EP3131732A1

EP3131732A1 - Axial extruder with rotatable die head

Info

Publication number: EP3131732A1
Application number: EP15724765.1A
Authority: EP
Inventors: Roman FEKETE; Marián PECIAR; Peter PECIAR
Original assignee: Slovenska Technicka Univerzita V Bratislave
Current assignee: Slovenska Technicka Univerzita V Bratislave
Priority date: 2014-04-14
Filing date: 2015-04-13
Publication date: 2017-02-22
Also published as: WO2015159198A1

Abstract

Axial extruder contains a rotary placed conical head (2), which alongside the conical end (1) of the screw (4) creates a tapering space (23) between the cones. The conical end (1) of the screw (4) can have a system of the alternately arranged axial transversal grooves (24, 25) and the inner surface of the rotating conical head (2) can have the system of the alternately arranged axial transversal grooves (24, 25, 26). The rotating conical head (2) with the outer teeth is placed at the end of the casing (9) of the screw (4) with the bearing (7) in the bearing housing (8) of the head. By means of a gear (12) a motor (10) for driving the head (2) is connected to the outer teeth of the conical head (2). The frequency and direction of the rotation of the head (2) is independent on the frequency and direction of the rotation of the screw (4). The conical end (1) of the screw (4) and the inner surface of the head (2) can have different conicity. The conical end (1) of the screw (4) is separated from the inner front of the head (2) by distance (L).

Description

AXIAL EXTRUDER WITH ROTATABLE DIE HEAD

Field of technology

An invention concerns the construction of an axial extruder, mainly for purpose of extrusion and/or mixing of pastes, where a special construction of the extruder with the deforming element in the zone of transition from the casing to the extruder nozzle is useful for extrusion of materials with problematic rheological characteristics and in cases where the addition of additives (mainly in cases of pure pharmaceutical products) in order for bettering of the products produces undesirable additions, lowers the quality of the product, or makes it more costly, and other typical extrusion procedures cannot be used. The invention can be used in various fields of industry, mainly in food industry, in chemical, pharmaceutical industry, but also in field of technology of processing of recycled materials and wastes and in field of processing of plastics. State of the art

The pastes are substances made of the mixture of the powder material and the liquid. These two components are mixed in such ratio that they create a disperse system which is able, under the outside force effect (for example pressure) to flow through the openings in the baffles of various geometrical shapes. In order to achieve the desired shape of the product, the disperse systems in the form of a paste are mainly processed by extrusion; that is, by extruding the pastes through matrices of various profiles, whose shape is the shape of the final product. The process of the extrusion itself and the quality of the product is conditioned by the rheological characteristics of the paste. These characteristics, alongside with the geometry of the openings in the nozzle, are the defining parameters determining the size of the extrusion pressure. The rheological characteristics of the pastes affect the size of the extrusion pressure greatly. The pastes are usually non- Newtonian, multi-phase liquids, whose rheological characteristics depend, firstly, on the volume of the liquid in the paste and also on the shear rate. Shear rate, and the corresponding shear stress in the material is a set of parameters which describes the rheological characteristics of the paste.

