WO2023160985A1

WO2023160985A1 - Heating device, heating element, printing station, heating station, and system for generatively producing components

Info

Publication number: WO2023160985A1
Application number: PCT/EP2023/052638
Authority: WO
Inventors: Manuel PÉREZ CASÁS
Original assignee: Grunewald Gmbh & Co. Kg
Priority date: 2022-02-25
Filing date: 2023-02-03
Publication date: 2023-08-31
Also published as: DE202022101081U1

Abstract

The present invention relates to a heating device for heating and/or controlling the temperature of an elongate component, in particular an extruding device for a system for generatively producing components, preferably for a system for three-dimensional printing of components, comprising two heating jaws, which are held on a main body and in particular can be moved translationally towards and away from one another between an open position, in which the heating jaws are far enough apart from each other that the component can be placed between the heating jaws, and a closed position, in which the heating jaws surround a receiving chamber for a component, which receiving chamber defines a longitudinal direction.

Description

DESCRIPTION

Heating device, heating element, printing station, heating station, and system for the generative production of components

The present invention relates to a heating device for heating and/or tempering an elongate component, in particular an extrusion device for a system for the generative production of components, preferably for a system for the three-dimensional printing of components. Furthermore, the present invention relates to a heating element for such a heating device. In addition, the invention relates to a printing station and a heating station, as well as a system for the generative production of components.

The three-dimensional printing of components is becoming increasingly important in many industrial applications. A major advantage of the generative creation of components using 3D printing is that components can be produced with practically any shape, which is not easily possible with conventional manufacturing processes. Especially for applications in the field of mold making, components are made of plastic using 3D printing. Devices for the defined dispensing of material, for example extruding devices, which have a nozzle for the defined dispensing of material at a front end, are often used for this purpose. Such extrusion devices usually have a tubular extruder housing with an extruder screw mounted rotatably in this housing. At the rear end there is usually a feed device into which, for example, starting material in granular form can be introduced. This is conveyed by the extruder screw in the direction of the front end and at the same time compressed and/or heated from the outside, so that it can exit through the nozzle in a viscous aggregate state.

In order to be able to reliably exit the material in a viscous state of aggregation, an exact temperature control of an extrusion device is necessary. To do this, it may be necessary to maintain a specific temperature profile over the length of the extrusion device. At the same time, it may be necessary to use different devices for dispensing material one after the other during a printing process, in particular if the material or the dimensions of the emerging material are to be varied.

Against this background, it is the object of the present invention to provide a heating device for heating and/or tempering an elongate component, in particular an extrusion device for a system for the generative production of components, preferably for a system for the three-dimensional printing of components, which is simple easy to handle and at the same time enables precise temperature control.

According to a first aspect of the present invention, this object is achieved in a heating device of the type mentioned above in that it has two heating jaws which are held on a base body and in particular can be moved towards and away from each other in a translatory manner between an open position in which the Heating jaws are far enough apart that a particularly elongate component can be placed between the heating jaws, and a closed position in which the heating jaws enclose a receiving space for the component that defines a longitudinal direction. This configuration is based on the consideration that two heating jaws, in their closed position, can enclose and heat up an elongate component arranged between them. At the same time, the elongate component can easily be positioned between the two heating jaws.

In a further refinement, both heating jaws can be movable relative to the base body, in particular symmetrically with respect to one another. This means that in the open position of the heating jaws a component, in particular an extrusion device, can be placed between them and both heating jaws are moved towards the component until they reach their closed position. At the same time, the component can be fixed by the heating jaws, so that a movement radially to the longitudinal direction can be ruled out.

According to a further aspect, the object on which the invention is based is achieved with a heating device, which encloses or can enclose a receiving space for a component that defines a longitudinal direction, in that a plurality of heating elements are provided, which are arranged in such a way that they are flat on one in the receiving space arranged in particular elongate component abut. Provision can thus be made for the heat to be transferred from the heating jaws, specifically the heating elements, to a component, in particular to an extrusion device, which is arranged in the receiving space, by means of surface contact.

The object on which the invention is based is also achieved by a heating element for such a heating device. In a further embodiment, several heating elements can be arranged one behind the other in the longitudinal direction. Furthermore, the heating elements can be arranged in pairs opposite one another in relation to the longitudinal direction. In particular--if the heating device comprises two heating jaws--each heating jaw can have a plurality of heating elements in the longitudinal direction. In this way it is achieved that heat is transferred from the heating jaws to the component over almost the entire length of a component, in particular an extrusion device, preferably over the area in which an extruder screw is located. This enables a constant temperature or a desired temperature profile to be achieved over the length of an attached extruder. The heating elements of the two heating jaws are preferably arranged in pairs opposite one another. This means that each heating element of one heating jaw is opposite an element in the other heating jaw in the same position in the longitudinal direction.

In order to achieve a flat contact with a component positioned in the receiving space, in particular an extrusion device, it can be provided that the heating elements are mounted in heating element recesses of the heating device, in particular of heating jaws of the heating device, so that they can move into and out of the receiving space. Such a movable mounting means that the heating elements can lie flat on the component, in particular on an extrusion device, and thus a favorable heat transfer can be achieved. Furthermore, dimensional tolerances, such as can occur on various extrusion devices, can be compensated for by such a movable bearing. The heating element recesses can be designed as depressions in the heating jaws. In a specific embodiment, spring elements can be provided, which press the heating elements inwards into the receiving space, so that a flat contact of the heating elements with an extrusion device arranged in the receiving space is ensured. The spring elements can be supported against the heating jaws, in particular the base of the heating element recesses, and against the heating elements, in particular a support body of the heating elements.

According to a preferred embodiment of the invention, at least one, in particular each heating element, can have several heating segments which are rotatably mounted about an axis of rotation running in the longitudinal direction and which each have a concave heating surface pointing towards the receiving space, which can be brought flatly into contact with a component. In other words, each heating element comprises a plurality of movable heating segments which, due to the movable mounting, can cling to the outer contour of an elongate component.

Each heating segment can be provided with an in particular electrically heatable heating cartridge, which is preferably inserted into a longitudinal bore of the respective heating segment. Each heating segment can thus have a cavity in which a heating cartridge is inserted. Electrically heatable heating cartridges are particularly easy to adjust in terms of their temperature and output and are therefore the preferred choice.

In order to realize the rotatable mounting of the heating segments, each heating element can have a front and a rear mounting plate, between which the heating segments are rotatably mounted. In concrete terms, each heating element can be fitted with a front and a rear projection in a corresponding intervene in the bearing bore of the front or rear bearing plate. The bearing hole can completely penetrate the bearing plate. As a result, a rotatable mounting of the heating segments is implemented in a simple manner.

