PLASTICIZING UNIT

MX435068BActive Publication Date: 2026-06-12KRAUSSMAFFEI TECHNOLOGIES GMBH +1

Patent Information

Authority / Receiving Office: MX · MX
Patent Type: Patents
Current Assignee / Owner: KRAUSSMAFFEI TECHNOLOGIES GMBH
Filing Date: 2022-10-19
Publication Date: 2026-06-12

AI Technical Summary

Technical Problem

Existing plasticizing units fail to ensure a homogeneous distribution of filler materials, particularly fiber materials, in the melt due to insufficient shear deformation, leading to undispersed agglomerates at the screw's end.

Method used

A plasticizing unit with a modified wave geometry screw featuring a shear section, including a locking band and a shear band with specific dimensions and configurations, ensures that filler material agglomerates experience a minimum shear rate and time without significant mechanical damage, promoting homogeneous distribution.

Benefits of technology

The solution achieves gentle dispersive mixing, reducing shear stress on filler materials like fibers, ensuring they are not mechanically damaged and are evenly distributed in the melt, improving the processing of elongated fillers such as fiber bundles.

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Abstract

The invention relates to a plasticizing unit with a cylinder and a screw rotatably mounted on the cylinder. The screw section is designed as a shearing section and includes a locking band helically surrounding the screw body and a main screw thread enclosed by the locking band. A shear band extends along the main screw thread parallel to the locking band at a height less than the locking band. This results in two screw threads that extend parallel to each other and are separated by the shear band. These threads are designed as wave-shaped screw threads.Each wave screw string is equipped with one or more wave peaks with a surface designed as a plate, forming a wave peak shear surface. The wave peak shear surface is located at the same height as the shear band surface in that region. The section of the shear band surface located in the region of a wave peak shear surface constitutes a shared shear band surface. A wave peak shear surface and a shear band shear surface together form a total shear surface. A specified total shear surface, together with the inner wall of the cylinder, forms a shear gap according to a specified shear gap size for that total shear surface.

