Perforated plate for melt hot cutting granulation and manufacturing method thereof

Abstract

The invention relates to a perforated plate (8) for hot-cut pelletizing of molten material such as polymer melt, the perforated plate comprising a perforated plate body (10) having melt channels (7) which pass through the perforated plate body and lead to an outlet face (6) distributed in an annular pattern, on which the discharged melt beam is cut by a rotating knife. The invention also relates to a pelletizing head having such a perforated plate and an underwater or water ring pelletizer having such a pelletizing head. According to the invention, the perforated plate body comprising at least one hollow chamber (12) for controlling the temperature of the perforated plate and / or for thermally isolating the melt channel and the main body surrounding the melt channel are formed into an integral layered structure by additive material coating, the individual material layers of which solidify layer by layer and individually, so that the hollow chamber walls and the melt channel walls can be organically rounded, thereby facilitating the flow of a temperature control medium. The invention also relates to a method for manufacturing such a perforated plate.

Description

Technical Field

[0001] The invention relates generally to the granulation of a melt-like material, such as a polymer melt, which is extruded through melt channels of a perforated plate and is hot-cut and divided into granules on the outlet side. The invention relates, on the one hand, to a perforated plate with a perforated plate body, comprising melt channels which pass through the perforated plate body and are connected in an annularly dispersed arrangement at an outlet face, on which the discharged melt strands are hot-cut by rotating knives, a granulator, in particular an underwater granulator, a water ring granulator or an air granulator. On the other hand, the invention relates to a method for producing such a perforated plate, a granulator head with such a perforated plate, and a granulator with such a hot-cut granulator head. Background Art

[0002] Such a perforated plate can work together with a cutter head of a granulator, the rotating cutter of which scrapes along the outlet surface of the perforated plate to hot cut the melt stream discharged from the melt channel, wherein the outlet surface forms an engagement surface or matching surface for the rotating cutter in a manner surrounding the orifice of the melt channel, and the engagement surface or matching surface is usually flat, but can also be convex, concave or curved so as to support the scraped blade planarly or linearly according to the contour of the cutter.

[0003] In the case of an underwater pelletizer, the knives rotate in a water bath so that the cut pellets do not stick together and solidify or cool to a point where they can be more easily handled.

[0004] In the case of a water ring pelletizer, the knives and the perforated plate end faces are not located in a water bath, but are surrounded on the circumference by an annular, flowing water flow, which entrains and transports the cut pellets and cools them here to start solidification. The rotating knives cut the melt strands that emerge from the perforated plate end faces in a dry manner and throw the still hot melt-like pellets into the surrounding water ring. Although the "water ring" can consist of water, it does not necessarily have to consist of water, but can also include another conveying and / or cooling medium, for example in the form of a liquid level mixture, or can also be present at least partially in the form of a droplet stream and / or a spray stream or a mixture thereof. Even in the case of the above-mentioned underwater pelletization, although the water bath or the water flow flowing through the perforated plate and the knives can consist of water, they do not necessarily have to consist of water, but another conveying and / or cooling medium can also be used in a similar manner.

[0005] In the case of air or cooled air granulators, hot cutting is carried out dry, wherein a rotating knife can also be scraped along a perforated plate here to cut off the melt strands emerging from the channel orifices. The hot cut granules are further conveyed and cooled by the air stream, which takes longer since the thermal conductivity of air is lower than that of water.

[0006] In the cases described, especially in the case of underwater granulation and water ring granulation, but also to a certain extent in the case of air granulation, the perforated plate is not only subjected to mechanical stresses caused by the scraping of the knife, but also to complex thermal requirements caused by hot cutting. On the one hand, the melt or melt strand should flow through the perforated plate and be discharged therefrom within a specific temperature window in order to prevent the melt channel from freezing and at the same time to comply with the temperature limits of the material to be granulated. This requires that the perforated plate should have a specific, usually relatively high temperature. On the other hand, the surroundings of the perforated plate in the form of a water bath or water ring are relatively cold, so that very high temperature gradients can occur across the perforated plate.

[0007] In order to prevent the perforated plate from being excessively cooled from its outlet side, in particular when it is used in an underwater pelletizer and is flushed by a water bath and in contact with cooler process water, such perforated plates are sometimes constructed to be thermally insulated or provided with thermal insulation. For example, such thermal insulation can include a hollow chamber inside the perforated plate body, which can be designed to be as large as possible in order to avoid heat being directly transferred from the hotter inlet side of the perforated plate to the cooler outlet side through the highly thermally conductive, usually metallic material of the perforated plate body.

