radially outside the diameter of the cutterhead, and in some cases also contacts blades radially projecting from the cutterhead body in a circumferential direction beyond the cutterhead, and contacts an annular area of ​​the die plate located radially outside the diameter of the cutterhead and in some cases also contacts blades radially projecting from the cutterhead body.

[0015] In a further development of the invention, the outlet port of the above-mentioned stationary annular distribution chamber, which opens directly into the cutting chamber, can be arranged at a greater distance from the axis of rotation of the cutter head than the outlet port of at least one co-rotating cutter head channel passing through the cutter head.

[0016] Furthermore, the outlet port directly leading to the cutting chamber may also be axially, i.e., perpendicular to the die plate, farther from the outlet port of the inlet that passes through the cutter head and provides a co-rotating flow passage. In particular, the inner inlet port providing the co-rotating flow passage may terminate or be located directly at the rear side of the cutter head or the rear side of the cutter support of the cutter head, and may be separated from the rear side of the cutter head by a small gap, if necessary, while the other outlet port providing the non-co-rotating flow passage is farther from the die plate and from the rear side of the cutter head, for example, by a distance corresponding to at least twice the height of the cutting blade. The axial distance of the outer inlet orifice providing the non-rotating flow passage from the rear surface of the orifice plate may be more than two, three, or five times the distance of the inlet orifice of the rotating flow passage from the rear surface of the orifice plate.

[0017] At least one outlet port of the annular distribution chamber, which leads directly to the cutting chamber, can be slot-shaped in the manner of an elliptical hole, for example, kidney-shaped, and / or extend, for example, in an arc around the rotation axis of the cutter head, so as to supply fresh treated water to the cutting chamber distributed over a larger sector. For example, the above-mentioned outlet port can extend in the form of a slit over a sector of more than 90°, more than 120°, or even more than 180°, in particular on the side of the cutting chamber opposite the outlet port, so as to supply fresh treated water to the correspondingly large sector-shaped cutting chamber, carrying the pellets cut in the cutting chamber and transporting them to the outlet port. If necessary, the above-mentioned outlet port of the annular distribution chamber can also extend completely annularly around the rotation axis of the cutter head, for example, in the form of a circular outlet slot in the end wall of the cutting chamber opposite the die plate.

[0018] Instead of or in addition to such slot-shaped or slot-shaped or annular outlet ports, the above-mentioned annular distribution chamber may also have a plurality of spaced-apart outlet ports, which may be arranged on the end face of the cutting chamber opposite the die plate and directed forward toward the die plate. In this context, being aligned forward with the die plate may mean that the longitudinal axis of the outlet port, and therefore the flow direction of the processing fluid entering the cutting chamber, is actually perpendicular to the die plate, but outlet ports set at a somewhat oblique angle to the cutting surface of the die plate, for example, an angle of 85° to 95°, or 80° to 100°, or 70° to 110°, may also be described as being aligned forward with the die plate.

[0019] At least one outlet port of the annular distribution chamber leading directly to the cutting chamber can in particular specify a flow direction of the treated water entering the cutting chamber that is aligned at least approximately parallel to the rotation axis of the cutter head.

[0020] However, instead of introducing the rinsing water directly in a strictly axial direction, the water can also be advantageously introduced into the cutting chamber with a twisting and / or circumferentially inclined motion component, in particular so that the water rotates or winds in the direction of rotation of the cutter head, i.e., so that in addition to the axial component, a circumferential motion component having a rotational direction corresponding to the rotation of the cutter head is generated. This can be achieved, for example, by eccentrically introducing the water into the corresponding distribution chamber. In particular, the water inlet of the non-rotating water supply can be arranged tangentially relative to the inlet chamber so that the flow direction in the inlet chamber is the same as the direction of rotation of the cutter head. In a further flow path, the water also flows axially from the inlet chamber toward the die plate, with the axial component being superimposed on the aforementioned circumferential motion, resulting in an overall vortex or spiral flow of the water. However, alternatively or additionally, at least one or more outlet ports can also have a correspondingly inclined opening area, for example, to introduce the water into the cutting chamber at an acute angle relative to the die plate.

[0021] In a further development of the invention, at least two separate distribution chambers can be provided in the cutting chamber housing, one of which is the already mentioned annular distribution chamber, one or more outlet ports of which lead directly into the cutting chamber in the forward direction to the die plate, and a further one of which is flow-connected to one or more co-rotating cutterhead channels, for example by a supply pipe which can run adjacent to and parallel to the rotation axis of the cutterhead or coaxially with the above-mentioned rotation axis of the cutterhead, to supply fresh treated water to one or more cutterhead channels.

[0022] The at least one cutterhead channel can open at least approximately parallel to the axis of rotation of the cutterhead and / or perpendicular to the die plate. However, the at least one cutterhead channel can also open at an angle relative to the die plate, for example in a radial plane containing the axis of rotation of the cutterhead, and open at an angle toward the die plate. Alternatively, or in addition, the at least one cutterhead channel can also be arranged at an angle in the circumferential direction, in particular so that the treated water leaving the cutterhead channel receives a circumferential motion component corresponding to the direction of rotation of the cutterhead. In principle, it is also possible to supply the treated water passing through the cutterhead to the inlet chamber via a tangential inlet channel, so that the treated water in the inlet chamber undergoes a circumferential movement corresponding to the rotation of the cutterhead, and advantageously flows axially through the co-rotating cutterhead channel toward the die plate.

[0023] In a further embodiment of the invention, the cutterhead channels may be spaced apart from one another, and in particular may be arranged in an annular region about the axis of rotation of the cutterhead. The annular region may be arranged within and / or adjacent to the blades of the cutterhead, such that the co-rotating flow passages direct the treated water within the blades of the cutterhead into the face gap region between the die plate and the cutterhead.

