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
  • B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
  • B29C71/0009—After-treatment of articles without altering their shape; Apparatus therefor using liquids, e.g. solvents, swelling agents
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B2230/00—Other cleaning aspects applicable to all B08B range
  • B08B2230/01—Cleaning with steam

Definitions

• the present invention relates to the field of polishing and smoothening plastic surfaces; more particularly, it refers to methods and devices for polishing plastic surfaces of parts made by 3D printing.
• 3D printing also known as additive manufacturing (AM) refers to processes used to synthesize a three- dimensional object in which successive layers of material are formed under computer control to create an object. Almost any shape or geometry can be obtained. Objects made by 3D printing are usually produced using digital model data from an electronic data source or file.
• AM additive manufacturing
• 3D printing is commonly used to prepare on a small scale prototype parts that, once perfected and/or optimized, will be produced on a large scale by other more efficient industrial processes. They are also used in the domestic, educational, research or artistic field for the production of pieces of any kind. These parts are usually made of plastic. The parts thus obtained have small imperfections and high roughness on their surface. As a consequence, parts obtained by 3D printing often require being polished or smoothened on their surface.
• a machine for polishing parts made by 3D printing has been commercialized by company Polymaker.
• This machine is made up of a vessel in which an entire part is deposited and, once the vessel is sealed, a polishing vapor obtained from a polishing liquid (isopropanol or ethanol) is poured into the vessel so as to polish the whole piece. This implies that selective polishing is not allowed because the entire part is exposed to the polishing vapor. Due to the size of the machine, the maximum dimensions of the part to be polished are 150 millimeter (mm) (diameter) x 180 mm (height).
• polishing vapor attacks areas of the part not requiring being smoothened, or on the contrary, areas requiring being polished remain unpolished because the total exposure time is fixed to be low in order not to damage other areas of the part not requiring being polished, for example because the surface of a plastic part made by 3D printing is usually rough or wrinkled only in certain areas, the remaining surface being smooth.
• the polishing vapor does not attack all areas equally, and it may generate blisters in the areas most exposed to vapor.
• immersing the whole part in polishing vapor implies a reduction in the dimensions of the part, which is often undesired.
• the device described in the present disclosure intends to solve the shortcomings of prior-art devices.
• the invention provides a device for the manual polishing of plastic parts.
• the device comprises a receptacle, box or housing connected or coupled to a dispenser configured to expel polishing vapor, in such a way that the vapor attacks the plastic surface to which the vapor is directed, thus selectively polishing rough areas on the surface of the plastic part.
• a first aspect of the invention relates to a device for manual polishing a plastic part by expelling a polishing vapor, the device comprising: a receptacle defining a first chamber configured to, in use of the device, house a liquid polishing solvent, and a second chamber configured to be, in use of the device, at a temperature T S c above the boiling point of the liquid polishing solvent, wherein the first and second chambers are communicated by an orifice stoppled by a cap; and a dispensing gun connected to the second chamber of the receptacle by means of a hollow flexible tube.
• the orifice is configured to be opened by actuating activation means, thus permitting liquid polishing solvent housed in the first chamber to pass through the orifice towards the second chamber, in which the liquid polishing solvent becomes vapor, the vapor being pressurized, the dispensing gun being configured to expel said vapor towards a surface of a plastic part, thus polishing its surface.
• the activation means comprises a push button, a rod connected to the push button and the cap.
• the cap is connected to the rod.
• the push button is configured to displace the rod when the push button is pressed, thus displacing the cap from the orifice.
• the device further comprises a lid for closing the receptacle.
• the push button may be disposed on the lid.
• the lid comprises a recess configured to receive an end of the dispensing gun when the device is not being used.
• the lid is removable.
• the second chamber comprises heating means configured to heat the second chamber until the second chamber reaches a temperature T S c above the boiling point of said liquid polishing solvent.
• the heating means is preferably a heating resistance.
• the first chamber is an upper chamber and the second chamber is a lower chamber, the orifice being configured to, when opened, permit the liquid polishing solvent to fall from the upper chamber to the lower chamber.
• the first chamber is separated from the second chamber by means of a wall.
• the dispensing gun comprises a nozzle for focusing the vapor jet to be expelled to a surface of the plastic part to be polished.
• the temperature in the second chamber is Tsc ⁇ 50 5 C.
• the dispensing gun is capable of expelling a vapor jet up to a distance of 8 cm from the end of the dispensing gun through which the vapor jet is expelled.
• the liquid polishing solvent is acetone.