[0008] As an alternative or in addition to such hollow chambers filled with air or gas or vacuum, it is also known to heat the perforated plates from the inside, wherein a heating fluid circulates through the hollow chambers or separate heating channels.

[0009] Even though cooling by means of a flowing water ring and freezing of the melt channels or channel openings are less problematic in water ring granulators, water ring granulators must also observe precise temperature control of the material to be granulated. In principle, this also applies in a similar manner to air granulators. Water ring granulators and air granulators are used not only for the granulation of thermoplastics, but also for the granulation of pharmaceuticals or foods, which often react sensitively to incorrect temperatures during the granulation process and require very narrow temperature windows, so that the perforated plates need to be precisely heated and / or cooled or insulated.

[0010] For example, documents US 2006 / 0165834 A1, US 2007 / 0254059 A1, WO 2010 / 019667 A1 or DE 40 36 196 A1 disclose perforated plates for underwater pelletizing.

[0011] Here, the last-mentioned document WO 2010 / 019667 A1 proposes to thermally isolate the melt channel and the wear ring to which the melt channel leads from the rest of the perforated plate body by means of an insert made of a relatively low conductivity material. DE 40 36196 A1 proposes to provide heating medium channels between the melt channels of the perforated plate and to form additional thermal insulation channels in the perforated plate body between these heating medium channels and the plate end face formed by the water bath and forming the porous portion outlet face (the melt channel leads to the perforated plate outlet face), through which inert gas as a thermal insulation medium flows.

[0012] For example, documents AT 508 199 B1 or DE 10 2012 012 070 A1 disclose perforated plates for water ring granulation.

[0013] For example, document EP 26 99 235 B1 discloses a perforated plate for air or cooled air granulation.

[0014] Due to various thermal insulation and temperature control measures, such perforated plates have increasingly complex geometries, which entails corresponding manufacturing costs. In particular, it is difficult to produce hollow chambers in perforated plates.

[0015] Furthermore, such perforated plates require sufficient stability to withstand external forces and thermal stresses. In addition to the stresses caused by the rotating cutters, the perforated plates must also withstand the hydraulic pressure of the process water in the underwater tank on the outlet side. In addition, large temperature gradients in the perforated plates can cause thermal stresses. It can be seen in this regard that the perforated plates are hollowed out over large areas for thermal insulation purposes or for temperature control, and the walls that delimit the temperature-controlled hollow chambers are usually very thin on the inlet and outlet sides of the perforated plates, so that even limited water pressure can lead to deformations. At the same time, the perforated plates must remain permanently sealed and crack-free to prevent the ingress of process water. Summary of the invention

[0016] In view of this, the object of the present invention is to provide an improved perforated plate, an improved granulating head with such a perforated plate, an improved granulating machine and an improved method for producing such a perforated plate, which avoid the disadvantages of the prior art and develop the prior art in an advantageous manner. In particular, an improved adaptability of the perforated plate structure to thermal requirements and conditions of use should be achieved without losing mechanical stability.

[0017] Therefore, it is proposed that the perforated plate is not assembled from various inserts and covers, but is constructed layer by layer by additive material coating with the required contour including at least one hollow chamber, thereby eliminating the geometric shape restrictions of conventional perforated plates, such as those caused by cutting and welding plate parts. According to the present invention, by additive material coating, the perforated plate body including at least one hollow chamber for temperature control and / or thermal insulation and the main part surrounding the melt channel is formed as an integral layered structure, and the individual material layers of the layered structure are solidified layer by layer and separately. By additive material coating and the contours generated layer by layer, on the one hand, complex, smooth and organically growing wall shapes can also be achieved in the area of ​​the hollow chamber designed for temperature control or thermal insulation, which makes the perforated plate stable and prevents the formation of cracks, and also facilitates the flow of the temperature control or thermal insulation medium flowing through the hollow chamber. At the same time, by the integral layered structure, a compact design can be achieved despite the presence of the hollow chamber and the melt channel.

[0018] In particular, the layer-by-layer structured perforated plate body can be formed from a metal material. Independently of this, the layer-by-layer structured perforated plate body can be constructed from a plurality of layers in a 3D printing process using a 3D printing head, in a stereolithography process or in other additive manufacturing processes.

