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WO2019077555A1 - Méthodes et appareil d'impression 3d - Google Patents

Méthodes et appareil d'impression 3d Download PDF

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Publication number
WO2019077555A1
WO2019077555A1 PCT/IB2018/058120 IB2018058120W WO2019077555A1 WO 2019077555 A1 WO2019077555 A1 WO 2019077555A1 IB 2018058120 W IB2018058120 W IB 2018058120W WO 2019077555 A1 WO2019077555 A1 WO 2019077555A1
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WO
WIPO (PCT)
Prior art keywords
liquid
silicone
print
water
printing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2018/058120
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English (en)
Inventor
Timothy Giffney
Oliver KLUPS
Jonathan Richard TANKERSLEY
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Auckland Uniservices Ltd
Original Assignee
Auckland Uniservices Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Auckland Uniservices Ltd filed Critical Auckland Uniservices Ltd
Publication of WO2019077555A1 publication Critical patent/WO2019077555A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • B29C64/124—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified
    • 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
    • B29C64/245—Platforms or substrates
    • 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
    • B33Y80/00—Products made by 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
    • B29C64/20—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
    • B29C64/364—Conditioning of environment
    • B29C64/371—Conditioning of environment using an environment other than air, e.g. inert gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2083/00—Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as moulding material
    • 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 present invention relates to methods and apparatus for additive
  • Known 3D printing technology include stereo-lithography (STL), where a laser is scanned selectively across a bath of photopolymer resin curing particular areas of the surface. The level of the uncured resin is increased slightly and the process repeated. While STL produces good detail rendition, multi-material printing is challenging and impractical as the entire resin bath needs to be changed, which can introduce cross- contamination issues.
  • STL stereo-lithography
  • FDM fused deposition modelling
  • Soft structures have been identified as the solution to problems faced in automation expansion as well as for wearable devices. Silicone has been recognised as the material of choice with the optimal blend of attributes.
  • the soft robot manufacturing methods presently popular are neither convenient nor efficient. At present, additive manufacturing techniques suitable for rigid materials are highly advanced in comparison to the techniques available for silicone and soft materials.
  • the invention broadly consists in a method for printing a silicone structure with a 3D printer, the 3D printer comprising a liquid bath configured to receive a liquid, a print-bed, and silicone deposition member, the method comprising :
  • the deposited silicone is the silicone structure, and maintaining a relative liquid level, where the relative liquid level is the level of liquid in the liquid bath relative to the silicone structure such that the silicone structure is at least partially submerged in the liquid .
  • the silicone structure is substantially submerged in the liquid.
  • the method further comprises depositing silicone onto the silicone structure.
  • the relative liquid level is maintained constant. In another embodiment, the relative liquid level is maintained at a variable level dependent on the volume of silicone printed.
  • the step of maintaining the relative liquid level comprises increasing amount of liquid in the liquid bath.
  • the step of maintaining the relative liquid level comprises changing the height of the print-bed.
  • the print-bed is lowered into the liquid bath.
  • the volume of liquid in the liquid bath is constant.
  • liquid is pre-heated to a curing temperature.
  • the water bath comprises a heating member.
  • the heating member maintains the liquid at substantially a curing temperature.
  • the liquid cures the silicone structure.
  • the print-bed is a heat bed .
  • the heat bed is heated to a heat bed curing temperature.
  • the heat bed curing temperature is 100°C.
  • the curing temperature is between 50°C and 100°C.
  • the curing temperature is between 85°C and 100°C. More preferably, the curing temperature is less than the boiling point of the liquid in the liquid bath. Even more preferably, the curing temperature is greater than 5°C less than the boiling point of the liquid in the liquid bath.
  • the heated liquid reduces the silicone curing time.
  • the liquid is water.
  • the liquid has a surfactant added to it.
  • the liquid comprises a surfactant.
  • the liquid comprises water and a surfactant.
  • the 3D printer further comprises one or more additional silicone curing devices.
  • the additional silicone curing devices may be any one or more of the following :
  • a hardware system is configured to execute and/or carry out the steps of the method.
