Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
  • B29C64/118—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using filamentary material being melted, e.g. fused deposition modelling [FDM]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/307—Handling of material to be used in additive manufacturing
  • B29C64/321—Feeding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/02—Small extruding apparatus, e.g. handheld, toy or laboratory extruders
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/05—Filamentary, e.g. strands
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/266—Means for allowing relative movements between the apparatus parts, e.g. for twisting the extruded article or for moving the die along a surface to be coated
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/269—Extrusion in non-steady condition, e.g. start-up or shut-down
  • B29C48/2694—Intermittent extrusion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/285—Feeding the extrusion material to the extruder
  • B29C48/288—Feeding the extrusion material to the extruder in solid form, e.g. powder or granules
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/475—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using pistons, accumulators or press rams
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/92—Measuring, controlling or regulating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
  • B29C64/205—Means for applying layers
  • B29C64/209—Heads; Nozzles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
  • B29C64/227—Driving means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
  • B29C64/295—Heating elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/307—Handling of material to be used in additive manufacturing
  • B29C64/314—Preparation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/307—Handling of material to be used in additive manufacturing
  • B29C64/321—Feeding
  • B29C64/329—Feeding using hoppers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/386—Data acquisition or data processing for additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/386—Data acquisition or data processing for additive manufacturing
  • B29C64/393—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
  • B33Y40/10—Pre-treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y50/00—Data acquisition or data processing for additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y50/00—Data acquisition or data processing for additive manufacturing
  • B33Y50/02—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92009—Measured parameter
  • B29C2948/92028—Force; Tension
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92323—Location or phase of measurement
  • B29C2948/92361—Extrusion unit
  • B29C2948/9238—Feeding, melting, plasticising or pumping zones, e.g. the melt itself

Definitions

• the present invention relates to a method for providing printable melt for operating a print head for a 3D printer and a print head for a 3D printer for carrying out the method.
• a 3D printer for a viscosity-changing material receives a solid phase of this material as a starting material, creates a liquid phase from it and applies this liquid phase selectively to the locations that belong to the object to be created.
• Such a 3D printer includes a print head in which the starting material is prepared ready for printing. Furthermore, means are provided for generating a relative movement between the print head and the work surface on which the object is to be created. Either only the print head, only the work surface or both the print head and the work surface can be moved.
• the printhead has a first operational condition in which it ejects liquid material and a second operational condition in which it does not eject liquid material.
• the second operating state is assumed, for example, when a different position on the work surface is to be approached and no material is to be discharged on the way there.
• Between the two operating states of the print head for example be switched by turning the propulsion of the solid feedstock on or off.
• FDM fused deposition modeling
• US 2016/082 627 A1 proposes feeding in the starting material in granular form and conveying it with a screw conveyor to a heated zone, from which it emerges in plasticized form.
• granules are significantly cheaper, and on the other hand, mixtures of different thermoplastic materials can be easily produced in this way.
• a print head is known from DE 102016222306 A1, in which a granulate is plasticized via a piston and a heated segment.
• the piston presses on the granules they are compacted and conveyed to a plasticizing zone at the bottom of the printhead.
• forces occur which place a great deal of stress on the piston and a cylinder wall of the print head and can lead to increased wear on the cylinder wall of the print head housing.
• a complex melting geometry with a thermal conduction structure is disclosed, which introduces the heat output of a heating element into the plasticized material in order to bring it into a liquid phase of the material.
• the object of the invention is to provide a method for providing printable melt for operating a print head for a 3D printer and a print head for a 3D printer, the method and the print head providing high-quality melt in reproducible quality.
• the method comprises the following steps:
• At least the closing, the conversion, the compression, the determination of the spring constant and the preparation for printing are carried out by actively regulating an actuator device by a control and regulation unit, with results from an evaluation unit from measured values from sensors being sent to the control and control unit are passed on.
• the entire process flow from filling to opening a nozzle of the print head during print preparation is also called the refill process, since it is a recurring process that is repeated as desired while a component is being pressed.
• the refill process is the process of providing printable melt to operate the print head for a 3D printer.
• the invention relates to a print head for a 3D printer for carrying out the method according to the invention.
• the print head includes an actuator device arranged in a housing of the print head for controlling the piston, the feed device for the printable material flange arranged on the housing and the feed device with a cooling device, the nozzle head with heating elements for converting the material from a solid phase via a plastic phase into a liquid phase and the nozzle for discharging the liquid phase of the material from the nozzle head, wherein according to the invention the control and a control unit is provided for active control of the actuator device for moving the piston according to an operating strategy to be executed for filling and printing and for active control of the heating elements.
• the evaluation unit is provided to evaluate measured values from sensors of the printhead and to forward the results to the control and regulation unit for active regulation of the actuator device and for active regulation of the heating elements.
• the evaluation unit can either be designed separately from the control and regulation unit or be integrated into it.
• the functionality of the print head can be checked by detecting and evaluating the sensor values as a function of the respective operating states, as a result of which errors or deviations in the process can advantageously be displayed at an early stage.
• defined target values can be controlled by detecting the sensor values. It is also possible for correction factors to be calculated and transmitted to the control and regulation unit. These can be added to the target values, for example, in order to advantageously achieve a desired and constant output of the melt from the nozzle.
• the active regulation of the heating elements enables a dynamic regulation of the temperature, which advantageously influences both the heating and the cooling. If, for example, the heating energy of the first heating element is reduced by the control and regulation unit, the cooling in the flange continues and this withdraws the energy from the plastic phase of the material, causing it to cool down abruptly.
• the active control of the actuator device and the heating elements enables material to be discharged from the nozzle as required, with different web speeds of the print head being able to be compensated for by the actively controlled discharged volume of the material. Active control therefore offers advantages over conventional NC systems, which always discharge the same volume regardless of their path speed, or control the quantity to be discharged with a constant feed rate without actively controlling this process.
• the actuator device for controlling the piston can be an electric motor, for example with a mechanical transmission, or a hydraulic drive with a hydraulic pressure source.
• An electric motor as an actuator device has a lower weight than a hydraulic drive and thus advantageously ensures high dynamics for the entire printer and the printing process, since less mass has to be accelerated.
• a hydraulic drive advantageously achieves high forces when driving the piston.
• the feed device for the printable material can be provided in particular as a feed for a material present as a granulate or starting material.
• the starting material can in particular be a thermoplastic material.
• pellets as a feedstock provides specific advantages over printheads using filaments of thermoplastic material, particularly in the cost of printer feedstock.