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Description

PLASTICIZING UNIT FIELD OF INVENTION The invention relates to a plasticizing unit for processing a mixture of a plastic material and a filler material, in particular a fiber material, wherein the plasticizing unit has a cylinder and a screw, by which the plastic material is melted and mixed with the filler material, in particular the fiber material, in such a way as to produce a melt, which can be used for further purposes, for example, an injection molding process or an extrusion process. BACKGROUND OF THE INVENTION Screws with a so-called wave geometry or energy transfer geometry are known from prior art. Such screws are also called wave screws or, respectively, energy transfer screws. Wave screws are known, for example, from US patent documents 4,285,600 and 4,356,140. An energy transfer screw is described in German patent DE 10 2012 008 023 B4. These screws are used for processing plastic material in a single-screw extruder, meaning the screw is driven exclusively by rotation. The wave geometry is used to achieve smooth and rapid melting of the supplied plastic material. Similarly, the wave geometry results in a better mixing effect compared to conventional screws.In the wave and energy transfer screws mentioned above, an offset locking band is provided between two screw strings, in order to transport the plastic molten mass from one string to the other string, i.e., in order to achieve a melt flow split. Injection molding machines for processing plastic material mixed with fibers are known from European patent EP 3098052 B1 and US patent 2018 / 0022003 A1. In these injection molding machines, a rotaryly and linearly driven screw is used. Such a screw is also referred to as an oscillating screw. In the screw known from European patent EP3098052 B1, there is a first section in which the supplied plastic material is melted. On the side furthest from the conveyor, a second section is attached, at the beginning of which a fiber material is provided. In this section, a barrier strip is placed, which forms a greater distance from the inner wall of the cylinder than the blocking strip that delimits a screw thread. Therefore, a backflow of molten plastic material can be generated from a screw thread on the side downstream of the barrier strip towards a screw thread on the side upstream of the barrier strip. European patent EP3098052B1 describes various configurations of the barrier strips. US patent 2018 / 0022003 A1 describes a plasticizing unit for processing a plastic-fiber mixture, wherein the plastic and fiber materials are fed together into the cylinder via a hopper. The screw of this plasticizing unit also has a barrier strip. Additionally, a transition piece is provided at one location to subject the plastic-fiber mixture to intense compression. Patent document WO 2019 / 076561 A1 describes the processing of a fiber-filled plastic melt using a screw with a shearing piece at the front end of the screw. BRIEF DESCRIPTION OF THE INVENTION The invention is based on the problem of indicating a plasticizing unit of the type referred to in the introduction, by which it is possible to provide a melt made of a plastic material with filler material placed inside, in particular a fiber material, wherein, at the front end of the screw, viewed in the transport direction of the melt, and, therefore, at the outlet of the plasticizing unit, as homogeneous a distribution as possible of the filler material or, respectively, of the fiber material is present in the melt. The solution to this problem is presented by means of the features of claim 1. Advantageous embodiments and further developments are set forth in the dependent claims. The solution according to the invention proceeds from the following considerations. To ensure a homogeneous distribution of the filler material in the melt at the downstream end of the screw (front end), it is necessary that, whenever possible, each filler agglomerate, composed of individual filler particles, undergoes a minimum amount of material-dependent shear rate for fragmentation (dispersive) mixing, and a minimum amount of shear time in the shear field for distribution (distributive) mixing. This also results in a minimum amount of shear deformation, which is the product of shear rate and shear time. Unlike the present invention, a minimum amount of shear strain is not guaranteed for each agglomerate in the wave screws mentioned in the introduction, because here the compressive and shear stresses are only significantly produced by the peaks or, respectively, the tips of the wave peaks. In the energy transfer screws mentioned in the introduction, the melt can further escape through the relatively narrow shear band in the adjacent wave screw thread, resulting in a very small shear time. Therefore, the shear strain exerted on the agglomerates remains relatively small. Consequently, agglomerates of undispersed particles or, respectively, the filler material may be present at the end of the screw. In the case of filler materials, the spatial degree, which is evidently greater in one spatial direction than in others, presents a similar challenge: these filler materials can only be distributed primarily homogeneously when they flow transversely to the flow direction over a wave peak of a wave screw. This is because these elongated filler materials generally have very good mechanical properties in the longitudinal direction. If such filler materials, in the longitudinal direction (i.e., parallel to the melt flow direction), flow over a wave rise or other flow barrier, they are not affected, or are only affected to a lesser degree, by the shear stresses acting upon them. Therefore, according to a key idea of the invention, a plasticizing unit is provided with a screw having a modified wave geometry, in order to take into account the above considerations. With a modified wave geometry according to the invention, it is ensured that any particle agglomeration of a filler material always experiences a minimal amount of shear deformation, regardless of its flow path, and namely, without the agglomeration particles being mechanically damaged. If, in the case of a particle, for example, this refers to an individual fiber, it means that this fiber is not significantly damaged in its length, i.e., it is not shortened. Based on the foregoing considerations, a plasticizing unit is proposed for a plastic processing machine, particularly for an injection molding machine or an extrusion system. This unit comprises a cylinder and a screw rotatably mounted thereon. The screw has a shear section configured according to the invention. In the shear section, configured according to the invention, the screw has a locking band helically surrounding it and a main screw thread surrounded by the locking band. A shear band, preferably parallel to the locking band, is positioned on the main screw thread. This shear band is at least partially shorter than the locking band. In these sections, the surface of the shear band forms a shearing surface.Therefore, two wave screw strings are formed on the main screw string, extending parallel to each other and separated by the shear band. Each of these wave screw strings has a string base, which extends in a wave-like manner, viewed in the melt transport direction, where the wave peaks of that wave screw string, viewed in the melt transport direction, are offset with respect to the wave peaks of the other wave screw string. On each wave screw string, one or more wave peaks are provided with a plate-like surface that forms a wave peak shear surface.The length Lw of a wave peak shear surface is comparatively long, viewed in the melt transport direction, particularly compared to the width of the blocking band and / or the width of the shear band is at least partly comparatively wide, particularly compared to the width of the blocking band and, namely, preferably in the sections of the shear band surface that are formed as the shear surface of the shear band. The formation of a wave peak shear surface as a plate means that the surface of a wave screw thread has a constant radius with respect to the longitudinal axis of the screw in the region of the wave peak shear surface. This region of a wave peak shear surface has a length Lw, viewed in the melt transport direction. This means that the surface of the wave screw thread has a constant radius with respect to the longitudinal axis of the screw over this length Lw. In a flattened view, a wave peak shear surface forms a plane. Viewed in the melt transport direction, this plane has a length corresponding to the length Lw of the wave peak shear surface. The width of this plane corresponds to the width of the wave screw thread. The shear surface of the wave peak can be rectangular or parallelogram-shaped. In both cases—viewed transversely to the melt transport direction—a constant length Lw of the wave peak shear surface is produced over the entire width of the wave screw chord. In other words, this means that parallel to the shear band and along a path from the shear band to the blocking band (or vice versa), the length Lw remains constant. The length Lw corresponds to the long side of the rectangle or parallelogram that is attached to the shear band. This also applies to the side of the rectangle or parallelogram that is attached to the blocking band. However, the peak shear surface can also have a different shape. For example, the peak shear surface could be trapezoidal or another polygon. In these cases, the length Lw must be defined as the minimum degree Lmin of the peak shear