Furthermore, the rear bearing plate or the front bearing plate can adjoin a feed plate in which feed slots for electrical lines to the heating cartridges are provided. The feed slots preferably extend away from the receiving space, starting from the axis of rotation of the respective heating segment. In this way, electrical lines that are required to power the cartridge heaters can be routed to the cartridge heaters in a simple manner.

The heating elements can be limited at the front by a base plate and at the rear by a cover plate. The base plate or the cover plate can rest against the edges of the heating element cutouts, so that the heating elements are positioned in the longitudinal direction in the heating element cutouts.

In a further embodiment, the rear bearing plate and the front bearing plate can be fixed to a support body, in particular screwed to the support body, which is inserted into the heating element recess of the respective heating jaw. The support body can extend in the transverse direction over the entire heating element and thus position the heating element in the heating element recess transverse to the longitudinal direction. Furthermore, the supporting body can be arranged in the longitudinal direction between the front mounting plate and the rear mounting plate, with the front and the rear mounting plate preferably lying flat against the supporting body. Toward the receiving space, the supporting body can have a U-shaped recess in which the heating segments are arranged. Springs can be arranged on the side of the support body facing away from the receiving space, via which the support body is supported against the heating element recess. As a result, a spring force is transferred to the heating segments via the support body and the bearing plates, so that their concave heating surface is pressed against a component placed in the receiving space in order to transfer the heat to it.

According to a further aspect, the object on which the invention is based is achieved in a heating device, which has a receiving space for a component that defines a longitudinal direction, in that at least one, in particular two, opposite cooling elements are arranged in a rear end region of the receiving space in such a way that they lie flat against a component arranged in the receiving space or can be brought into contact.

This configuration is based on the idea of using a cooling element in the rear end area of the receiving space to provide thermal decoupling between the area of an extrusion device placed in the receiving space, in which the material is conveyed and heated, and the rear end area, in which there may be coupling means, storage means for the extruder screw and sealants, sealing elements or the like. In other words, a front area of the heater is used as a heating area and a rear area is used as a cooling area. This can prevent damage to components. It is provided that a cooling surface of the cooling element can be brought into direct contact with the component used. In a specific embodiment, the cooling element can have a flow channel for cooling water. If the heating device has two heating jaws which, as described above, can be moved between an open position and a closed position, then each heating jaw preferably has a cooling element recess into which a cooling element is inserted.

In order to monitor the temperature in a component positioned between the heating jaws, the heating device can be provided with temperature sensors which protrude into the receiving space. Specifically, a temperature sensor can be provided in each case in the longitudinal direction between two heating elements. When the heating jaws are in their closed position and enclose an elongate component, these temperature sensors can engage in corresponding recesses in the component, so that a direct contact measurement of the temperature of the component, in particular an extrusion device, is possible, resulting in the temperature of the material can be closed inside the extruder housing. The temperature sensors can contain a resistance thermometer and/or a thermocouple.

In order to fix a front end of an elongate component in the closed position of the heating jaws, fixing means can be provided at a front end of the heating jaws. Specifically, a fixing element can be arranged at the front end of each heating jaw, which has a semi-circular recess directed inwards towards the receiving space, in which a corresponding annular collar of a component, in particular an extrusion device, preferably a nozzle, can be engaged in order to insert a component into support their front end. By supporting the front end area near the nozzle, an exact positioning and a stable fixing of an attached component can be achieved, particularly at the printing station. The object on which the invention is based is also achieved by a printing station for a system for the generative production of components, in particular for a system for the three-dimensional printing of components, which is designed in such a way that an extrusion device for the defined dispensing of material can be detachably attached to it, wherein the printing station has a heating device as described above for tempering an attached extruding device.

The printing station can be moved relative to a component to be produced. This means that, for example, the component to be produced is produced on a stationary workpiece table and all relative movements are carried out by the printing station. It is also conceivable that individual degrees of freedom of movement are carried out by a workpiece table or a workpiece holder and other degrees of freedom by the printing station. It is equally conceivable that only one workpiece table or one workpiece holder is moved relative to a stationary printing station. A movable printing station can specifically be designed as a portal system. This means that the printing station can be moved along a number of translational axes.

The printing station can also have drive means for driving the extruder screw of an extrusion device, which preferably comprise an electric motor. Furthermore, the printing station can have coupling means in order to couple the drive means to the extruder screw of an extruding device in a torque-proof manner. In addition, the printing station can comprise feed means, for example in the form of a feed funnel, which are designed and suitable for continuously feeding material for producing a component to an extrusion device attached to the printing station. Furthermore, the object on which the invention is based is achieved by a heating station for a system for the generative production of components, in particular for a system for the three-dimensional printing of components, to which an extrusion device for the defined dispensing of material can be detachably attached, the heating station having a heating device as before described for heating an attached extrusion device.

Both the printing station and the heating station can have a holding device in order to detachably fix the rear end region, in particular the head of an extrusion device, to a base body. This configuration is based on the idea of fixing an extrusion device with its rear end area to a base body of the printing station or the heating station. Thus, the holding device is preferably arranged at the rear of the heating device. In particular, if there is also a fixation at a front end area, as is possible, for example, using appropriate fixation means of a heating device, a stable fixation is achieved which also withstands high mechanical stresses.

Specifically, the holding device can have a base element, which has a central receiving recess, in which the head of an extrusion device can be positioned, and holding elements, which are arranged in the base element and between a release position, in which the holding elements are moved so far out of the receiving recess that a Extrusion device can be inserted into the receiving recess or removed from it, and a holding position in which the retaining elements protrude so far into the receiving recess that an extruding device inserted into the receiving recess is held in a non-positive and/or positive manner. The base element is preferably on the Body of the printing station or the heating station or a storage station attached.

The holding elements are preferably designed as balls. In particular, a total of four holding elements can be provided, two of which are arranged on opposite sides of the receiving recess. In other words, two holding elements can be positively engaged on two opposite sides of the extruder head. In this way, a high level of stability against twisting of the extrusion device about its longitudinal axis is achieved, since a total of four holding elements can be brought into engagement.

The receiving recess formed on the base member may be open on two sides of the base member. As a result, a head of an extrusion device can be introduced into the holding device in a simple manner. Specifically, the base element can be essentially cuboid and the receiving recess can be open to a front side and to an adjacent side, in particular to a side facing away from the respective base body. The receiving recess can have a cuboid basic shape.