In order to make it possible to extrude the paste with the given rheological features through the nozzle with a given free cross-section of the baffle, it is necessary to act upon the paste with a force effect which causes necessary extrusion pressure. This pressure can be caused, for example, by a straightforward movement of a piston, or by rotation of the screw, both present in the casing on the end of which the nozzle or the baffle with the shaped or straight openings, respectively, is mounted. For every extruder this zone is critical, that is, the zone where the casing or screw ends and where the nozzle is mounted. The free cross-section of the nozzle is always smaller than the free cross- section of the casing. This is so because the pressure has to be distributed equally in the cross-section. This also creates the differences in free cross-sections and it creates zones where the paste does not flow. A reduction of the free cross-section in passing from the casing to the nozzle is also important because of the need to create a resistance against the paste's flow, which invokes the extrusion pressure. The extrusion pressure's function is not only to extrude the paste with the desirable rheological characteristics through the free cross-section of the nozzle, but the purpose is also - so it is called - to consolidate the paste. The principle of consolidation means the pressing of the skeleton, created by the grains of the particular substance (powder) under the influence of the extrusion pressure. There are free spaces or pores between such ordered particles. The pressing of the skeleton proceeds until there is a balance between the mechanical solidity, or submissiveness, respectively, of the grainy skeleton and the effecting extrusion pressure. The phenomenon itself is much more complicated, though, because there is a liquid in the pores which, alongside the particles, creates a two-part solid-liquid system. As the porosity diminishes as the effect of the extrusion pressure, the liquid fills these pores and the saturation of the paste increases. If the saturation level surpasses the value S=1, the pressure has such effect that the redundant volume of the liquid is pressed out and the paste is drawn out. In this phenomenon the pores are filled with liquid and the grainy skeleton is pressed further as an effect of the extrusion pressure, and the redundant liquid flows through its pores and out of the nozzle, outside of the device. This phenomenon of migration of the liquid phase is undesirable, because it lowers the amount of liquid in the pores, which changes the rheological characteristics and causes an enormous rise in the extrusion pressure. In critical circumstances, the values of this pressure can be so high that it causes the extrusion process to stop because of the clogged nozzle and this can cause the device to crash. The main cause of the migration of the liquid and change in the extrusion pressure is precisely this static part of the working zone of the extruder; that is, the place where the casing ends and extruding nozzle begins. A situation can occur where, due to the inappropriate rheological characteristics of the paste and due to the too high reduction of the ratio of the free cross-sections of the casing and the nozzle, there can be a critical rise of the pressure in this zone. This undesired phenomenon can be eliminated in multiple ways. Most often, the rheological characteristics of the processed pastes are altered. The disadvantage of this approach is that it is difficult to choose appropriate additive or lubricating substance, whose main function is to limit the migration of the liquid, to diminish the inter-particle friction and therefore to positively affect the rheological characteristics of the paste in its transfer through different parts of the extruder. The problem is that the additive is a substance which is, in principle, not desired in the final product from the point of view of the composition of the processed system. Its presence can therefore negatively affect the quality and cost of the final product. It is therefore desirable to reduce its presence in the paste to minimum, or to avoid it completely. An effort to do so, however, often runs into insurmountable problem concerning the relatively narrow spectrum of the usable types of extruders, which differ in principle by its construction and realization of the process of the extrusion.

A piston extruder is known in the prior state of the art, whose basic principle of extrusion is based on the pressing out of the paste by the piston of the cylindrical shape. It allows for unproblematic extrusion only in cases of paste with appropriate rheological characteristics. If the paste is sufficiently prepared in the mixer and the homogenizer, if it has homogenous structure in all its volume, the homogeneity is not disrupted - or it is disrupted only in the limited manner - in the piston extruder.

The disadvantage of the piston device is that it usually cannot operate continually. If it is necessary to mix the paste during the extrusion - for example due to the addition of the additive - it is not possible for the piston device to operate continually because of the spatial flow. This flow also causes that in the zone of transfer of the paste from the casing to the nozzle the paste is usually pressed by normal stress, whereby the rheological characteristics are mainly affected by the presence of the shear stress, without which there is a danger of halting of the extrusion.

The basic principle of the screw extruder is based on the extrusion of the paste by one or multiple screws which are placed in the cylindrical casing, on the end of which there is a nozzle or a matrix. The advantage of this device is that it can work continually. The paste is filled continually through the hopper, whereby the screw delivers the paste towards the nozzle. The screw rotates and its shape causes the paste to rotate around the screw's axis at speed different from the speed of the screw's rotation due to the friction of the paste on both the casing's and screw's surface. This friction causes the mixing of the paste and its compression in the screw. It is therefore possible to use the screw for homogenization of the additives added to the extruder during the extrusion, too. The extrusion pressure created by the screw on its end presses the paste to the nozzle by the normal stress, but the screw's rotary movement creates a shear stress in the paste (as opposed to the piston extruder), which positively affects the rheological characteristics of the paste and the process of extrusion itself. The ratio of the normal and shear stresses in the paste corresponds to the geometry of the screw. Rising the frequency (or speed) of the rotation of the screw does indeed rise the shear stress of the paste, which is a positive thing from the point of view of its rheological characteristics; however, the amount of the extruded material also rises and the extrusion pressure rises alongside it, which means that normal stress also rises and this has negative effects in the extrusion of the paste, such as the leak of the liquid.