surface thus configured, viewed in the melt transport direction. In other words, there is a line on the peak shear surface that extends parallel to the shear band or, respectively, to the blocking band, and this line has the aforementioned minimum length Lmin. This line of length Lmin serves as the reference for the length Lw of the peak shear surface thus formed.This means that the length Lmin should be considered as the length Lw of a peak wave shear surface thus configured. According to a first embodiment, it can be stipulated that, with respect to the screw diameter D, the length Lw of a shear surface of the wave peak, viewed in the molten transport direction, has a dimension of at least 0.15xD, preferably greater than or equal to 0.20xD, and very specifically, preferably greater than or equal to 0.30xD. Additionally or alternatively, it can be stipulated that the width of the shear band has, at least in part, a dimension of at least 0.15xD, preferably greater than or equal to 0.20xD, and very specifically, preferably greater than or equal to 0.30xD. The width of the shear band can preferably have the aforementioned dimension in the sections of the shear band surface that are formed as the shearing surface of the shear band (SFs). The surface of the shear band forms a shear band gap with the inner wall of the cylinder, and the surface of a wave peak shear surface forms a wave peak shear gap with the inner wall of the cylinder. According to one configuration of the invention, the size of the shear band gap, at least in the region of a shear band shear surface, can have a value between 0.1 mm and 1.2 mm, and / or the size of the wave peak shear gap can have a value between 0.1 mm and 1.2 mm. According to an additional configuration, it can be foreseen that the size of the shear gap of the shear band at least in the region of a shear surface of the shear band (SFs) has a value between 0.2 mm to 2.0 mm, preferably between 0.3 mm to 0.9 mm, very particular and preferably between 0.4 mm to 0.8 mm, and / or the size of the shear gap of the wave peak has a value between 0.2 mm to 2.0 mm, preferably between 0.3 mm to 0.9 mm, very particular and preferably between 0.4 mm to 0.8 mm. Depending on which shear gap (shear band-shear gap) / peak-shear gap) has which value, different case constellations may be present. Therefore, one or more peak shear surfaces may be found at least in the region of a shear band shear surface at the same height as the shear band surface and / or one or more peak shear surfaces at least in the region of a shear band shear surface may be found lower than the shear band surface and / or one or more peak shear surfaces at least in the region of a shear band shear surface may be found higher than the shear band surface. It can also be anticipated that the surface of the shear band, viewed in the direction of molten transport, will have a profile, and therefore will not be of a constant height, or will be continuously formed even with a positive or negative slope. In particular, the profile may be stepped or wavy. Preferably, the profile may be configured such that the surface of the shear band in the region of a wave peak is lower than in other regions, and that in the region of a wave trough, the surface of the shear band is preferably at the same height as the surface of the blocking band. Therefore, it can be achieved that the molten mass undergoes splitting only predominantly in the region of the wave peaks, and in this region, the molten mass flows over the shear band in the adjacent wave screw chord.In the remaining regions, however, overflow of the shear band is prevented. In particular, when the surface of the shear band is at the same height as the surface of the locking band, overflow into an adjacent screw thread is prevented. Furthermore, the size of the shear gap in the shear band and / or the size of the shear gap at the wave peak can be further reduced in the molten transport direction. In this document, the maximum size of one of the aforementioned shear gaps can vary from 1 mm to 2 mm, preferably from 1.2 mm to 1.6 mm. This maximum size, viewed in the molten transport direction, is present at the beginning of the shear section according to the invention. The minimum size of one of the aforementioned shear gaps can vary from 0.2 mm to 0.8 mm, preferably from 0.3 mm to 0.4 mm. This minimum size, viewed in the molten transport direction, is present at the end of the shear section according to the invention. It can be predicted that the peak shear surface is located at the same height as the shear band surface in this region. The section of the shear band surface that lies within the peak shear surface region constitutes a shear band surface. In this region, the shear band surface has the same constant radius with respect to the longitudinal axis of the screw as the peak shear surface. A peak shear surface and a shear band surface together form a IVIA / a / ZUZZ / UI or I DO general shear surface. A particular general shear surface forms a shear gap with the inner wall of the cylinder according to a specified shear gap size for this general shear surface. Consequently, the general shear surface is formed as a plate. This means that the surface of the wave screw thread and the surface of the shear band over the length Lw of a wave peak shear surface have the same radius with respect to the longitudinal axis of the screw. In a flattened view, a general shear surface forms a plane with a constant radius with respect to the longitudinal axis of the screw. Viewed in the melt transport direction, this plane has a length corresponding to the length Lw of the wave peak shear surface.The width of this plane corresponds to the sum of the width of the wave screw chord and the width of the shear band. Preferably, the plane can be formed as a rectangle. However, it can also be formed wholly or partially as a parallelogram. In particular, the shear surface of the shear band can be formed as a rectangle and the shear surface of the wave peak can be formed as a parallelogram, or vice versa. The aforementioned plate forms a curved plane with a radius corresponding to the root radius of the associated wave screw string in this region. In the melt transport direction, this plane has a length Lw and a width corresponding to the string width of the wave screw. The plane preferably takes the form of a rectangle with length Lw and the corresponding wave screw string width. However, in the top view, the plane can also have different shapes; for example, it could be a parallelogram. The aforementioned plate lies at the same height as the shear band surface over a certain length. Therefore, a wave peak shear surface is connected to the shear band surface over a certain length, where both shear surfaces are at the same height.In other words, the peak shear surface and the shear band shear surface lie in a curved plane with a shared radius and collectively form a single, shared general shear surface. Ultimately, the challenge lies in having only one peak shear surface of a suitable size that can cooperate with a suitable shear band shear surface. In this document, the plane of a peak wave can be connected to the shear band surface over a certain length. In the case of a rectangular plane, this corresponds to the previously mentioned length Lw. In the case of a parallelogram, the side of the parallelogram that is attached to the shear band can have this length Lw. The length of the screw's shear section depends on the specific application. For example, it depends on whether the screw will be used as a rotary screw for an injection molding machine or as a screw for a single-screw extruder. It also depends on the materials the screw will process. Therefore, the entire screw can be configured with a shear section, or, conversely, the screw may only have a single shear section. ινΐΛ / a / zuzz / ui ó i oo A preferred field of application of the invention is the processing of filler materials, the spatial degree of which is evidently greater in one spatial direction than in the other. Such filler materials may also be referred to as elongated filler materials. In particular, fiber material, for example, chopped fiber granules, is considered an elongated filler material. In such granules, the fiber material is present in bundles of fibers which are necessary for dispersion and which undergo reorientation in the melt. With the shear section configured according to the invention, it is guaranteed that any particle agglomerate will always experience a minimal amount of shear rate and shear time (shear deformation) regardless of the flow path, without significantly damaging the individual particles mechanically. Therefore, a filler material, in particular a fiber material processed by the plasticizing unit and omitted with the plastic, is also only slightly damaged mechanically. Unlike the wave screws mentioned in the introduction, the invention provides a plate over a wave peak, thereby reducing the shear rate exerted on the filler material particles, particularly the fiber material, and extending the shear time. The application of shear strain to the filler material or, respectively, the fiber material, is therefore not predominantly dependent on the maximum shear rate. This results in a particularly gentle dispersive mixing process. Since the shear band also forms a shear surface, the application of shear energy to the particles escaping via the shear band on the back-wave screw string remains at an identical level compared to the particles flowing through the wave peak plate. Depending on the width of the locking band, the