In a further embodiment, the base element can have a positioning recess for positioning an extrusion device inserted into the receiving recess. This can be formed on a rear side of the receiving recess. Accordingly, the base surface of the receiving recess pointing to a front side can form a stop surface against which a corresponding end surface of an extrusion device, in particular an extruder head, can be brought into contact in order to rotate the extrusion device to be clearly positioned together with the holding elements in the longitudinal direction. The positioning recess preferably penetrates the base element completely towards the rear.

In order to move the holding elements between the release position and the holding position, the holding device can comprise a confirmation element which can be moved, in particular displaced, relative to the base element. The actuating element can preferably be displaced transversely to the longitudinal direction relative to the base element.

Specifically, a pneumatic cylinder can be provided in order to move the actuating element relative to the base element, with a housing of the pneumatic cylinder preferably being firmly connected to the base element.

The actuating element can be designed in several parts and can comprise a rear actuating yoke and a front support element on which the pneumatic cylinder acts. The support element is preferably screwed to the actuating yoke.

In a further embodiment, the actuating element can be C-shaped, with the two C-legs encompassing the base element and on both C-legs an inwardly projecting link guide is formed, which cooperates with the holding elements in such a way that a movement of the actuating element relative to the Base element is converted into a movement of the holding elements in the direction of the release position or in the direction of the holding position. In other words, a translational movement of the actuating element transverse to the longitudinal direction is converted into a translational movement of the holding elements in a different direction via such a link guide, which can be in direct contact with the holding elements, which are preferably spherical. Specifically can to do this, engage the link guide from the outside in guide slots of the base element, into which the holding elements protrude from the inside of the C-legs.

Furthermore, the object on which the invention is based is achieved by a system for the generative production of components, in particular for the three-dimensional printing of components, with a printing station as described above and at least one heating station as described above. This embodiment is based on the idea of providing at least one heating station, in addition to a printing station, to which an extrusion device can be attached. This allows the extrusion device to be preheated outside of the printing station before it is attached to the printing station and used to create a component. In this way, lengthy heating-up at the printing station and thus a temporary system downtime when changing the extrusion device in the printing station can be avoided. Different extrusion devices can thus be used in a simple manner one after the other when producing a component, without long downtimes occurring when changing.

The system according to the invention can also have at least one, in particular several, extrusion devices which have an opening at a front end for the defined discharge of material and a feed device for feeding material into the extrusion device at a rear end area. This refinement is based on the consideration that the system contains a plurality of extrusion devices which are provided for different materials or for dispensing material in different dimensions. Optionally, one of these extruders can be attached to the printing station when it is used directly to create a component. Each extrusion device preferably has a tubular, elongate extruder housing which defines a longitudinal axis, and an extruder screw which extends inside the extruder housing and is rotatably mounted in the extruder housing. Such an extruder screw is used to convey material from a rear end of the extruder to the opening for the defined discharge of material. The extruder screw can have a central shaft body and a spiral profile projecting outwards from this body. The spiral profile can have a continuous gradient over its entire length. Alternatively, the gradient can vary over the length; in particular, sections with different gradients can be provided. The diameter of the shaft body can also vary over the length, so that the distance between the shaft body and the inner wall of the extruder housing changes over the length. In particular, the distance can decrease towards the front, so that the conveyed material is compressed.

For the defined discharge of material, each extrusion device can have a nozzle at a front end of the extruder housing, the nozzle being in particular detachably fastened to the extruder housing, preferably screwed into it. A nozzle, which is arranged at a front end of the extruder housing, can thus form the opening for the defined discharge of material.

The nozzle can have an annular collar whose outside diameter is in particular larger than the outside diameter of the extruder housing. This configuration is based on the consideration that such an annular collar can engage in corresponding fixing means in order to stably support the extrusion device in its front end area. In a specific embodiment, the extruder housing can have an extruder head, in particular a cuboid, on the back. Such an extruder head can have or carry appropriate means for attachment to a heating station or to the pressure station. Furthermore, an extruder head can be used for gripping a transport unit, for example a robot.

Retaining recesses can be formed on the extruder head of the extrusion devices, in which the retaining elements of a retaining device can be brought into engagement in a non-positive and/or positive manner. Two corresponding holding recesses are preferably formed on opposite sides of the extruder head. In other words, retaining recesses are provided on the extruder head corresponding to the retaining elements of the retaining device, which are preferably designed as balls, so that a detachable connection can be established between the retaining device and the extrusion device by engaging the retaining elements in the retaining recesses.

In a further embodiment, the holding recesses can be designed to be open towards the front. Specifically, the retaining recesses may be formed by grooves extending rearwardly into the extruder head from a front end thereof and having a circular cross-section. The grooves preferably do not run continuously, but instead end in an end section within the respective side surface of the extruder head. This can preferably have a hollow contour corresponding to a segment of a sphere. The spherical end portion and the retaining elements formed as balls longitudinally position the head of the extruder and exert a rearward force on the extruder when the retaining elements are engaged. The holding recesses are preferably designed in such a way that the extruder head is pressed with its rear end face against the rear face of the receiving recess of the base element of the holding device when the holding elements are engaged in the corresponding holding recesses. In this way, a flat contact and a stable positioning in the longitudinal direction of the extruder head in the base element are realized.

In addition, the extruder head can have a rear drive opening from which coupling means protrude in order to couple the extruder screw to a drive of the printing station in a rotationally fixed manner, the drive opening preferably being arranged coaxially with the axis of rotation of the extruder screw. The extruder screw can also be connected directly to the coupling means in a rotationally fixed manner. The coupling means can be common coupling elements which can establish a connection to a drive of the printing station in a positive and/or non-positive manner. Specifically, it can be one half of a gear coupling or a claw coupling, which is preferably connected to the extruder screw in a torque-proof manner.

To position the extrusion device on a holding device of a printing station or on a holding device of a heating station or on a holding device of a transport unit, a positioning projection, in particular a positioning projection with a substantially hexagonal base, can be formed on the rear of the extruder head. In other words, a positioning projection can protrude from the rear end face of the extruder head and can be engaged in a corresponding recess of a holding device. In this way, the extrusion device can be clearly positioned on such a holding device on the extruder head side. A positioning projection with an essentially hexagonal base area, in which case the corners can be rounded in particular NEN, and a complementarily formed recess on a holding device also prevents incorrect, ie twisted about the longitudinal axis attachment of the extrusion device.