• the device comprises a lever configured to action the opening and closing of a gate that allows to gain access to the first chamber in order to add liquid polishing solvent.
• the device is suitable for polishing plastic parts made by 3D printing, but it is also suitable for polishing plastic parts obtained in other industrial processes, such as machining. It is also suitable for sealing walls, for example for waterproofing walls.
• Figure 1 shows a view of a device for manual polishing of plastic parts according to an embodiment of the invention.
• Figure 2A and 2B show section views of the device shown in figure 1 .
• the push button is released.
• the push button is pressed.
• Figure 3A shows another section view of the device shown in figure 1 .
• Figure 3B shows in detail a recess for resting the dispensing gun when it is not being used.
• Figure 4 shows a dispensing gun and a portion of flexible cable with which the dispensing gun is connectable to the receptacle of the device, according to an embodiment of the invention.
• FIG. 1 shows a device 10 for manual polishing of plastic parts according to an embodiment of the invention.
• the device 10 has a receptacle, box, container or housing 20 covered by a lid 50.
• the lid 50 may be removable, enabling to open and close the receptacle 20.
• the device 10 also has a dispenser or dispensing gun 30 connected or coupled to the inner part of the receptacle 20.
• the dispensing gun 30 has an elongated pipeline, tube or tubular body.
• the dispensing gun 30 is connected to the receptacle by means of a hollow flexible cable 40.
• the dispensing gun 30 may be rested on a recess, slot or groove 51 made on the lid 50.
• the device 10 is therefore portable and easily manipulated by a single person.
• the device 10 may rest on a surface (for example a table) and an person may direct the dispensing gun 30 towards the surface of the part to be polished and press a push button for jetting vapor through the dispensing gun 30, as explained next.
• Figures 2A and 2B show section views of the device 10 shown in figure 1 , in which only the lower portion of the device is fully illustrated. That is to say, a portion of the receptacle 20 has been removed (approximately half of the receptacle has been removed) in order to show the inner design and configuration of the device 10.
• Figure 3A shows another section view of the device 10. Internally, the receptacle 20 has or defines a first chamber (the upper chamber in the shown embodiment) 21 and a second chamber (the lower chamber in the shown embodiment) 22.
• the first chamber 21 is also referred to as cold chamber because in use of the device 10 it is at room temperature and the second chamber 22 is also referred to as hot chamber because in use of the device 10 it is heated, as explained next.
• the first chamber 21 is separated from the second chamber 22 by means of a wall 23. In embodiments of the invention, this separating wall 23 is substantially parallel to the lower surface of the device 10.
• the upper chamber 21 is configured to house or store a liquid polishing solvent.
• the liquid polishing solvent may be any solvent provided that it is able to attack the plastic material of which the plastic part to be polished is made, and that the boiling point of the liquid polishing solvent is lower than the temperature reachable at the second chamber 22, as will be explained next.
• the liquid polishing solvent is an organic solvent, such as a ketone or an alcohol.
• the liquid polishing solvent is acetone.
• the liquid polishing solvent is an alcohol, such as isopropanol or ethanol.
• the liquid polishing solvent is ethyl ethanoate (also referred to as ethyl acetate).
• the lower chamber 22 houses heating means.
• the heating means is a heating resistance 24.
• the heating resistance 24 is on and therefore the temperature of the second chamber 22 is higher than room temperature.
• the required temperature in the second chamber 22 depends on the selected solvent.
• a heating resistance 24 is selected such that the temperature Tsc within the second chamber 22 is ⁇ 50 5 C (degrees Celsius), such as ⁇ 60 5 C, ⁇ 70 5 C, ⁇ 80 5 C or ⁇ 85 5 C.
• the heating resistance 24 is a conventional one and is out of the scope of the present invention.
• Non-limiting examples of heating resistances that may be used are wire or strip resistances, such as round wire, flat wire or stranded wire heating resistances.
• the heating resistance may be made of iron, chromium, aluminium, nickel, copper and combinations thereof.
• the heating resistance 24 may comprise insulation and coating.
• the device 10 When the device 10 is powered (preferably plugged to an electric socket or, alternatively, by means of a battery), the heating resistance 24 starts to get warm until the second chamber 22 reaches the target temperature Tsc
• the device 10 has a switch 53 (for example on the cover 50, as shown in the illustrated embodiments) which triggers the activation of the heating resistance 24 once the device 10 is powered.
• the first and second chambers 21 , 22 are connected by an orifice that is closed, stoppled or sealed by a cap 27.
• the device 10 comprises activation means.
• the activation means comprises a push button 25, a rod 26 and the cap 27.
• the rod 26 Upon pushing or pressing on the push button 25, the rod 26 transmits the activation and displaces the cap 27, that is to say, the orifice in unsealed and liquid polishing solvent is allowed to pass from the first chamber 21 to the second chamber 22.
• the push button 25 is disposed on the lid 50 of the device 10, but it may alternatively be disposed somewhere else on the device 10, for example on a side wall thereof.