Another disadvantage is that if the performance of the extruder needs enhancing, this is realized by raising the rotation frequency (or speed) of the screw, thereby by increasing the amount of the transferred material. This causes the extrusion pressure to rise. It is a consequence of the ratio between the normal and shear stresses in the paste, where the increase in the amount of the transferred material causes the normal stress to rise, whereby the simultaneous rise in the shear stress is not very significant and it is affected mainly by the increase in the rotation frequency of the screw. Construction of the known extruders does not allow one to lower this pressure to the optimal level.

The screw extruder with the dome-shaped nozzle operates on the principle of extrusion of the paste by the screw with specially modified end of the screw in the shape of the spatula through the matrix in the nozzle, which is shaped for example in the shape of the hemisphere. The screw is modified in such a way that there are spatulas placed at its end, which - during the movement - copy the inner surface of the matrix. This solution allows one to produce significant shear stress just by the inner surface of the matrix.

The disadvantage of such solution lies in the fact that the spatulas are located at the end of the screw and they rotate with it at the same rotation frequency. This solution does not allow one to regulate the amount of the extruded paste and the level of the extrusion pressure. The regulation of he pressure is only possible by changing the moisture of the processed paste. A radial extruder is known in the prior state of the art, which has a matrix in the cylindrical shape, whereby several spatulas move on the surface of the matrix, whereby these spatulas are inclined against the inner surface at the given angle.

Its disadvantage lies in its complicated construction but also in the fact that, since the extruder's chamber is not closed, it is not possible to produce any other pressure in the extruder but the atmospherical. Extrusion of paste takes place only under the effect of the pressure produced in the tapering wedge gap between the spatula and the matrix. Another disadvantage is the fact that the geometry of the matrix is usually limited to the cylindrical openings and to the relatively thin matrices, for which the low level of the extrusion pressure is sufficient.

The principle of the functioning of the radial screw extruder is in the transfer of the paste to the head by means of the screw, or pair of the screws. The spatulas are located at the end of the screw, inclined against the surface of the matrix. In this way, the tapering wedge gap is created between the surface of the matrix and front of the spatula. The screw creates a necessary extrusion pressure, it secures the performance of the device, and the sloped spatulas ensure the shear stressing of the paste, which positively affects its rheological characteristics.

The disadvantage lies once again in the fact that the spatulas are located at the end of the screw, which means that their rotation frequency (or speed) is the same as the rotation frequency (or speed) of the screw. This means that the spatulas can press out only as much of the paste, as the screw delivers. If the screw's performance is not enough to transfer the paste to the head, the spatulas rub it through the matrix, the head of the extruder is not filled, and there is not necessary pressure in the device, which can cause the final product to be lacking in its desired features. Opposite situation can take place if the extruded paste has bad flow characteristics. The rheological characteristics do not allow necessary flow through the openings of the matrix, the head is filled with paste, and the extrusion pressure reaches critical levels. Because of the persistent problems with the extrusion such construction of an extruder is needed which would ensure sufficient stress, that is, sufficient ratio between the normal and shear stresses, which has to be produced in the paste.

Essence of the invention

The abovementioned deficiencies are remedied by the construction of the axial extruder according to claims 1 to 17. The essence of the invention lies in the fact that the head of the extruder is rotary placed in the construction of the device, which allows it to rotate independently on the rotation of the screw during the operation. This is not a rotary placement which serves only the purpose of exact setting of the head's position, or which is purposeful only during the mounting of the device to the system. At the same time, the head of the extruder has an axis of the placement basically parallel to the axis of the screw. Such arrangement dramatically changes the kinematic relations between the surfaces which effect upon the extruded material. The rotary head can rotate both in and against the direction of the rotation of the screw, or it can remain in static position for some time. This allows for vast amount of possible settings of the mutual kinematics of the screw and the opposing head. Hitherto known constructions of the extruders did not allow one to change the relative speed of the inner surfaces of the head as opposed to the concurrently operating surfaces of the end of the screw without the amount of the material transferred to the extrusion zone being affected. This invention solves this deficiency and it offers new possibilities of adaptation to different rheological characteristics of the materials.