The feed device of the extrusion device can have a feed housing which projects radially from the extruder housing in relation to the longitudinal axis and has a feed opening for material which is open in particular towards the rear. In other words, provision is made to provide a further housing on the extruder housing, through which material can be fed from the rear. The corresponding feed opening can be arranged coaxially to a corresponding opening of the printing station when the extrusion device is located at the printing station. In this way, material can be continuously fed to the extrusion device in an automated manner.

In a further embodiment, the feed housing can have a storage space which is connected to the interior of the extruder housing via a through-opening in order to continuously feed material into the interior of the extruder housing. This configuration is based on the consideration that a storage space can accommodate a certain supply of material, so that a printing process does not have to be interrupted even if the supply to the supply device is interrupted.

In order to monitor the temperature prevailing in the extruder device, recesses can be formed in the extruder housing, into which temperature sensors of the heating device(s) can be engaged. These recesses are preferably designed as radial blind holes. In a specific embodiment, a plurality of recesses can be spaced apart from one another in the longitudinal direction. In a further embodiment of the system according to the invention, a transport device can be provided in order to transport an extrusion device between the printing station and a heating station. In other words, provision is made for automatically transporting an extrusion device with a corresponding transport device, for example if it is to be removed from a heating station preheated and attached to a printing station. In concrete terms, the transport device can be designed to move an extrusion device attached to it along a number of axes, in particular to move translationally in three directions and/or to rotate about an axis. Such a transport device can, for example, comprise a multi-armed robot. This can be equipped with a corresponding position and/or displacement control.

The system can also include at least one storage station, at which extruders that are not needed at the moment and also do not have to be heated up, ie that have to be prepared for a printing process, can be stored. Such a storage station may include a holding device as previously described to securely hold an extrusion device. The storage station and/or the transport device can also have a holding device as described above.

Furthermore, control means can be provided in order to control the individual components of the system. These can include separate controls for the heating device, the transport device and the printing station, as well as possible storage stations. Furthermore, the respective components can be coupled via a common central system controller. In this way, the entire system can be monitored from a central control station. For example, the data provided by the temperature sensors of the heating devices can be monitored centrally and the corresponding heating power of the heating elements can be monitored if required be adjusted. This enables easy control of the entire system.

For the further development of the invention, reference is made to the dependent claims and to the description of an exemplary embodiment with reference to the drawing. Show in the drawing:

FIG. 1 shows a system for three-dimensional printing of components according to the present invention;

FIG. 2 shows an extrusion device of the system from FIG. 1 in a perspective view;

FIG. 3 shows the extrusion device from FIG. 2 in a longitudinal sectional view;

FIG. 4 shows the extrusion device from FIG. 2 in an exploded view;

FIG. 5 shows the printing station of the system from FIG. 1 with an inserted extrusion device in a perspective view;

FIG. 6 shows the printing station from FIG. 5 without the inserted extrusion device and with the heating jaws open, in a perspective view;

FIG. 7 shows the printing station from FIG. 5 in an exploded view;

FIG. 8 shows a perspective view of a heating station of the system from FIG. 1 with an inserted extrusion device;

FIG. 9 shows the heating station from FIG. 8 with the heating jaws open; FIG. 10 shows a perspective representation of a heating jaw of the heating device of the printing station or heating stations;

FIG. 11 shows the heating jaw from FIG. 10 in an exploded view;

FIG. 12 shows the transport device of the system from FIG. 1 with an extrusion device held thereon, in a perspective representation;

FIG. 13 shows the transport device from FIG. 12 in a different perspective illustration;

FIG. 14 shows the transport device from FIG. 12 in an exploded view;

FIG. 15 shows a storage station of the system from FIG. 1 in a perspective representation;

FIG. 16 shows the storage station from FIG. 15 in an exploded view;

FIG. 17 shows the printing station of the system in a detailed embodiment in a perspective view;

FIG. 18 shows the heating jaw of the heating device of the printing station or the heating station in a detailed configuration in a perspective view;

FIG. 19 shows the heating jaw from FIG. 18 in an exploded view;

FIG. 20 shows the heating element of the heating device of the printing station or the heating station in a detailed configuration in a perspective view; FIG. 21 shows the heating element from FIG. 20 in an exploded view;

FIG. 22 shows a holding device and an extrusion unit in a detailed configuration in a perspective representation; and

FIG. 23 shows the holding device from FIG. 22 in an exploded view.

FIG. 1 schematically shows a system for three-dimensional printing of components according to the present invention. The system comprises a number of stations, at each of which an extruding device 1 can optionally be detachably removed.

Specifically, the system includes a printing station 2, which is shown on the right in FIG. The printing station 2 is used for the generative production of a component and is designed in such a way that, for the defined dispensing of material, an extrusion device 1 can be detachably attached to it in order to generatively produce a component.

Furthermore, the system comprises two heating stations 3 which are arranged separately from the printing station 2 and which are designed and suitable for receiving and preheating an extrusion device 1 when this is not attached to the printing station 2 . Thus, an extrusion device 1 can be attached to the heating station 3 and preheated before it is attached to the printing station 2 in order to generate a component there.

The system also includes two storage stations 4, which are arranged to the left of the two heating stations 3 in FIG. An extruder 1 can be detachably attached to each of the storage stations 4, in particular if the respective extruder 1 has a is not required for a long period of time. Finally, the system includes a transport device 5, by means of which an extrusion device 1 can be transported between the various stations 2, 3, 4.

The system shown in FIG. 1 also includes a total of three extrusion devices 1 for the defined dispensing of material. One of the three extrusion devices 1 is detachably attached to one of the two storage stations 1 and another extruder device 1 is detachably attached to a heating station 3 . In addition, a third extrusion device 1 is detachably held on the transport device 5 .

The basic structure of the extrusion device 1 is shown in FIGS. 2 to 4, a detailed representation of an extrusion device can be found in FIG. A nozzle 7 for dispensing material is screwed into the front end of the extruder housing 6 . The extruder housing 6 has a cuboid extruder head 8 on the back.

The extruder device 1 also has a rotatably mounted extruder screw 9 extending inside the extruder housing 6 . As can be seen in particular in Figures 3 and 4, the extruder screw 9 has an inner shaft body 10 and a spiral profile 11 arranged on the outside of the shaft body 10. The diameter of the shaft body 10 increases slightly from the rear end to the front end, whereas the depth of the spiral profile 11 decreases correspondingly. By rotating the extruder screw 9 relative to the extruder housing 6, material can be conveyed from the rear end to the front end of the extruder device 1, it being simultaneously compressed by the increasing diameter of the shaft body 10. In a rear end area, the extrusion device 1 has a feed device for feeding in material. In concrete terms, the feed device comprises a feed housing 12 which protrudes radially from the extruder housing 6 with respect to the longitudinal axis X and has a feed opening 13 for material which is open to the rear. The feed housing 12 forms a storage space 14 which is connected to the interior of the extruder housing 6 via a through-opening 15 so that material can be fed continuously into the interior of the extruder housing 6 .