  • the invention broadly consists in a 3D printing device for printing a structure, wherein the improvement comprises :
  • the structure being a silicone structure
  • a liquid bath configured to receive a volume of liquid
  • a relative liquid level where the relative liquid level is the level of liquid in the liquid bath relative to the silicone structure
  • the relative liquid level is maintained such that the silicone structure is at least partially submerged in the liquid .
  • the silicone structure is substantially submerged in the liquid.
  • the relative liquid level is maintained constant. In another embodiment, the relative liquid level is maintained at a variable level dependent on the volume of silicone printed.
  • the relative liquid level is maintained by increasing amount of liquid in the liquid bath.
  • the relative liquid level is maintained by changing the height of the print-bed.
  • the print-bed is configure to be lowered into the liquid bath.
  • the volume of liquid in the liquid bath is constant.
  • liquid is pre-heated to a curing temperature.
  • the water bath comprises a heating member.
  • the heating member maintains the liquid at substantially a curing temperature.
  • the liquid cures the silicone structure.
  • the print-bed is a heat bed.
  • the heat bed is heated to a heat bed curing temperature.
  • the heat bed curing temperature is 100°C.
  • the curing temperature is between 50°C and 100°C.
  • the curing temperature is between 85°C and 100°C. More preferably, the curing temperature is less than the boiling point of the liquid in the liquid bath. Even more preferably, the curing temperature is greater than 5°C less than the boiling point of the liquid in the liquid bath. In one embodiment, the heated liquid reduces the silicone curing time.
  • the liquid is water.
  • the liquid has a surfactant added to it.
  • the liquid comprises a surfactant.
  • the liquid comprises water and a surfactant.
  • the 3D printer further comprises one or more additional silicone curing devices.
  • the additional silicone curing devices may be any one or more of the following :
  • the invention broadly consists in an add-on for a 3D printing device comprising a print-bed and a material depositing member, wherein the add-on comprises:
  • a liquid bath configured to receive a volume of liquid, the print-bed is located within the liquid bath
  • a relative liquid level where the relative liquid level is the level of liquid in the liquid bath relative to the height silicone structure
  • the structure height tracking module tracks the height of the structure being 3D printed and maintains the relative liquid level such that the silicone structure is at least partially submerged in the liquid .
  • the silicone structure is substantially submerged in the liquid.
  • the relative liquid level is maintained constant. In another embodiment, the relative liquid level is maintained at a variable level dependent on the volume of silicone printed.
  • the relative liquid level is maintained by increasing amount of liquid in the liquid bath.
  • the relative liquid level is maintained by changing the height of the print-bed.
  • the print-bed is configure to be lowered into the liquid bath.
  • the volume of liquid in the liquid bath is constant.
  • liquid is pre-heated to a curing temperature.
  • the water bath comprises a heating member.
  • the heating member maintains the liquid at substantially a curing temperature.
  • the liquid cures the silicone structure.
  • the print-bed is a heat bed.
  • the heat bed is heated to a heat bed curing temperature.
  • the heat bed curing temperature is 100°C.
  • the curing temperature is between 50°C and 100°C.
  • the curing temperature is between 85°C and 100°C. More preferably, the curing temperature is less than the boiling point of the liquid in the liquid bath. Even more preferably, the curing temperature is greater than 5°C less than the boiling point of the liquid in the liquid bath.
  • the heated liquid reduces the silicone curing time.
  • the liquid is water.
  • the liquid has a surfactant added to it.
  • the liquid comprises a surfactant.
  • the liquid comprises water and a surfactant.
  • the 3D printer further comprises one or more additional silicone curing devices.
  • the additional silicone curing devices may be any one or more of the following :
  • the invention broadly consists in a 3D printing device for printing a silicone structure, wherein the 3D printing device comprises:
  • a liquid bath configured to receive a volume of liquid
  • a relative liquid level where the relative liquid level is the level of liquid in the liquid bath relative to the height silicone structure
  • the 3D printing device is configured to maintain the relative liquid level, such that the silicone structure is at least partially submerged in the liquid .
  • the silicone structure is substantially submerged in the liquid.