• the print head according to the invention can be built more compactly. This in turn means that the print head is lighter and easier to move. This is particularly advantageous when the print head is to be moved very quickly, in particular at speeds of 100 mm/s or more.
• the flange includes a cooling device, as a result of which optimized thermal management is achieved in the area of the feed device, so that the material or the granules can advantageously be prevented from sticking to the piston.
• the nozzle head has heating elements for converting the Material from a solid phase, especially granules, into a liquid phase. The heating elements in the nozzle head ensure that the heating power is applied in a targeted manner to the material to be melted. The liquid phase or melt can then be discharged through the nozzle of the nozzle head by a piston movement.
• the piston bushing is designed as a separate piston bushing to guide the piston and allows the piston to be guided directly in the piston bushing and no longer in the housing or a cylinder of the print head. In this way, it is achieved in an advantageous manner that possible wear no longer occurs directly on the inner wall of the housing or the cylinder, but rather inside the piston sleeve.
• the piston sleeve as a separate component offers the advantage that it can be replaced if necessary.
• pistons and piston bushes that are matched to one another can be used with different diameters without further structural changes, for example on the flange and the nozzle head.
• the filling of the cavity, in particular a heatable cavity, with printable material by the feed device includes at least the following steps:
• the granulate pieces are filled in manually or automatically, with the granulate pieces slipping into the lower area of the feed device due to the influence of gravity.
• the generation of air pulses is carried out at intervals and the granulate pieces are thrown in the area of the air impulses in such a way that when they fall down again they exert an impulse on the underlying granulate pieces and encourage them to slide down into the heated cavity of the print head.
• the process of effective refilling requires back blowing of the granules, creating an effect of lifting the granules so that they then slide into the printhead.
• the slinging or whirling up is necessary for an automated application and due to the resulting gravitational impulse or impact, the granulate slides down in an advantageous manner. If necessary, jammed granules can also be loosened by the air pulses, which advantageously avoids downtimes of the print head.
• the closing of the opening cross section of the piston sleeve by the piston includes the following steps:
• the granulate is sheared off by the piston head sliding past the gate.
• the piston sleeve has an upper part that projects into the flange and a lower part that projects into the nozzle head.
• the upper partial area is arranged in the active area of a cooling zone of the cooling device of the flange and the lower partial area is arranged in the active area of a heating zone of the nozzle head, which advantageously achieves effective energy dissipation from the material within the cooling zone or effective energy supply into the material within the heating zone becomes.
• An opening or an opening cross-section is arranged in the upper partial area of the piston bushing, which enables material to be fed from the feed device into the piston bushing.
• the gate is arranged, which is formed at an obtuse angle to the inner surface of the piston sleeve.
• the area of the gate is hardened, or alternatively designed as a separate hardened insert.
• the print head Starting from the upper part of the piston sleeve, through a kidney piece to the nozzle, the print head has different state zones, with the state zones representing an aggregate state of the material depending on its temperature Ts.
• the state of aggregation of the material can be changed across the state zones from a solid phase to a plastic phase to a liquid phase.
• the state zones of the print head include a cold zone with solid phase material, a plasticizing zone with plastic phase material, a melt zone and a process zone with liquid phase material, respectively, and a mixing zone with plastic and liquid phase material.
• the cooling device in the flange and a piston cooling system integrated in the piston are intended to keep the temperature Ts of the plastic phase of the material in the plasticization zone below a glass transition temperature Tg, above which the material would plasticize and change into a liquid phase.
• the fully plasticized phase has a tough, sticky consistency with a high tendency for surface adhesion. If the piston comes into contact with this phase, it can stick to it, causing, for example, the trickling of fresh Granulate is obstructed when the plunger is withdrawn. This effect is advantageously avoided.
• the nozzle head has two heating zones.
• a partial area of the plasticizing zone, the mixing zone and a partial area of the melting zone are arranged in the first heating zone, with a first heating element being arranged in the upper nozzle head in such a way that the heating energy is transmitted from the first heating element via the lower partial area of the piston sleeve, the kidney piece and a partial section of the upper Nozzle head can be introduced into the material.
• a partial area of the melt zone and the process zone are arranged in the second heating zone, with a second heating element being arranged in the lower nozzle head in such a way that the heating energy from the second heating element can be introduced into the liquid phase of the material via the lower nozzle head.
• the arrangement of the two heating zones in the nozzle head ensures more effective thermal management of the print head, since the heating energy of the first heating zone ensures advantageous pre-plasticization of the material without the material going into the liquid phase. This advantageously ensures that the piston does not stick during compression and the print head functions properly. This effect is optimized in interaction with the cooling device in the flange. Furthermore, the material is pre-plasticized in the plastic phase in such a way that the actuator device requires less effort when advancing the piston, as a result of which smaller actuators can advantageously be used to advance the piston. This reduces the cost of the system and leads to improved dynamics of the print head, since the weight of the print head is reduced. As a result, the print head can be better accelerated and decelerated during a so-called path control for the production of a component.
• the melt is produced in the second heating zone and the heating energy introduced ensures a relatively constant melt temperature over the entire melt space.
• the melt temperature can be regulated within the second heating zone in such a way that the material does not heat up too much.
• fission products are formed as a result of excessive thermal loading, primarily Gases, which accelerate further decomposition of the material due to the pressures prevailing in the system and also directly influence its quality negatively.
• the compaction of the material during the compaction process includes the following steps:
• the material is pre-compacted by advancing the piston under pressure and/or force control, pre-compacting to a position that is reached when a material-dependent gradient and/or a material-dependent gradient angle of a force and/or pressure curve is reached and/or exceeded.
• the material is compressed by advancing the piston with the nozzle closed, pressure-controlled and a holding position is approached until a peak pressure is reached.
• the nozzle is closed during compression and a piston needle dips into a melt chamber of the nozzle head in such a way that part of the liquid phase is displaced from an upper area of the melt chamber through openings in the kidney piece from the melt zone back into the mixing zone, as a result the part of the liquid phase mixes with the plastic phase from the plasticizing zone in the mixing zone.
• the piston is held in the holding position, with the pressure and temperature of the liquid phase being measured during the holding process and the measured values being checked by the evaluation unit for checking the function of the compression process.
• the nozzle is closed and the piston needle is immersed in the melt space in such a way that part of the liquid phase flows out of the upper area of the melt space through the openings in the kidney piece from the melt zone back into the Mixing zone is displaced, whereby the part of the liquid phase mixes with the plastic phase from the plasticizing zone in the mixing zone.
• the pre-compacting is carried out by force or pressure-controlled actuation of the piston by the actuator device, with the target position of the piston head being in the first third of the plasticizing zone, starting from the cold zone.