Rotating conical head of the extruder alongside the conical end of the screw creates a tapering space between cones, where the paste is under strong influence of the shear stresses due to the tapering space between cones, but also because of the different circumferential shear rate resulting from the different rotation frequency of the screw with the conical end and the rotating conical head. The conical end of the screw as well as the inner surface of the rotating conical head can be equipped by the system of grooves. In case of the conical end of the screw, this can be for example a system of alternately arranged axial transversal grooves and/or short grooves. The inner surface of the rotating head can also have a system of alternately arranged axial transversal grooves and/or short grooves and/or long grooves. The grooves prevent the creation of the liquid film between the paste, the surface of the cone and the surface of the head.

Different parts of the device are placed on the single frame. The screw is located in the casing with the hopper. The screw is rotary placed in the bearing housing or similar arrangement. It is preferable when the screw is driven by a motor which can regulate the rotation frequency, for example by means of frequency alternator. The motor is connected by the coupler with the first torque and screw's rotation frequency sensor. The first torque and screw's rotation frequency sensor is connected with the screw by the safety coupling which protects the device in case of a crash. The screw is on the other end positioned in the casing of the screw and it is slidably supported in the cross. The screw is ended conically, with its end containing grooves in axial direction. At the end of the casing of the screw there is a bearing housing of the head with the bearing inside it. Conical head can be placed in the bearing. In the preferable arrangement, the head can be equipped by internal grooves in the axial direction.

A nozzle is attached to the head's output. The nozzle can be rotary placed in the head, so that it can be rotary anchored to the frame. Such arrangement would be preferable if we want to rule out the rotation of the material exiting the nozzle, for example due to the further processing following just after the output from the nozzle.

On the outer side of the rotary conical head there can be outer teeth, which alongside the given toothed gear wheel allow the conical head to rotate alongside its axial axis. A gear connected to the motor can include second torque sensor. The second torque sensor can be combined with the sensor of the frequency and direction of the rotation of the conical head. The motor allows a gradual change of the frequency and the direction of the rotation. The gear presents just one possibility of connection with the motor. Another appropriately effective torque gear can be used, for example a chain, a toothed belt, a threaded gear whose thread acts directly upon the head's rim, and so on.

Rotation frequency of the rotating conical head can be set independently on the rotations frequency of the screw. Measuring and control unit records the rotation frequency of the screw, the torque level necessary for the drive of the conical head, the rotation frequency of the conical head and the extrusion pressure in the head, recorded by the pressure sensor. Parameter of distance „L" discloses the mutual position of the conical end of the screw and the conical head, and this distance needs to be experimentally set up according to the dimensions of the nozzle and the paste's character. In the preferable arrangement, the conical end of the screw and the inner surface of the rotating conical head have different conicity. The „L" distance (or parameter) can be set by changing the heads with different depth of the conical surface, or by a sliding mechanism which can change the mutual distance of the end of the screw and the head, for example by sliding the screw's casing with the head against the static screw. The sliding mechanism can be controlled electromechanically from the central control unit. If need arises, this mechanism can be used to diminish the critical pressure in the head.

The advantages of the construction of the axial extruder with the rotating head according to this invention are apparent from its effects. The important feature is the construction solution of the extruder's head, which brings the additional shear stresses into the paste. The origin of these additional shear stresses is different to the shear stresses that are produced by effect of the extrusion pressure as a result of the stress of the particular substance passing through the zone of reduction of the free cross-section. The additional shear stresses originate as a result of an additional tensity created by the additional construction element other than the screw or the piston. If the stress in the paste in the zone of the transfer from the casing to the nozzle is analyzed as a planar one, then the plane of the main tensity lies in the axis of the device. The plane of the additional stress is perpendicular on this plane. In both cases the analyzed zone is the zone of transfer from the casing to the nozzle. Their resulting effect is achieved by counting the vectors, which creates a spatial stress as a concurrent effect of the normal and shear stresses operating from the main construction element, for example from the screw, and from the additional construction element, for example the spatulas. If these two elements are driven independently and their rotation frequencies can be regulated independently, a high variability is achieved in terms of how the ratios between the main and the additional tensity can be set. If the construction of the additional deforming element is chosen preferably, this element will in the transfer zone bring mainly shear stresses to the paste. If it is possible to regulate its speed, this will also regulate the shear rate (or shear deformation rate) of the paste, whereby these parameters are important aspects of the resultant rheological characteristics. The primary function of the deforming element is to regulate the additional stress in the paste, mainly the shear stresses, and by this also to regulate the shear rate, which is thoroughly achieved in this case. Its operation results in such effects on the stresses in the paste at the place of the reduction of the cross-sections between the casing and the nozzle, where these stresses cause the change of the rheological characteristics of the paste, which in the end appears as a change in the extrusion pressure while the device's continual operation is preserved. This deformation element thoroughly ensures the change of the flow in the zone of the transfer from the casing to the nozzle in such a way that the shear rate is increased and the sheer stresses are increased as well by bringing the energy from the environment to this zone by means of rotation of the deforming element by the motor.