  • the relative liquid level is maintained constant. In another embodiment, the relative liquid level is maintained at a variable level dependent on the volume of silicone printed. In one embodiment, the relative liquid level is maintained by increasing amount of liquid in the liquid bath.
  • the relative liquid level is maintained by changing the height of the print-bed.
  • the print-bed is configure to be lowered into the liquid bath.
  • the volume of liquid in the liquid bath is constant.
  • liquid is pre-heated to a curing temperature.
  • the water bath comprises a heating member.
  • the heating member maintains the liquid at substantially a curing temperature.
  • the liquid cures the silicone structure.
  • the print-bed is a heat bed.
  • the heat bed is heated to a heat bed curing temperature.
  • the heat bed curing temperature is 100°C.
  • the curing temperature is between 50°C and 100°C.
  • the curing temperature is between 85°C and 100°C. More preferably, the curing temperature is less than the boiling point of the liquid in the liquid bath. Even more preferably, the curing temperature is greater than 5°C less than the boiling point of the liquid in the liquid bath.
  • the heated liquid reduces the silicone curing time.
  • the liquid is water.
  • the liquid has a surfactant added to it.
  • the liquid comprises a surfactant.
  • the liquid comprises water and a surfactant.
  • the 3D printer further comprises one or more additional silicone curing devices.
  • the additional silicone curing devices may be any one or more of the following :
  • the invention broadly consists of a product produced by the method according to the first aspect.
  • the product is a soft robot member.
  • the invention broadly consists of a product produced by the devices according to any one of the second, third, or fourth aspects.
  • the product is a soft robot member.
  • the invention broadly consists of method for printing a silicone structure, the method comprising : depositing silicone onto a print-bed via a silicone deposition member, and maintaining a liquid level of a liquid in a liquid bath such that the deposited silicone is substantially submerged in the liquid.
  • the invention broadly consists of method for printing a silicone structure, the method comprising :
  • the invention broadly consists of method for printing a silicone structure, the method comprising :
  • the invention broadly consists in a 3D printing device for printing silicone, the device comprising a liquid bath configured to receive a volume of liquid, wherein, when the 3D printer is printing, a relative liquid level, being the level of liquid in the bath relative to the silicone being printed, is maintained in the liquid bath such that the silicone being printed is at least partially submerged in the liquid .
  • any form of computing, processing or programmable electronic device, platform or system including, but not limited to, portable or non-portable consumer electronic devices such as smartphones, cellphones, tablets, e-Reader or e-book devices, laptops, and notebooks, gaming machines or consoles, server, smart televisions, general purpose computers such as desktop computers, specific purpose computers or the like, and is intended to include one or more linked or communicating hardware or processing devices or systems which work together.
  • 'and/or' means 'and' or 'or', or where the context allows both.
  • This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.
  • Figure 1 shows a graph of cure times for various silicones.
  • Figure 2 shows a 3D printing experiment using a solder rework gun.
  • Figure 3 shows a graph of the change in viscosity of silicones over time.
  • Figure 4 shows an example 3D printer.
  • Figure 5 shows a 3D printing experiment using hydrogel.
  • Figure 6 shows an example 3D printer modified to print silicone.
  • Figure 7 shows an example 3D printer modified to print silicone.
  • Figure 8 shows example 2.5D printed silicone.
  • Figure 9 shows example 3D printed silicone.
  • Figure 10 shows example 3D printed silicone.
  • Figure 11 shows example 3D printed silicone.
  • Figure 12 shows an embodiment of a liquid bath.
  • Figures 13A to 13C show embodiments for maintaining relative liquid level.
  • Silicones are widely used in products around the world due to be flexible but are time consuming to make. This is due to needing a mould for the silicones which must be manufactured for each new part which slows down and increases the cost of prototyping of silicone devices. Developing an additive material process for silicone parts would increase the speed of prototyping and increase the number of people that had easy access to it. It would also allow for more complex flexible devices to be manufactured.
  • Example silicones include Smooth-On's EcoFlex 0030 (referenced as “EcoFlex 0030”), Dow Coming's 732 RTV silicone, and Sylgard's 184 (referenced as "Sylgard 184").