• the granules are compressed in the plasticizing zone by the advance of the piston, while at the same time there is melt in the melt zone between the cavity and the nozzle.
• the plasticized granules are thereby pressed into the melt in the mixing zone.
• melt is already emerging from the nozzle, as a result of which it is advantageously achieved that any air or air pockets that may still be present are displaced from the nozzle head. This will free the nozzle.
• the nozzle of the print head is closed.
• the piston is advanced under pressure control by the actuator device until a defined peak pressure and thus a peak pressure position is reached.
• the nozzle is closed and the plunger needle dips into the melt space in such a way that part of the liquid phase from the upper area of the melt space escapes through the openings of the kidney piece from the melt zone is displaced back into the mixing zone, whereby the part of the liquid phase mixes with the plastic phase from the plasticizing zone in the mixing zone.
• peak print position is then held for a material-dependent, predefined period of time, which is why the peak print position is also the hold position of the print head.
• the holding process forces out residual air and the melt is homogenized in mixing zone C. As a result, a better flow of energy is advantageously achieved and a more homogeneous material is produced.
• the melt that flows back becomes plastic and the granulate parts, which are pushed into the kidney piece, become molten. This creates a mixing of the material.
• the holding process described here is also advantageously used for analysis and for a system check of the print head, since the following effects can result when the pressure is measured.
• An increase in the pressure in the melt would mean that the melt would outgas, for example because the temperature of the melt is too high. Melt temperatures that are too high are not desirable, since air plasma can form, which would lead to chemical decomposition.
• determining a spring constant of the liquid phase includes the following steps:
• the spring constant results from the compressibility of the melt and leads to a correction factor or shape factor that is required for the actuator device to control the piston precisely.
• Determining the spring constant of the melt advantageously means that the actuator device can control the piston in a controlled manner, with the spring constant making it possible, among other things, for the actual discharge of the melt to have the correct, calculated volume flow of the melt as a function of a web speed of the moving print head reached when printing. This means that the required amount of melt is applied to the component at every printing position and at every web speed of the print head.
• the preparation for printing the liquid phase includes the following steps:
• the piston is pulled back by approximately 1 to 2 millimeters depending on the spring constant determined, which advantageously ensures that no melt escapes from the nozzle or nozzle opening leaks out when opened. This would be the case if the position were held further due to the open system in place due to the influence of gravity. At the same time, the melt is relieved like a spring.
• the printing process then begins with further preparation for printing by compression.
• the overall system of the print head is a compressible system, since the melt can have a compression of about 20%, for example.
• the volume displaced by the advance of the piston does not correspond to the volume of material discharged, which can result in imprecise and irregular discharges.
• the discharge of the liquid phase i.e. printing, is carried out under pressure control, with:
• the piston is actively controlled via the control and regulation unit, with the advance of the piston being adjusted as a function of the pressure by a correction factor, the correction factor resulting from the calculated spring constant of the liquid phase of the material.
• the pressure measured corresponds to the pressure created by the discharge of the liquid phase onto the component and the correction factor is advantageous in order to compensate for the compressibility of the liquid phase.
• the compression of the melt in the melt space at the start of printing is generated partly by friction at the nozzle opening of the nozzle when the melt is "squeezed out” and partly by the resistance when printing on the component or a substrate carrier on which the component is built.
• An electrically driven actuator device proves to be dynamic and very effective in this case.
• the piston sleeve can have a stop between the upper and lower partial area, by which the flange and the nozzle head are separated from one another.
• the piston bushing and in particular the stop thus advantageously separates the cooled flange from the heated nozzle head, as a result of which they are not in contact with one another.
• a kidney piece can be arranged on the lower partial area of the piston sleeve, the kidney piece having a centrally running bore for receiving a piston needle of the piston.
• the piston of the print head comprises a first piston part for connection to the actuator device, a piston head for connection to the first piston part and for accommodating the piston needle.
• the first piston part is preferably designed as an aluminum hollow piston, as a result of which coolant can be conducted through the first piston part and piston cooling is thereby advantageously achieved.
• the piston head has an underside on the side facing the nozzle, with the piston needle protruding from the center of the underside.
• the area of the bottom of the piston head minus the virtual area of the piston needle forms a piston area for creating a pressure on the material.
• the underside of the piston head is also cooled by the piston cooling and thereby locally reduces the viscosity of the melt or the plastic material on the piston crown.
• a temperature sensor is preferably attached to the underside of the piston head or to the piston head. This arrangement of the temperature sensor enables thermal management of the print head depending on the piston position, which means that the material heats up more quickly without the melt coming into contact with the underside of the piston head. As a result, an acceleration of a filling process of the print head can be achieved in an advantageous manner.
• the piston head is designed as a cylindrical component and is preferably made from a thermally resistant material.
• the combination that the first piston part is made of aluminum and the piston head is made of steel, for example, has proven to be advantageous because the piston has an elastic upper area to absorb the mechanical stresses and a thermally resistant lower area in the area of the heated material .
• the plunger needle protrudes only partially or completely through the bore of the kidney piece, as a result of which the plunger needle is advantageously guided in the central bore of the kidney piece.
• the kidney piece has concentrically arranged openings, which form a fluidic connection between a cavity arranged in the piston sleeve and a melt space arranged in a lower part of the nozzle head.
• the cavity is located within the plunger sleeve and is defined by a volume whose outer surface is formed by the inside of the plunger sleeve, the outside of the plunger needle, the top of the kidney piece and the bottom of the plunger.
• the material or the granulate is compressed by moving the piston over the underside of the piston head or the piston surface.
• the thermal management of the print head is set in such a way that no liquid phase of the material or no melt forms within the cavity, but the material is formed as a plastic phase. This turns into advantageously achieved that no plasticized material adheres to the underside of the piston.
• part of the liquid phase or melt in the melt chamber is pushed out of the melt chamber through the concentrically arranged openings of the kidney piece and into the cavity of the piston bushing by the piston needle penetrating the melt chamber. In the process, parts of the melt mix with parts of the plastic phase.
• the melt releases energy into the plastic phase, which advantageously produces a more homogeneous material.
• the kidney piece thus forms a mixer, or a static mixer, since, apart from the piston movement, no further moving parts are advantageously required for mixing the plastic phase with the liquid phase.
• the configuration of the kidney piece thus advantageously ensures a diaphragm effect, which leads to better mixing of the material or the melt with the plasticized material.