In the preferable arrangement the measuring and control unit will be equipped by or connected to the two frequency alternators that can regulate the motor of the screw and the motor of the head. The measuring and control unit can also be equipped by the appropriate software with the memory to store the settings of the mutual kinematic relations of the screw and the head, depending on the characteristics of the processed materials. The tested setting of the motors for the different materials with different characteristics can be stored in the memory of the measuring and control unit, and it can be used for a similar task in the future. The appropriate software can also deduce from the data the approximation to the critical values and it can assess the energetic demands of the different settings of the motors.

Last but not the least, the advantage of the device according to this invention is its relatively simple construction, which allows one to keep the high productivity and at the same time to affect the shear and pressure stresses at the critical place of the extrusion.

Brief description of drawings

Construction of the axial extruder with the rotary head according to this invention is further disclosed by the attached drawings. For example, on fig. 1 the optimal solution is disclosed in the view from the side. On fig. 2, the construction system is shown from the upper view and in partial cross-section. On fig. 3a is the detail of the conical end of the screw with the longitudinal transversal groove and the short groove. On fig. 3b there is a detail of the conical head with the longitudinal transversal groove and the short groove. On fig. 3c there is a mutual position of the conical end of the screw and the rotating conical head.

Examples of realization Following examples are for the illustration purposes only and cannot be interpreted as limiting the technical solutions. A person skilled in the art can find, by use of no more than routine experimentation, many equivalents to the specific realizations of the technical solutions according to this invention, which are described below. These equivalents fall within the scope of the following patent claims. A person skilled in the art will have no problem to dimension and set such device and to choose suitable materials and construction arrangements, even if such features are not analyzed in detail.

Example

In this example of the concrete realization of the invention according to the figures 1 and 2 an optimal construction solution of the axial extruder, for purpose of extruding and/or mixing of the pastes and paste materials, is described. The axial extruder with the rotating head according to this technical solution is solved in such a way that the rotating conical head 2 of the extruder alongside with the conical end 1 of the screw 4 creates a tapering space between the cones 23.. The conical end 1 of the screw 4 is equipped by the system of alternately arranged axial transversal grooves 24 and the short grooves 25, as depicted on the fig. 3a. Also, the inner surface of the rotating conical head 2 has a system of the alternately arranged axial transversal grooves 24, short grooves 25 and long grooves 26., as depicted on the fig. 3b. Individual parts of the device are placed on the common frame 1_8. The screw 4 is located in the casing 9 with the hopper. The screw 4 is rotary placed in the bearing housing 1_5 and it is driven by the motor 13 with the possibility of regulating of rotation frequency. Motor 1_3 is connected by a coupler 1_7 to the first screw's 4 rotation frequency and torque sensor 1_4. First screw's 4 rotation frequency and torque sensor 1_4 is connected with the screw 4 by the safety coupling 1_6. The screw 4 is on the other end placed in the casing 9 of the screw 4 and it is slidingly supported in the cross 5. The screw 4 is ended by the conical end with the grooves in the axial direction. At the end of the casing 9 of the screw a bearing housing 8 of the head is located; there is a bearing 7 in the bearing housing 8. In the bearing 7 a conical rotating head 2 with the grooves in the axial direction and a nozzle 3 is placed. On the outer side of the rotating conical head 2 there are the outer teeth. A gear 1_2 is placed on the shaft of the second torque sensor 1J_, which is connected to the motor 1_0 with the gradual change of the frequency and the direction of the rotation. The frequency and the direction of the rotation of the rotating conical head 2 are regulated independently on the frequency and the direction of the rotation of the screw 4. The measuring and control unit 1_9 is connected to the signal cable 20. with the values of the screw's torque and operating speed of the screw, the signal cable 2J_ with the value of the conical head's torque and operating speed of the conical head, and the signal cable 22 with the value of the extrusion pressure. The conical end 1 of the screw 4 and the conical head 2 are separated by distance „L", as depicted on fig. 3c. The conical end 1 of the screw 4 and the inner surface of the rotating conical head 2 have different conicity.