shear band can be significantly wider than the locking band. Specifically, the width of the shear band can be a multiple of the width of the locking band; ideally, the width of the shear band can be two to five times the width of the locking band. An additional aspect concerns the filler materials, the spatial degree of which is evidently greater in one spatial direction than in the others. In many cases, this refers to a fiber material containing fiber bundles. However, it can also refer to a different material, such as needle-shaped mineral fillers or platelet-shaped pigments. For the dispersion of the fiber bundles or, respectively, fiber agglomerates, the fiber orientation is critical in the region of a shear surface and, therefore, in the shear gap formed between this shear surface and the cylinder.Tests have shown that agglomerates with fibers oriented transversely to the flow direction of the melt exhibit better dispersion when flowing through a shear gap than agglomerates in which the fibers are parallel to the flow direction through the shear gap. The additional shear surface on the shear strip allows the melt, on the one hand, to escape in the backward wave screw thread and, on the other hand, to be... IVIA / a / ZUZZ / UI 31 00 thus reorients through flow mechanisms; moreover, the melt can flow away over the peak wave plate, which constitutes a peak wave shear surface. With the configuration according to the invention, with two shear surfaces, i.e., a peak wave shear surface and a shear band shear surface, it is further achieved that there are sufficient bundles of fibers which are oriented transversely to the respective flow direction of the melt when flowing over a shear surface or, respectively, through a shear gap.Ideally, at each wave peak, approximately one half of agglomerates should be present, in which the fibers are oriented such that they are transverse to the flow direction of the melt component flowing over the shear surface of the wave peak, such that the fibers flow through the shear gap of the wave peak in this orientation. The same applies analogously to the melt component flowing through the shear gap of the shear band that joins this wave peak over the shear surface of the shear band in the direction of the adjacent wave screw thread. This means that, ideally, this melt component also contains one half of agglomerates in which the fibers are oriented such that they are transverse to the flow direction of this melt component. According to one embodiment of the invention, the shear band may have a greater width than the locking band. In particular, the width of the shear band may be a multiple of the width of the locking band, preferably the width of the shear band may be 2 to 5 times the width of the locking band. According to an advantageous configuration, several general shear surfaces (SFn) can be present on both wave screw threads, and the shear gap size Dn (n=1,2,3...) can be further reduced or, respectively, decreased in the melt transport direction. This allows for a higher shear intensity along the screw length. Combined with multiple melt flow splits, this ensures that fiber agglomerates still present in the flow direction on one shear surface also spread onto a subsequent shear surface after being reoriented by the melt flow split, because the fibers then align themselves transversely to the flow direction. According to an additional advantageous configuration, in the region of a general shear surface (SFn), the width of the shear band can be smaller on its surface or equal to the length Lw of a peak wave shear surface, viewed in the melt transport direction, where the width preferably has a lower threshold value of between 50% and 60% and an upper threshold value of between 80% and 90% of the length Lw. Therefore, a predetermined minimum amount of fiber material can be flowed over the shear surface of a shear band. Furthermore, as a result of the fibers in a fiber bundle aligning transversely to the flow direction as they flow over this shear surface, improved dispersion of the fiber bundles can be achieved. ινΐΛ / a / zuzz / ui ó i oo Preferably, the arrangement of the wave peak shear surfaces and the length Lw of the wave peak shear surfaces should be such that the wave peak shear surfaces of one wave screw string and the wave peak shear surfaces of the other wave screw string, viewed in the melt transport direction, are separated from each other, wherein preferably a wave peak shear surface in one wave screw string is associated with a wave transversely in the other wave screw string. This configuration has a positive effect on dividing the melt flow several times. According to further development, a wave peak, viewed in the melt transport direction, can be predicted to have a rising flank upstream of the wave peak shear surface (SFw) and a falling flank downstream of the wave peak shear surface (SFw). The rising flank forms a first angle (α) with the shear band surface, while the falling flank forms a second angle (β) with the shear band surface, with the first angle (α) being smaller than the second angle (β). Therefore, viewed in the melt flow direction, a relatively flat rising flank is formed upstream of a wave peak plate, and a relatively steep falling flank is formed downstream of this plate.Therefore, the advantage lies in the fact that, through a sudden relaxation of the viscoelastic melt, a swelling behavior of the melt will be observed. The melt deforms when pressed through a shear gap. At the exit of the shear gap, the stress applied by the shear gap is distributed, and the polymer molecules return in the most thermodynamically favorable form of unaltered groups. The melt conveniently expands at right angles to the flow direction. Undispersed solid particles located in the melt experience a force oriented at right angles to the flow direction, which allows for the dispersion of the solid particles within the melt. According to one configuration of the invention, the cylinder with the screw formed by a shear section may constitute a first cylinder, and in addition to the first cylinder, a second cylinder with a second screw may be provided. The second additional cylinder has an outlet at its front end, which is in fluid communication with an inlet in the rear region of the first cylinder. The second cylinder is provided for the production of a molten plastic material (P), wherein the molten plastic material (P) can be passed from the second cylinder to the first cylinder. In the first cylinder, an inlet is provided for the addition of filler material, preferably fiber material (F), particularly for chopped fiber granules.The inlet for the molten plastic material (P) and the inlet for the filler material or, respectively, the fiber material (F) are placed on the first cylinder, viewed in the direction of transport of the molten mass, before the shearing section (B). A plasticizing unit according to the invention can be used in an injection molding machine. Such an injection molding machine comprises a clamping unit and a plasticizing and injection unit, wherein the plasticizing and injection unit of this injection molding machine has a plasticizing unit according to the invention, and wherein the screw is operatively connected to a rotary drive and a linear drive. A plasticizing unit according to the invention can also be used in an extrusion system. Such an extrusion system comprises a plasticizing unit, wherein, viewed from the melt transport direction, an extrusion tool and, if applicable, additional system components of an extrusion system are positioned downstream of the cylinder, where the concern is with system components according to an extruded product to be produced. BRIEF DESCRIPTION OF THE FIGURES The invention will be described in more detail below with the help of exemplary embodiments and with reference to Figures 1 to 11. They are shown: Figure 1 is a schematic illustration of a laminating unit. Figure 2 is a cross-section of the shear section B of the screw in Figure 1. Figure 3 is a perspective illustration of a flattened portion of the shear section B of the screw in Figure 1. Figure 4 is the VV cut in Figure 3. Figure 5 is section XX in Figure 3. Figure 6 is the YY cut in Figure 3. Figure 7 is the ZZ cut in Figure 3. Figure 8 is the path of the SP shear gap size. Figure 9 is an injection molding machine with the first modality of a plasticizing and injection unit according to the invention. Figure 10 is an injection molding machine with a second modality of a plasticizing and injection unit according to the invention. Figure 11 is an additional embodiment of a plasticizing unit according to the invention. DETAILED DESCRIPTION OF THE INVENTION In the following embodiments, a fiber material will be used as the filler material. Figure 1 shows a schematic illustration of a plasticizing unit 1, marked as an assembly by reference number 1, comprising a cylinder 2 and a screw 3 with a helically wrapped screw band 4. When the plasticizing unit 1 is implemented as a component of an injection molding machine, the screw 3 is configured as an oscillating screw and can be rotated by means of a suitable drive unit and is displaced in the longitudinal direction. When the plasticizing unit 1 is implemented as a component of an extruder, only a rotary drive for the screw 3 is required. The screw 3 has several sections A and B. In the first section A, a plastic material P, which is fed in via a feed hopper, is drawn in and melted. A fiber material F is also added via this feed hopper. Section A is implemented as a three-zone screw and thus has a feed zone, a