[0019] In particular, the material layers can be liquefied and / or solidified layer by layer by energy beams. For example, one or more materials in powdered and / or pasty and / or liquid form can be applied layer by layer, and they are melted and / or solidified and / or hardened and / or chemically reacted layer by layer by laser beams, electron beams or plasma beams to form hardened layers respectively. By layer-by-layer design, even small parts of the surface profile can be precisely matched in the area of ​​the temperature-controlled and / or thermally isolated hollow chamber or in other difficult-to-form parts (for example, melt channel walls or heating fluid joints or channels with varying curvatures and / or ridged or rounded transitions between different profile parts).

[0020] The melt channels can be formed in channel columns which are at least partially arranged in a self-supporting manner in the hollow chamber of the perforated plate body and are formed integrally and homogeneously with the walls of the perforated plate body which delimit the hollow chamber on opposite sides. Here, the channel columns through which the melt channels extend can grow organically from the inlet-side and outlet-side body walls which delimit the cavity between them, thereby not only creating a stable structure, but also avoiding sealing problems at the outlet of the melt channels.

[0021] The channel column can be constructed layer by layer in the described manner together with other contour parts of the perforated plate body in parallel or continuous working steps, in particular by printing through a 3D printing process. Here, the channel column can first be formed as a solid material body, and then the corresponding melt channel is processed in the channel column in a subsequent processing step. Alternatively, the channel column can also be provided with blind holes or through holes during the layer-by-layer construction, and then the blind holes or through holes can be processed in subsequent processing steps, for example, drilling and / or polishing and / or grinding. Advantageously, the melt channel has a wall surface with a lower roughness that is as smooth as possible, so as to hinder the melt flow as little as possible. The outer wall of the channel column can remain unprocessed or have a layered structure surface, while the melt channel wall is advantageously processed, in particular drilled and / or milled and / or polished and / or ground and / or honed.

[0022] In order to reduce stress peaks in the root region of the channel column or even prevent crack formation in the transition region to the inlet and outlet side main body wall, the channel column can preferably have smoothly widening ends and / or have a rounded peripheral contour in the transition region to the adjacent perforated plate wall when viewed in cross section. In particular, the channel column can be undercut on its outer wall in two axial directions parallel to the melt flow. However, due to the layer-by-layer construction, demoulding problems that are common to such undercut contours do not occur.

[0023] In an improved example of the present invention, in order to achieve sufficient stability of the end wall of the perforated plate defining the hollow chamber even when the hollow chamber extends over a large area, a supporting wall or pillar can be arranged inside the hollow chamber, which connects the inlet-side main body wall to the outlet-side main body wall and supports them mutually.

[0024] In a refinement of the invention, the supporting walls and / or struts are also constructed layer by layer or are designed as a layered structure and / or are integrally formed onto the main body wall which delimits the hollow chamber on opposite sides, in particular on the inlet and outlet sides of the perforated plate. By integrally forming the supporting walls and / or struts onto the end walls of the perforated plate, the stability can again be significantly increased. At the same time, by means of the additive layer-by-layer construction, a very slender profile of the supporting walls or struts can be achieved, thereby avoiding undesired heat transfer.

[0025] Advantageously, a plurality of supporting walls and / or pillars may be arranged dispersedly on the hollow chamber in order to achieve uniform support and / or also achieve distribution of the temperature control fluid when the temperature control fluid flows through the hollow chamber. Advantageously, for example, more than 10, more than 20, or more than 30 supporting walls and / or pillars may be arranged in the hollow chamber.

[0026] The wall thickness or column thickness or the wall diameter or column diameter of the support wall and / or the support column may be less than 40% or less than 30% or less than 20% of the height of the corresponding support wall or the corresponding support column.

[0027] In a refinement of the invention, the support walls and / or the struts may form a support structure which is substantially evenly distributed in the hollow chamber and / or forms a uniform support pattern.

[0028] In an improved example of the present invention, the support walls and / or support columns can form a wavy pattern and / or have a wavy profile when viewed from a cross section perpendicular to the main flow direction of the melt and / or when the exposed hollow chamber is observed in a direction roughly parallel to the melt flow direction when the end wall of the perforated plate is cut off.