• the kidney piece conducts the heating energy of the heating element from the nozzle head both into the melt and into the plunger needle, which advantageously ensures improved energy management when heating up the melt.
• the kidney piece can also be designed as a separate component or in one piece with the piston bushing.
• a pressure sensor for the pressure pi_ and/or a temperature sensor for the temperature TL of the liquid phase is arranged in the melt space.
• the measurement of the pressure pi_ is the primary parameter that decides on the output or discharge or mass flow of melt from the outlet opening.
• An additional measurement of the temperature TL makes it possible to also take into account the temperature dependence of the viscosity of the material when determining the mass flow Q.
• the amount to be metered can be precisely controlled by the piston feed.
• the control of the temperature TL in particular in the form of constant and precise regulation, is even more important in order to avoid thermal degradation of the material.
• a path measuring system for the position s of the piston, and / or a sensor for the piston on the Material force F exerted or for a hydraulic pressure P H exerted on the piston is provided.
• the advance of the piston is a measure of the amount of material to be discharged. This quantity can be controlled, among other things, via the position measuring system. Furthermore, the force F correlates directly with the pressure in the material.
• a temperature sensor for the temperature TK of the plastic phase of the material is arranged on the piston, in particular on the underside of the piston head of the piston.
• This arrangement of the temperature sensor enables thermal management of the print head depending on the piston position, which means that the material heats up more quickly without the melt coming into contact with the underside of the piston head.
• an acceleration of a filling process of the print head or a reduction in the time required for the filling process can be achieved in an advantageous manner.
• Figure 1 shows a print head according to the invention
• 4 shows a schematic representation of the print head according to the invention
• 5 shows a flow chart of the method according to the invention for providing printable melt
• FIG. 6 shows a section of the print head according to the invention with a pressure curve
• FIG. 8 shows a flow chart of a method for filling a cavity of the print head
• FIG. 9 shows a flow chart of a method for closing an opening cross section of a piston bushing of the print head
• FIG. 10 is a flow chart of a process for converting a material from a solid phase through a plastic phase to a liquid phase
• FIG. 11 shows a flow chart of a method for compacting the material
• Figure 13 is a flow chart of a process for preparing the liquid phase of the material for printing.
• a print head 100 for a 3D printer comprising an actuator device 110 arranged in a housing 1 of the print head 100 for controlling a piston 3, a feed device 2 for a printable material 10, a flange arranged on the housing 1 and the feed device 2 5 with a cooling device 50, a nozzle head 6 with heating elements 61, 63 for converting the material 10 from a solid phase 10 via a plastic phase 11 into a liquid phase 12 and a nozzle 8 for dispensing the liquid phase 12 of the material 10 from the nozzle head 6.
• the print head 100 comprises a separate piston bushing 4 for guiding the piston 3.
• the piston 3 comprises a first piston part 31 for connecting the piston 3 to the actuator device 110, a piston head 34 which is attached to the first piston part 31 and accommodates a piston needle 32 in the direction of the nozzle 8.
• a temperature sensor 36 for measuring the temperature TK of the plastic phase 11 of the material is arranged on the piston 3 or on an underside 35 of the piston head 34 .
• the underside 35 of the piston head 34 forms a piston head 35.
• the first piston part 31 is preferably designed as an aluminum hollow piston, with this having a cavity on the inside which is designed as a cooling channel.
• a piston cooling system 33 is arranged at the lower end of the first piston part 31 and is cooled by a coolant system.
• the piston cooling 33 ensures that the material 11, 12 solidifies on the piston head 35 and thereby seals the piston 3 in the direction of the actuator device 110, or thereby prevents liquid melt 12 from flowing in the direction of the actuator device 110.
• a cooling liquid is preferably used as the coolant , whereby this is conveyed via connections and flexible lines through the housing 1 into a cooling connection 37 of the first piston part 31 .
• the cooling device 50 in the flange 5 is supplied with coolant by the same coolant system.
• the feed device 2 is funnel-shaped, with the material 10, which is preferably a granulate, being filled into an opening of the feed device 2 from above.
• the material 10 reaches an opening 21 or an opening cross section to the piston bushing 4 by gravity.
• an air duct 20 is arranged in the lower region of the feed device 2 above the opening. This is acted upon by a pneumatic valve 22 with air pulses.
• the pneumatic valve 22 and the air duct 20 form an injection device which subjects the granulate 10 to blasts of air at intervals in such a way that the granulate is thrown in the direction of the area of the feed device 2 that is further up, thereby separating the individual granulate pieces 10 from one another.
• the air flow is switched off, the granules 10 located in the lower area of the feed device 2 fall into the piston bushing 4 when the opening cross section 21 is open.
• the injection device of the feed device 2 thereby prevents the granulate pieces 10 from jamming, thereby preventing the feed device 2 from becoming clogged, and it ensures that the piston sleeve 4 is reliably filled with granulate 10. Furthermore, smaller diameters can be used in the inlet of the feed device 2.
• the process of refilling requires the granules 10 to be back-blown, which creates an effect of lifting the granules so that they then slide into the printhead 100.
• the whirling up is necessary for automated use and the granulate 10 slides down due to the resulting gravitational impulse or impact.
• the piston bushing 4 has an upper subarea 41 protruding into the flange 5 and a lower subarea 42 protruding into an upper subarea 60 of the nozzle head 6 .
• a stop 43 is arranged between the upper 41 and lower 42 partial area of the piston sleeve 4, by means of which the flange 5 and the nozzle head 6 are separated from one another.
• the opening 21 or the opening cross section is arranged in the upper partial area 41 of the piston bushing 4 and has a cut on the inner surface of the piston bushing 4 44 on.
• the gate 44 has the effect that when the opening cross section 21 is closed by the piston 3 granulate 10 is sheared off between the gate 44 and the piston head 35 until the piston head 35 has reached a position below the gate 44 .
• the piston sleeve 4 has an obtuse angle at the gate 44, which is sharp-edged and hardened. Local hardening is advantageous here.
• the cut 44 can also be formed by a separate insert, analogous to a turning plate.
• the design of the gate 44 advantageously ensures a reduction in the forces required to shear off the granules 10, as a result of which energy can be saved and the materials of the piston sleeve 4 and the piston 3 are less susceptible to wear.
• the edge of the cut 44 is extremely susceptible to wear.
• a kidney piece 7 is arranged on the lower partial area 42 of the piston sleeve 4 , the kidney piece 7 having a centrally running bore 70 for receiving a piston needle 32 of the piston 3 .
• the kidney piece 7 also has concentrically arranged openings 71 which form a fluidic connection between a cavity 40 arranged in the piston sleeve 4 and a melt space 81 arranged in a lower part 62 of the nozzle head 6 .