The extruder screw 9 is rotatably mounted in the extruder head 8 . At the rear, the extruder head has a drive opening 16, from which one half 17a of a toothed coupling 17 protrudes. With this half of the gear coupling 17, the extruder screw 9 is rotatably connected.

Furthermore, a positioning projection 18 with a substantially hexagonal base area is provided on the rear of the extruder head 8 . The corners of the hexagonal base are rounded.

In the figures 5 to 7, the basic structure of the printing station 2 is shown. The printing station 2 has a base body 19 which can be screwed laterally to a fixed bracket or to a portal system for moving the printing station 2 .

Furthermore, the printing station 2 comprises a receptacle for an extrusion device, as well as a heating device 20 for tempering an attached extrusion device 1 .

In the arrangement shown in Figure 5, an extrusion device 1 is attached to the printing station 2. The printing station 2 comprises feed means, presently in the form of a feed funnel 20, which is arranged coaxially to the feed opening 13, so that material can be fed continuously to the extrusion device 1.

Furthermore, drive means are provided in order to set the extruder screw 9 of an extruder device 1 used in a rotary motion. For this purpose, as can be seen clearly in FIG. 7, a drive motor 21 is provided, which in the present case is designed as a speed-controlled electric motor. The axis of rotation of the drive motor 21 runs parallel to the longitudinal axis X of an extrusion device 1 used. Specifically, the drive motor 21 is flanged to a drive housing 22 , which in turn is fastened to the base body 19 . The second half of the toothed coupling 17 is rotatably mounted in the drive housing 22 coaxially to the extruder screw 9 of an extruder device 1 used. The drive motor 21 and the second half 17b of the gear coupling 17 are coupled to one another in a torque-proof manner. This can be done, for example, via a belt drive or a gear train. In this way, the rotational movement of the drive motor 21 can be transmitted to the extruder screw 9 of an extruding device 1 used.

The basic structure of a heating station 3 is shown in FIGS. The heating station 3 also has a base body 23 which can be screwed to a support or to a wall, for example. The heating station 3 serves to receive and preheat an extruding device 1 as long as it is not attached to the printing station 2. In this way, a preheated extruder 1 can be removed from the heating station 3 and attached to the printing station 2 when needed there.

Both the printing station 2 and both heating stations 3 each have a heating device 24. The heating devices 24 of the printing station 2 and the heating station 3 are of identical design in the present case. Each heating device 24 comprises two heating jaws 25a, 25b, which are held on the respective base body 19 of the printing station 2 or the base body 23 of the respective heating stations 3. The two heating jaws 25a, 25b can be moved towards and away from one another between an open position and a closed position. In the open position, as shown for example in FIG. 6 and in FIG. 9, the two heating jaws 25a, 25b are so far apart that an extrusion device 1 can be placed between the two heating jaws 25a, 25b. In their closed position, which is shown for example in FIG. 8 and FIG. 5, the heating jaws 25a, 25b enclose a receiving space for an extrusion device 1. Specifically, the heating jaws 25a, 25b surround the extrusion device 1 in a middle section between the extruder head 8 or the feed housing 12 and the nozzle 7.

The basic structure of the heating jaws 25a, 25b is shown in FIGS. Each heating jaw 25a, 25b carries a plurality of heating elements 26 which are arranged in such a way that, when the heating jaws 25a, 25b are in the closed position, they lie flat against an extrusion device 1 arranged in the receiving space. In concrete terms, a plurality of heating elements 26 are arranged one behind the other in the longitudinal direction in each heating jaw 25a, 25b. At the same time, the heating elements 26 of the two heating jaws 25a, 25b are arranged in pairs opposite one another.

In order to ensure a flat contact with an extrusion device 1 inserted into the receiving space, the heating elements 26 are mounted in heating element recesses 27 of the heating jaws 25a, 25b so that they can move into and out of the receiving space. A cooling element 28 is arranged in each case in a rear end region of the heating jaws 25a, 25b. This is designed in such a way that it lies flat against the extrusion device 1 when the heating jaws 25a, 25b are in the closed position. In this way, when an extrusion device 1 is used, thermal decoupling takes place between a front area of the extrusion device 1 and a rear end area, in which drive elements, seals, etc. can be located.

Fixing means are provided at a front end of the heating jaws 25a, 25b in order to fix a front end of an extrusion device 1 in the closed position of the heating jaws 25a, 25b. Specifically, a fixing element 29 is attached to the front end of each heating jaw 25a, 25b. In the arrangement shown in FIGS. 10 and 11, this has a semicircular recess 30 directed towards the receiving space. The nozzle 7 of the extrusion device 1 has a corresponding annular collar 31 which can be engaged in the recess 30 in order to support an extrusion device 1 in its front end area. As a result, a particularly stable attachment of the extrusion device 1 in a heating station 3 or in the printing station 2 can be realized.

The specific design of the heating jaws 25a, 25b and the heating elements 26 and the cooling element 28 can be seen in FIGS. 18 to 21. The heating jaws 25a, 25b have a heating jaw housing 32 which is designed as a sheet metal construction. A cover plate 33 is provided inward towards the receiving space. The heating jaw housing 32 has a plurality of heating element recesses 27 in the longitudinal direction, in each of which a heating element 26 is inserted. In the figures 20 and 21, the design of the heating elements 26 is shown in detail. Each heating element 26 has five heating segments 34 mounted so as to be rotatable about an axis of rotation running in the longitudinal direction. These each have a concave heating surface 35 pointing towards the receiving space, which can be brought into surface contact with an extruding device 1 . Each heating segment 34 has a longitudinal bore 36 into which an electrically heatable cartridge heater 37 is inserted.

Furthermore, each heating element 26 has a front bearing plate 38 and a rear bearing plate 39, between which the heating segments 34 are rotatably mounted. Specifically, each heating element 34 engages with a front projection 40 and a rear projection 41 in the corresponding bearing bore 42 of the front and rear bearing plates 38, 39, respectively.