compression zone, and a metering zone. Viewed in the direction of melt flow, a shearing section B is attached according to the invention. At the beginning of section B, a mixture of molten plastic material P and fiber material F is present. The plastic material P and the fiber material F can be fed into the cylinder 2 via the same feed hopper, as shown in Figure 1. However, the fiber material F can also be added after the plastic material P, viewed in the direction of flow.The mixture of molten plastic material P and fiber material F is conveyed through section B by the rotation of screw 3. Section B is formed according to the invention as the shear section B, as explained in more detail below. At the end of section B, a molten mixture of plastic material P and fiber material F is present, distributed within it, where the fiber material F, due to the action in section B, has been dispersed such that the individual filaments of fiber material F are now primarily homogeneously distributed in the mixture. A screw with a shear section configured according to the invention may also be referred to herein as a shear screw. The configuration of shear section B will be described in more detail below with the help of Figures 2 to 7. Figure 2 shows a cross-section of a screw 3 with the shear section B configured according to the invention, and Figure 3 shows a perspective illustration of a flattened partial portion of the shear section B of the screw 2. The screw band 4 is formed as a shear band, i.e., it forms a locking gap SP with the inner wall of the cylinder. The size of the locking gap SP is dimensioned such that no molten material, or only a small amount of it, can flow through this locking gap SP. The size of this gap corresponds to half the screw clearance in the cylinder 2. The surrounding locking band 4 forms a main screw thread 5 of thread width Gs.In the main screw thread 5, an additional band, the shear band 6, is provided and positioned on the main screw thread 5 such that two screw threads, 7 and 8, are present on either side of the shear band 6. As explained in more detail below, the two screw threads 7 and 8 are formed with a wave-shaped thread base, viewed in the melt transport direction, i.e., in the manner of a so-called wave screw. Therefore, these screw threads are also referred to herein as wave screw threads 7 and 8. The thread widths Gs and Gs of the wave screw threads 7 and 8 are the same size.The path of the wave screw strings 7 and 8 is such that a wave peak 9 in the wave screw string 7 and a wave sine 12 in the wave screw string 8 occur together in a position on both sides of the shear band 6 or on a portion on both sides of the shear band 6. It is also provided that a wave peak 10 in the wave screw string 8 and a wave sine 11 in the wave screw string 7 occur together in a position on both sides of the shear band 6 or by means of a portion on both sides of the shear band 6. This path of the wave screw strings 7 and 8 is analogous to the principle as known in the so-called double-wave screws of the prior art cited in the introduction (US 4,285,600 and US 4,356,140). According to the invention, on the one hand, the width Be of the shear band 6 is evidently greater than the width B4 of the blocking band 4. Furthermore, the height of the wave peaks 9, 10 is dimensioned such that in each wave screw string 7, 8 there is a portion in which the surface of the shear band 6 and the surface of a wave peak form a shared surface. Furthermore, the wave peaks are formed with a plate, i.e., there is a surface of a wave peak which in the melt transport direction has a length Lw and whose width corresponds to the chord width G?, Gs of a wave screw chord 7, 8. Therefore, the previously mentioned shared surface of the shear band 6 and the wave peak 9, 10 is present over the entire length Lw of the area of a wave peak 9, 10.The shared surface width corresponds to the sum of the Be width of the shear band 6 and the chord width G?, Gs of the wave peak 9, 10 involved respectively in the shared surface. The function of the shared surface mentioned above is to exert a shearing effect on the mixture of plastic material P and fiber material F present in a wave screw string and flowing upwards at a wave peak. This mixture is divided according to the flow such that one portion continues flowing over the wave peak plate and remains in the wave screw string where the mixture arrived, while another portion flows over the shear band away from the adjacent wave screw string. Therefore, the shared surface should also be referred to hereafter as the general shear surface SF.Therefore, this general shear surface SF is composed of a shear surface SFw corresponding to the plate surface of a wave peak 9, 10 and a shear surface SFs of a shear band 6, which corresponds to the product of the length Lw of the shear surface SFw and the width Be of the shear band 6, i.e., SFs = Lw x Be. Depending on whether the SFw shear surface is present with a wave peak 9 on the wave 7 screw thread or with a wave peak 10 on the wave 8 screw thread, the following shear surfaces can be differentiated. SFw7= LwxG? (shear surface with wave peak on the wave screw string 7). SFws = Lw x Gs (shear surface with wave peak on the wave screw string 8). The configuration of the wave screw strings 7 and 8 and the shear band 6 is such that the width Βθ of the shear band 6 is less than or equal to the length Lw of a shear surface SFw with a wave peak. In a preferred embodiment, the width Βθ can be 50% of Lw or greater. Particularly and preferably, the lower limit of Βθ ranges from 50% to 60% of Lw, and the upper limit of Βθ ranges from 80% to 90% of Lw. The appropriate numerical values refer to the plastic material P and the fiber material F being processed. The ratio of width Be to length Lw must be such that for the material to be processed in the region of a general shear surface SF, a division of the material flow occurs, according to which at least half of the incoming material flows through the shear band 6 into the adjacent wave screw thread. Viewed in the flow direction, in each of the wave shear chords 7, 8 several wave peaks 9 or, respectively, 10 one after the other. An arrangement with two to five wave peaks one after the other can be considered sufficient for most applications. However, it may also be the case that a larger number of wave peaks is required. Figure 3 shows a perspective illustration of a flattened partial portion of the shear section B of screw 2. It can be seen how a wave peak in one wave screw string and a wave sine in the other wave screw string are adjacent to each other. The lengths of Lw in the wave peak plates are dimensioned such that the shear surfaces SFws of the wave peaks 9 in wave screw string 7 and the shear surfaces SFws of the wave peaks 10 in wave screw string 8 are sufficiently spaced apart.Due to the displacement of the shear surfaces, a partial flow is generated from one wave screw string to the other and back, namely, always through the SFs shear surface of the shear band 6, which forms with the respective shear surface of a wave peak a shared surface or, respectively, a general SF shear surface. The length Lw of a wave peak shear surface, viewed in the melt transport direction, is configured to be comparatively long, particularly compared to the width of the blocking band and / or the width of the shear band is configured to be at least partially comparatively wide, particularly compared to the width of the blocking band and, namely, preferably in the portions of the shear band surface formed as a shear surface of the shear band. According to one embodiment, it may be provided that, with respect to the screw diameter D, the length Lw of a wave peak shear surface, viewed in the melt transport direction, has a dimension of at least 0.15xD, preferably greater than or equal to 0.20xD, and very specifically, preferably greater than or equal to 0.30xD. Additionally or alternatively, it may be provided that the width of the shear band has, at least in part, a dimension of at least 0.15xD, preferably greater than or equal to 0.20xD, and very specifically, preferably greater than or equal to 0.30xD. The width of the shear band may preferably have the aforementioned dimension in the portions of the shear band surface configured as the shear band shear surface (SFs). Figure 4 shows a section along line VV in Figure 3, namely in a view from the direction of the arrow towards line VV in Figure 3. Consequently, in wave screw chord 7 the chord base is formed upwards in the flow direction (from right to left in Figure 4) and joins surface 6a of shear band 6 at an angle α. This is the start 9a of the wave peak plate 9. From there, the wave peak surface 9c extends over a length Lw at the same height as the surface 6a of the shear band 6. Starting from the end 9b of the wave peak plate 9, the wave peak 9 descends at an angle β in the direction of the chord base of the wave screw chord 7, until the valley floor of the wave screw chord 7 is reached, which is designated in Figure 3 by reference number 11.In the viewing direction behind the shear band 6, the portion of the blocking band 4 that projects beyond the shear band 6 can be observed. The wave peaks are configured in such a way that a slowly rising edge 13 and an abruptly falling edge 14 occur, i.e., α < β. Figures 5, 6, and 7 illustrate the additional sections of Figure 3, which are selected so that, viewed in the flow direction of the molten mass, they are located one behind the other. ινΐΛ / a / zuzz / ui ó i oo Figure 5 shows a section along line XX in Figure 3, where it can be