Pressing tool, underwater pelletizing device

Abstract

Pressing tool (100) for cutting and pre-pressing sealing cords (200) for stuffing box seals (300), wherein the pressing tool (100) comprises: a tool body (110) with a circularly circumferential recess (120) with a rectangular cross-section, which is bounded on one side by an outer wall (112) of the tool body (110), on an opposite side by an inner wall (114) of the tool body (110) and on a side between the outer wall (112) and the inner wall (114) by a bottom (116) of the tool body (110) and into which a sealing cord (200) can be inserted from a side opposite the bottom (116); characterized by the fact that the outer wall (112) and the inner wall (114) each have at least one slot (132, 134) extending from a top surface (118) of the tool body (110) to the bottom of the recess (120); the slot (134) in the inner wall (114) is a straight extension of the slot (132) in the outer wall (112); and the slots (132, 134) are suitable for receiving a knife with which a sealing cord (200) inserted into the recess (120) can be cut.

Description

[0001] The present invention relates to pressing tools and devices for underwater pelletizing which have stuffing box seals with such sealing cords.

[0002] Gland seals (or stuffing boxes) are used today in various technical fields to seal rotating shafts, e.g., in underwater pelletizing or twin-screw extruders. A gland seal typically consists of a bushing surrounding the shaft, into which a packing or sealing cord is inserted. This packing is pressed onto a constriction in the bushing by means of a so-called gland, an attachment that also surrounds the shaft. For example, the gland is screwed into the bushing or by screwing the gland onto the bushing or the constriction.

[0003] Stuffing boxes often serve to limit the leakage of medium, but not to completely prevent it. The axial pressure generated by the gland creates radial pressure, which presses the packing or packing cord against the shaft. This makes the gap so small that liquids or gases are blocked from passing through the stuffing box. To ensure the packing lasts longer than a few hundred shaft revolutions, lubrication is required. This preferably results from a thin film of liquid between the packing and the shaft. A slight leakage is therefore necessary for proper operation.

[0004] If a fluid-lubricated stuffing box is dry inside, it must be assumed that the packing and probably the shaft will soon need to be replaced. Lack of lubrication and pressure generate frictional heat, causing the packing to harden and lose its sealing function. Furthermore, steel shafts may begin to "flow" due to a lack of rust, meaning the shafts experience plastic deformation on their surface, which manifests as circumferential scoring and cannot be reversed. Even with a new packing, a seal will no longer be achieved.

[0005] The sealing packing or the sealing cord must be cut to the correct size to allow the sealing cord to be inserted into the bushing and to completely enclose the shaft. Typically, if the sealing packing consists of one or more sealing cords, particularly sealing cords with an essentially rectangular or square cross-section, the sealing cord is wound around the shaft and cut off by hand. This requires skill, as the cut surfaces must fit together exactly and must not be frayed. It is also advantageous to cut the sealing cord at a miter angle, e.g. with a miter of 30° or 45°. This makes the cut even more difficult due to the roundness of the shaft and thus of the sealing cord. A device that makes cutting sealing cords easier is therefore desirable.

[0006] A further problem with the use of sealing cords is that the shaping and pulling of the sealing cord required for cutting typically results in a trapezoidal cross-section of the sealing cord, with the sealing cord being wider on the side closest to the shaft than on the side furthest from the shaft. This trapezoidal shape is particularly harmful when multiple sealing cords are used, which must lie flush against one another to achieve the desired sealing effect. Due to the trapezoidal profile, the contact surfaces of the various sealing cords do not fully contact one another when pressed together using the gland. Since the sealing cords return to rectangular / square cross-sections over time due to their elastic properties, this causes a reduced sealing function.For this reason, a device is desirable that allows the cut sealing cords to be pre-pressed into a rectangular or square cross-section before being inserted into the stuffing box seal.

[0007] Sealing cords that must be cut and pre-pressed in the above manner are used, among other things, in underwater granulation devices, in which a rotating shaft rotates a cutting tool that cuts the plastic strands emerging underwater into granules. A device of this type with an improved gland seal is also desirable.

[0008] The above objects are achieved by the subject matter of the claims which define the present invention.