[0024] In particular, the cutterhead channels can open directly to the inside of the cutting blades of the cutterhead on the cutterhead surface facing the die plate. This allows treated water supplied through the cutterhead channels to flush out pellets cut by the blades from the surface gap region between the cutterhead and the die plate, preventing pellets from accumulating in the center surface gap region between the cutterhead and the die plate. In particular, the co-rotating flow passages can be used to generate a treated water flow parallel to the die plate from the center region of the end surface gap to the outside beyond the blades, thereby carrying the pellets.

[0025] In a further embodiment of the present invention, the two annular distribution chambers may each be annular in shape and positioned on the end face of the cutting chamber on opposite sides of the die plate. Since the two distribution chambers feed into separate outlet ports, the two annular distribution chambers may have different diameter ranges, particularly non-overlapping diameter ranges. In particular, the two annular distribution chambers may be configured to be positioned inside each other, with the smaller diameter distribution chamber positioned inside the larger diameter distribution chamber. In particular, the annular distribution chamber feeding the cutter head channel may be positioned inside the annular distribution chamber that has a fixed outlet port directly connected to the cutting chamber, i.e., that is not connected to the cutting chamber via the cutter head.

[0026] In a further development of the invention, the above-mentioned annular distribution chamber, which opens directly into the cutting chamber through a fixed outlet port, can have an inlet inclined tangentially to the peripheral wall of the distribution chamber and / or an inlet inclined obliquely to the radial direction, so that before the treated water flows forward towards the die plate through the above-mentioned at least one outlet port into the cutting chamber, the treated water flowing into the annular distribution chamber forms a circulating flow within the distribution chamber or flows spirally around the annular distribution chamber and / or along the peripheral wall, respectively.

[0027] In a further development of the invention, the aforementioned inlets can be arranged inclined and / or tangentially, in particular so that the treated water in the distribution chamber has a direction of rotation and / or a flow direction with a component corresponding to the direction of rotation of the cutter head when it enters the cutting chamber. In other words, the inlets of the distribution chamber can create a spiral flow whose direction of rotation corresponds to the direction of rotation of the cutter head.

[0028] Alternatively or additionally, in a similar manner, the annular distribution chamber feeding the co-rotating flow passages or feeding the cutterhead channels may also have inlets oriented tangentially to the circumferential wall and / or inclined radially to create a circulating flow of treated water within said annular distribution chamber or to cause the treated water to spiral around the distribution chamber, particularly in a rotational direction corresponding to the direction of rotation of the cutterhead, thereby more efficiently feeding the cutterhead channels.

[0029] In an advantageous further development of the invention, the flow rate ratio can be variably adjusted and / or controlled, for example, in the form of a volume ratio and / or pressure ratio and / or temperature ratio of the treated water streams supplied via two separate flow passages, i.e., the treated water stream supplied to one co-rotating flow passage and the treated water stream supplied to the other non-co-rotating flow passage. In particular, the flow rate and / or pressure and / or temperature of the treated water supplied to the co-rotating flow passage can be adjusted and / or controlled independently from the treated water supplied to the other flow passage. Alternatively, or in addition, the flow rate and / or pressure and / or temperature of the treated water supplied directly to the cutting chamber via at least one fixed outlet can also be adjusted and / or controlled independently from the treated water supplied to the co-rotating flow section.

[0030] Alternatively, or in addition, the distribution between the two flow passages can be adjusted and / or the total volumetric flow rates can be adjusted or controlled to match each other.

[0031] In a further aspect of the invention, the cutting chamber can be specially shaped, independent of the aforementioned multiple flow channels for the treated water, in order to equalize the residence time of the pellets in the cutting chamber and prevent multiple recirculation of already cut pellets. In particular, the cutting chamber can be shaped so that the envelope volume defined by the cutting chamber around the cutting blade, into which the treated water can spread, becomes larger as it approaches the outlet when viewed in the direction of rotation of the cutter head. In particular, in the sector of the cutting chamber reached immediately after the cutting blade has passed the outlet, the aforementioned envelope volume of the cutting chamber can be smallest around the blade and then gradually increase to a maximum as it approaches the outlet.

[0032] In this case, the cutting chamber may increase in depth and / or width, as viewed in the direction of rotation, starting in the area immediately behind the outlet when viewed in the direction of rotation of the cutter head, towards the outlet, like a worm house when viewed in the direction of rotation. The depth of the cutting chamber means its extension in the axial direction or in the direction of the axis of rotation of the cutter head. The width here means the circumference of the cutting chamber and the envelope of the cutting head blades or the cutting head itself, depending on how the blades are arranged.

[0033] In particular, along its outer periphery, and therefore adjacent to the cutting blade of the cutter head, or adjacent to the outer periphery of the cutter head, the cutting chamber can define a tubular volume area which can increase continuously, or if necessary also in steps, towards the outlet from the sector of the cutting chamber reached after the blade has passed through the outlet.

[0034] The increasing volume around the cutting blade towards the outlet allows for a very equal residence time for the pellets. In the area with the smallest gap size, or the sector immediately after the outlet in the circulation direction and narrowing around the cutter head, the incoming rinsing water has little space to expand, resulting in a higher pressure and therefore a higher flow rate of the water. This allows the pellets cut there to flow out much faster.

[0035] On the one hand, as viewed in the direction of rotation of the cutter head, more pellets accumulate between or around the cutting blades as they approach the outlet, because, on the other hand, pellets that have already been cut further ahead as viewed in the direction of rotation are carried along with them, and newly cut pellets are added, so to speak, in the sectors located downstream.

[0036] In sectors closer to the outlet when considering the circulation direction of the cutter head, the cutting chamber around the cutter head has a larger volume, so the treated water has more space and / or the pressure of the treated water is lower and / or the flow rate of the treated water is lower, so that, when considered as a whole, the residence time of the cut pellets in the various circulation sectors is equal.