In the present case, the rear storage plate 39 adjoins a feed plate 43 in which feed slots 44 for electrical lines 45 to the heating cartridges 37 run. Starting from the axis of rotation of the respective heating segment 34, the feed slots 44 extend away from the receiving space and parallel to one another.

Each heating element 26 is delimited at the front by a base plate 46 and at the rear by a cover plate 47 . The storage plates 38, 39, the feed plate 43 and the base plate 46 and the cover plate 47 are screwed to a support body 48 with a substantially semi-circular through-hole 49. In this way, each heating element 26 forms a structural unit.

On the side facing away from the receiving space of the support body 48 springs 50 are arranged, via which the support body 48 against the base of the Heating element recess 27 is supported. In this way, the heating element 26 is pressed with a defined force against an extrusion device 1 inserted into the receiving space, so that a planar contact of the heating segments 34 via their heating surface 35 on the extruder housing 6 of an inserted extrusion device 1 is ensured.

A cooling element 28 is provided on a rear end area of each of the heating jaws 25a, 25b and has a flow channel for cooling water.

A sensor element 51 for measuring a temperature is arranged between the cooling element 28 and the adjacent heating element 26 and between the heating elements 26 in each case. This includes a temperature sensor 52 which protrudes into the receiving space in order to measure the temperature of an extrusion device 1 used. For this purpose, recesses designed as radial blind bores 53 are provided in the extruder housing 6 of the extruding devices 1 to accommodate the respective temperature sensor 52 .

Both the printing station 2 and each heating station 3 and each storage station 4 also have a holding device 54 in order to fix the rear end region, in particular the head 8, of an extruding device 1 in a detachable manner. The exact structure of the holding device 54 is shown in FIGS.

The holding device 54 has a stationary cuboid base element 55 which has a central receiving recess 56 for the extruder head 8 of an extruder device 1 . The receiving recess 56 is open on two sides of the base member 55, in this case on a front side and on an adjacent side. Furthermore, the holding device 54 has a total of four holding elements 57 designed as balls. The holding elements 57 are each arranged in pairs on opposite sides of the receiving recess 56 in the base element 55 . For this purpose, a total of four through-holes 58 are formed in the base element 55, which extend outwards from two sides of the receiving recess 56. Inwards, ie towards the receiving recess 56 , the through bores 58 are tapered in order to prevent the holding elements 57 embodied as balls from being able to exit completely into the receiving recess 56 .

The holding elements 57 are movable between a release position and a holding position. In their release position, the holding elements 57 are moved so far out of the receiving recess 56 that an extrusion device 1 can be inserted into the receiving recess 56 or removed from it. In the holding position, the holding elements 57 protrude so far into the receiving recess 56 that an extrusion device 1 inserted into this is held in a form-fitting manner. For this purpose, holding recesses 59 are formed on the extruder head 8 of the extruding device 1 . The holding elements 57 can be positively engaged in these. In a specific embodiment, the holding recesses 59 are open to the front and are formed by grooves 60, which have a cross section corresponding to a segment of a circle. The grooves 60 extend rearward from a front end of the extruder head 8 . They end within the respective side surface of the extruder head 8 in an end section 61 which has a hollow contour corresponding to a segment of a sphere.

The base element 55 of the holding device 54 has a positioning recess 62 for positioning an extrusion device 1 inserted into the receiving recess 56 . In the present case, this is formed on the back of the receiving recess 56 and has an essentially hexagonal shape Cross-section and passes through the base member 55 to the rear completely. The positioning projection 18 of the extruding device 1 can be inserted into this positioning recess 62 .

The holding device 54 also includes an actuating element 63 which, in the present case, is of multi-part design and includes a rear-side actuating yoke 64 and a front-side piece element 65 . The actuating yoke 64 is screwed to the support element 65 .

The actuating member 63 is slidable relative to the base member 55 to move the holding members 57 between their release position and their holding position. The holding device also includes a pneumatic cylinder 66 which is provided to move the actuating element 63 relative to the base element 55 . For this purpose, the piston of the pneumatic cylinder 66 is firmly connected to the base element 63 , specifically to the support element 65 .

Specifically, the actuating element 63 is C-shaped. The two C-legs 67a, 67b embrace the base element 55. A link guide 68 projecting inwards is formed on each of the two C-legs 67a, 67b. This engages in corresponding guide slots 69 which pass through the through bores 58 and into which the retaining elements 57 protrude.

In this way, the actuating element 63 cooperates with the holding elements 57 such that a movement of the actuating element 63 relative to the base element 55 is converted into a movement of the holding elements 57 in the direction of the release position or in the direction of the holding position. The corresponding bevels 70 of the link guide 68 are - as can be seen in Figure 23 - shaped so that a movement of the actuating element 63 relative to the base element 55 to the bottom right in Figures 22 and 23, the Holding elements 57 are moved to their holding position, whereas movement to the top left in Figures 22 and 23 moves the holding elements 57 to their release positions.

FIGS. 12 to 14 show the basic structure of the transport device 5. The transport device 5 is used to transport an extrusion device 1 between the various stations 3, 4 and the printing station 2. For this purpose, the transport device 5 is designed to move an extruding device 1 attached to it along a number of axes. The different axes are represented by arrows in FIG. Thus, an attached extrusion device 1 can be translated in all three directions; it is also provided to carry out a rotational movement about a longitudinal axis.

Appropriate gripping means are provided for holding the extrusion device 1 on the transport device 5 . In the arrangement shown in FIGS. 12 to 14, the transport device 5 has an upper gripping device 71 and a lower gripping device 72 which is attached to a base body 73 of the transport device 5. The upper gripping device 71 grips the extruder device 1 on the feed housing 12 , whereas the lower gripping device 72 grips a middle region of the extruder housing 6 . In this way, safe transport can be realized.

Finally, in FIGS. 15 and 16, the basic structure of a storage station 4 is shown. This is used to safely store extrusion devices 1 that are not needed for a longer period of time. For this purpose, the storage station 4 also has a base body 74 which can be screwed to the side of a support or a wall. On the body is also a Holding device 54 is arranged in the embodiment already described above, so that an extrusion device 1 that is not currently in use can be detachably attached to the storage station 4 .

The system also includes control means not shown in the figures. These can include, for example, a central system control and/or decentralized control units at the heating stations 3, the printing station 2 and the transport device 5.

If an extruding device 1 arranged in the printing station 2 is to be changed during a printing process, the extruding device 1 to be newly attached to the printing station 2 can first be removed from the storage station 4 . Specifically, the transport device 5 is positioned in front of the storage station 4 so that the upper gripping device 71 and the lower gripping device 72 can grip the extrusion device 1 .