observed that the wave peak plate 10, with its surface 10c, is present in wave screw string 8. Therefore, the string base of wave screw string 8 is at the same height as surface 6a of shear band 6. Furthermore, a wave sine 11 is present in wave screw string 7; that is, the string base of wave screw string 7 is at its lowest point at this point. The dashed lines mark the connection points between the locking band 4, wave screw strings 7 and 8, and shear band 6. Figure 6 shows a section along the YY line in Figure 3, where it can be observed that at this point on the screw in both wave screw strings 7 and 8 the respective string base has a height which is below the surface 6a of the shear band 6. The string base in the wave screw string 7 is slightly higher than the string base in the wave screw string 8, because in the wave screw string 7 the YY line intersects the rising surface 13 of the wave peak 9 and in the wave screw string 8 a wave sine 12 is present there. Figure 7 shows a section along line ZZ in Figure 3, where it can be observed that in wave screw string 7 the wave peak plate 9 is present with its surface 9c and, therefore, the string base of wave screw string 7 is at the same height as surface 6a of the shear band 6. On the other hand, in wave screw string 8 a wave sine 12 is present, that is, the string base in wave screw string 8 has its lowest level at this point. The surface of the shear band forms a shear band gap with the inner wall of the cylinder, and the surface of a wave peak shear surface forms a wave peak shear gap with the inner wall of the cylinder. According to one configuration of the invention, the size of the shear band gap, at least in the region of a shear band shear surface, can have a value from 0.1 mm to 1.2 mm, and / or the size of the wave peak shear gap can have a value from 0.1 mm to 1.2 mm. Depending on which shear gap (shear band gap / wave peak shear gap) has which value, different case configurations may be present.Therefore, one or more peak wave shear surfaces, at least in the region of a shear band shear surface, may be at the same height as the shear band surface (see Figures 3, 5, and 7), and / or one or more peak wave shear surfaces, at least in the region of a shear band shear surface, may be lower than the shear band surface, and / or one or more peak wave shear surfaces, at least in the region of a shear band shear surface, may be higher than the shear band surface. Furthermore, the size of the shear band shear gap and / or the size of the peak wave shear gap may be further reduced in the melt transport direction. Between a general shear surface SF and the inner wall of cylinder 2, there is a gap SZ, which will also be referred to hereafter as the shear gap SZ. The size of this shear gap SZ with a specified shear surface SFn (n = 1, 2,...) will be referred to hereafter as Δη (n = 1, 2, 3, ...). The screw 2 is configured such that the shear gap SZ is further reduced, viewed in the flow direction, i.e., Δ1 > Δ2 > Δ3 and so on. Therefore, the following effect is achieved: By reducing the shear gap SZ, an increase in shear strain is produced, which produces an improvement in the dispersive and distributive mixing effect in order to further disperse the agglomerates that are further reduced during the process. Figure 8 illustrates an embodiment in which the surface 6a of the shear band 6, viewed in the melt transport direction, is formed with a profile and therefore does not have the same height continuously as in Figures 3 to 7. The profile can be, in particular, a stepped or wavy profile. Preferably, the profile is configured such that the surface 6a of the shear band 6 in the region of a wave peak 9, 10 is lower than in other regions, and that in the region of a wave trough, the surface 6a of the shear band 6 is preferably at the same height as the surface of the blocking band 4. Such a profile, as a stepped profile, is illustrated in Figure 8. Figure 9 shows an example embodiment of an injection molding machine with a plasticizing and injection unit 15 and a clamping unit 30, both of which are supported on a machine pedestal 40. The plastic material P and the fiber material F are fed together into the cylinder 2 via a feed hopper 20. In this document, a finished premix may be used, or—as illustrated—the plastic material P and the fiber material F are supplied to the feed hopper 20 by means of separate metering devices, i.e., a fiber material metering device 21 and a plastic material metering device 22. The screw 2 is configured as an oscillating screw, i.e., it is operatively connected at its rear end to a rotary drive 23 and a linear drive 24.The clamping unit 30 may conform to a known design type and is therefore only illustrated schematically. It practically comprises a fixed platen 31 and a movable platen 32, movable relative to it. In addition, a movable mold half 33a and a fixed mold half 33b of an injection molding tool are provided, which in the closed state form one or more cavities. When the plasticizing and injection unit 15 is mounted onto the fixed mold half 33b, a mixture of plastic material P and fiber material F can be injected into the cavity in the known manner. Figure 10 shows an example embodiment of an injection molding machine with a plasticizing and injection unit 16 and a clamping unit 30, both supported on a machine pedestal 40. Unlike the plasticizing and injection unit 15 in Figure 9, in this embodiment, the plastic material P and the fiber material F are fed separately into the cylinder 2. The plastic material P is fed into the cylinder 2 by a first feed hopper 20 at the rear end of the plasticizing and injection unit 16. Downstream, viewed in the melt transport direction, but before the start of the shearing section B, the fiber material F is fed into the cylinder 2. The fiber material F is supplied by a fiber material metering device 22 to a screw conveyor 25, which is mounted horizontally or vertically above the cylinder 2. Figure 11 shows a vane for spatial separation for the addition of plastic material P and the addition of fiber material F. This structure allows the separation of the plasticizing process from the homogenization process of the fiber material and thus improves the calculation of the mechanical stresses of the latter. The plasticizing and injection unit 17 of the third design type, illustrated herein, comprises a first cylinder 18 with a screw 19 and a second cylinder 26 with a second screw 27. The cylinder 18 contains the screw 19, formed with a shear section B. The additional second cylinder 26 has a melt outlet 28 at its front end, which is in fluid communication with a melt inlet 29 in the rear region of the first cylinder 18, for example, by means of a pipe 35. Only a rotary drive 34 is provided for the second screw 27.The first screw 19 can be operationally connected to a rotary drive 23 and a linear drive 24, as previously described, such that rotary and linear movement of the screw 19 is possible, as illustrated by the arrows at the rear end of the screw 19. The second cylinder 26 is provided for the production of a molten plastic material (P), wherein the molten plastic material (P) is transferred from the second cylinder 26 to the first cylinder 18. An inlet is provided in the first cylinder 18 for the addition of the fiber material (F), in particular for the chopped fiber granules. The inlet for the molten plastic material (P) and the inlet for the fiber material (F) are located on the first cylinder 18, viewed in the direction of melt flow, before the start of the shearing section B. List of reference numbers for plasticizing unit, cylinder, screw, locking band, main screw rope, shear band 6a surface of the shear band 6 first wave screw string second wave screw string wave peak on the wave screw string 7 9a start of the peak wave shear surface 9 9b end of the peak wave shear surface 9 9c wave peak surface 9 (shear surface) wave peak on the wave screw string 8 10c wave peak surface 10 wave sine on the wave screw thread 7 wave sine on the wave screw thread 8 rising flank falling flank first type design plasticizing and injection unit second type design plasticizing and injection unit third type design plasticizing and injection unit first cylinder of plasticizing and injection unit 17 first screw of plasticizing and injection unit 17 feed hopper plastic material measuring device fiber material measuring device rotary drive linear drive screw conveyor second cylinder of plasticizing and injection unit 17 second screw of plasticizing and injection unit 17 melt outlet melt inlet clamping unit fixed platen movable platen 33a half of mobile mold 33b fixed half mold rotary drive for second screw 27 machine pedestal pipe To the first screw section B second screw section C third screw section P plastic material F fiber material Gs main screw thread width 5 G? string width of the wave screw string 7 Ge string width of the wave screw string 8 B4 blocking band bandwidth 4 Be shear band bandwidth 6 Lw length of the plate of a wave peak 9, 10 SF shear surface SFs shear surface of the shear band 6 SFw shear surface of a wave peak 9, 10 SFw7 shear surface of a wave peak on the wave screw string 7 inaLa / a / zuzz / u 1 01 os SFW8 shear surface of a wave peak on the wave screw thread 8 Δ gap size between the shear surface and the inner wall of the cylinder SP gap between the locking band and the inner wall of the cylinder sz gap between the shear surface and the inner wall of the cylinder 5 a angle between the rising flank and the surface of the shear band β angle between the falling flank and the surface of the shear band