  • the present invention provides accelerated silicone curing times for use with standard silicone types. Accelerating silicone curing times gives for faster 3D printing times and may allow for silicone to be used as a viable rapid prototyping material.
  • Table 1 gives the pot life and curing time of each material. These curing times are not suitable for working with a 3D printing, rapid prototyping environment or system.
  • Figure 1 shows the time taken to cure the Sylgard 184 and EcoFlex 0030 silicones at various temperatures.
  • the more steeply slanted line represents the Ecoflex 0030, and the shallower line represents the Sylgard 184.
  • a successful deposition was found to have a cure time that was approximately 5-7 seconds.
  • Figure 5 shows red EcoFlex printed inside a clear bubbly hydrogel solution .
  • a thick gel was obtained and watered down to form a hydrogel solution.
  • EcoFlex was extruded manually with a long 18-gauge syringe needle into a helix shape.
  • the container of hydrogel was placed in a warm water bath to accelerate curing and hereby reduce the likelihood of distortion prior to full cure.
  • the "Rising Water Level” system is used in conjunction with any one or more of the following techniques described in the sections:
  • a Kellerman K8200 3D printer was obtained to be modified for the use of this project.
  • the printer was originally a kit set printer that had modifications in the extrusion head as well as in the heat bed of the printer.
  • the heat bed was previously modified to allow more current to decrease rise time for heat bed temperature. Some cables had to be replaced in the printer due to damage.
  • Repetier host is a software that controls the printer through manual control as well as G-code that can be hand written or acquired through the use of the inbuilt Slic3r which converts an STL file into G-code ready for printing.
  • a thin 3mm aluminium plate was manufactured to cover the heat bed of the printer to avoid damaging it through extrusion directly onto the heat bed, partially when scrapping off the print.
  • Figure 4 shows the original, unmodified 3D printer used in this example.
  • the 3D printer has been retrofitted to include the extrusion rig design described in the "extrusion rig design" section below.
  • the retrofitting was conducted by way of convenience so that a new 3D printer didn't need to be constructed.
  • a new 3D printer may be constructed using the techniques described in the
  • an add-on, plugin, or enhancement may be designed using the techniques described in the "extrusion rig design" section such that the add-on, plugin, or enhancement can be incorporated into other 3D printers without substantial
  • Figure 6 shows an example extrusion rig 60 according to an embodiment of the invention. Also shown in Figure 6 is an example test print of a heart 65.
  • the extrusion rig 60 is an example of a silicone depositing member or a silicone dispensing member.
  • a powered syringe system 62 was designed that worked using a stepper motor 64 that was in line with the axis of the syringe 66 to avoid any unnecessary torques.
  • This stepper motor 64 preferably pushes a plate down causing the plunger of the syringe 66 to plunge into the barrel of the syringe 66.
  • test printing extrusion rig 60 was assembled, it was tested using by plugging the stepper motor into the extrusion plug of the 3D printer. Manual control was then used to valid the design by movement in both directions of the motor. Water was then added into the syringe 66 to prove that the system would extrude a liquid before mounting it to the 3D printer.
  • the extrusion rig was tested by printing a love heart shape 65 part that was one layer thick and only one loop. This test was to validate that this extrusion rig system worked as an extrusion system for silicone. This test printing required changing parameter settings inside of the slicer program. These included making sure that only one layer and one loop was being printed as well as manually adjusting the flow rate to increase the amount of silicone coming out. It was found that the existing firmware requires the extruder to have reached a minimum temperature for extrusion to be permitted. Initially we allowed the ABS print-head to be heated and thus were able to test the extrusion system. Later it was found the permission requirement could be overrode using G-code command "M302". This prevented a slow drip of melted ABS. The ABS extruder had a step-up ratio of 5: 1. The software was calibrated to this, so 50mm extrusion resulted in a ⁇ 10mm vertical displacement of the syringe plunger.
  • peristaltic pumps were used to pump the two parts of Ecoflex through and into an epoxy mixing nozzle.
  • This example made use of SLA printing to manufacture a Y section part to combine the two Ecoflex parts from two inlets to one outlet going into the mixing nozzle.