[0037] In order to prevent the cut pellets from circulating multiple times or even endlessly, in an advantageous further development of the invention, flow guide plates and / or deflectors can be arranged in the cutting chamber in the area of ​​the outlet in order to guide the pellets flowing with the treated water, in particular towards the outlet. Such baffles and / or shell-shaped or panel-shaped deflectors can in particular extend between the contour of the cutter head or the envelope contour of the cutting blade and the outlet, so that the baffles or deflectors can in particular extend from the circumferential wall of the cutting chamber adjacent to the envelope contour of the cutter head, against its circumferential direction, towards the cutting chamber and protrude from a cross section of the circumferential wall of the cutting chamber that defines a trailing edge contour towards the outlet, as seen in the circumferential direction of the cutter head.

[0038] For example, the baffle or deflector may extend in an arcuate curve around the envelope contour of the cutterhead and project from the root region of the outlet in the manner described above.

[0039] In an advantageous further development, the cutting chamber housing can be designed to be separable so that the cutting chamber and / or the cutter head can be exposed by moving one cutting chamber housing part away from another cutting chamber housing part so that cleaning or maintenance work can be performed. In an advantageous further embodiment of the present invention, the cutting chamber housing can include a fixed housing part, which can be fixedly attached to and / or fixedly connected to the die plate even when the cutting chamber housing is open. The movable or openable housing part can have a bearing for the cutter head and / or be supported by a cutter head drive and / or be mounted so that it can move away from and towards the die plate together with the cutter head. In particular, the movable housing part can be designed to move together with the cutter head away from the die plate and the fixed housing part to open the cutting chamber.

[0040] Independently of the allocation of the pelletizer components to the aforementioned housing parts, the aforementioned housing parts can be designed so that the movable housing part can move translationally, linearly away from the fixed housing part or translationally, linearly towards the fixed housing part. In particular, the movable housing part can move away from the fixed housing part and move towards the movable housing part in the direction of the rotation axis of the cutter head to connect. The connection direction of the two housing parts can be aligned approximately parallel to the rotation axis of the cutter head.

[0041] In particular, the intersection or connection point between two housing parts that are movable relative to each other may be such that the intersection or connection point can be joined and separated by translational movement of the movable housing half in the direction of the axis of rotation of the cutterhead.

[0042] The above-mentioned intersection or connection point between two housing parts that are movable relative to one another can advantageously extend at least primarily in an inclined plane that is set at an acute angle to the rotation axis of the cutter head. In this case, the entire contour of the cutting or connection point does not have to lie in a common plane; rather, for example, a U-shaped interface contour can be provided in a plane, the missing piece of which can extend, for example, in the form of a further interface sector in a plane angled thereto, or can have a step-shaped jump, or can also extend along a free-form surface. Considering the above-mentioned interface between two housing parts as a whole, the interface can generally extend at least primarily in an inclined plane.

[0043] In particular, the interface slope may be closer to the die plate at a lower portion than at an upper portion, in other words the interface extends from a bottom portion close to the die plate to a top portion remote from the die plate.

[0044] Regardless of the specific external shape, the interface between the two housing parts that can be connected and disconnected can extend into the area of ​​the cutting chamber and / or across the distribution chamber for the treated water, so that, for example, at least a part of the annular distribution chamber for directly supplying the cutting chamber can be formed in the retractable housing part, and the other part in the stationary housing part. Alternatively or additionally, the distribution chamber for supplying the co-rotating flow channels can also be formed partly in one half of the housing and partly in the other housing part, whereby it can also be advantageous if the distribution chamber for supplying the co-rotating flow channels is formed entirely in one of the aforementioned housing parts, in particular in the movable housing part that can move together with the cutter head away from the die plate and the housing part connected thereto.

[0045] The two fixed and movable housing parts described above may each form half of a housing, with the housing as a whole being able to move apart into the two housing parts, although in principle it would also be possible to provide a three-part, four-part or multi-part design, with multiple movable housing parts being able to move apart from one or more fixed housing parts.

[0046] In an advantageous further development of the invention, the outlet for the mixture of treated water and granules from the cutting chamber can be connected to a housing part that is stationary mounted on the die plate, nevertheless, one or two or all of the inlets through which treated water can be supplied to the cutting chamber can be provided in the movable housing half so as to be movable together with the movable housing half away from the stationary housing half.

[0047] In particular, in a further development of the invention, the outlet for the mixture of treated water and granules can be located in the upper half of the housing, while the inlet for supplying fresh treated water to the cutting chamber can be allocated to the lower half of the housing.

[0048] Advantageously, a seal may be provided between the connectable housing parts, and may include, for example, an annular seal that may extend along the interface between the two housing parts. For example, an elastic O-ring may be provided between the separable housing parts to provide a water-tight or liquid-tight seal when connected together. The above-mentioned seal at the interface of the two housing parts may in particular be provided to make the cutting chamber watertight, such that process water can enter or leave the cutting chamber only at the inlet and outlet.

[0049] To allow for easy and quick coupling and decoupling while still providing a satisfactory seal at the interface, a clamping device can be provided between the two housing parts that are movable relative to one another, which allows the two housing parts to be clamped or pressed together in the coupled state.

[0050] Such a clamping device can advantageously be designed to apply a clamping force at least approximately parallel to the axis of rotation of the cutter head and / or to clamp the two housing parts together in the direction of the axis of rotation of the cutter head.

[0051] Advantageously, the clamping device may comprise one or more quick-action clamps, for example in the form of a movable clamping lever and / or clamping cylinder actuatable by pressure means. Alternatively, or in addition, clamping screws may also be used.

[0052] In an advantageous further development of the invention, hydraulic clamping cylinders can be provided that are arranged on the periphery of the housing parts, which can work with counterparts on the opposite housing part and, for example, be locked or hooked or fixed there, and by hydraulically actuating the clamping cylinders, the housing parts can be clamped against each other with a positive and a negative fit to obtain the desired seal.

