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
  • B29C64/112—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using individual droplets, e.g. from jetting heads
• • 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
  • B29C64/165—Processes of additive manufacturing using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber
• • 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

Definitions

• the invention relates to a method for applying a volume flow of successive drops for producing a three-dimensional object according to the preamble of claim 1.
• Such a process is known from DE 10 2004 025 374 A1, in which drops of a reaction component are discharged and brought into contact with a base reaction component applied to a substrate in order thereby to build up in layers a three-dimensional article with changing material properties. This results in an article section in which there is a gradual transition from one material property to another material property.
• the droplet size can be regulated as required, without paying attention to the viscosity of the material being processed which may change during the production process.
• EP 1 886 793 B1 it is known to couple a known in the injection molding plasticizing unit to a pressurized material storage for the production of a fluid phase of a material. To produce an object on a slide in a construction space, this material is discharged via a discharge opening in the form of drops, wherein due to the adhesive force of the
• CONFIRMATION COPY Material a high pressure and usually high temperatures must be applied.
• the viscosity decreases at relatively high shear rates, which in turn has an influence on the droplet size and its tendency to fuse with drops that have already been applied previously.
• a measuring method is known in which the mass output per time is determined from a nozzle. The value is given in g / 10 min, whereby the plastic is pressed by means of a pestle through a nozzle with a diameter of 2.095 mm. By a weight of the required force is applied.
• the test temperature and the nominal mass used must always be specified. The method is defined in accordance with DIN EN ISO 1133.
• the MFI value determined in accordance with the melt flow rate the flowability of the plastic is determined only at a defined operating point. The change in the flowability with changing process parameters in particular as a function of the residence time is not taken into account here.
• the present invention has the object to provide a method for achieving a constant discontinuous volume flow available.
• the process-relative instantaneous starting intrinsic viscosity is determined to be a starting point or reference point and, as a correction variable, by means of the process actuator, correctively intervenes in the droplet size.
• the manipulated variable is preferably the pressure in the material store, the measured variable preferably being the average displacement speed of the pressure-generating conveying element per discharged drop, and the change in the otherwise recorded process parameters being applied to the pressure as a correction control variable.
• the cycle time or shutter speed t ⁇ or the clock movement SB or the stroke of the outlet opening or the diaphragm of a solid-body joint preferably used there can be used as a manipulated variable.
• the melt temperature ⁇ is also suitable as a control variable, but since it is considerably slower in its reaction and partly non-linear, a regulator is much more difficult to set up.
• a controller would have a high D component or would have to be operated as a fuzzy controller.
• disturbances or differences in the general intrinsic viscosity can be compensated, for example, by variations in the batches of a raw material with respect to an independently measured model reference point. Similar disturbances can also occur due to the residence time of the material in the material reservoir.
• the pressure is applied by a conveying element, such as an injection screw, to which or at which a return flow lock is attached as a closure element.
• a conveying element such as an injection screw
• a return flow lock can cause leakage.
• Have flow which can be taken into account by a correction factor in the determination of the characteristic number of the control algorithm.
• Fig. 2 is a flowchart for the code control for drop constancy means
• Fig. 3 is a partially sectioned view of an apparatus for producing a three-dimensional object.
• the material which is either in the initial state in a fluid phase or can be liquefied, is used to produce a three-dimensional object 50 by sequentially discharging drops 70. This can be done, for example, by sequentially ejecting individual drops 70 from an exit orifice 12b of a dispenser. unit 12 are discharged, so that layer by layer of the object 50 results on a by a drive unit 6 relative to the outlet opening 12 b movable slide 13 in the space 20.
• the solidifiable material is a plasticized material, such as silicone or a plasticizable material such as thermoplastics or powdery materials. These materials may be those commonly available in the injection molding process and thus relatively inexpensive because no special rapid prototyping materials are required.
• the material may also be a heat-reversible meltable and therefore recyclable material. Any other materials may be used, provided that these materials can be plasticized by the device and, above all, can be discharged by the at least one discharge unit 12.
• the material is plasticized or processed in the processing unit 11 arranged on a machine table 15 and pressurized by the pressure generating unit 10.
• the pressure p determines the formation of the drops 70 and thus the quality of the article 50 to be produced.
• the desired volume of the drop 70 is in particular in the range of 0, 01 to 1 mm 3 .
• the diameter of the outlet opening 12b is in particular less than or equal to 1 mm, preferably about 0.1 mm.
• the processed material is generally so-called non-Newtonian fluids.
• Their intrinsic viscosity ⁇ is strongly dependent on arbitrary process settings such as temperature, pressure, residence time under temperature, degree of drying of the starting solids, etc.