  • This example functioned fine with it pumping liquid through the nozzle. Problems were identified with the printing speed which required the peristaltic pump to rotate very slowly. This caused the Ecoflex to not be mixed properly resulting in no curing even after hours on the heat bed.
  • a peristaltic pump driven passive mixing system that employed the epoxy mixing syringe nozzles but replaced the cartridges and accompanying plungers with a peristaltic pump.
  • the solution 100 is introduced to the water bath 101.
  • the first version of this example used 3mm ID hoses, however given the length of tube in use this resulted in a significant quantity of EcoFlex sitting in the hose. It was established that material in the hoses was partially curing before being printed, especially if there was delay between prints. This resulted in a switch to 1.59mm and 2mm ID tubes, resulting in a volume of 0.7ml_, a volume decrease of 180%.
  • Limitations of this example may also include the ability to seal hose connections to other hardware. Under greater pressure, which occurs when there is partial curing or the extrusion rate is too high, the system may begin to slowly leak, which may affect print quality as the calculated amount of material was not deposited. Heat through convection and radiation from the print bath initially encouraged partial curing in the pipes. This may be largely overcome through heat shielding and a fan blowing cooler ambient air towards the tubing. Cleaning of the system may prove to be difficult:
  • isopropyl alcohol may be flushed through but this may not dissolve the silicone and air of 4 bar pressure also may struggle to clear the system.
  • the liquid being used is water and as such, the liquid bath is described as a water bath.
  • the stage being used is a heated stage.
  • the heated stage is described as a "heat bed”. A person skilled in the art will appreciate that it is not essential that the stage be heated and is merely an option.
  • FIG 7 best shows the example water bath (labelled "Water Bath”).
  • Water Bath the water needed to be heated in a controlled environment for printing.
  • a water bath that had a kettle element in the bottom was placed on the heat bed.
  • the kettle element was connected to a Bang-Bang temperature controller which had a PT100 probe place in the bath. This allowed for control of water
  • Gaps between the print-bed and container walls resulted in additional volume of water, which is undesired as it increases the volume of water that sloshes as the print- bed moves in the XY-directions. Scouring pads were inserted into these gaps to reduce the volume of water whilst still being water-permeable. Water-permeability was desired as it allowed convection of heated water from beneath the platform as well as slowing waves caused by print-bed motion.
  • Z-height is commonly an important parameter for 3D printing. For Z-height to be correct over the entire print area it is necessary to have a level print-bed, for this reason the existing print-bed was left underneath the water bath as it had levelling screws.
  • a hardware system may be used to control the water volume in the water bath.
  • an chicken controlled peristaltic pump system was developed for water level regulation.
  • custom layer-change G-code paused the extrusion to wait for the water level increase to take place.
  • the volume of water, added upon button press, was based off the average cross-sectional area of the part.
  • the new hardware system may be an add-on to a pre-existing hardware system associated with the pre-existing 3D printer. Communication between the hardware systems may be done via any standard hardware system interfaces such as Bluetooth, SPI, or I2C. Alternatively, the pre-existing hardware system of the 3D printer may updated with additional functionality to control the water level in the water bath.
  • the water bath may comprise a constant volume of water and the pre-existing hardware system of the 3D printer controls the height of the stage (or heat bed) such that the structure being printed is submerged or substantially submerged.
  • the water level can be determined and adjusted using any one or more of the following variables or parameters:
  • a sensor may be used to determine the height of the structure and therefore the level of water required.
  • the heat bed may have an adjustable height.
  • the height may be adjusted such that the heat bed remains completely submerged in the water.
  • the height of the heat bed way be such that the structure being printed on the heat bed is partially submerged in the water.
  • the height of the heat bed is set or adjusted such that highest point of the structure is not submerged in the water in the water bath.
  • This alternative embodiment may be used in conjunction with water level control, or as an alternative to water level control.
  • This example 3D printer had movement in the X-Y directions on the base and Z direction on the printer head. This caused problems with the method of printing. In particular because of the large bath of water used. Movements in the base caused large ripples that sloshed the water around. This proved problematic as deposition was occurring on top of the water level. Changing to a printer that had the X-Y-Z movement directions in the printer head while the base/heat bed/water bath remained stationary would be the best case. Although due to the rate of change in the Z direction being so small, the base could theoretically have movement in the Z direction without comprising the print.