[0029] The supporting walls and / or struts can extend along parallel wavy lines from one side of the perforated plate to the opposite side of the perforated plate, in particular from the side of the perforated plate having the inlet for the temperature control medium to the opposite side of the perforated plate having the outlet for the temperature control medium. Thus, despite the presence of a large number of supporting walls and / or struts, the temperature control fluid introduced into the hollow chamber can flow uniformly through the perforated plate. In the case of a wavy profile of the supporting walls, the temperature control effect of the fluid flowing through can be further improved.

[0030] In a modified example of the invention, the support wall can have openings whose edge contours can be at least partially rounded and / or designed as an arch. In particular, the arch-shaped openings can be arranged in a row adjacent to each other in the support wall, so that the corresponding support wall has a row of window-shaped or arch-shaped openings. By means of the rounded edge contours, stress peaks can be avoided and a uniform introduction of forces can be achieved.

[0031] In an improved example of the present invention, the hollow chamber can extend at least in the inner area of ​​the perforated plate surrounded by the annular pattern of the melt channel and / or at least in the outer area of ​​the perforated plate surrounding the annular pattern of the melt channel. Advantageously, the hollow chamber extends on the outside and inside of the melt channel so that two adjacent adjacent areas of the annular melt channel pattern are thermally isolated and / or can be temperature controlled. In particular, the hollow chamber extends from the inside to the outside beyond the melt channel or the channel column with the melt channel formed inside, so that the melt channel is arranged in the hollow chamber independently.

[0032] The hollow chamber can extend over at least 30% or even more than 50% or more than 60% or more than 70% of the cross-sectional area of ​​the perforated plate to achieve the best possible thermal isolation and / or temperature control. Independently of this, the height of the hollow chamber in the axial direction (i.e., in the direction of the tool axis of rotation or in the melt flow direction) can be at least 25% of the height or thickness of the perforated plate, or also greater than 33% or also greater than 50%.

[0033] In order to discharge the unsolidified raw material powder or raw material from the hollow chamber formed during the additive manufacturing of the perforated plate, the perforated plate can have at least one drain opening, preferably a plurality of dispersed drain openings, which lead out of the hollow chamber and open to the outside of the perforated plate, preferably to one of the opposite end faces of the perforated plate. Advantageously, the drain opening can open to the inlet side of the perforated plate, through which the perforated plate is placed on the connecting body of the granulation head, so that the drain opening is covered or closed in the assembled state of the granulation head.

[0034] To avoid premature wear of the perforated plate, a wear-resistant hard material ring can be placed on the outlet side of the perforated plate, along the outer side of which the tool of the tool head moves in order to cut off or cut off the discharged melt strand. The outer side of the wear-resistant hard material ring forms a tool sliding surface that interacts with the tool, along which the rotating tool can slide and against which the tool can be pressed.

[0035] The wear-resistant hard material ring can be manufactured separately from the layered structure of the perforated plate and fastened to the perforated plate body designed as a layered structure in various ways (for example, brazing or soldering).

[0036] However, in an alternative improved example of the present invention, the perforated plate body constructed layer by layer can also be connected to the hard material ring in a material-bonded manner and / or constructed on the hard material ring during the layer-by-layer construction. The hard material ring can be used as a substrate, and then the perforated plate body is constructed layer by layer on the substrate, wherein the lowest layer of the layered structure or a layer directly adjacent to the hard material ring is connected to the hard material ring by material bonding and / or micro-shape matching and / or chemical bonding. If the powder layer or raw material layer directly located on the hard material ring melts and solidifies, the solidified layer material engages into the micropores of the hard material and firmly covers them. Therefore, not only subsequent connection steps such as welding are saved, but also a tight connection between the hard material ring and the adjacent perforated plate body is achieved.

[0037] The hard material ring may be a single layer design, or not constructed in 3D printing.

[0038] However, on the other hand, the perforated plate body designed as a layered structure can also be constructed from the opposite side (i.e., the inlet side), wherein, in an advantageous improved example of the present invention, the layered structure can be directly constructed on a connecting piece of the granulation head adjacent to the layered structure. The connecting piece can have a distribution chamber and / or a distribution channel to distribute the molten material from a melt source (e.g., an extruder) to the melt channel of the perforated plate.

[0039] Here, the perforated plate body constructed layer by layer in the additive process can be connected to the connecting body of the granulation head in the described manner by material bonding and / or micro-form fit, for example by melting and solidifying the powder layer located on the connecting part, so that material bonding and / or micro-form fit and / or chemical bonding are produced in the described manner.