As soon as the extrusion device 1 is attached to the transport device 5, the holding device 54 of the storage station 4 can be controlled. In concrete terms, the actuating element 63 is moved relative to the base element 55 by means of the pneumatic cylinder 66, so that the holding elements 57 are moved from their holding position to their release position via the link guide 68. In this way the extrusion device 1 can be separated from the storage station 4 .

The transport device 5 is then positioned in front of a heating station 3 in such a way that the holding device 54 of the heating station 3 can grip the extrusion device 1 . For this purpose, the extruder device 1 is positioned between the heating jaws 25a, 25b, which are in their open position, so that the positioning projection 18 of the extruder head 8 fits into the positioning recess 62 of the Base member 55 is engaged. For gripping, the actuating element 63 of the holding device 54 of the heating station 3 is then moved relative to the base element 55 so that the holding elements 57 designed as balls are moved into their holding position and thereby engage in the holding recesses 59 of the extrusion device 1. The design of the end sections 61 of the grooves 60 applies a force in the rearward direction to the extruder device 1, so that the extruder head 8 is clamped between the holding elements 57 and the base of the receiving recess 56, which forms a stop surface for the extruder head 8.

In a next step, the upper gripping device 71 and the lower gripping device 72 of the transport device 5 are disengaged from the extruding device 1 before the transport device 5 is moved away from the heating station 3 .

The heating jaws 25a, 25b are then moved toward one another so that they assume their closed position. The heating jaws 25a, 25b completely enclose the extrusion device 1 in a central longitudinal area.

When the heating jaws 25a, 25b are brought into their closed position, the heating segments 34 move about their respective axis of rotation in such a way that their heating surface 35 comes into flat contact with the extruder housing 6. At the same time, the springs 50 press the heating segments 34 against the extruder housing 6, so that a flat contact is ensured.

The extrusion device 1 can now be heated to a specific operating temperature between the two heating jaws 25a, 25b. For this purpose, the heating cartridges 37, which are located in corresponding longitudinal bores 36 of the heating segments 34, are supplied with electrical power, so that their temperature increased. At the same time, the cooling element 28 arranged at the rear in the heating jaws is supplied with cooling water, so that damage to the rear end area of the extruder device 1 as a result of high temperatures can be ruled out, since thermal decoupling takes place.

When the heating jaws 25a, 25b are moved towards one another, the temperature sensors 52 automatically engage in the corresponding blind bores 53 in the extruder housing 6. This allows the temperature of the extruder housing 6 and thus indirectly the temperature inside the extruder housing 6 to be recorded.

When a certain temperature level is reached, the extruding device 1 can be removed from the heating station 3 and inserted into the printing station 2 . For this purpose, the heating jaws 25a, 25b are first moved from their closed position to their open position, so that the upper gripping device 71 and the lower gripping device 72 of the transport device 5 can grip the extrusion device 1. The holding elements 57 of the holding device 54 of the heating station 3 are then brought into their release position, as has already been described in connection with the storage station 4 .

The transport device 5 with the extruder device 1 attached to it can now be moved in front of the printing station 2 . Extruding device 1 can now be attached to printing station 2 in the same way as described above when attaching extruding device 1 to heating station 3 . Specifically, this means that first the holding elements 57 of the holding device 54 of the printing station 2 are brought into their holding position, so that the extruding device 1 is already held at the printing station 2 at its rear end. Then the upper gripping device 71 and the lower gripping device 72 of the transport device 5 are released before the transport device 5 is moved away from the printing station 2 . Thereafter, the heating jaws 25a, 25b of the heating device of the printing station 2 can be brought into their closed position, so that the heating surfaces 35 come into contact with the extruder housing 6 in the same manner as already described. When the heating jaws 25a, 25b reach their closed position, the annular collar 31 of the nozzle 7 simultaneously comes into engagement with recesses 30 of the two fixing elements 29. In this way, the extruding device 1 is also supported at the front end.

Printing can now be continued. The heating elements 26, which are arranged in the heating jaws 25a, 25b of the printing station 2, regulate the temperature of the extrusion device 1, so that the corresponding operating temperature is maintained. At the same time, the cooling element 28 leads to a thermal decoupling of the rear end area of the extruder device 1.

The system according to the invention shown can significantly reduce downtimes when changing the extrusion device 1 in the printing station 2, since the extrusion device 1 is already heated to its operating temperature in the heating station 3 before it is attached to the printing station 2, so that time-consuming heating in the Printing station 2 is omitted.

Reference List

1 extrusion device

2 printing station

3 heating station

4 storage station

5 transport device

6 extruder body

7 nozzle

8 extruder head

9 extruder screw

10 shaft bodies

11 spiral profile

12 feeder housing

13 feed opening

14 pantry

15 through hole

16 drive opening

17 tooth clutch

17a, 17b half of the gear coupling

18 positioning projection

19 basic bodies

20 feeds judge

21 drive motor

22 drive housing

23 body

24 heater

25a, 25b heating jaw

26 heating element

27 heating element recess 28 cooling element

29 fixing element

30 recess

31 ring collar

32 heating jaw housing

33 cover plate

34 heating segment

35 heating surface

36 longitudinal bore

37 cartridge heater

38 front storage plate

39 rear storage plate

40 front protrusion

41 rear projection

42 bearing bore

43 feed plate

44 feed slot

45 electric line

46 base plate

47 cover plate

48 support body

49 through hole

50 feathers

51 sensor element

52 temperature sensor

53 blind hole

54 holding device

55 basic element

56 recording recess

57 holding element 58 through hole

59 retaining recess

60 slots

61 end section 62 positioning recess

63 actuator

64 operating yoke

65 support element

66 pneumatic cylinders 67a, 67b C-legs

68 link guide

69 guide slot

70 slant

71 upper gripping device 72 lower gripping device

73 body

74 body

Claims

EXPECTATIONS

1. Heating device (24) for heating and/or tempering an elongate component, in particular an extrusion device (1) for a system for the generative production of components, preferably for a system for the three-dimensional printing of components, with two heating jaws (25a, 25b), which are held on a base body (19, 23) and can in particular be moved towards and away from one another in a translatory manner between an open position in which the heating jaws (25a, 25b) are spaced far enough apart that the component between the heating jaws (25a, 25b) and a closed position in which the heating jaws (25a, 25b) enclose a component receiving space defining a longitudinal direction.

2. Heating device (24) according to claim 1, characterized in that both heating jaws (25a, 25b) are movable relative to the base body (19, 23).