• the cavity 40 is arranged within the piston bushing 4 and is formed by the inside of the piston bushing 4, the outside of the piston needle 32, the top of the kidney piece 7 and the bottom 35 of the piston 3.
• a preferred task of the kidney piece 7 is the conduction of heat or energy transfer from the heating elements 61, 63 of the nozzle head 6 into the liquid phase 12 of the material or the melt 12. This is achieved in particular by increasing the contact area with the cavity 40 and thus the plastic phase 11 of the material is reached.
• Another task is to guide the piston needle 32, the contact of the piston needle 32 within the bore 70 also ensuring that the piston needle 32 is heated to the required process temperature.
• the final process temperature is only reached in the nozzle head 6 towards the nozzle 8 .
• the nozzle 8 is closed if necessary and when the piston 3 is activated by the actuator device 110, the material 10, 11, 12 located in the cavity 40 and melt space 81 is compressed by the piston advance.
• the nozzle head 6 comprises the heating elements 61, 63 of the print head 100, a first heating element 61 being arranged in the upper nozzle head 60 and a second heating element 63 being arranged in the lower nozzle head 62.
• the upper nozzle head 60 has a section 64 which is arranged between the upper 60 and the lower 62 nozzle head and on which the kidney piece 7 rests.
• a cooling ring 84 is arranged on the nozzle head 6 in the area of the nozzle 8 . This cools the component to be printed and thermally shields the component from the print head 100 .
• the heating elements 61, 63 in the nozzle head 6 heat the material 10, 11, 12 within the cavity 40, the kidney piece 7 and the melt chamber 82 until the liquid phase 12 of the material has reached its process temperature and can be discharged from the nozzle 8.
• the melt chamber 82 is designed in such a way that it tapers from the partial section 64 of the upper nozzle head 60 to the nozzle 8 .
• the conical inlet of the melt space 81 enables an increase in the volume flow and prevents the material from being deposited on the inner wall of the nozzle head 6. Because there is less material 12 or volume in a conical melt space 81 in relation to a cylindrical melt space 81, the mixing process is further optimized. As a result, the piston needle 32 has to displace less volume in order to force parts of the melt 12 back through the openings 71 of the kidney piece 7 from the melt space 81 into the cavity 40 during compression.
• the print head 100 comprises further sensors, a pressure sensor 83 for the pressure pi_ and a temperature sensor 82 for the temperature T L of the liquid phase 12 of the material being arranged in the melt chamber 81 .
• Additional sensors are arranged on the actuator device 110, with a position measuring system 111 for the position s of the piston 3, and a sensor 112 for the force F exerted by the piston 3 on the material 10, 11 or for a hydraulic pressure P H exerted on the piston 3.
• the sensors 111, 112 can also be arranged on the piston 3 of the print head 100.
• the solid phase 10 of the material comprises the granulate pieces 10 and the feed device 2 has the injection device 25 for releasing the granulate pieces 10 from one another.
• the injection device 25 comprises the pneumatic valve 22 and the air duct 20, the air duct 20 being arranged in a housing part 27 of the feed device 2 and opening in a lower region 24 of the feed device 2 above the opening cross section 21 of the flange 5.
• the air channel 20 can be acted upon by the pneumatic valve 22 with air impulses 26, the air impulses 26 acting on the granulate pieces 10 in the lower region 24 in such a way that they become detached from one another.
• the feed device 2 is funnel-shaped, with the granulate pieces 10 being filled into an opening 23 of the feed device 2 from above.
• the material 10 reaches the opening cross section 21 of the flange 5 as far as the piston bushing 4 or the opening cross section 21 of the piston bushing 4 by gravity .
• Air duct 20 is acted upon by air pulses 26 by pneumatic valve 22 .
• the injection device 25 comprises the pneumatic valve 22 and the air duct 20, with the granules 10 being subjected to air blasts at intervals in such a way that they are thrown in the direction of the area of the feed device 2 that is further up, causing the individual granules 10 to become detached from one another.
• the granules 10 located in the lower region 24 of the feed device 2 fall into a cavity 40 of the piston bushing 4 when the opening cross section 21 is open is prevented and it ensures a safe filling of the Piston sleeve 4 with granules 10.
• the refilling process requires the granules 10 to be back-blown, which creates an effect of lifting the granules so that they then slide into the printhead 100. The whirling up is necessary for automated use and the granulate 10 slides down due to the resulting gravitational impulse or impact.
• Fig. 3 shows a section of the print head 100 according to the invention in a view rotated by 90°, starting from the upper partial area 41 of the piston sleeve 4 via the kidney piece 7 to the nozzle 8, status zones A, B, C, D, E of the material 10 , 11, 12 filled print head 100 are shown during operation.
• the state zones A, B, C, D, E represent a state of aggregation of the material 10 depending on its temperature Ts, the state of aggregation of the material 10 over the state zones A, B, C, D, E of a solid phase 10 over a plastic phase 11 can be changed into a liquid phase 12.
• the temperature Ts or the temperature profile of the material 10, 11, 12 within the print head 100 is shown in a diagram displayed above the print head 100, this being displayed over the path s or the length of a working area 120 of the print head 100.
• the state zones A, B, C, D, E of the print head 100 include a cold zone A with material in the solid phase 10, a plasticizing zone B with material in the plastic phase 11, a melting zone D and a process zone E, each with material in the liquid phase 12 Further, the conditioning zones include a mixing zone C with plastic 11 and liquid 12 phase material.
• the cooling device 50 in the flange 5 and the piston cooling 33 integrated in the piston 3 are provided in order to keep the temperature Ts of the plastic phase 11 of the material in the plasticization zone B below a glass transition temperature T g from which the material 11 plasticizes and into a liquid phase 12 passes.
• the plasticization zone B with the material in the plastic phase 11 describes a state of the material or of the granules in which the viscosity of the granules is already changing, resulting in a compression and a mixing process be optimized, but the plastic phase 11 of the granules is just not in the liquid phase 12 over.
• the nozzle head 6 comprises two heating zones 65, 66.
• a partial area of the plasticizing zone B, the mixing zone C and a partial area of the melting zone D are arranged in the first heating zone 65, with a first heating element 61 being arranged in the upper nozzle head 60 in such a way that the heating energy from the first heating element 61 passes over the lower partial area of the piston sleeve 42 , the kidney piece 7 and a section 64 of the upper nozzle head can be introduced into the material 10, 11, 12.