[0053] The present invention will now be described in more detail with reference to preferred embodiments and associated drawings. [Brief explanation of the drawings]

[0054] [Figure 1] FIG. 1 is a perspective view of an underwater pelletizer showing the cutting chamber housing, the cutterhead drive, and process water connections on the cutting chamber housing for flowing process water to the cutting chamber. [Figure 2] 2 is a longitudinal cross-sectional view of the cutting chamber housing of the underwater pelletizer of FIG. 1 showing the cutter head attached to the die plate and the flow passages for the treated water to flow into the cutting chamber. [Figure 3] FIG. 3 is a side view of the cutting chamber housing of the underwater pelletizer of the previous figures in the open extended position of the two housing parts of the cutting chamber housing, showing the cutter head moved apart with the movable housing part and the hydraulic clamping cylinder for connecting the two housing parts. [Figure 4] FIG. 4 is a cross-sectional view of the cutting chamber of the underwater pelletizer shown in the previous figures, taken from the die plate towards the cutter head, showing the mouth area of ​​the flow passage through the cutter head and the eccentric arrangement of the cutting chamber around the cutter head. [Figure 5] Figure 5 is a cross-sectional view of the cutting chamber of the underwater pelletizer of the previous drawing, in a view direction opposite to that of Figure 4, so to speak, relative to the rear face of the cutter head, showing the mouth area of ​​the treated water outlet leading directly to the cutting chamber and the eccentric arrangement of the cutter head within the cutting chamber. [Figure 6] FIG. 6 is a further cross-sectional view of the cutting chamber of the underwater pelletizer, similar to FIG. 5, but in a cross-section that is axially offset in comparison. [Figure 7] FIG. 7 is a perspective view of the cutting chamber with the cutterhead positioned therein, showing the three-dimensional contour of the cutting chamber, with the cross-sectional volume of the cutting chamber increasing towards the outlet. [Figure 8] FIG. 8 is a perspective view of the cutting chamber in which the cutter head is arranged, similar to FIG. 7, and compared to FIG. 7, a guide plate arranged at the outlet of the cutting chamber to prevent the cut pellets from circulating multiple times can be seen. DETAILED DESCRIPTION OF THE INVENTION

[0055] As shown in Figure 1, the underwater pelletizer 1 includes a melt feed head 15, which can be connected to a melt feed device (not shown), e.g., including an extruder, and which includes or can be connected to a die plate 2, which includes a nozzle-like melt channel for forcing the melt strand through or exiting the die plate. The above-mentioned melt channel of the die plate can open at an end face of the die plate 2 facing the cutter head 5, forming a cutting surface 23 (see Figure 2).

[0056] The above-mentioned die plate 2 is thereby connected to a cutting chamber housing 3, which encloses a cutting chamber 4 adjacent to the above-mentioned end face of the die plate 2 that forms the cutting surface of the die plate 2. In this case, the above-mentioned end face of the die plate 2 defines the cutting chamber 4 at one end face, while the cutting chamber housing 3 can define the cutting chamber 4 in the circumferential direction and at the opposite end face of the die plate 2.

[0057] The above-mentioned cutting chamber 4 accommodates a cutter head 5 which can be rotated about a cutter head rotation axis which can extend substantially perpendicular to the cutting surface of the die plate 2 .

[0058] A cutterhead drive 16 is provided for rotationally driving the cutterhead 5 (see Figure 1) and may also include, for example, an electric motor 17 or a hydraulic motor which may be drivingly connected to the cutterhead 5 via a gear stage and drive shaft 18 (see Figure 1) as required.

[0059] The assembly including the cutter head 5, the cutter head drive 16, and the cutting chamber housing 3 or at least part of the cutting chamber housing 3 can be mounted on a support slide 19 so as to be able to move in translation, in particular in a direction that is at least approximately parallel to the rotation axis 20 of the cutter head.

[0060] As shown in FIG. 2, the cutting chamber 4 may have an outer shape that is at least approximately cylindrical or disc-shaped when viewed as a whole, and may be installed on one side of the die plate 2 so that the cutter head 5 can be received in the cutting chamber 4.

[0061] The above-mentioned cutter head 5 in this case comprises a cutter support 21 on whose end face and / or peripheral side it sweeps over the die plate 22, in particular in the annular region where the above-mentioned melt channel of the die plate 2 opens into its end cutting surface, so that the blade 22 can cut off the molten strand output from the melt channel and cut it into pellets.

[0062] Treated water flows through the cutting chamber 4, and the treated water is supplied to the cutting chamber 4 through a plurality of inlets 6 and 7, and is discharged together with the cut pellets through an outlet 8 in the form of a mixture of treated water and pellets (see Figure 2).

[0063] The above-mentioned outlet 8 may be located on the upper side of the cutting chamber housing 2, may lead tangentially from the peripheral wall of the cutting chamber 4 and / or may be positioned at an angle to the radial direction at the periphery of the cutting chamber 4 (see Figures 1 and 2).

[0064] The inclined portion of the outlet 8 described above can be adapted to the direction of rotation of the cutter head 5 so that the treated water flowing spirally around the inside of the cutting chamber 4 or along the circumferential wall of the cutting chamber 4 can flow out tangentially at the circumferential side without any significant detours or reversals in direction.

[0065] The above-mentioned inlets 6, 7 for supplying treated water can be arranged on the underside of the cutting chamber housing 3 and / or in the region of the lower half of the cutting chamber housing 3 (see Figures 1 and 2).

[0066] Treated water is supplied to the cutting chamber 4 via the inlets 6, 7 mentioned above and along various flow paths.

[0067] As shown in Figure 2, both inlets 6, 7 lead into the cutting chamber 4 from the rear end face, i.e. the end face of the cutting chamber 4 opposite the die plate 2. In this case, one inlet 7 is positioned more centrally, i.e. closer to the axis of rotation 20 of the cutter head 5, and the other inlet 6 is positioned less centrally or more eccentrically, i.e. further away from the axis of rotation 20 of the cutter head 5.