3. Heating device (24) for heating and/or tempering an elongate component, in particular an extrusion device (1) for a system for the generative production of components, preferably for a system for the three-dimensional printing of components, in particular according to one of the preceding claims, wherein the Heating device (24) encloses or can enclose a longitudinally defining receiving space for a component, characterized in that several heating elements (26) are provided, which are arranged in such a way that they lie flat against a component arranged in the receiving space or can be brought into contact.

4. Heating device (24) according to claim 3, characterized in that several heating elements (26) are arranged one behind the other in the longitudinal direction, and/or two heating elements (26) are arranged in pairs opposite one another in relation to the longitudinal direction.

5. Heating device (24) according to claim 3 or 4, characterized in that the heating elements (26) can be moved into and out of the receiving space in heating element recesses (27) of the heating device (24), in particular of heating jaws (25a, 25b) the heating device (24) are mounted.

6. Heating device (24) according to claim 5, characterized in that spring elements are provided which press the heating elements (26) inwards into the receiving space, so that a flat contact of the heating elements (26) with a component arranged in the receiving space is ensured.

7. Heating device (24) according to one of Claims 3 to 6, characterized in that at least one, in particular each heating element (26) has a plurality of heating segments (34) which are mounted rotatably about an axis of rotation running in the longitudinal direction and which each have a concave heating surface pointing towards the receiving space (35) have, which can be brought into contact with a component over a large area.

8. Heating device (24) according to claim 7, characterized in that each heating segment (34) is provided with an in particular electrically heatable heating cartridge (37), which is preferably inserted into a longitudinal bore (36) of the respective heating segment (34).

9. Heating device (24) according to claim 7 or 8, characterized in that each heating element (26) has a front (38) and a rear bearing plate (39), between which the heating segments (34) are rotatably mounted, with each heating element preferably (26) engages with a front and a rear projection (40) in a corresponding bearing bore (42) of the front and the rear bearing plate (39).

10. Heating device (24) according to claim 9, characterized in that the rear bearing plate (39) or the front bearing plate (38) adjoins a feed plate (43) in which feed slots (44) for electrical lines (45) to the heating cartridges (37) are provided, the feed slots (44) extending away from the receiving space, starting from the axis of rotation of the respective heating segment (34).

11. Heating device (24) according to one of Claims 7 to 10, characterized in that the heating elements (26) are delimited at the front by a base plate (46) and at the rear by a cover plate (47).

12. Heating device (24) according to one of claims 7 to 11, characterized in that the rear bearing plate (39) and the front bearing plate (38) are fixed to a support body (48), in particular screwed to the support body (48), the is inserted into the heating element recess (27) of the heating device (24), in particular a respective heating jaw (25a, 25b).

13. Heating device (24) according to claim 12, characterized in that springs (50) are arranged on the side of the support body (48) facing away from the receiving space, via which the support body (48) is supported against the base of a heating element recess (27). .

14. Heating device (24) according to Claim 1 or 2 and one of Claims 3 to 13, characterized in that each heating jaw (25a, 25b) carries a plurality of heating elements (26) which are inserted in heating element recesses (27) in the heating jaws (25a, 25b). are stored.

15. Heating device (24) for heating and/or tempering an elongate component, in particular an extrusion device (1) for a system for the generative production of components, preferably for a system for the three-dimensional printing of components, in particular according to one of the preceding claims, wherein the Heating device (24) has a receiving space for a component that defines a longitudinal direction, characterized in that at least one, in particular two, opposite cooling elements (28) are arranged in a rear end region of the receiving space in such a way that they lie flat against a component arranged in the receiving space or can be brought into the system.

16. Heating device (24) according to claim 15, characterized in that each cooling element (28) has a flow channel for cooling water.

17. Heating device (24) according to one of claims 1 or 2 and one of claims 15 or 16, characterized in that each heating jaw (25a, 25b) has a cooling element recess, in each of which a cooling element (28) is inserted.

18. Printing station (2) for a system for the generative production of components, in particular for a system for the three-dimensional printing of components, which is designed in such a way that an extrusion device (1) for the defined dispensing of material can be detachably attached to it, the Printing station (2) has a heating device (24) according to one of the preceding claims for tempering an attached extrusion device (1).

19. Heating station (3) for a system for generatively producing components, in particular for a system for three-dimensional printing of components, to which an extrusion device (1) for defined dispensing of material can be detachably attached, and the heating station (3) has a heating device (24) according to any one of claims 1 to 17 for heating an attached extrusion device (1).

20. System for the generative production of components, in particular for the three-dimensional printing of components, with a printing station (2) according to claim 18 and at least one heating station (3) according to claim 19.

21. System according to claim 20, characterized in that the system further comprises at least one extrusion device (1) for the defined dispensing of material.

22. The heating element (26) for a heating device (24) according to any one of claims 3 to 14, characterized in that the heating element (26) has a plurality of heating segments (34) mounted rotatably about an axis of rotation, each of which has a concave segment, in particular a segment of a Circular cylinder corresponding heating surface (35) which can be brought into extensive contact with a component to be heated.

23. Heating element (26) according to claim 21, characterized in that each heating segment (34) is provided with an in particular electrically heatable heating cartridge (37) which is preferably inserted into a longitudinal bore (36) of the respective heating segment (34).

24. Heating element (26) according to claim 22 or 23, characterized in that the heating element (26) has a front (38) and a rear bearing plate (39), between which the heating segments (34) are rotatably mounted, with each heating element preferably (26) engages with a front and a rear projection (40) in a corresponding bearing bore (42) of the front and the rear bearing plate (39).

25. Heating element (26) according to claim 24, characterized in that a feed plate (43) adjoins the rear bearing plate (39) or the front bearing plate (38), in which feed slots (44) for electrical lines (45) to the Heating cartridges (37) are provided, the feed slots preferably extending away from the respective heating surface (35) starting from the axis of rotation of the respective heating segment (34).

26. Heating element (26) according to one of claims 22 to 25, characterized in that the heating elements (26) are delimited at the front by a base plate (46) and at the rear by a cover plate (47).

tj Heating element (26) according to one of Claims 22 to 26, characterized in that the rear mounting plate (39) and the front mounting plate (38) are fixed to a support body (48), in particular screwed to the support body (48).

28. Heating element (26) according to claim 27, characterized in that springs (50) are arranged on a side of the supporting body (48) facing away from the heating surfaces (35), via which the supporting body (48) is supported against a heating element recess (27). can be.