[0009] In particular, a pressing tool for cutting and pre-pressing sealing cords for stuffing box seals is specified, wherein the pressing tool has a tool body with a circular recess of rectangular cross-section, which is delimited on one side by an outer wall of the tool body, on an opposite side by an inner wall of the tool body, and on a side lying between the outer wall and the inner wall by a base of the tool body, and into which a (preferably rectangular or square) sealing cord can be inserted from a side opposite the base. The outer wall and the inner wall each have at least one slot extending from an upper side of the tool body to the base of the recess, wherein the slot in the inner wall is a linear extension of the slot in the outer wall.The slots are designed to accommodate a knife with which a sealing cord inserted into the recess can be cut.

[0010] What is essentially provided is a plate made of a sufficiently hard material, e.g. a metal such as iron, steel, aluminum or a hard plastic such as polyamide, which has a recess into which a sealing cord can be inserted. The recess can be located within the plate and can be produced, for example, by a machining process. In this case, the walls of the recess are part of the plate. However, the recess can also be formed by walls protruding from the upper side of the plate, e.g. in the form of a channel or trough. A tool body designed in this way can be produced, for example, by injection molding. The recess can also be a combination of both designs, e.g. it is partially recessed into the plate and partially formed by walls protruding from the plate.The tool body and all other parts of the press tool described below can also be manufactured using a 3D printing process.

[0011] The recess has a rectangular cross-section, allowing a sealing cord with the appropriate cross-section to be inserted into it. The pressing tool is designed for a specific sealing cord dimension, e.g., for graphite sealing cords with a square cross-section and an edge length of 14 mm. The pressing tool is also designed for a specific shaft dimension, e.g., for shafts with a diameter of 110 mm. Other typical edge lengths for sealing cords are 157 to 1414 mm, and other shaft diameters are 50 to 450 mm. The dimensions of the recess correspond to the desired dimensions of the sealing cord or shaft.

[0012] The pressing tool has slits in the walls forming the recess for cutting through a sealing cord lying in the recess. The slits can also be thought of as a single slit through which the recess runs. A knife can be guided safely and reliably from one slit to the other to cut the sealing cord along a smooth, precisely predefined cutting surface. In particular, it is possible to cut through an overlapping sealing cord inserted into the recess in the area of ​​the overlap, thus producing a sealing cord whose dimensions exactly match the dimensions of the shafts for which the pressing tool was designed. By precisely guiding the cut in the slits, the cutting process is simplified and a clean cut is possible regardless of the personal skill of the cutter. In addition, the recess prevents the sealing cord from fraying at the sides.

[0013] This significantly improves the quality of the cut and thus the usability of the sealing cord for waterproofing. Furthermore, the time required for cutting sealing cords is significantly reduced.

[0014] The slots in the outer and inner walls of the tool body can be arranged in such a way that they allow a 30° or 45° miter cut by inserting a sealing cord into the recess. This allows for precise and quick miter cuts, which are desirable for improved sealing.

[0015] The tool body can have a plurality of slot pairs consisting of a slot in the outer wall of the tool body and a slot in the inner wall of the tool body. This allows, on the one hand, various miter cuts to be made with the same tool body. On the other hand, a plurality of slots means that more cuts can be made with the same tool body. Even if a slot pair widens due to the large number of cuts made within it to the point where further cuts can no longer be made safely, additional slot pairs are available. This increases the service life of the tool body.

[0016] The tool body can have recesses that extend from the outer wall to the base of the tool body and allow a sealing cord inserted in the recess to be viewed from the outside and moved out of the recess from the side of the base. In addition to the slots on the top side of the tool body, the tool body also has recesses or slots that extend from the bottom of the tool body to the outer wall of the tool body. These recesses are used for visual inspection of the position of the sealing cord in the recess, particularly during the pre-pressing of the sealing cord as described below. They also allow the sealing cord to be removed from the recess again after cutting (and pre-pressing if necessary), e.g. by using a suitably shaped tool such as a screwdriver or spatula.This makes the pressing tool easier to operate, which in turn speeds up the production of suitably cut sealing cords.

[0017] The height of the inner wall, measured from the bottom of the recess, can be less than the radial width of the recess and preferably between 98% and 99% of the radial width of the recess. This allows the sealing cord to be pre-pressed by simply pressing on a cover in the area of ​​the inner wall. This facilitates and thus accelerates the production of a correctly cut and pre-pressed sealing cord.

[0018] The pressing tool can further comprise a cover that can be firmly pressed onto the tool body, preferably by screwing it to the tool body via openings provided in the cover and corresponding screw holes in the tool body. When pressed onto the tool body, the cover closes the recess with a smooth surface, and a sealing cord inserted into the recess is pressed into the shape of the closed recess when the cover is pressed onto the tool body.