[0068] In particular, the inlet 7 is positioned and oriented so that the treated water leaving the cutting chamber 4 from the inlet 7 is led directly to the end face of the cutter head 5. The cutter head 5 is formed with a cutter head channel 10 that opens onto the end face of the cutter head 5 facing the die plate, allowing the treated water to flow through the cutter head 5 and towards the die plate 2 in a forward direction.

[0069] As a result, the cutter head channel 10 is provided in an annular region or diameter region radially inside the diameter region in which the blades 22 are arranged, and the treated water enters the front gap between the die plate 2 and the cutter head 5 inside the blades 22. As a result, a treated water flow is formed between the die plate 2 and the cutter head 5, flowing substantially parallel to the die plate 2 and at least roughly radially outward, and the pellets deposited on the blades 20 flow outward into the cutting chamber 4.

[0070] The inlet 7 mentioned above feeds into a co-rotating flow passage 9 formed by a cutter head channel 10, which leads to a central region of the face gap between the die plate 2 and the cutter head 5, forming a flow extending from the center outwards, parallel to the die plate 2, to prevent pellet accumulation in the central region.

[0071] As shown in FIG. 2, the inlet 7 may form an annular channel extending around the drive shaft 18 and specifically aligned coaxially with the cutterhead axis 20 .

[0072] As shown in FIG. 2, the aforementioned inlet 7 on the outside of the cutting chamber housing 3 may have an inlet port 7a or inlet connection for connecting to a treated water line that opens into an annular distribution chamber 12 formed inside the cutting chamber housing 3 and for communicating with an annular inlet channel 7i that directs treated water to the back of the cutter head 5 or feeds the aforementioned cutter head channel 10.

[0073] The other inlet 6 also includes an inlet port 6a or connection on the outside of the cutting chamber housing 3 for connection to a process water line. However, this further inlet 6 does not supply process water through the cutter head 5, but rather over the cutter head 5 directly into the cutting chamber 4, and at this point into a flow passage 11 which does not rotate with it.

[0074] In particular, the aforementioned further inlet port 6a may initially be formed in the cutting chamber housing 3 and communicate with a further annular distribution chamber 12 provided rearward of or adjacent to the end face of the cutting chamber 4. The aforementioned annular distribution chamber 12 may be formed around the previously described inner inlet 7 (see FIG. 2) and may open into the aforementioned cutting chamber 4 from the opposite end face of the die plate 2 and have one or more outlet ports 13 that lead the treated water forward toward the die plate 2 beyond the outer periphery of the cutter head 5. As FIG. 2 shows, the outlet ports 13 may be arranged in a diameter range that is larger than the diameter of the blade holder 21 of the cutter head 5, and / or larger than the diameter range in which the cutter head channel 10 is arranged, and / or larger than the diameter range in which the inner inlet 7 has its mouth area.

[0075] In particular, treated water flowing forward from the outlet port 13 towards the die plate 22 can flow over the outer region of the cutting blade 22 or flow towards the die plate 22 in the region of the blade 22 where it can combine with treated water flowing outward from the center of the die plate 22 via the flow passages 9 which rotate together.

[0076] In an advantageous further development of the invention, the inlets 6 and 7 can be controlled or regulated with regard to the flow rate and / or pressure and / or temperature of the treated water independently of one another and / or in conjunction with one another and / or in each case individually, for example by suitable flow control devices such as valves, flow dividers, or possibly also by separate pressure sources such as pumps, and / or temperature control devices such as heat exchangers or heating or cooling elements, so that for each flow channel 9 and 11 the flow rate and / or flow pressure and / or flow temperature in the region of the respective inlets 6 and 7 can be set individually in the desired manner.

[0077] Regardless of the multiple inlets 6, 7 described, the cutting chamber 4 may have a generally spiral three-dimensional contour and / or the cutter head 5 may be eccentrically positioned within the cutting chamber 4 to facilitate the passage of the cut pellets to the outlet 8 and to equalize the residence time of the cut pellets in various sectors at various distances from the outlet 8.

[0078] In particular, the cutting chamber 4 has an envelope volume defined around the cutting blade, in which the treated water can spread, and which, as it were, can be larger towards the outlet when viewed in the direction of rotation of the cutter head. For example, in sector A of the cutting chamber, which the cutting blade reaches just after passing the outlet (see FIG. 4), the above-mentioned envelope volume of the cutting chamber can be smallest around the blade and then gradually increase towards the outlet to become a maximum. For example, the above-mentioned envelope volume can continuously increase towards sector B, which is opposite the outlet 8, and from there, can also continuously increase towards sector C, which is upstream of the outlet 8 in the direction of rotation of the blade (see FIG. 4).

[0079] In this case, the cutting chamber 4 seen in the direction of rotation of the blades may in particular start from an area A located directly behind the outlet 8 seen in the direction of rotation of the cutter head and increase by a depth T and / or width S like a snail's shell towards the outlet 8. The depth T of the cutting chamber means its extension in the axial direction or in the direction of the axis of rotation of the cutter head (see FIG. 2). The width S means the width of the gap between the peripheral wall of the cutting chamber 4 and the envelope of the blades of the cutting head 5 or the cutting head 5 itself, depending on how the blades are arranged.

[0080] In particular, along its periphery, and therefore adjacent to the cutting blade of the cutter head 5, or adjacent to the periphery of the cutter head 5, the cutting chamber 3 can define a tubular volume area which can increase continuously, or in steps as needed, from sector A of the cutting chamber 5, which the blade reaches after passing through the outlet 8, towards the outlet 8. This volumetric tube forms a spatial area not directly swept by the blade itself, or adjacent to that area swept by the blade, forming, as it were, a clearance or avoidance space in which the treated water surrounding the cutter head can avoid around the cutter head.