[0040] However, as an alternative to such shaping of the perforated plate body during additive manufacturing of the perforated plate body, the perforated plate body can also be connected to the pelletizing head in a different manner, for example screwed and / or welded and / or fastened thereto in another manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The invention will be explained in more detail below on the basis of preferred exemplary embodiments and the corresponding drawings.

[0042] Figure 1 A schematic partial cross-sectional view of a pelletizing head and a cutter head of a hot-cut pelletizer (eg, an underwater pelletizer) is shown, showing an additively manufactured perforated plate placed on a connector of the pelletizing head and a cutter of the cutter head scraping across the perforated plate.

[0043] Figure 2 Show Figure 1 A perspective view of a hot-cut pelletizing head in , showing a perforated plate and its hard material ring into which the melt channel opens.

[0044] Figure 3 A cross-sectional view of the perforated plate in the above figures is shown, illustrating the hollow chamber inside the perforated plate and the channel pillars through which the melt channels extend.

[0045] Figure 4 A partial perspective oblique view of a section of a perforated plate is shown illustrating the profile of the channel pillars.

[0046] Figure 5 A perspective cutaway view of a perforated plate is shown showing the perforated plate body without hard material rings and with melt channels not yet drilled, wherein supporting walls and / or strut structures according to an advantageous embodiment of the invention are shown in the hollow chamber of the perforated plate.

[0047] Figure 6 Shows something like Figure 5A perspective, cross-sectional oblique view of a perforated plate showing the inlet side of the perforated plate and illustrating the arched opening through the supporting wall.

[0048] Figure 7 Show Figure 5 and 6 Cross-sectional view of the perforated plate in .

[0049] Figure 8 The above figures show a top view of the perforated plate and a cross-sectional top view of the supporting wall structure in the hollow chamber of the perforated plate, which shows the wavy supporting wall shape of the supporting wall structure. DETAILED DESCRIPTION

[0050] like Figure 1 As shown, the hot-cut granulator 1 includes a fixedly arranged granulator head 2 and a tool head 3, which can be driven rotationally around a tool head axis 4 and can be pressed and / or pushed and / or pre-tensioned onto the granulator head 2 in the direction of the tool head axis 4, so that the tool 5 arranged on the end face of the tool head 3 can slide along the tool sliding surface 6 of the granulator head 2.

[0051] Melt channels 7 distributed in an annular pattern open into the tool sliding surface 6. These melt channels 7 pass through the pelletizing head 2 and can be supplied with melt from the inlet side of the pelletizing head 2, for example, by an extruder, which kneads the melt and conveys it under pressure to the pelletizing head 2. The melt channels 7 distributed in an annular pattern can communicate on the inlet side with a distribution chamber, which is supplied with pressurized melt in the described manner.

[0052] The melt channels 7 can be arranged on a common pitch circle, but can also be arranged offset inwardly and / or outwardly relative to such a pitch circle if necessary, wherein more than two rows of melt channels can also be arranged dispersedly in an annular manner.

[0053] like Figure 1 As shown, the granulation head 2 comprises a perforated plate 8, which is placed with its inlet-side end face on a connecting body 9 of the granulation head 2. The annular pattern of the melt channel 7 extends through the perforated plate body 10 of the perforated plate 8 and communicates with a correspondingly arranged melt channel in the connecting body 9.

[0054] A wear-resistant hard material ring 11 is placed on the outlet side of the perforated plate body 10, through which the melt channel 7 continues and leads to the outside of the hard material ring. Here, the outside of the hard material ring 11 forms a tool sliding surface 6, along which the tool 5 of the tool head 3 slides to cut off or cut off the discharged melt strand.

[0055] As shown in the figure, the tool sliding surface 6 and / or the outlet end face of the perforated plate 8 can be designed to be substantially flat and / or extend substantially perpendicularly or transversely to the tool head axis 4, about which the tool head 3 rotates. However, alternatively, the outlet side of the perforated plate 8 and / or at least the tool sliding surface 6 to which the melt channel 7 leads can also have an arched or conical or inclined profile relative to the tool head axis 4, such as a truncated spherical or truncated cone or other annular surface profile, wherein, in this case, the melt channel 7 can advantageously lead to the inclined tool sliding surface 6 at an angle and / or perpendicularly relative to the tool head axis 4.