• the layer structure of a part to be formed calculated from the CAD models is preferably based on a constant droplet size.
• the intrinsic viscosity is inversely proportional to the droplet size, it is necessary to compensate for a temporary change in intrinsic viscosity during the construction time of the article 50, or to adjust it from the beginning with respect to batch fluctuations. The following procedure is used for this.
• the fluid phase of the material is introduced into the material reservoir 12c.
• a pressure p is applied to the fluid phase of the material in the material reservoir 12c.
• the material in the form of droplets 70 is discharged from a tactile outlet opening 12b to thereby construct the three-dimensional object 50 in the construction space 20.
• the fluid phase has a temperature ⁇ .
• one of the process parameters comprising the pressure p, the cycle time t B or clockwise movement s B of the outlet opening 12b or the temperature ⁇ is controlled regulated with changes in the viscosity of the fluid phase of the material while maintaining the other process parameters.
• the parameters required for this are measured in step 100 according to FIG. 1, that is to say in particular the pressure p (to), the theoretically calculated flow volume v D (to) through the diaphragm, the leakage volume v L (t 0 ) through the locking ring of the backflow preventer 27 and the temperature ⁇ of the material.
• the frequency f of the number of drops per second, the Path s of a conveying element, the cycle time t B or clock movement s B of the outlet opening 12b, the cross-sectional area A s of the processing unit, in which the conveying screw 26 is received, and the diameter do of the outlet opening are measured.
• the regulation of the constant drop volume will be described on the basis of the manipulated variable of the pressure p produced by the conveying element (screw 26).
• the cycle time t B , the clock movement s B of the outlet opening 12 b or the temperature ⁇ can also be used as a manipulated variable of the control loop with otherwise recorded further process parameters.
• a reference index is formed as a replacement for the theoretical viscosity, where t 0 is the time after which n 0 drops were discharged and at a later time t, which is any integer Multiple of the measurement interval t 0 is: ⁇ (a, p, t)
• the discharged mass volume can be measured up to the time t 0 or in the time interval between t and t-to by determining the corresponding screw displacement paths.
• the average single drop volume V T (t) is derived by dividing the number n 0 Swept drop in the corresponding interval t 0:
• V T ropfen measured (t) f (p (t)) * Schneckenwe g (t Screw (tt 0 ) ⁇ Slightly larger
• n 0 ⁇ 10 to 100 drops should be averaged over a larger number of drops.
• the change of the screw path over a certain number n 0 of drops is considered.
• the gap between the cylinder tube and the locking ring acts in the same way as a leakage flow orifice for the pressurized plasticized mass.
• v L volume via return flow block 27 in the measuring interval t 0
• the value of the leakage volume v L (t) in a measuring interval t 0 can be measured at any time by closing the outlet nozzle:
• VL, measured (t) (screw path (t) - screw path (t-to)) * screw diameter (formula 11)
• the outlet opening 12b is opened when the state remains constant, the total volume change at the mass pressure generator increases. It is possible to measure the total volume v (t) with simultaneous actuation of the discharge nozzle by means of an orifice function t ⁇ (t) in accordance with formula 11.
• v D v - v L (formula 12)
• the system constant K * thus calculated in step 101 essentially contains the geometry of the leakage gap between the locking ring and the cylinder tube of the mass pressure generator as well as the outlet geometry of the discharge nozzle with a constant iris time and aperture opening path. It can be determined by means of preliminary tests as a characteristic field depending on the set process parameters and the material used and can be redetermined at each start of construction in order to improve the precision of the layer dissection of the component. If K * is within the tolerance range with reference to this map data (query 102), K * can be transmitted as a correction factor to the layer decomposition program before the component process is started (step 104) and the component formation program with corrected layer decomposition or droplet size can be started (step 105). Otherwise, the system is stopped in step 103.
• the process variable pressure regulator serves to determine varying viscosities of the material through residence time or small changes, e.g. in the closing mechanism of the discharge nozzle to compensate.
• a maximum process window can be defined (query 111), at which a plant defect is detected (eg clogged discharge or leakage between material storage 12c and discharge orifice at the discharge opening 12b) and the system according to step 112 is stopped.
• step 113 the pressure in step 113 is readjusted, if necessary, until the component is ready (query 114, step 115).

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Optics & Photonics (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2012
  • 2012-03-14 DE DE102012004988A patent/DE102012004988A1/de not_active Withdrawn
• 2013
  • 2013-03-12 CA CA2866297A patent/CA2866297C/en active Active
  • 2013-03-12 CN CN201380013978.5A patent/CN104334354B/zh active Active
  • 2013-03-12 DK DK13715886.1T patent/DK2825384T3/en active
  • 2013-03-12 PL PL13715886.1T patent/PL2825384T3/pl unknown
  • 2013-03-12 JP JP2014561315A patent/JP6046172B2/ja active Active
  • 2013-03-12 WO PCT/EP2013/000717 patent/WO2013135367A1/de not_active Ceased
  • 2013-03-12 EP EP13715886.1A patent/EP2825384B1/de active Active
  • 2013-03-12 HU HUE13715886A patent/HUE029777T2/en unknown
• 2014
  • 2014-03-11 US US14/203,860 patent/US9539765B2/en active Active
  • 2014-08-20 IL IL234220A patent/IL234220B/en active IP Right Grant

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