• a partial area of the melt zone D and the process zone E are arranged in the second heating zone 66, with a second heating element 63 being arranged in the lower nozzle head 62 in such a way that the heating energy from the second heating element 63 can be introduced into the liquid phase 12 of the material via the lower nozzle head 62 is.
• the temperature Ts of the material 10, 11, 12 increases steadily over the path s of the working area 120 of the print head 100.
• the effect of the cooling device 50 of the flange 5 is predominant, as a result of which the granulate 10 is only slowly heated over the path s.
• the influence of the first heating zone 65 with the first heating element 61 begins to increase, with the temperature curve rising sharply until the glass transition temperature T g is reached, and from there the mixing zone C begins.
• the temperature Ts continues to increase in the mixing zone C with a lesser gradient until the melting zone D is reached.
• the zone of influence of the second heating zone 66 begins there with the second heating element 63, this allowing the temperature Ts of the melt 12 to rise sharply until the process temperature of the melt 12 in the process zone E is reached and the printable melt 12 has formed.
• the temperature Ts must be set so that the granulate 10 can trickle into the cavity 40 during filling without sticking but is also preheated in such a way that the material 10, 11 can be sheared off at the cut 44 with as little effort as possible.
• the temperature management of the print head 100 is set so that the cooling device 50 in the flange 5 brings a cooling temperature of approx. 40°C into the piston sleeve 4 and thereby into the material 10, 11 and the first heating element 61 of the first heating zone 65 brings a heating temperature of approx. 30°C below the glass transition temperature T g or the melting point of the Materials 10, 11, 12.
• the temperature sensor 36 on the piston head 35 measures the temperature TK at the point of contact between the piston 3 and the material 10, 11, whereby the cooling and heating capacity of the print head 100 can be calculated so that the glass transition temperature T g of the material 10 is not exceeded. Due to the arrangement of the temperature sensor 36 or temperature sensor on the piston head 35, it is possible to regulate the heating elements 61, 63 as a function of the piston position and thus to set the temperature Ts. As a result, the material 11, 12 is heated up more quickly. The thermal management of the print head 100 also enables processing of plastics with a low melting temperature of less than 60 to 80°C.
• the nozzle 8 is closed.
• the nozzle 8 can be closed, for example, by a non-illustrated shut-off valve, or by positioning the print head 100 on a plate in the printer's installation space. Furthermore, an area of a component 9 that has already been printed can also be approached and the nozzle 8 can thereby be closed.
• the piston needle 32 is immersed in the melt chamber 81 and moves further into it in such a way that parts of the liquid phase 12 are displaced from the melt zone D back into the mixing zone C, as a result of which the liquid phase 12 mixed with the plastic phase 11 from the plasticizing zone B.
• the liquid phase 12 from the melt zone D is thereby displaced from the upper area of the melt space 81 through the openings 71 of the kidney piece 7 back into the cavity 40 of the piston sleeve 4 in the mixing zone C.
• Fig. 4 shows a schematic representation of the print head 100 according to the invention with a control and regulation unit 113 for active regulation of the actuator device 110 for moving the piston 3 and an evaluation unit 114, which is designed to measure the measured values of the sensors 36, 82, 83, 111, 112 to evaluate and to forward the results to the control and regulation unit 113 for active regulation of the actuator device 110 and for active regulation of the heating elements 61, 63.
• the control and regulation unit 113 is provided for active regulation of the actuator device 110 for moving the piston 3 according to an operating strategy to be executed for filling and printing and for active regulation of the temperatures of the first 61 and second 63 heating elements.
• the sensor signals received by the evaluation unit 114 and the results calculated from the respective values are decisive for the active regulation of the actuator device 110 .
• the pressure sensor 83 for the pressure pi_ and the temperature sensor 82 for the temperature TL of the liquid phase 12 are arranged in the melt space 81 .
• the displacement measuring system 111 for the position s of the piston 3 and the sensor 112 for the force F exerted by the piston 3 on the material 10, 11 or for a hydraulic pressure PH exerted on the piston 3 are arranged on the actuator device 110 or on the piston 3 .
• the temperature sensor 36 for the temperature TK of the plastic phase 11 of the material is arranged on the piston 3 .
• the signals s, F, PH, TK, TL, PL of the sensors 111, 112, 36, 82, 83, represented by dashed arrows, are transmitted to the evaluation unit 114, then evaluated in this or in a cloud and the results according to an operating strategy as Control variable i is transmitted to the control and regulation unit 113 and the actuator device 110 and the heating elements 61, 63 are controlled accordingly.
• 5 shows a flowchart of a method 200 according to the invention for providing printable melt 12 for operating the print head 100 according to the invention, the method 200 comprising the following steps:
• At least the closing 220, the conversion 230, the compression 240, the determination 250 of the spring constant and the preparation for printing 260 of the method 200 are carried out by active regulation of the actuator device 110 by the control and regulation unit 113, with the results of the evaluation unit 114 from the Measured values of the sensors 36, 82, 83, 111, 112 are passed on to the control and regulation unit 113.
• FIG. 6 shows a section of the print head 100 according to the invention and two diagrams 6a, 6b, which show a pressure or pressure/force profile during the provision of printable melt 12, or various method steps of the method 200 for providing printable melt.
• Fig. 7 shows the different positions of the piston 3 for the various process steps or states from Fig. 6 beginning at the starting position 3a to the end position 3z of the piston crown 35.
• the cooling devices 50, 33 in the flange 5 and Piston 3, as well as the heating elements 61, 63 active and the melt space 81, as well as the kidney piece 7 are filled with melt 12 and in the lower part of the cavity 40 there is still granulate in the plastic phase 11.
• FIG. 6 shows two curves which are plotted against the path s covered by the piston 3.
• the path s is measured by the path measuring system 111 or path sensor 111 on the actuator device 110 or on the piston 3 .
• the upper curve represents a force, pressure curve for the force F exerted by the piston 3 on the material 10, 11 or for the hydraulic pressure PH exerted on the piston 3 during the advance of the piston 3 by the actuator device 110 during closing 220 and compression 240 , wherein the force or pressure sensor 112 is arranged on the actuator device 110 or on the piston 3 .
• the lower curve in diagram 6a represents a pressure profile of the melt pressure PL in the melt chamber 81 over the path s of the piston 3 during compression 240.
• the pressure sensor 83 for the pressure pi_ of the liquid phase 12 or the melt 12 is arranged in the melt chamber 81 .
• the second diagram 6b shows a partial section of the lower curve of the first diagram 6a, with the pressure profile of the melt pressure pi_ in the melt chamber 81 being shown here over the path s of the piston 3 during compression 240 (curve profile from p c to p d ).