[0019] This makes it easy to press a cut-to-size sealing cord into the cross-section of the recess. In particular, this avoids the formation of a trapezoidal cross-section. Because of the smooth design of the cover in the area of ​​the recess, the cover only needs to be pressed firmly enough onto the tool body. The smooth surface of the cover then forms the missing side of the rectangle defined by the recess. The cover can be pressed onto the tool body in a press, for example. However, it is preferable to connect the cover and tool body with screws, as the pressing tool can then be used to produce cut-to-size and pre-pressed sealing cords without the aid of additional devices.

[0020] When pressed against the tool body, the lid can rest on the inner wall but not the outer wall, and can touch the outer wall on its inside. This corresponds to a design of the tool body in which the outer wall is higher than the inner wall. The lid is then pressed against the inner wall, thereby exerting pressure on the sealing cord. The lid extends to the outer wall in such a way that it does not rest on it, but closes off the recess by resting against an inner side of the outer wall. This allows pressure to be exerted on a sealing cord inserted in the recess in a simple manner and with a simple design of the lid.

[0021] The cover can be disc-shaped and designed to close the recess with either side when pressed onto the tool body. If both sides of the cover are designed the same, this allows the cover to be applied to the tool body in any orientation. This facilitates the pre-pressing of sealing cords.

[0022] Alternatively, the lid can be flat on one, first side and have a circular elevation on the other, second side with a width equal to the width of the recess, which engages into the recess when the lid is pressed onto the tool body with its second side, wherein the height of the elevation is preferably between 0.5% and 2% of the height of the inner wall of the tool body measured from the bottom of the recess. In this way, pressure of varying strengths can be exerted on the sealing cord. A first pressure is created when the lid is pressed onto the tool body with the first, smooth side. A second, higher pressure is created when the elevation on the second side engages in the recess, since the height of the resulting cross-section of the recess is then smaller than in the case of the smooth side.This allows the pressure to be increased during the pre-pressing process if it is found that the pressure exerted by the smooth side is too low.

[0023] The lid can have at least one slot which, when the lid is pressed onto the tool body, is aligned with the at least one slot in the outer wall of the tool body and the at least one slot in the inner wall of the tool body. A sealing cord inserted into the recess can then be cut through the slot in the lid when the lid is pressed onto the tool body.

[0024] An underwater pelletizing device comprises an injection device for dispensing plastic strands, a cutting device attached to a rotating shaft for forming pellets by cutting the plastic strands, a water chamber through which the cutting device shaft runs and into which the pellets fall after the plastic strands are cut, and a stuffing box seal for sealing a passage of the shaft through an outer wall of the water chamber. The stuffing box seal comprises at least one, preferably several, sealing cords cut and pre-pressed using the pressing tool described above. This improves the sealing and lubricating effect of stuffing box seals in underwater pelletizing devices and thus the service life of the device or the shaft used therein.

[0025] The invention is described below by way of example with reference to the figures. This description should not be considered limiting. The invention is defined solely by the subject matter of the claims. It shows: Fig. 1A and Fig. 1B schematic views of a pressing tool. Fig. 2 another schematic view of a pressing tool. Fig. 3 a schematic view of an underwater granulation device.

[0026] The Fig. 1A and Fig. 1B show schematic views of a pressing tool 100 for cutting and pre-pressing sealing cords 200 for stuffing box seals 300. The Fig. 1A shows a top view of the pressing tool 100. The Fig. Figure 1B shows a section along line AA of the Fig. 1A.

[0027] As in the Fig. 1A and Fig. 1B, the pressing tool 100 has a tool body 110 with a circular recess 120 with a rectangular cross-section. In the example of Fig. 1A and Fig. 1B, the tool body 110 is cylindrical, and the circular recess 120 is arranged concentrically with the center of the tool body 110. However, the tool body can also have any other shape, as long as a circular recess 120 is arranged therein or thereon. The tool body 110 is formed from a hard material, e.g., a metal such as iron, steel, or aluminum, or a hard plastic such as polyamide. The tool body 110 can be produced using any manufacturing method known for the respective material, in particular by casting, injection molding, or 3D printing.