[0081] The residence time of the pellets in the cutting chamber 4 can be significantly reduced by the "volume tube" around the cutting blade, which increases in size towards the outlet 8. In the area of ​​smallest gap size, or sector A, which is located just after the outlet 8 in the circulation direction and narrows around the cutter head 5, there is little space for the incoming rinsing water to expand, resulting in a higher pressure and therefore a higher flow rate of the water, which allows the pellets cut there to flow out much faster.

[0082] On the one hand, as viewed in the circulation direction of the cutter head 5, more pellets accumulate between or around the cutting blades as they approach the outlet 8, because, on the other hand, pellets that have already been cut further ahead as viewed in the circulation direction are carried along with them and are added to them by newly cut pellets in the sectors located downstream, as it were.

[0083] In sectors B and C, which are closer to the outlet 8 when considering the circulation direction of the cutter head 5 (see Figure 4), the cutting chamber 4 around the cutter head 5 has a larger volume, so that the treated water has more space and / or the pressure of the treated water is reduced and / or the flow rate of the treated water is reduced, so that, considered as a whole, the residence times of the cut pellets in the various circulation sectors A, B, C are equal.

[0084] In order to prevent the cut pellets from circulating multiple times or even endlessly, in an advantageous further development of the invention, flow guide plates 31 and / or deflectors can be arranged in the cutting chamber 4 in the area of ​​the outlet 8 or slightly downstream thereof to guide the pellets flowing with the treated water specifically towards the outlet and prevent them from circulating multiple times (see Figure 8).

[0085] Such a guide plate and / or shell- or panel-shaped deflector can in particular extend between the contour of the cutter head 5 or the envelope contour of the cutting blade on the one hand and the outlet 8 on the other hand, so that the guide plate 31 or deflector can in particular protrude from the peripheral wall of the cutting chamber 4 adjacent to the envelope contour of the cutter head 5, against the direction of rotation thereof, into the cutting chamber 4. The deflector can in particular protrude from the peripheral wall of the cutting chamber 4 adjacent to the envelope contour of the cutter head 5, against the direction of rotation thereof, into the cutting chamber 4 (see FIG. 8), for example protruding from a cross section of the peripheral wall of the cutting chamber 4 that defines a trailing edge contour towards the outlet 8, as seen in the direction of rotation of the cutter head 5 (see FIG. 8).

[0086] For example, the deflector 31 or deflector may be curved in an arc and inclined at an acute angle to the envelope contour of the cutterhead 5, and may protrude inward from the root region of the outlet 8 below the blade in the manner described above in order to "pick" pellets circulating with the blade or deflect them towards the outlet 8, preventing them from circulating multiple times, i.e. preventing them from diverting from the outlet region towards sector A instead of the outlet 8 again or for the first time, preventing them from circulating multiple times, i.e. preventing them from turning away from the outlet region towards sector A instead of flowing into the outlet 8 again or for the first time.

[0087] 3 shows, the cutting chamber housing 3 may advantageously be of split design and may include multiple housing parts 3a, 3b, for example two housing halves, which may be moved towards or away from each other to close or open the cutting chamber housing 3. Advantageously, the cutting chamber housing 3 may be split into two housing halves, one of which is fixed and the other of which is movable.

[0088] In particular, the cutting chamber housing 3 may have an interface or joint 26 between the two housing portions 3a, 3b that extends at least partially in an angled plane through the cutting chamber 4 so that the cutting chamber 4 opens when the housing portions 3a, 3b move apart.

[0089] The aforementioned interface 26 may extend at least primarily in an inclined plane, which may be perpendicular to a vertical plane containing the rotation axis 20 of the cutter head and may be inclined at an acute angle to the aforementioned rotation axis 20 of the cutter head, in particular so that the interface 26 is located closer to the die plate 2 in the lower part of the cutting chamber housing 3 than in the upper part of the cutting chamber housing 3 (see FIG. 3 ). In particular, the aforementioned interface 26 may be located approximately at the position of the die plate 2 at the lower edge of the cutting chamber 4, and may be further away from the die plate 2 in the upper end part of the cutting chamber housing 3 than in the thicker cutting chamber 4, and / or may extend into the region of the annular distribution chamber 25 located behind the end face of the cutting chamber 4 opposite the die plate 2.

[0090] For example, the plane in which the majority of the interface 26 extends may extend at an angle of between 45° and 80° relative to the axis of rotation 20 of the cutterhead.

[0091] Advantageously, one housing part 3a can be arranged in a fixed position, in particular fixedly connected to the die plate 2, while the other housing part 3b can be movably mounted and / or form a mobile housing part. In particular, the above-mentioned mobile housing part 3b can be translated away from and towards the fixed housing part 3a along a straight line or, if necessary, along an arcuate path. For example, the mobile housing part 3b can move away from and towards the fixed housing part 3a, or can be coupled to and decoupled from the fixed housing part 3a, parallel to the cutter head rotation axis 20.

[0092] The above-mentioned movable housing part 3b may in particular form a movable assembly together with the cutter head 5. For example, the cutter head 5 may be rotatably mounted on the movable housing part 3b.

[0093] The movable assembly including the movable housing part 3b and the cutterhead 5 may in particular be movably mounted on a carriage or other suitable support device, whereby the carriage 19 may also carry, for example, the cutterhead drive 16 (see Figure 1).

[0094] The two housing parts 3 a and 3 b may be sealingly joined together, whereby a seal 28 may be provided in the region of said interface 26 and seated between the edges of the housing parts at said interface. Said seal 28 may for example be an annular seal or sealing ring, for example in the form of an elastic sealing ring or O-ring, arranged between the edges of the housing parts 3 a and 3 b which can move towards each other.

[0095] In order to be able to firmly connect the housing parts 3 a, 3 b to one another, the connection device may advantageously comprise a positive and / or non-positive clamping device 29. Such a clamping device 29 may advantageously comprise a plurality of clamps, in particular quick clamps 30, which may be distributed along the interface 27 so as to be able to clamp the two housing parts 3 a, 3 b one on top of the other. The clamping device 29 may apply a clamping force in the direction of the axis of movement of the movable housing part, for example in the direction of the axis of rotation 20 of the cutter head, to clamp the movable housing part 3 b to the fixed housing part 3 a.