[0056] Independently of this, the inlet-side end face of the perforated plate 8 can also have an arched structure or a conical profile, or be designed to be concave or convex in other ways. Figure 1 In the substantially flat design shown, the inlet side can be placed on a likewise flat end face of the connecting body 9 .

[0057] In the case of underwater granulation, the knife 5 rotates in a water bath in a cutting chamber that surrounds the knife head 3 and adjoins the perforated plate outlet face, so that the emerging melt strand is cut off in the water bath (see WO 2010 / 019667A1). In the case of a water ring granulator, the knife and the perforated plate end face are not located in a water bath, but are surrounded on the circumference by a flowing annular water flow, which entrains and transports the cut pellets and cools them there to initiate solidification. The rotating knife cuts off the melt strand emerging from the perforated plate end face in an inherently dry manner and throws the still hot melt-like pellets into the surrounding water ring (see AT 508 199 B1).

[0058] As shown, the perforated plate 8 has a hollow chamber 12 in its interior, which is configured to thermally isolate and / or temperature control the perforated plate 8, such as heating or cooling the perforated plate, and is bounded by two main body walls 13 and 14 towards the inlet side end face and the outlet side end face of the perforated plate. The hollow chamber 12 is closed toward the peripheral side by a peripheral side wall 15, which is circumferentially connected to the main body walls 13 and 14 of the two end sides, and is particularly formed integrally with the main body walls of the two end sides using homogeneous materials. In particular, the hollow chamber 12 can be arranged to temperature control the melt channel 7, for example, by heating the melt channel by a heating medium flowing through the hollow chamber 12, and / or thermally isolating these melt channels from the outlet end face of the perforated plate 8.

[0059] As shown, the temperature-controlled and / or thermally isolated hollow chamber 12 can extend substantially over the entire cross-sectional area of ​​the perforated plate 8, in particular filling the inner region within the melt channel annular pattern and / or filling the region of the annular pattern surrounding the melt channel on the outside. In particular, the hollow chamber 12 can extend from the inside to the outside across the melt channel 7, so that the melt channel 7 or the channel column 16 through which the melt channel 7 extends is arranged independently in the hollow chamber 12 and passes through the hollow chamber 12.

[0060] The perforated plate body 10, which includes the end body wall and the peripheral side walls 13, 14 and 15 and the channel column 16 that jointly define the hollow chamber 12, is designed as a layered structure (Schichtbaukörper), and the individual layers of the layered structure are solidified layer by layer. In particular, the layered structure can be manufactured by a 3D printing process, wherein the body wall and the peripheral side walls 13, 14, 15 and the channel column 16 can be connected to each other in an integral manner and homogeneously, and are respectively constructed layer by layer.

[0061] like Figures 3 to 6 As shown, the channel column 16 can first be constructed layer by layer as a solid material column. Then, the melt channel 7 can be processed in the channel column 16 so that the melt channel 7 can extend from the inlet side of the perforated plate 8 through the perforated plate to the outlet side of the perforated plate in the form of a through hole with a variable cross section as required.

[0062] As shown in the figures, the channel pillar 16 may advantageously have a tapered profile overall, or have an outer side with a tapered profile, which may taper gradually from the inlet side towards the outlet side, for example.

[0063] Independently of this conical profile, the ends of the channel column 16 can widen toward the adjacent main body walls 13 and 14 and / or have a rounded profile, so that the channel column 16 can have a smooth thickening or widening portion at the end and a smooth, rounded transition portion to the main body walls 13 and 14.

[0064] In order to support the relatively thin end body walls 13 and 14, support walls 17 and / or pillars may be provided in the hollow chamber 12, which may form an integral honeycomb support structure 18 that interconnects or supports the opposing body walls 13 and 14.

[0065] The support structure 18 can be integrally connected to one or both of the opposing main body walls 13 and 14, in particular can be materially formed thereon by layer-by-layer construction. Independently of this, the support structure 18 can be formed layer-by-layer as a layered structure, in particular by a 3D printing process. Advantageously, the support structure 18 can be manufactured in parallel with the layer-by-layer construction of the main body walls and / or the peripheral side walls 13, 14, 15 or the channel pillars 16 during the 3D printing process.

[0066] In this case, the supporting wall 17 can be characterized by a relatively thin wall thickness, wherein, for example, a wall thickness / wall height ratio of 1:5 or 1:7 or even less can be provided.