Claims

CLAIMS 1. A plasticizing unit (1) for a plastic processor, in particular for an injection molding machine or an extrusion system, comprising a cylinder (2) and a screw (3) rotatably mounted thereon, wherein the screw (3) has a screw section formed as a shear section (B), characterized in that in the shear section (B) the screw (3) has a locking band (4) helically surrounding the screw body, and a main screw thread (5) surrounded by the locking band (4), wherein a shear band (6) is placed on the main screw thread (5), preferably extending parallel to the locking band (4), wherein the shear band (6) has at least partly a lower height than the locking band (4) and in these sections the surface (6a) of the shear band (6) forms a shear band shear surface (SFs),wherein two wave screw strings (7, 8) are provided on the main screw string (5), extending parallel to and separated from each other by the shear band (6), wherein each of these wave screw strings (7, 8) has a string base (15, 16), extended in a wave-like manner in the molten transport direction, wherein the wave peaks (9) of said wave screw string (7), viewed in the molten transport direction, are offset with respect to the wave peaks (10) of the other wave screw string (8), wherein on each wave screw string (7, 8) one or more wave peaks (9, 10) are provided with a surface (9c, 10c) configured as a plate and forming a wave peak shear surface (SFw), and wherein the length (Lw) of a wave peak shear surface (SFw), viewed In the direction of transport of the molten mass, it forms to be comparatively long,in particular compared to the width (B4) of the blocking band, and / or the width (Be) of the shear band (6) is configured at least in part to be comparatively wide, in particular compared to the width (B4) of the blocking band and preferably in the sections of the surface (6a) of the shear band (6) formed as a shear surface of the shear band (SFs), wherein one or more peak wave shear surfaces (SFw) are at the same height as the surface (6a) of the shear band (6), wherein the section of the surface (6a) of the shear band (6) that is in the region of a peak wave shear surface (SFw) represents an associated shear surface of the shear band (SFsz),wherein a wave peak shear surface (SFw) and an associated shear band shear surface (SFsz) together form a general shear surface (SFn), wherein a specified general shear surface (SFn) forms with the inner wall of the cylinder (2) a shear gap of the shear surface (SZ) according to a predetermined shear gap size Δη (n=1,2,3...) for this general shear surface (SFn), and wherein in both wave screw strings (7, 8) several general shear surfaces (SFn) are present and the shear gap size Δη (n=1,2,3...) is further reduced in the melt transport direction.