• FIG. 2B shows the inner volume of device 10, in a position in which the push button 25 has been pressed and therefore the orifice connecting the upper and lower chambers 21 , 22 is open and liquid from the upper chamber 21 is permitted to fall in the lower chamber 22.
• the separating wall 23 may define a hollow cavity 28 separating a first layer of the wall 23 in contact with the first chamber 21 and a second layer of the wall 23 in contact with the second chamber 22.
• the hollow cavity 28 increases the thermal isolation between the first and second chambers 21 , 22.
• the separation wall 23 is solid.
• the second chamber 22 communicates with a dispensing gun 30 by means of a hollow flexible tube 40.
• Figure 4 shows a dispensing gun 30 according to an embodiment of the invention.
• the dispensing gun 30 permits to apply the vapor produced in the second chamber 22 towards selected areas in the surface of a plastic part (not shown), thus polishing those selected areas of the surface of the part.
• the vapor travels from the second chamber 22 within the hollow flexible tube until it reaches the dispensing gun 30, from which the vapor is expelled towards the surface to be treated.
• the dispensing gun 30 preferably has a nozzle 31 , of small diameter, for focusing or precisely focusing the vapor stream (or vapor jet) to the portion of the part that needs polishing.
• the vapor in the second chamber 22 is pressurized, so that when it passes through the tube 40, then through the tubular body of dispensing gun 30 and finally through the small diameter nozzle 31 , it comes out of the dispensing gun 30 with a certain pressure that allows to direct the vapor jet very precisely on specific or delimited areas of the part surface, without affecting the rest of the part. So, control on the portions of the part to be polished is achieved, and efficient polishing is also achieved. Due to the pressure of the vapor within the second chamber 22, the dispensing gun 30 is capable of expelling a vapor jet that travels up to 7-8 cm (centimeters) from the nozzle tip.
• the dispensing gun 30 may also have a button 32 for controlling (blocking/ unblocking) the flow way of the passage towards the nozzle.
• button 32 for controlling (blocking/ unblocking) the flow way of the passage towards the nozzle.
• first and second chambers 21 , 22 have been also referred to as upper and lower chambers due to their location in the device 10, in embodiments of the invention the two chambers may occupy a different position; for example, the first chamber 21 may occupy a first volume of receptacle 20 from top to bottom, while the second chamber 22 may occupy a second volume of receptacle 20 from top to bottom, in which case the wall 23 separating the chambers is a substantially vertical wall.
• the first and second chambers 21 , 22 may be side chambers.
• Other configurations of the first and second chambers are also possible, provided that they communicate by means of an orifice configured to open/close actioned by a push button.
• feeding liquid polishing solvent from the first chamber (cold chamber) 21 to the second chamber (hot chamber) 22 is as follows: Pressing the push button 25 for a certain time permits to keep the orifice separating the chambers open and therefore liquid solvent enters the second chamber 22. When it is estimated that enough liquid solvent has accessed the second chamber 22, pressing the push button 25 is stopped (push button released) and a spring (not shown) retracts the push button 25 and therefore the cap 27, thus sealing the orifice and isolating the first chamber 21 with respect to the second chamber 22. The liquid solvent housed in the second chamber 22 starts then to evaporate and to be dispensed through the dispensing gun 30.
• the device 10 is specially suitable for polishing plastic parts made by means of 3D printing.
• Plastic parts made by 3D printing are usually made of polyamides or of thermoplastic polymers, such as acrylonitrile butadiene styrene (ABS).
• ABS acrylonitrile butadiene styrene
• the device 10 is suitable for polishing plastic parts made of any plastic provided that a solvent capable of attacking the plastic material of which the part is made, is used.
• the solvent is acetone.
• the dispensing gun 30 expels for example acetone vapor, acetone vapor attacks the plastic surface to which the vapor is directed, thus selectively polishing rough areas on the surface of the plastic part.
• the lid 50 covering receptacle 20 may have a recess, slot or groove 51 on which the dispensing gun 30 may be rested, for example by inserting on the recess 51 the end of the dispensing gun 30 not coupled to cable 40.
• a small chamber 28 is defined below the lid 50 in order to house or isolate the recess 51 with respect to the rest of the device, for example with respect to the first chamber 21 .
• the lid 50 may also have a lever 52 configured to action the opening and closing of a gate 54 that allows to gain access to the first chamber 21 (cold chamber) in order to add liquid polishing solvent when required.
• the lever 52 and gate 54 are disposed on the cover 50. In other embodiments they may be disposed on other zones of the device 10. In figure 1 the gate 54 is closed.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Coating Apparatus (AREA)
• Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)

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Citations (3)

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• 2017
  • 2017-03-31 ES ES201700355A patent/ES2635543B1/es not_active Expired - Fee Related
• 2018
  • 2018-03-12 WO PCT/EP2018/056121 patent/WO2018177734A1/en active Application Filing

Patent Citations (3)

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