  • the hotter the water bath the better for curing silicone.
  • Increasing the water temperature to boiling point would interfere with the silicone depositing/dispensing and result in a jagged, poorly printed 3D structure.
  • the temperature of the liquid in the liquid bath is close to boiling point. More preferably, the temperature of the liquid in the liquid bath is slightly less than the boiling point of water.
  • Extrusion Multiplier this is for fine-tuning the flow rate. It was necessary in various embodiments to scale this down by a factor of 5 for the preliminary syringe extrusion system as the filament extruder supplied with the system has a step-up gearing ratio of 5 : 1 between the stepper motor and the filament feed- wheel. For the pump system, this the value became 2.
  • Extrusion Diameter this controls the extrusion stream width. It was set to the inner diameter of the hose, which was 2mm.
  • Feed rate - this is calculated by Slic3r based off values entered for ⁇ , ⁇ , ⁇ , bridges and gaps speed.
  • To reduce sloshing of water we set the print speed to 15mm/s, which is a reduction by a factor of three from the default setting. Consequently, this resulted in a factor of three increase in print time. Very slow speeds caused extremely long printing time and resulted in frequent print failures due to material curing in the system.
  • EcoFlex 0030 is pre-mixed with a 50 : 50 ratio of the two components. If desired, dye may be added . Degassing was not required as the pumping procedure sufficiently negated bubbles that arose during mixing. Additionally, for all prints the print bath must preferably be filled to at least be in contact with the underside of the print-bed with the water-surfactant solution prior to powering on for water bath pre-heating. Z-height has been set as part of Printing System Parameterisation (as described in the "Printing System Parameters") and remains a constant even with nozzle replacement. Using the manual control settings, silicone is preferably pumped into the system until it has reached the nozzle. Finally, the part is prepared for printing by Slic3r and all axes are zeroed.
  • the initial layer is printed onto the dry, contaminant-free, print-bed.
  • the print- bed is heated to 85°C through water contact on its underside. This may ensure good adhesion of the silicone, vital for a successful print.
  • the initial layer preferably begins with three perimeter loops to ensure a smooth stream of silicone is being extruded prior to part printing.
  • Subsequent layers are printed either with rising water level, water or hydrogel submersion.
  • Thin objects up to 3 layers thick, can however be printed using simply a dry print-bed and allowing for heat to propagate through previous layers.
  • new silicone must preferably be pre-mixed and added to the system. This may preferably done in small quantities to ensure it is consumed prior to partial curing.
  • the button When using the rising water level procedure, upon layer change the button must preferably be pressed for addition of water via pump. If water-submersion of hydrogel are used, upon reaching the third layer the required quantity must be added to ensure submersion throughout the remaining print.
  • the part preferably be left in the bath for a few additional seconds to ensure the last layer is fully-cured before removal.
  • the example printing process can also be described by the following the steps:
  • step 7 If doing an underwater print/in gel print, replace step 7 with the addition of enough water/gel to cover the entire completed print. Also skip step 9.
  • the method of printing comprises the steps:
  • the deposited silicone forms the start of the silicone structure to be printed, 2. modifying the relative level of liquid in the liquid bath to the height of the silicone structure, such that the silicone structure is at least partially submerged in the liquid.
  • the relative level of liquid in the liquid bath to the height of the silicone structure may be modified by increasing the volume of liquid in the liquid bath.
  • the height of the print-bed may be lowered so that the silicone structure currently printed on the print-bed is at least partially
  • surfactants or other additives may be added to the liquid bath.
  • the addition of surfactants reduces the surface tension between the liquid contents of the water bath and the 3D structure being printed .
  • the surfactants may be already present in the liquid contained in the water bath, or may be added during the 3D printing process as required.
  • Example surfactants include dish washing liquid.
  • Post processing is a method that is used in most manufacturing processes.