[0028] The recess 120 is bounded on one side by an outer wall 112 of the tool body 110, on an opposite side by an inner wall 114 of the tool body 110 and on a side lying between the outer wall 112 and the inner wall 114 by a bottom 116 of the tool body 110. In the example of Fig. 1A and Fig. 1B, the recess 120 is located within the tool body 110, i.e., the tool body 110 essentially consists of a plate within which the recess 120 is machined, e.g., by a machining process or by appropriate casting or injection molding. However, the walls 112, 114 of the tool body 110 can also protrude beyond a surface 118 of the tool body 110. In this case, the recess 120 can be arranged only partially within or completely above a base plate of the tool body 110. The decisive factor here is that the recess 120 has a stable inner contour with a rectangular cross-section.

[0029] In particular, the recess 120 is suitable for inserting a sealing cord 200 from a side opposite the base 116 of the tool body 110, which sealing cord is to be cut to size and pre-pressed in the pressing tool 100. The dimensions of the recess 120 or of the pressing tool 100 are therefore determined by the dimensions of the sealing cords 200 that are to be processed with the pressing tool 100. The pressing tool 100 is designed for a specific type of sealing cord 200, e.g., for sealing cords 200 with a square cross-section and an edge length between 3 mm and 30 mm, e.g., 10 mm, 14 mm, or 22 mm, which are made, for example, of graphite enclosed in a fabric, of PTFE, or the like. Since such sealing cords 200 are sufficiently known to a person skilled in the art, further description can be omitted here.

[0030] The dimensions of the recess 120 / the pressing tool 100 are further determined by the dimensions of the shaft to be sealed using the sealing cord 200 to be cut to size. Thus, the inner contour of the recess 120 precisely corresponds to the outer contour of the shaft to be sealed. The outer contour of the recess 120 is defined by the gland seal 300 used. It can correspond to the inner contour of the bushing of the gland seal 300 or have a larger diameter than the inner contour of the bushing. For example, the outer diameter of the recess can be between 1% and 3% of the shaft diameter larger than the inner contour of the bushing. The shaft can have a diameter in the range of 50 mm to 200 mm, e.g., 70 mm, 90 mm, 110 mm, or 150 mm. This then corresponds to the diameter of the inner contour of the recess 120.

[0031] As in the Fig. 1A and Fig. 1B, various slots 132, 134 are provided in the outer wall 112 and the inner wall 114, each extending from a top side 118 of the tool body 110 to the bottom of the recess 120. Although the Fig. 1A and Fig. 1B shows several such slot pairs 130, only a single pairing can also be present. The slots 134 in the inner wall 114 form rectilinear extensions of the slots 132 in the outer wall 112. In this sense, the slot pairs 130 can also be viewed as a slot each, which is separated by the recess 120 into the two slots 132, 134 in the walls of the recess 120. The slots 132, 134 are sufficiently dimensioned to accommodate a knife with which a sealing cord 200 inserted into the recess 120 can be cut through. For example, the slots have a thickness of 0.5 mm to 2.5 mm, e.g. 1 mm or 2 mm, depending on which type of knife must be used to cut through the material of the sealing cord 200.

[0032] Since the slots 132, 134 of the respective slot pairs 130 extend in a straight line to one another, a knife (or a comparable cutting tool) can be easily guided from one of the slots 132, 134 into the other, similar to the use of a miter saw. In particular, the knife can penetrate deeply into one slot 132, 134, while only shallowly into the other slot 132, 134 to define the cutting direction. The cut can then be accomplished simply and reliably by moving the knife from one slot 132, 134 to the other slot 132, 134. Preferably, the knife is moved from the inner slot 134 to the outer slot 132. The knife can also penetrate fully into both slots 132, 134 from above, thereby cutting the sealing cord 200.

[0033] Although in the Fig. 1A, the slots 132, 134 in the walls 112, 114 of the tool body 110 can be connected by a slot in the bottom 116 of the tool body 110. This further stabilizes the cut. However, such an additional slot is preferably not present to prevent the sealing cord 200 from being forced into this slot during cutting and thereby excessively deformed.

[0034] The pressing tool 100 therefore easily makes smooth and precise cuts through a sealing cord 200 that has been inserted into the recess 120 such that it overlaps in the area of ​​one of the pairs of slots 130. This allows a sealing cord 200 to be easily and reliably cut to the exact length required to encompass a corresponding shaft. The production of a correctly cut sealing cord 200 is thus significantly simplified and its quality improved compared to manual cutting.