[0096] Advantageously, the above-mentioned quick action clamp 30 can have a clamp actuator that is actuated by external energy, for example in the form of a pressure medium cylinder, which can be attached to one of the housing parts and hooked or in some other way held in form-fitting fashion in the opposite housing part, so that a clamping force can be applied by actuating the clamp actuator.

Claims

1. 1. An underwater pelletizer comprising a die plate (2), a cutting chamber housing (3) containing a cutting chamber (4), and a rotatably drivable cutter head (5) arranged in the cutting chamber (4) for dividing the molten strand output from the die plate (2) into pellets, The cutting chamber (4) is capable of receiving treated water that can be introduced into the cutting chamber (4) through at least one inlet (6, 7) and can be discharged from the cutting chamber (4) via an outlet (8) together with the cut pellets, the cutting chamber (4) houses the rotatable cutter head, the cutting chamber (4) has a first end surface and a second end surface that are opposite to each other in an axial direction along the rotation axis of the cutter head and define the cutting chamber, the first end surface of the cutting chamber is formed / defined by the die plate, and the second end surface of the cutting chamber is formed / defined by a housing wall of the cutting chamber housing (3), The cutting chamber housing (3) is provided with a plurality of flow channels and / or flow chambers for generating different treated water flows, the plurality of flow channels and / or flow chambers including at least one co-rotating flow passage (9) passing through at least one cutter head channel (10) passing through the rotating cutter head (5), and at least one non-rotating flow passage (11) that does not rotate with the cutter head (5) and leads from a fixed inlet (6) to the cutting chamber (4); At least two separate inlets (6, 7) are led into the cutting chamber (4) for separately feeding the co-rotating and non-co-rotating flow channels; The non-co-rotating flow passages and the co-rotating flow passages generate different treated water flows toward the die plate in the axial direction of the rotation axis of the cutter head (5); The cutting chamber housing (3) is provided with at least one annular fixed distribution chamber (12) adjacent to the second end face of the cutting chamber, the distribution chamber (12) having at least one outlet port (13) including one or more outlet openings passing through the second end face of the cutting chamber (4) to supply the non-co-rotating flow passage (11), and the distribution chamber (12) is connected in fluid communication with the cutting chamber (4) via the at least one outlet port; The one or more outlet openings have a longitudinal axis and define a flow direction of the non-co-rotating flow passages toward the die plate at an angle in the range of 70° to 110° relative to a cutting plane of the die plate.

2. 2. The underwater pelletizer according to claim 1, wherein the non-co-rotating flow passages (11) are connected to the die plate (2) radially outward of the co-rotating flow passages (9) and / or are farther from the rotation axis (20) of the cutter head than the co-rotating flow passages (9).

3. 3. The underwater pelletizer according to claim 1 or 2, wherein the non-co-rotating flow passages (11) are directed to the cutting blades of the cutter head (5) in a direction at least approximately parallel to the rotation axis of the cutter head (5) and / or in a direction substantially perpendicular to the outlet face of the die plate (2).

4. 3. The underwater pelletizer according to claim 1, wherein the flow passages (11) that do not rotate together are inclined at an acute angle to an axial direction defined by the rotation axis (20) of the cutter head, are inclined at an acute angle to the axial direction in an imaginary plane including the rotation axis (20) of the cutter head, and / or are inclined at an acute angle outside the imaginary plane.

5. 2. The underwater pelletizer according to claim 1, wherein the outlet ports (13) for feeding the non-co-rotating flow passages (11) open into the cutting chamber (4) in a diameter region larger than the outer diameter of the blade holders (21) of the cutter head (5), and are dimensioned and / or positioned so that the treated water flow entering the cutting chamber (4) from the outlet ports (13) flows towards the die plate (2) at the outer periphery of the cutter head (5).

6. 2. The underwater pelletizer of claim 1, wherein the outlet ports (13) feeding the non-co-rotating flow passages (11) are farther from the die plate (2) than the outlet ports of the inlets (7) feeding the co-rotating flow passages (9).

7. 2. The underwater pelletizer according to claim 1, wherein the cutting chamber housing (3) is provided with two separate annular fixed distribution chambers (12, 14), of which the first distribution chamber (12) opens into the cutting chamber (4) via the flow passage (11) which does not rotate together, and the second distribution chamber (14) opens into the cutting chamber (4) via the flow passage (9) which rotate together.

8. 2. The underwater pelletizer according to claim 1, wherein the co-rotating flow passage (9) opens into a front gap between the die plate (2) and the cutter head (5) through the at least one cutter head channel (10) in the cutting blade of the cutter head (5).

9. 2. The underwater pelletizer according to claim 1, wherein the co-rotating flow passages (9) are directed at least approximately parallel to the rotation axis (20) of the cutter head and / or axially substantially perpendicular to the die plate (2).

10. 2. The underwater pelletizer according to claim 1, wherein the co-rotating flow passages (9) are directed towards the die plate (2) at an acute angle inclined relative to the die plate (2), and are inclined at an acute angle in the circumferential direction and / or inclined at an acute angle radially inward or radially outward.

11. 2. The underwater pelletizer according to claim 1, wherein the two separate inlets (6, 7) for separately feeding the co-rotating and non-co-rotating flow passages (9, 11) are nested within each other and each form annular flow channel extending at least approximately parallel to and coaxial with the axis (20) of rotation of the cutter head.

12. 2. The underwater pelletizer according to claim 1, wherein the two separate inlets (6, 7) have discharge openings that open into the cutting chamber (4), the discharge openings being arranged in annular regions with diameters of different sizes.

13. 2. The underwater pelletizer according to claim 1, wherein the outlet port (13) for feeding directly into the cutting chamber (4) beyond the cutter head (5) is slot-type and has a curved profile in the shape of an arc and / or forms an annular outlet slot around the cutter head (5) at the second end face of the cutting chamber (4).