  • the example prints had uneven edges and needed to be cut if they wanted to look completely square. Since this is common practice in most manufacturing processes, it was deemed acceptable to have a small amount of post-processing to tidy up the print. Most of the deformation in the edges can be blamed on the movement in the X-Y direction of the heat bed. Changing this to a printer that had X-Y direction in the printer head may significantly reduce the need for post-processing.
  • FIGs 13A through 13C describe various embodiments according to the present invention relating to the relative liquid height in a water bath 1304.
  • the relative liquid height is the height of the liquid 1320 relative to the height of the structure being printed 1306, 1334.
  • Figure 13A shows an example the 3D printing system 1302.
  • the 3D printing system 1302 may be in the form of an add-on for an existing 3D printer, a new 3D printer, or a retrofitter 3D printer.
  • the system 1302 comprises a water bath 1304, a print-bed member 1312, the print-bed member comprising a print-bed 1308 and a stand or standoff 1310.
  • the house-like 3D printed structure 1306 has an associated height 1362.
  • the water bath 1304 comprises a water 1305.
  • the water 1305 has an associated water height 1364.
  • the relative liquid level 1366 is such that the 3D printed structure 1306 is not submerged in the water 1305.
  • Figure 13B discloses a 3D printing system 1342, a variation of the system of Figure 13A wherein the print-bed member 1316 is adjustable.
  • the height of the print-bed member 1316 is adjustable.
  • the water level 1320 is higher than the height of the 3D printed structure 1322.
  • the relative liquid level 1324 is such that the 3D printed structure is submerged in the water 1320.
  • the example shown in Figure 13B is configured to adjust the height of the print- bed 1308, or print-bed member 1316, such that the 3D structure being printed 1306 at the time is at least partially submerged in the water 1305.
  • maintaining the 3D structure 1306 in the water 1305 assists in accelerating the silicone cure time.
  • the silicone cure time is reduced when the silicone is in the water.
  • the water is also heated to further reduce curing times.
  • the height of the print-bed 1308, or print-bed member 1316 is adjusted using a print-bed adjustment member 1314.
  • the height of the print-bed 1308 is adjust such that the 3D printed structure 1306 is at least partially submerged in the water 1305 during the printing of the 3D structure.
  • the 3D printed structure 1306 may be completely submerged in the water 1305 while the 3D printed structure 1306 is being printed.
  • Figure 13C shows an alternative embodiment 1352 wherein the relative liquid level is maintained by increasing the volume of water 1305 in the water bath 1304.
  • the 3D structure being printed 1334 is completely submerged in the water 1305.
  • the volume of water is increased such that the relative liquid level is maintained.
  • a system of this form requires a controller or hardware system capable of determining the liquid level and the structure height. Determining the liquid level and/or structure height can be conducted using routine measuring methods, or based on the volumes of liquid and/or silicone added.
  • control system may be used to adjust the liquid level and/or print-bed height.
  • the control system adjusts either the print-bed height, or the total liquid volume, to maintain a constant liquid relative liquid height.
  • the relative liquid level is maintained substantially constant.
  • the relative liquid level may also be maintained in other ways.
  • the relative liquid level may be maintained to change linearly with amount of silicone printed such that there is enough thermal mass in the water to cure the silicone.
  • the relative liquid level will also change so that a user can remove the 3D printed structure without touching the hot water.
  • the squares 82, 86 and circle 84 depicted in Figure 8 are 3 layers (1.5mm) thick where each layer is 0.5mm and prove the example system's ability to print highly accurate objects without water contact.
  • curing is taking place through the heating of the print-bed, which is warmed to 85°C through water contact on its underside.
  • Figure 9 shows the quality achievable currently with using the example 3D printer configuration with the rising water level and water-submerged techniques.
  • Figure 9 shows particularly jagged edges for the sample produced under rising water level on the left.
  • Figure 9 also shows the structure on the right created using the water-submerged technique. It is believed this may be radically reduced with a change of printer configuration to one where the print bath does not have X- or Y-direction motion which causes unfavourable sloshing of water. Water-submerged printing was affected less by sloshing water but saw increased rates of curing in the extrusion nozzle.