[0035] As in the Fig. As can be seen in Figure 1A, the pairs of slots 130 can define different angles at which the sealing cord 200 is cut. For example, the Fig. 1A, the upper slot pairs 130 produce miter cuts at an angle of 30°, while the lower slot pairs 130 produce cuts at an angle of 45°. Depending on the position of the slots 132, 134, other cutting angles can also be realized.

[0036] The Fig. The plurality of slot pairs 130 shown in Figure 1A not only allows for the realization of different cutting angles, but also allows for redundancy of slots for a specific angle. It is to be expected that after numerous cuts along a slot pair 130, the respective slots 132, 134 will be notched, frayed, or widened by the knife. A smooth, precise cut may then no longer be possible for this slot pair 130. In this case, the pressing tool 100 can continue to be used for cutting if another slot pair 130 for the same cutting angle is available. This extends the service life of the pressing tool 100.

[0037] As in the Fig. 1A and especially in the Fig. As can be seen in Figure 1B, the tool body 110 has recesses 140 that extend from the outer wall 112 into the bottom 116 of the tool body 110. In the recesses 140, a portion of the outer wall 112 and the bottom 116 is missing in the area where the sealing cord 200 comes to rest in the recess. This makes it possible to view a sealing cord 200 inserted in the recess 120 from the outside through the recesses 140 and to move it out of the recess 120 from the side of the bottom 116.

[0038] Especially if the sealing cord as in the Fig. 1B is pressed into the recess 120 to impart a rectangular outer contour, the recesses 140 can be used to check whether the pressure on the sealing cord 200 is already sufficient to achieve the desired shape. Furthermore, after the pressing process, the sealing cord 200 can be grasped from below using a suitable tool, such as a screwdriver, a spatula, or the like, and pulled upward through the recess 140. Since the recesses 140 extend into the outer wall 112, the sealing cord 200 can be easily pulled upward across its full width, thereby reducing deformation of the sealing cord 200.

[0039] In principle, it would also be possible to distribute the functions of visual inspection and application of the sealing cord 200 to different recesses, which are then arranged only in the outer wall 112 and only in the bottom 116 of the tool body 110.

[0040] As particularly in the Fig. As can be seen in Figure 1B, the height of the inner wall 114, measured from the bottom of the recess 120, can be less than the width of the recess 120 in the radial direction. Preferably, the height of the inner wall 114 is between 98% and 99% of the width of the recess in the radial direction. This allows a cover 150 of the pressing tool 100 to abut the top side of the inner wall 114 and thereby exert pressure on a sealing cord 200 whose outer contour corresponds to the width of the recess 200. In this way, the sealing cord 200 can be pressed into shape particularly easily.

[0041] As in the Fig. As shown in Figure 1B, the pressing tool 100 preferably comprises a cover 150 that can be firmly pressed onto the tool body 110. In principle, the cover 150 could also be replaced by a punch of a pressing device into which the pressing tool 100 can be inserted. However, the cover 150 is preferably present so that cutting and pre-pressing can be performed solely with the pressing tool 100 without the aid of additional devices.

[0042] The cover is preferably screwed to the tool body 110 via openings 152 provided in the cover 150 and corresponding screw holes 115 in the tool body 110. However, any other method can also be used that ensures that the cover 150 is pressed sufficiently tightly onto the tool body 110. Sufficiently tightly means that the cover 150 hits the surface of the tool body 110 and cannot be brought closer to the tool body 110 even by applying further force (without deformation or destruction). An alternative to screwing is the use of a press or external screw clamps. However, the use of screws is preferable due to their simplicity.

[0043] As in the Fig. 1B, the cover 150, when pressed onto the tool body 110, closes the recess 120 with a smooth surface. As a result, the rectangular cross-section defined by the recess 120 on three sides is completed from above by the cover 150. By pressing on the cover 150, a sealing cord 200 inserted into the recess 120 is then pressed into the shape of the closed recess 120. This makes it easy to correct any trapezoidal cross-section of the sealing cord 200 that may have arisen during cutting (for sealing cords for whose dimensions the pressing tool 100 is designed). It goes without saying that this function of the pressing tool 100 can also be used for sealing cords 200 that were not cut in the pressing tool 100, since the dimensions of the pressing tool 100 are determined by the dimensions of the shaft to be sealed.