• FIG. 7a shows a starting position 3a of the piston 3 during the filling process 210 of the print head 100, the piston head 35 being positioned at the top of the opening 21 of the piston sleeve 4.
• FIG. The entire process sequence from filling 210 to opening 820 of the nozzle during the preparation for printing 260 is also called the refill process, since it is a recurring sequence that is repeated as desired while a component 9 is being pressed.
• the refill process is the method for providing printable melt 12 for operating the print head 100 for a 3D printer.
• the position of the piston 3 is analogous to the position of the piston 3 from FIG.
• the piston 3 is then controlled by the actuator device 110 into the position 3b shown in FIG. 7b.
• the piston head 35 slides past the gate 44 of the piston sleeve 4 and the granules 10 protruding from the opening 21 into the cavity 40 are sheared off between the piston head 35 and the gate 44 . Therefore this position is called shearing position 3b. After shearing off 420, the opening cross section 21 is closed 220.
• the force and pressure profile F, PH increases from the starting position 3a to the shearing position 3b, with the force exerted by the actuator device 110 being the highest at the gate 44 or at the shearing position 3b, since the actuator device 110 generates the force to shear off the granulate 10 have to raise.
• the effort required can be reduced by suitable measures such as optimizing the gate geometry in connection with the nature of the piston head 35 and preheating the granulate 10 .
• the pressure profile pi_ of the melt 12 changes only slightly or hardly increases, since the nozzle 8 is still open and no pressure builds up in the melt space 81 .
• the compression process 240 then begins and the piston 3 is moved under force or pressure control by the actuator device 110 to the position 3c.
• the force F exerted on the material or granules 10, 11 or the hydraulic pressure PH exerted on the piston 3, and the pressure pi_ in the melt 12 are measured.
• the material 10, 11, 12 is pre-compacted.
• Position 3c is defined by the increase in force or pressure, ie position 3c is controlled, with no direct point being controlled, but rather a flank of the curves shown in diagram 6a.
• the edge occurs at a change point pi_c , Fc , PHc from the straight line with little or no gradient (the area from position 3a to position 3c) to the rise of the curve (at position 3c), at which a predefined Slope or a predefined slope angle is reached and/or exceeded.
• the position 3c is is in the first third of the plasticizing zone B.
• the granules 10, 11 are compressed in the plasticizing zone B by the advancement of the piston 3, with melt 12 being located in the melt zone D between the cavity 40 and the nozzle 8 at the same time.
• the plasticized granules 11 are thereby pressed into the melt 12 in the mixing zone C.
• melt 12 is already emerging from the nozzle 8, which means that any air or air pockets that may still be present are displaced from the nozzle head 6. As a result, the nozzle 8 is free.
• the position 3c is provided with a tolerance due to the method and material, as a result of which the position 3c of the piston 3 can be slightly different in different refill processes of the print head 100 that are carried out one after the other.
• the position 3c is therefore not a fixed point. If the position 3c is within the specified tolerance, it is ensured that the filling process 210 was successful, ie that enough granules 10 were filled into the cavity 40 and that the melt space 81 is already filled with melt 12 . For example, if the flank begins too far before position 3c, there is too much highly viscous or hard material 10, 11 in the area from the piston head 35 to the nozzle 8 and the mixing process in the mixing zone C may not have been successful. If, for example, the flank begins far behind position 3c, too little material 10 may have been refilled.
• the pre-compression 610 is completed and the nozzle 8 of the print head 100 is closed 620.
• the piston 3 is advanced in a pressure-controlled manner, starting from position 3c, until a previously defined peak pressure p d is reached and the piston head 35 has been moved to the position 3d shown in FIG. 7c.
• the peak pressure p d can be between approx. 100 and 300 bar, depending on the material 10 and requirements.
• the so-called peak pressure position 3d is then held for a material-dependent, predefined period of time.
• the piston head 35 protrudes into the first heating zone 65 and the piston needle 32 into the melt chamber 81 and while it is being held, part of the melt 12 flows out of the melt chamber 81 of the nozzle head 6 through the openings 71 in the kidney piece 7 back into the mixing zone C into the plastic granulate 10 located there homogenized.
• a better energy flow is achieved and a more homogeneous material 11, 12 is produced.
• the melt 12 flowing back becomes plastic and the granulate portions 11, which are pushed into the kidney piece 7, become molten. This results in a mixing of the material 11, 12.
• the holding process 640 described here is also used for analysis and for a system check of the print head 100, since the following effects can result in the pressure measurement of the pressure pi_.
• An increase in the pressure pi_ in the melt 12 would mean that the melt 12 outgassing because, for example, the temperature TL is too high. Melt temperatures TL that are too high are not desirable, since air plasma can form, which would lead to chemical decomposition.
• a strong pressure drop in the melt pressure pi_ could mean, for example, that the system of the print head 100 is leaking or there was still too much air in the system. This effect could occur if, for example, too much cold material 10, 11 was present in the cavity 40 because the temperature management of the print head 100 was not set optimally.
• the piston 3 is retracted 710 from the peak pressure position 3d by the actuator device 110 under pressure control until a target pressure pe of approximately 0 bar is reached.
• the system is relaxed. This ensures that the melt 12 is pressure-relieved and vented, resulting in a pure melt 12, particularly in the process zone E, which is now of high quality and printable.
• the target pressure position 3e shown in FIG.
• the spring constant results from the compressibility of the melt 12 and leads to a correction factor or shape factor that is required for the precise control of the piston 3 by the actuator device 110 .
• the actuator device 110 can control the piston 3 in a controlled manner, with the spring constant making it possible, among other things, for the real discharge of the melt 12 to have the correct, calculated volume flow of the melt 12 as a function of a web speed V B of the moving print head 100 during printing reached. This means that at each printing position and at each path speed V B of the print head 100, the quantity of melt 12 required in each case is applied to the component 9.
• the process of dispensing 270 the melt 12, or the pressure process 270, is then prepared 260 via active decompression 810 by retracting the piston 3.
• the piston 3 is pulled back by approximately 1 to 2 millimeters, which ensures that no melt 12 emerges from the nozzle 8 or nozzle opening when it is subsequently opened 820 . This would be the case if position 3e were to be held further due to the existing open system due to the influence of gravity. At the same time, the melt 12 is relieved analogously to a spring.
• the overall system of the print head 100 is a compressible system since the melt 12 can have a compression of approximately 20%, for example.
• the volume displaced by the advancement of the piston 3 therefore does not correspond to the volume of the material discharged 12, which can result in inaccurate and irregular outputs.