  • a person skilled in the art will appreciate that these and other further configuration and/or customisation options may be used to improve the results presented .
  • the results presented are indicative of a correctly functioning system and should not be used as examples of desired output.
  • Figure 10 shows a bridge successfully printed in a water-surfactant solution clearly showing the potential of the rising water level procedure even with the evident flaws in the sample produced.
  • the inconsistent material deposition was the result of partial curing of the material in the system, as it was noticeable that this increased as the print progressed .
  • FIG 11 shows a successfully bridge successfully printed in hydrogel.
  • EcoFlex was initially extruded onto the dry print-bed in the heated bath. After this initial layer had adhered and extrusion of consequent layers had begun, the hydrogel solution was poured onto the print-bed, submerging the so far deposited material. The remainder of the bridge print occurred with the nozzle dragging through the hydrogel solution.
  • the 3D printer of the present invention uses a higher force than a standard 3D printer. In an embodiment, the 3D printer of the present invention uses a sufficient force to move the nozzle while printing silicone.
  • the following features may improve the quality of the 3D printer technology and techniques described.
  • An active mixing system may allow high duration prints to run without constant refilling with freshly mixed silicone. This may help automate the system. When designing this system consideration should be given to the ability to clean the parts that come in contact with the two-component solution.
  • evaporation rate adjustment is likely to improve the fidelity of prints in the Z- direction. Improving the water temperature control may also be beneficial to enable higher bath temperatures to be maintained with smaller temperature fluctuations.
  • the new Rising Water Level technique provides a number of potential advantages. Over the hydrogel technique, some advantages include:
  • ⁇ avoids dragging a needle through support material which can cause distort prints.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
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  • Mechanical Engineering (AREA)
  • Optics & Photonics (AREA)

Abstract

Des articles peuvent être formés par diverses méthodes d'impression par dépôt ou d'impression 3D. Pour certaines applications, il peut être souhaitable d'avoir les capacités de prototypage rapide que l'impression 3D nécessite, mais également que l'article formé présente des propriétés flexibles. La présente invention concerne une méthode et un appareil d'impression d'une structure silicone, de manière à former un article souple. La méthode comprend l'étape de dépôt de silicone sur un lit d'impression par l'intermédiaire d'un élément de dépôt de silicone. Le dépôt de la silicone est effectué à l'intérieur d'un bain liquide. Pendant que la silicone est déposée sur le lit d'impression pour former la structure de silicone, un niveau de liquide est maintenu à l'intérieur du bain par rapport à la structure en cours d'impression. Le niveau de liquide est maintenu de telle sorte que la silicone déposée est au moins partiellement immergée dans le liquide.
PCT/IB2018/058120 2017-10-20 2018-10-19 Méthodes et appareil d'impression 3d Ceased WO2019077555A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111331837A (zh) * 2020-03-19 2020-06-26 合肥工业大学 一种湿固化硅胶3d打印机及其打印方法
CN113968024A (zh) * 2021-10-09 2022-01-25 中国科学院沈阳自动化研究所 一种精准温控式生物3d打印系统

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017040874A1 (fr) * 2015-09-03 2017-03-09 Dow Corning Corporation Procédé d'impression 3d utilisant une composition de silicone thermodurcissable
US20170283655A1 (en) * 2014-09-17 2017-10-05 Dow Corning Corporation 3d printing method utilizing a photocurable silicone composition

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170283655A1 (en) * 2014-09-17 2017-10-05 Dow Corning Corporation 3d printing method utilizing a photocurable silicone composition
WO2017040874A1 (fr) * 2015-09-03 2017-03-09 Dow Corning Corporation Procédé d'impression 3d utilisant une composition de silicone thermodurcissable

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111331837A (zh) * 2020-03-19 2020-06-26 合肥工业大学 一种湿固化硅胶3d打印机及其打印方法
CN113968024A (zh) * 2021-10-09 2022-01-25 中国科学院沈阳自动化研究所 一种精准温控式生物3d打印系统
CN113968024B (zh) * 2021-10-09 2022-08-23 中国科学院沈阳自动化研究所 一种精准温控式生物3d打印系统

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