2. The plasticizing unit according to claim 1, further characterized in that with respect to the screw diameter D, the length (Lw) of a wave peak shear surface (SFw), viewed in the melt transport direction, has a dimension of at least 0.15xD, preferably greater than or equal to 0.20xD, particularly and preferably greater than or equal to 0.30xD, and / or that the width (Be) of the shear band (6) has at least partly a dimension of at least 0.15xD, preferably greater than or equal to 0.20xD, particularly and preferably greater than or equal to 0.30xD, wherein the width (Be) of the shear band (6) preferably has the aforementioned dimension in the sections of the surface (6a) of the shear band (6) formed as a shear surface of the shear band (SFs).

3. The plasticizing unit according to claim 1 or 2, further characterized in that the surface (6a) of the shear strip (6) forms a shear strip shear gap with the inner wall of the cylinder (2), that the surface (9c, 10c) of a wave peak shear surface (SFw) forms a wave peak shear gap with the inner wall of the cylinder (2), and that the size of the shear strip shear gap, at least in the region of a shear strip shear surface (SFs), has a value between 0.2 mm and 2.0 mm, preferably between 0.3 mm and 0.9 mm, particularly and preferably between 0.4 mm and 0.8 mm, and / or the size of the wave peak shear gap has a value between 0.2 mm and 2.0 mm, preferably between 0.3 mm and 0.9 mm. 0.9 mm, very particular and preferably between 0.4 to 0.8 mm.

4. The plasticizing unit according to any of the preceding claims, further characterized in that one or more peak wave shear surfaces (SFw) at least in the region of a shear band shear surface (SFs) are at the same height as the surface (6a) of the shear band (6), and / or that one or more peak wave shear surfaces (SFw) at least in the region of a shear band shear surface (SFs) are located lower than the surface (6a) of the shear band (6) and / or that one or more peak wave shear surfaces (SFw) at least in the region of a shear band shear surface (SFs) are located higher than the surface (6a) of the shear band (6).

5. The plasticizing unit according to any of the preceding claims, further characterized in that the surface (6a) of the shearing strip (6), viewed in the melt transport direction, has a profile, in particular a stepped or wavy profile, wherein the profile is preferably configured such that the surface (6a) of the shearing strip (6) in the region of a wave peak (9,10) is lower than in other regions, and that in the region of a wave trough the surface (6a) of the shearing strip (6) is preferably at the same height as the surface of the blocking strip (4).

6. The plasticizing unit according to one of the preceding claims, further characterized in that the size of the shear gap of the shear band and / or the size of the shear gap of the wave peak is further reduced in the melt transport direction.

7. The plasticizing unit according to any of the preceding claims, further characterized in that in the region of a general shear surface (SFn), the width (Be) of the shear band (6) on its surface (6a) is less than or equal in size to the length Lw of a wave peak shear surface (SFw), viewed in the melt transport direction, iviA / a / zuzz / ui or i oo wherein the width (Be) preferably has a lower threshold value of between 50% and 60% and an upper threshold value of between 80% and 90% of the length Lw.

8. The plasticizing unit according to one of the preceding claims, further characterized in that the arrangement of the wave peak shear surfaces (SFw) and the length Lw of the wave peak shear surfaces (SFw) are such that the wave peak shear surfaces (SFW?) of said wave screw string (7) and the wave peak shear surfaces (SFWs) of the other wave screw string (8), viewed in the melt transport direction, are separated from each other, wherein preferably a wave trough (12) in the other wave screw string (8, 7) is associated with a wave peak shear surface (SFw) in said wave screw string (7, 8).

9. The plasticizing unit according to any of the preceding claims, further characterized in that a wave peak (9, 10), viewed in the melt transport direction, has an ascending flank (13) facing the wave peak shear surface (SFw), and a descending flank (14) following the wave peak shear surface (SFw), wherein the ascending flank (13) forms a first angle (a) with the surface (6a) of the shear band (6), wherein the descending flank (14) forms a second angle (β) with the surface (6a) of the shear band (6), and wherein the first angle (a) is less than the second angle (β).

10. The plasticizing unit according to any of the preceding claims, further characterized in that the cylinder with the screw formed with a shearing portion (B) constitutes a first cylinder (18) with a first screw (19), in addition to the first cylinder (18) a second cylinder (26) with a second screw (27) is provided, the second cylinder (26) having at its front end a melt outlet (28) which is in fluid communication with a melt inlet (29) in the rear region of the first cylinder (18), the second cylinder (26) being provided for the production of a molten plastic material (P), wherein the molten plastic material (P) can be transferred from the second cylinder (26) to the first cylinder (18), and in the first cylinder (18) an inlet is provided for the addition of the filler material, in particular the fiber material (F), preferably for chopped fiber granules,and that in the first cylinder (18) the inlet for the plastic material (P) and the inlet for the filler material, viewed in the direction of transport of the melt, are placed opposite the shearing portion (B).

11. An injection molding machine with a clamping unit (30) and with a plasticizing and injection unit (15), wherein the plasticizing and injection unit (15) has a plasticizing unit according to one of claims 1 to 9, characterized in that the screw (3) is operatively connected to a rotary drive (23) and a linear drive (24).

12. An injection molding machine with a clamping unit (30) and with a plasticizing and injection unit (17), wherein the plasticizing and injection unit (17) has a plasticizing unit according to claim 10, characterized in that the first screw (19) in the first cylinder (18) is operatively connected to a rotary drive (23) and to a linear drive (24), and wherein the second screw (27) in the second cylinder (26) is operatively connected to a second rotary drive (34).

13. An extrusion system with a plasticizing unit according to any one of claims 1 to 9, characterized in that an extrusion tool and, if applicable, additional system parts of an extrusion system are placed downstream of the cylinder (2) viewed in the melt transport direction 5, wherein the concern is with system parts according to an extrusion product to be produced.