[0067] like Figure 8 As shown, when the support wall 17 is viewed in a direction parallel to the tool head axis, the support wall 17 can have a wavy linear profile. Here, the wavy shape can follow a substantially straight wave extension direction, but if necessary, an arc-shaped wave extension direction can also be provided. In particular, the wavy support wall 17 can extend from one side of the perforated plate towards the opposite side of the perforated plate.

[0068] Independently of this, the support walls 17 can extend substantially parallel to one another and / or be designed with a substantially constant gap dimension between them.

[0069] Advantageously, more than 10 or more than 20 support walls 17 can be provided, which are in particular arranged to extend parallel to one another.

[0070] As shown in the figure, the support walls 17 can be respectively provided with openings 19, preferably in the form of windows or arches, through which adjacent channels between adjacent support walls are connected to each other. If the temperature control fluid flows through the support structure 18, the temperature control fluid can flow through the openings in a manner transverse to the direction of the support walls and be evenly distributed on the hollow chamber.

[0071] Advantageously, the opening 19 in the support wall 17 may be at least partially rounded in an arcuate manner, in particular rounded in an arcuate manner or have a rounded portion towards at least one main body wall 14. The support wall 17 may form an arch around the opening 19.

[0072] like Figure 3 As shown, the perforated plate 8 can have an inlet connection and an outlet connection 21 and 22, through which a temperature control medium such as oil or water or a mixture for the temperature control of the perforated plate can be introduced into the perforated plate or discharged from it or passed through the perforated plate ring. Here, the temperature control medium can especially circulate through at least a portion of the hollow chamber 12, wherein the supporting wall 17 can disperse the temperature control medium.

[0073] like Figure 4 and Figure 6 As shown, the perforated plate 8 may also have an exhaust opening 23, which may connect the hollow chamber 12 to the outside. The exhaust opening 22 enables uncured powder from the 3D printing process to be removed from the hollow chamber 12.

[0074] Advantageously, the drain opening 23 can open into the inlet end face of the perforated plate 8 , so as to be covered when the latter is placed on the connecting body 9 of the granulating head 2 .

[0075] Advantageously, the perforated plate body 10 can be constructed on the connecting body 9 of the granulating head 2 so that the perforated plate body 10 is fastened to the connecting body 9 by material bonding and / or micro-form fit and / or chemical bonding. In particular, the connecting body 9 can be used as a matrix in the 3D printing process, on which material powder or raw material is deposited or applied so as to be subsequently liquefied and solidified layer by layer. In this case, the layer directly on the connecting body 9 is firmly connected to the connecting body 9.

[0076] Conversely, however, the perforated plate body 10 can also be fastened in a corresponding manner to a wear-resistant hard material ring 11 , wherein in this case the hard material ring can be used as a base body in a 3D printing process.

[0077] Alternatively, however, the perforated plate body 10 can also be connected to the connecting body 9 and / or the hard material ring 11 in a conventional manner, for example by welding and / or screwing and / or pressing.

[0078] Here, the hard material ring 11 can be integral or, if necessary, also consist of different annular segments. The same applies to the connecting body 9 and, if necessary, also to the layer-by-layer structured perforated plate body 10, which can consist of two halves or four parts or be segmented in another way. However, the perforated plate body 10 advantageously has no interface or parting line through the melt channel.

Claims

1. A perforated plate for hot-cutting granulation of a melt, the perforated plate comprising a perforated plate body (10) having melt channels (7), the melt channels passing through the perforated plate body (10) and leading to an outlet surface in a manner distributed in an annular pattern, on which the discharged melt beam can be hot-cut by a rotating knife, wherein: The perforated plate body (10) has at least one hollow chamber (12) for controlling the temperature of the perforated plate and / or for thermally isolating the melt channel (7) at least partially within the annular pattern of the melt channel, and is characterized in that the perforated plate body (10) is designed as an integral layered structure, and the individual material layers of the layered structure are solidified layer by layer and individually.

2. The perforated plate according to claim 1, wherein: The melt channel (7) is formed in a channel column (16), which is at least partially self-supportingly arranged in the hollow chamber (12) and is integrally and materially homogeneously connected to the main wall of the perforated plate body (10) that delimits the hollow chamber (12) on the outlet side and the inlet side.

3. The perforated plate according to claim 2, wherein: The channel column (16) is designed as a layered structure, and each material layer of the layered structure is solidified layer by layer and individually.