Industrial applicability

Axial extruder with the rotating head can be used in various fields of industry, mainly in food industry, in chemical, pharmaceutical industry, but also in field of technology of processing of recycled materials and wastes and in field of processing of plastics.

Claims

P A T E N T C L A I M S

1. An axial extruder, mainly for an extrusion and/or mixing of pastes, which on a frame (18) contains a screw (4) with a conical end (1), a casing (9) of the screw with a hopper, a drive of the screw and a head (2) adjacently placed at an end of the casing (9), whereby the head (2) with an output opening and an inner conical surface is in an axis of the screw (4), whereby the inner conical surface of the head (2) follows upon an inside of the casing (9), whereby the head (2) alongside the conical end (1) of the screw (4) creates a tapering space between cones (23) for processing of a material supplied by the screw (4) from the hopper, is characterized by the fact that the head (2) is rotary placed and it is connected with the drive of a rotation of the head (2) during an operation of the extruder, the drive is adapted for regulating a direction and/or frequency and/or speed of the rotation of the head (2) independently on a direction and/or frequency and/or speed of a rotation of the screw (4).

2. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to claim 1 is characterized by the fact that the conical end (1) of the screw (4) and the inner surface of the head (2) have a system of axial grooves.

3. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to claim 2 is characterized by the fact that the conical end (1) of the screw (4) has a system of alternately arranged axial transversal grooves (24) and short grooves (25) and the inner surfaces of the rotating conical head (2) has a system of alternately arrange axial transversal grooves (24), short grooves (25) and long grooves (26).

4. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 3 is characterized by the fact that the rotating conical head (2) with outer teeth is placed at an end of the casing (9) of the screw (4) with a bearing (7) in a bearing housing (8) of the head (2).

5. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 4 is characterized by the fact that the drive of the rotating conical head (2) includes a motor (10) and a mechanic gear, preferably a toothed gear with a toothed gear wheel (12), and it also includes a torque sensor (11).

6. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 5 is characterized by the fact that the drive of the screw (4) includes a first torque sensor (14).

7. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 6 is characterized by the fact that the drive of the head (2) includes the second torque sensor (11).

8. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 7 is characterized by the fact that it includes a pressure sensor (6) of a pressure of the material in proximity of the head (2).

9. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 8 is characterized by the fact that it includes at least one sensor of a speed of the screw (4) and/or the speed of the head (2).

10. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 6 to 9 is characterized by the fact that at least one torque sensor and/or sensor of the speed is connected to a measuring and control unit (19).

11. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 10 is characterized by the fact that a nozzle is connected to the output of the rotating conical head (2).

12. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 11 is characterized by the fact that the rotation frequency of the rotating head (2) is independent on the rotation frequency of the screw (4).

13. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 12 is characterized by the fact that the conical end (1) of the screw (4) and the inner surface of the conical head (2) have different conicity.

14. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 1 to 13 is characterized by the fact that the conical end (1) of the screw (4) is separated from a front of the rotating conical head (2) by a distance (L).

15. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to claim 14 is characterized by the fact that it includes a mechanism for setting and/or changing the distance (L).

16. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 10 to 15 is characterized by the fact that the measuring and control unit (19) is equipped by two frequency alternators for regulating a motor (13) of the drive of the screw (4) and a motor (10) for regulating the drive of the head (2).

17. The axial extruder, mainly for the extrusion and/or mixing of the pastes according to any of the claims 10 to 16 is characterized by the fact that the measuring and control unit (19) is equipped by a software with a memory for storing settings of mutual kinematic relations of the screw (4) and the head (2), depending on characteristics of the processed materials.