14. 2. The underwater pelletizer of claim 1, wherein the outlet port (13) comprises a plurality of outlet ports with the same or different profiles for feeding the cutting chamber (4).

15. 2. The underwater pelletizer of claim 1, wherein the cutter head (5) has a plurality of cutter head channels (10) formed therein, the cutter head channels (10) being arranged along an annular contour around the rotation axis (20) of the cutter head and / or being arranged centrally and / or eccentrically with respect to the rotation axis (20) of the cutter head and passing through the cutter head (5) from one end face of the cutter head (5) to the opposite end face of the cutter head (5).

16. 16. The underwater pelletizer of claim 15, wherein the cutterhead channels (10) are aligned parallel to the cutterhead axis of rotation (20) or are inclined outwardly and / or circumferentially at an acute angle to the cutterhead axis of rotation (20).

17. 2. The underwater pelletizer according to claim 1, wherein at least one of the separate inlets (6, 7) has a nozzle-shaped inlet port (6a, 7a) on the outer circumferential side of the cutting chamber housing (3), the inlet port (6a, 7a) being arranged tangentially to the circumferential direction and / or inclined at an acute angle to the radial direction so that the treated water supplied through the inlet port (6a, 7a) flows spirally and / or along the circumferential wall through the distribution chambers (24, 25) connected to the separate inlets (6, 7).

18. 18. The underwater pelletizer according to claim 17, wherein the inclination of the inlet port is selected so that the treated water in the distribution chamber has a direction of circulation corresponding to the direction of rotation of the cutter head (5).

19. 2. The underwater pelletizer according to claim 1, wherein a flow control and / or temperature control device is provided for controlling and / or regulating the flow rate and / or pressure and / or temperature of the process water supplied to one of the separate inlets (6) independently from the flow rate and / or pressure and / or temperature of the process water supplied to the other of the separate inlets.

20. 20. The underwater pelletizer of claim 19, wherein the flow control and / or temperature control device is configured to individually control and / or regulate the treated water flow at each of the separate inlets (6, 7) in terms of flow rate and / or pressure and / or temperature.

21. 2. The underwater pelletizer according to claim 1, wherein the cutting chamber housing (3) is divided into at least one fixed housing part (3a) and at least one movable housing part (3b), and the cutting chamber housing (3) and its cutting chamber (4) can be opened by moving the movable housing part (3b) away from the fixed housing part (3a).

22. 22. The underwater pelletizer of claim 21, wherein the intersection and / or connection point (26) between the fixed and movable housing parts (3a, 3b) extends at least predominantly in an oblique plane inclined at an acute angle to the axis of rotation (20) of the cutterhead, at an angle in the range of 30° to 80°, or 45° to 80°, or 50° to 80°.

23. 23. The method according to claim 22, wherein the intersection and / or connection point (26) between the movable and fixed housing parts (3a, 3b) at the bottom part of the cutting chamber housing (3) is closer to the die plate (2) than to the upper end part of the cutting chamber housing (3), and the intersection and / or connection point (26) divides the cutting chamber (4) at the bottom part of the cutting chamber housing (3) at the level of the die plate (2) and divides an annular distribution chamber (25) for supplying the non-co-rotating flow passages (11) at the upper end part of the cutting chamber housing (3). Underwater pelletizer.

24. 22. The underwater pelletizer according to claim 21, wherein the fixed housing part (3a) is fixed to the die plate (2) and the movable housing part (3b) forms a cooperatively movable assembly together with the cutter head (5).

25. 22. Underwater pelletizer according to claim 21, wherein the outlet (8) is provided in the fixed housing part (3a) and the separate inlets (6, 7) are provided in the movable housing part (3b).

26. 2. The underwater pelletizer according to claim 1, wherein the outlet (8) is provided on the upper side of the cutting chamber housing (3) and the separate inlets (6, 7) are provided in the lower half of the front cutting chamber housing (3).

27. 2. An underwater pelletizer according to claim 1, comprising a die plate (2), a cutting chamber housing (3) having a cutting chamber (4), and a rotatably drivable cutter head (5) arranged in the cutting chamber (4) for dividing the molten strand output from the die plate (2) into pellets, The cutting chamber (4) allows the flow of treated water which can be introduced into the cutting chamber (4) through at least one inlet (6, 7) and can be discharged from the cutting chamber (4) via an outlet (8) together with the cut pellets; The cutting chamber (4) has a volume that increases toward the outlet (8) when viewed from the circulation direction of the cutter head (5), The underwater pelletizer, wherein, viewed from the circumferential direction of the cutter head (5), the gap dimension (S) between the envelope contour of the cutter head (5) and the peripheral wall of the cutting chamber (4) and / or the axial depth (T) increases towards the outlet (8) in the direction of the rotation axis (20) of the cutter head.

28. 28. The underwater pelletizer according to claim 27, wherein the gap size (S) and / or the depth (T) respectively increase continuously towards the outlet (8) and / or are smallest in a sector located immediately after the outlet (8) and largest in a sector located immediately before the outlet (8), as viewed in the circulation direction of the cutter head (5).

29. 29. An underwater pelletizer according to claim 27 or 28, wherein the cutter head (5) is displaced eccentrically relative to the center of the cutting chamber (4), such that the displacement is directed towards a sector of the cutting chamber (4) reached by a cutting blade of the cutter head (5) after passing through the outlet (8).

30. 2. The underwater pelletizer according to claim 1, wherein at least one flow guide plate and / or at least one deflector (31) is provided in the cutting chamber (4) to prevent the cut pellets from circulating multiple times.

31. 31. The underwater pelletizer according to claim 30, wherein the at least one guide plate and / or the at least one deflector (31) in the region of the outlet (8) protrudes against the flow direction therein along the envelope contour of the cutter head (5) and / or is inclined at an acute angle to the envelope contour of the cutter head (5).

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