4. The perforated plate according to claim 2 or 3, wherein: The end of the channel column (16) widens toward the adjacent main body wall and / or has a widened rounded portion, and the rounded portion forms a smooth transition portion that transitions to the adjacent main body wall.

5. The perforated plate according to claim 4, wherein: The outer wall of the channel column (16) is undercut in an axial direction parallel to the melt flow direction.

6. The perforated plate according to claim 4, wherein: A support structure (18) is formed in the hollow chamber (12) to support the opposing body walls defining the hollow chamber (12) to each other.

7. The perforated plate according to claim 6, wherein: The support structure (18) forms a wave-shaped pattern extending from one peripheral side of the perforated plate to an opposite peripheral side of the perforated plate along a wave extension direction.

8. The perforated plate according to claim 6 or 7, wherein: The support structure (18) comprises a support wall (17) and / or a support column, which is integrally and materially homogeneously connected to the opposite main body wall.

9. The perforated plate according to claim 6 or 7, wherein: The support structure (18) comprises a support wall (17) and / or a support column, wherein the support wall (17) and / or the support column are integrally formed to the opposite main body wall.

10. The perforated plate according to claim 9, wherein The supporting wall (17) and / or the pillar are constructed as a layered structure and solidified layer by layer.

11. The perforated plate according to claim 10, wherein: More than 15 supporting walls are arranged in the hollow chamber (12).

12. The perforated plate according to claim 11, wherein More than 25 of the support walls are arranged in the hollow chamber (12).

13. The perforated plate according to any one of claims 10 to 12, wherein: The support walls (17) and / or the struts are arranged along lines parallel to each other.

14. The perforated plate according to claim 13, wherein: The support wall (17) and / or the support column are provided with an arch-shaped or window-shaped opening (19), wherein the opening (19) is rounded at least toward one of the body walls delimiting the hollow chamber (12).

15. The perforated plate according to claim 8, wherein The supporting wall (17) and / or the pillar has a wall thickness / height ratio of less than 1:

5.

16. The perforated plate according to any one of claims 1 to 3, wherein: The perforated plate body (10) has at least one drain opening (23) for removing unsolidified raw material from the hollow chamber (12).

17. The perforated plate according to claim 16, wherein The at least one drain opening (23) opens into the inlet-side end face of the perforated plate (8).

18. A perforated plate according to any one of claims 1 to 3, wherein: A wear-resistant hard material ring (11) forming a matching surface for the rotating tool is located on the outlet side of the perforated plate body (10), and the melt channel (7) leads to the outside of the hard material ring (11).

19. The perforated plate according to claim 18, wherein When the molten material layer of the layered structure adjacent to the hard material ring (11) solidifies, the perforated plate body (10) is connected to the hard material ring (11) by material bonding.

20. The perforated plate of claim 18, wherein: When the molten material layer of the layered structure adjacent to the hard material ring (11) solidifies, the perforated plate body (10) is connected to the hard material ring (11) by micro-form fit.

21. The perforated plate of claim 18, wherein: When the molten material layer of the layered structure adjacent to the hard material ring (11) solidifies, the perforated plate body (10) is connected to the hard material ring (11) by chemical bonding.

22. A hot-cutting pelletizing head (2) having a connecting body (9) on which a perforated plate (8) according to any one of claims 1 to 21 is mounted.

23. The hot-cutting granulation head according to claim 22, wherein: When the molten material layer of the layered structure adjacent to the connecting body (9) solidifies, the perforated plates (8) are connected by material bonding.

24. The hot-cutting granulation head according to claim 22, wherein: When the molten material layer of the layered structure adjacent to the connecting body (9) solidifies, the perforated plates (8) are connected by a micro-form fit.

25. The hot-cutting granulation head according to claim 22, wherein: When the molten material layer of the layered structure adjacent to the connecting body (9) solidifies, the perforated plates (8) are connected by chemical bonding.

26. A hot cut granulator comprising a granulator head according to claim 22 or 23.

27. The hot-cut granulator according to claim 26, wherein: The pelletizer is designed as an underwater pelletizer or a water ring pelletizer.

28. The hot-cut granulator according to claim 26, wherein: The granulator is designed as an air granulator.

29. A method for producing a perforated plate (8) according to any one of claims 1 to 21, wherein: The perforated plate body (10) is formed layer by layer by additive material coating.

30. The method of claim 29, wherein: The perforated plate body (10) is formed by a 3D printing head during the 3D printing process.

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