[0044] As in the Fig. 1B, the cover 150, when pressed against the tool body 110, rests on the inner wall 114, but not on the outer wall 112, even though the inner wall 114 has a lower height than the outer wall 112. The cover 150 is thus dimensioned such that its diameter exactly corresponds to the diameter of the outer contour of the recess 120. The cover therefore fits exactly onto the recess 120 and touches the outer wall 112 on its inner side. As a result, by simply screwing it tight onto the inner wall 114, which is lower than the outer wall 112 and whose height is less than the width of the recess 120, pressure can be exerted on the sealing cord 200, which pressure is sufficient to press the sealing cord 200 into shape.

[0045] The cover 150 is preferably disc-shaped and suitable for closing the recess 120 with each of its two sides 154, 156 when it is pressed onto the tool body 110 with the respective side 154, 156. This enables a "blind" closure of the recess 120 without consideration of the side of the cover 150 resting on the tool body 110, in particular if both sides 154, 156 are of the same design in the region of the recess 120. However, it goes without saying that the cover 150 can also have any other shape that closes the recess 120 as explained above. In particular, the cover 150 can also be designed such that it has only one side with which the recess 120 can be closed. The cover 150 can, for example, essentially have the shape of a cone or truncated cone.

[0046] It is particularly advantageous if the cover 150, as in the Fig. 1B, is flat on one, first side 154 and has a circular elevation 158 on the other, second side 156 with a width equal to the width of the recess 120, which engages into the recess 120 when the cover 150 is pressed onto the tool body 110 with its second side 156. The height of the elevation 158 is preferably between 0.5% and 2% of the height of the inner wall 114 of the tool body 110, measured from the bottom of the recess 120.

[0047] In the Fig. 1B shows how the cover 150 is screwed with its first side 154 onto the inner wall 114 of the tool body 110. This exerts a certain pressure on the sealing cord 200, which depends on the deviation of the height of the inner wall 114 from the outer contour of the sealing cord 200 and thus on the width of the recess 120. If it is determined during or after the pressing process, e.g. by visual inspection through the recesses 140 or by removing the cover 150, that this pressure is insufficient to press the sealing cord 200 into shape, the cover 150 can be turned over and pressed / screwed back onto the tool body 110. The second side 156 then rests on the inner wall 114, and the elevation 158 engages into the recess 120 between the inner wall 114 and the outer wall 112.This reduces the space between the cover 150 and the bottom 116 of the tool body 110 / the recess 120 compared to mounting the cover 150 with the first side 154 on the tool body 110. This reduction in space corresponds to an increase in the pressure on the sealing cord 200, which can thereby be (fully) pressed into shape. A cover 150 as shown in FIG. Fig. 1B, ie a cover with a projection 158 engaging in the recess 120 ensures that sealing cords 200 with slightly reduced dimensions can also be pressed into shape.

[0048] Although not shown in the figures, the cover 150 can also have at least one slot which, when the cover 150 is pressed onto the tool body 110, is aligned with the at least one slot 132 in the outer wall 112 of the tool body 110 and the at least one slot 134 in the inner wall 114 of the tool body 110. A sealing cord 200 inserted into the recess 120 can then be cut through by the slot in the cover 150 when the cover 150 is pressed onto the tool body 110.

[0049] The Fig. 2 shows a schematic exploded view of the pressing tool 100 and a pre-cut sealing cord 200 inserted therein. The pressing tool 100 of the Fig. 2 corresponds to the pressing tool 100 described above of the Fig. 1A and Fig. 1B. The Fig. 2 therefore serves only for further illustration.

[0050] The underwater pelletizing device 400 comprises an injection device 410 for dispensing plastic strands, a cutting device 425 attached to a rotating shaft 420 for forming pellets by cutting the plastic strands, a water chamber 430 through which the shaft 420 of the cutting device 425 passes and into which the pellets fall after the plastic strands are cut, and a stuffing box seal 300 for sealing a passage of the shaft 420 through an outer wall 435 of the water chamber 430. The structure of the underwater pelletizing device 400 thus corresponds to the typical structure known to a person skilled in the art. A further detailed description can therefore be omitted.