• the possible volume of the melt 12 for an advance of the printing process is defined by the target position 3e and the path to the end position 3z shown in FIG. 7e.
• the melt 12 is compressed during the start of printing.
• the compression of the melt 12 in the melt space 81 at the start of printing is generated partly by friction at the nozzle opening of the nozzle 8 when the melt 12 is "squeezed out” and partly by the resistance during printing on the component 9 or a substrate carrier on which the Component 9 is built.
• a uniform discharge of the melt 12 is achieved by intelligent control of the print head 100, with asynchronous movements of the piston 3 being adjusted by a correction factor by using an electronic gear on the actuator device 110.
• the correction factor which results in particular from the determined spring constant 740 of the melt 12, is mixed into the system, so to speak.
• the print head 100 according to the invention is therefore not restricted to synchronous movements analogous to conventional NC systems.
• the printing process is carried out under pressure control, the pressure pi_ of the melt 12 being measured continuously via the pressure sensor 83 in the nozzle head 6 .
• the measured pressure pi_ is the pressure that arises as a result of the melt 12 being discharged onto the component 9 or onto the substrate carrier (if no component is present). Without this effect of printing on an object, there would be no back pressure at the nozzle 8 other than frictional pressure which would cause too much material/melt 12 to be discharged from the nozzle 8 .
• the printing process is started by actively mixing in the melt 12 through the intelligent control and activation of the piston 3 .
• “more” stroke is performed in order to compensate for the compressibility of the melt 12.
• too much melt 12 is pressed out of the nozzle 8, but the pressure sensor 83 is read out in parallel with the mixing in of the melt 12, as a result of which counter-regulations can be made as a function of the pressure.
• an electrically driven actuator device 110 proves to be dynamic and very effective.
• the melt temperature Ts is continuously measured and in the heating zone 2 the melt 12 is controlled via the heating elements 63 in the nozzle head 6 to the required set value of the process temperature in the area of the process zone E.
• the piston 3 is actuated by the actuator device 110 in accordance with a web speed of the print head 100 , as a result of which the melt 12 is discharged from the nozzle 8 .
• the control and regulation unit 113 of the print head 100 is activated and actively intervenes in the control of the actuator device 110 in order, for example, to admix an additive desired value or an additive amount of material 12 if required. If, for example, an additive target value is mixed in and as a result more material 12 is discharged or extruded from the nozzle 8 than would be the case with continuous control, the pressure pi_ on the nozzle head 6 also increases as a result.
• the additive target value is the mixed-in value or The additional piston path that must be covered in order to discharge the desired volume of melt 12 according to the correction value determined from the spring constant 740 . As a result, a steady state is achieved, as a result of which the quantity of melt 12 discharged onto the component 9 remains constant.
• the use of the plunger needle 32 ensures the advantageous effect that this allows direct volume displacement within the melt 12 in the melt chamber 81, as a result of which a smaller spring constant is achieved.
• the small spring constant in turn enables high dynamics of the print head 100.
• the effect results from the fact that the piston needle 32 transmits pressure more directly to the melt 12.
• the printing process can be carried out until the piston head 35 reaches the position 3z, the position 3z being defined in such a way that the piston head 35 just does not reach a mechanical stop, but as in FIG. 7e shown, just before reaching the kidney piece 7 comes to a standstill. Thereafter, no more material 12 can be discharged and the refilling process according to the invention described above is restarted.
• FIGS. 8 to 13 Individual flowcharts of the method steps of method 200 according to the invention are shown in FIGS. 8 to 13 in addition to the embodiments of the invention described in the preceding figures.
• Fig. 8 shows a flowchart of a method for filling 210 the cavity 40 with printable material 10 by the feed device 2, the method 210 comprising at least the following steps:
• the filling 310 of the granulate pieces 10 is carried out manually or automatically, with the granulate pieces 10 slipping into the lower region 24 of the feed device 2 due to the influence of gravity.
• the generation 320 of air impulses 26 is carried out at intervals and the granulate pieces 10 are thrown in the area of the air impulses 26 in such a way that when they fall down they exert an impulse on the underlying granulate pieces 10 and encourage them to slide down into the heated cavity 40 of the print head 100.
• Fig. 9 shows a flow chart of a method for closing 220 the opening cross section 21 of the piston sleeve 4 by the piston 3, the method 220 comprising the following steps:
• FIG. 10 shows a flowchart of a method for converting 230 the material from a solid phase 10 via a plastic phase 11 to a liquid phase 12, the method 230 comprising the following steps:
• FIG. 11 shows a flow chart of a method for compacting 240 the material 10, 11, 12.
• This compacting process 240 comprises the following steps:
• the pre-compacting 610 of the material 10, 11, 12 is carried out under pressure and/or force control by advancing the piston 3, with pre-compacting being carried out up to position 3c and this being reached when a material-dependent gradient and/or a material-dependent gradient angle of a force and/or pressure curve is reached and/or exceeded.
• the compression 630 of the material 10, 11, 12 is carried out under pressure control by advancing the piston 3 with the nozzle 8 closed, and the holding position 3d is approached until a peak pressure p d is reached or is defined by the peak pressure p d .
• the nozzle 8 is closed and the piston needle 32 dips into the melt space 81 of the nozzle head 6 in such a way that part of the liquid phase 12 flows out of an upper area of the melt space 81 through openings 71 in the kidney piece 7 from the melt zone D is displaced back into the mixing zone C, whereby the Part of the liquid phase 12 mixed with the plastic phase 11 from the plasticizing zone B in the mixing zone C.
• the piston 3 is held in the holding position 3d, the pressure pi_ and the temperature T L of the liquid phase 12 being measured during the holding process 640 and the measured values being checked by the evaluation unit 114 for checking the function of the compression process 240 .
• FIG. 13 shows a flowchart of a method for preparing the liquid phase 12 for printing 260, the method 260 comprising the following steps:

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• 2021
  • 2021-03-18 DE DE102021202649.4A patent/DE102021202649A1/de active Pending
• 2022
  • 2022-03-17 JP JP2023555683A patent/JP2024512429A/ja active Pending
  • 2022-03-17 WO PCT/EP2022/057035 patent/WO2022195031A1/de active Application Filing
  • 2022-03-17 WO PCT/EP2022/057027 patent/WO2022195027A1/de active Application Filing
  • 2022-03-17 EP EP22716207.0A patent/EP4308369A1/de active Pending
  • 2022-03-17 CN CN202280022220.7A patent/CN116997456A/zh active Pending
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