[0051] The stuffing box seal 300 has at least one, preferably several, sealing cords 200, which are cut and pre-pressed using the pressing tool described above. This allows the shaft 420 to be reliably sealed. List of reference symbols 100 pressing tools 110 tool bodies 112 Outer wall of the tool body 114 Inner wall of the tool body 115 screw holes in the tool body 116 Bottom of the tool body 118 Top of the tool body 120 deepening 130 pairs of slots 132 Slot in the outer wall 134 Slot in the inner wall 140 recesses 150 lids 152 openings in the lid 154 First side of the cover 156 Second side of the lid 158 elevation on the lid 200 sealing cord 300 stuffing box seal 400 Underwater pelletizing device 410 Spraying device 420 wave 425 cutting device 430 Water Chamber 435 Outer wall of the water chamber

Claims

[1] Pressing tool (100) for cutting and pre-pressing sealing cords (200) for stuffing box seals (300), the pressing tool (100) comprising: a tool body (110) with a circular recess (120) with a rectangular cross-section, which is delimited on one side by an outer wall (112) of the tool body (110), on an opposite side by an inner wall (114) of the tool body (110) and on a side lying between the outer wall (112) and the inner wall (114) by a bottom (116) of the tool body (110) and into which a sealing cord (200) can be inserted from a side opposite the bottom (116); characterized by , that the outer wall (112) and the inner wall (114) each have at least one slot (132, 134) extending from a top side (118) of the tool body (110) to the bottom of the recess (120); the slot (134) in the inner wall (114) is a straight extension of the slot (132) in the outer wall (112); and the slots (132, 134) are suitable for receiving a knife with which a sealing cord (200) inserted into the recess (120) can be cut through. [2] Press tool (100) according to claim 1, wherein the slots (132, 134) in the outer wall (112) and the inner wall (114) of the tool body (110) are arranged such that they allow a mitre cut of 30° or 45° by a sealing cord (200) inserted into the recess (120) and / or the tool body (110) has a plurality of slot pairs (130) consisting of a slot (132) in the outer wall (112) of the tool body (110) and a slot (134) in the inner wall (114) of the tool body (110). [3] Press tool (100) according to one of the preceding claims, wherein the tool body (110) has recesses (140) which extend from the outer wall (112) into the bottom (116) of the tool body (110) and allow a sealing cord (200) inserted in the recess (120) to be viewed from the outside and moved out of the recess (120) from the side of the bottom (116). [4] Press tool (100) according to one of the preceding claims, wherein a height of the inner wall (114) measured from the bottom of the recess (120) is less than a width of the recess (120) in the radial direction and preferably between 98% and 99% of the width of the recess in the radial direction. [5] Press tool (100) according to one of the preceding claims, further comprising a cover (150) which can be pressed firmly onto the tool body (110), preferably by screwing it to the tool body (110) via openings (152) provided in the cover (150) and corresponding screw holes (115) in the tool body (110); wherein the cover (150) closes the recess (120) with a smooth surface when pressed onto the tool body (110); and a sealing cord (200) inserted into the recess (120) is pressed into the shape of the closed recess (120) when the cover (150) is pressed onto the tool body (110). [6] Press tool (100) according to claim 5, wherein the cover (150) in a state pressed against the tool body (110) rests on the inner wall (114) but not on the outer wall (112) and touches the outer wall (112) on its inside and / or the cover (150) is disc-shaped and is suitable for closing the recess (120) with each of its two sides (154, 156) when it is pressed onto the tool body (110). [7] Press tool (100) according to claim 6, wherein the cover (150) is flat on one, first side (154) and has on the other, second side (156) a circular elevation (158) with a width equal to the width of the recess (120), which engages in the recess (120) when the cover (150) is pressed with its second side (156) onto the tool body (110), wherein a height of the elevation (158) is preferably between 0.5% and 2% of the height of the inner wall (114) of the tool body (110) measured from the bottom of the recess (120). [8] Press tool (100) according to one of claims 4 to 7, wherein the cover (150) has at least one slot which, when the cover (150) is pressed onto the tool body (110), is aligned with the at least one slot (132) in the outer wall (112) of the tool body (110) and the at least one slot (134) in the inner wall (114) of the tool body (110); and a sealing cord (200) inserted into the recess (120) can be cut through the slot in the cover (150) when the cover (150) is pressed onto the tool body (110). [9] Device (400) for underwater granulation with a spraying device (410) for dispensing plastic strands; a cutting device (425) attached to a rotating shaft (420) for forming granules by cutting the plastic strands; a water chamber (430) through which the shaft (420) of the cutting device (425) runs and into which the granulate falls after the plastic strands have been cut; and a stuffing box seal (300) for sealing a passage of the shaft (420) through an outer wall (435) of the water chamber (430); characterized by , that the stuffing box seal (300) has at least one, preferably several, sealing cords (200) cut and pre-pressed by means of the pressing tool (100) according to claims 1 to 8.

Images