BACKGROUND

[0001] Articles, such as 3D printed plastic parts, may be treated to alter their outer surface. The articles may be treated by placing them into a treatment chamber and exposing them to a treatment agent. To ensure that the article is treated completely, the treatment agent may be dispersed within the interior of the treatment chamber to ensure an even coverage of the treatment agent on the article being treated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Figure 1 is a schematic representation of an example of treatment apparatus;

[0003] Figure 2 is a schematic representation of another example of treatment apparatus;

[0004] Figure 3 is a perspective view of an example of a diffusion plate;

[0005] Figure 4 is a perspective view of an example of an impeller;

[0006] Figure 5 is a schematic representation of the apparatus of Figure 2 in use;

[0007] Figure 6 is a flow diagram of an example of a system;

[0008] Figure 7 is a flow diagram of an example of a system; and

[0009] Figure 8 is block diagram of example instructions executable by a processor. DETAILED DESCRIPTION

[0010] A number of examples will be discussed in detail below. Where like parts in different Figures are discussed, the same reference numeral will be used.

[0011] Different articles may be treated using a range of different treatment agents. An example of an article that may be treated includes 3D-printed plastic parts. These can be post-processed after printing by exposure to a vaporised solvent, where contact of the vaporised solvent polishes and/or smooths a surface of the 3D-printed plastic part. In an example, metals may be post- processed in the presence of a gas that reacts with the surface of the metal. The metal articles to be treated may be produced by 3D printing methods. Other examples of articles to be treated include ceramics and resins. Ceramic and resin articles to be treated may be produced by 3D printing methods. The choice of treatment agent will depend on the nature of the article being treated. Numerous other examples of articles that can be treated with a treatment agent exist, which may fall within the scope of the present disclosure.

[0012] As shown in Figure 1 , treatment of an article to be treated by a treatment agent may be conducted within an hermetically sealable treatment apparatus, generally indicated 100. The treatment apparatus includes a treatment chamber, generally indicated 110, having an interior 120, a disperser 130, and a pump 140 in fluidic communication with the treatment chamber 1 10. The pump 140 is connected to an inlet 150 and outlet 160 of the treatment chamber 1 10 with tubing 170, so the interior 120 of the treatment chamber 1 10 and the pump 140 form a closed loop about which a treatment agent, when added, can circulate. The disperser 130 is connected to the inlet 150. An article to be treated may be disposed within the interior 120 of the treatment chamber 1 10, where in use it may be exposed to a treatment agent.

[0013]The treatment chamber 1 10 can be of any size or shape, depending on the size or quantity of articles to be treated. The treatment chamber 1 10 may be made of a material such as plastic, metal or glass, or a combination thereof. The treatment chamber 1 10 may be subject to strong negative pressure, and exposed to highly reactive treatment agents, so the design of the treatment chamber 1 10 will need to take these conditions into account. The design of the treatment chamber 110, such as the size and shape, may also take into account fluid dynamics, as a treatment agent may be circulated around the interior 120 of the treatment chamber 1 10 in order to evenly cover the outer surface of the article to be treated.

[0014]The tubing may have a fluid-proof seal with the treatment chamber 1 10 and/or the pump 140, and may be made of a material suited to the treatment agent used. Some solvents and gases which may be used as treatment agents can be highly reactive and/or flammable and/or poisonous, so in order to maintain a hermetic seal within the treatment chamber 1 10, suitable unreactive, fluid-proof and strong materials may be chosen.

[0015]The pump 140 may be a vacuum pump such as a positive displacement pump, an example of which includes a peristaltic pump. The pump 140 may comprise an inlet and an outlet to connect to the tubing 170, which is connected to the treatment chamber 1 10.

[0016] In the example shown in Figure 2, the hermetically sealable treatment chamber 1 10 is provided with two inlets 150a, 150b and one outlet 160, all connected to the pump 140 via tubing 170, effectively forming two closed loops. A treatment chamber 1 10 may have any number of inlets and outlets, connected to one or more pump 140, and the number and arrangement of inlets and outlets may be optimised depending on the size and shape of the treatment chamber 1 10 and also of the article to be treated.

[0017] One or more disperser 130 is disposed within the treatment chamber 1 10. In another example, not shown in Figure 2, a disperser 130 may be provided in a tube 170 leading into the interior 120 of the treatment chamber 110. The term disperser can encompass any apparatus that can disperse a fluid. The dispersers 130 are arranged to disperse treatment agent within the treatment chamber 1 10 to ensure even coverage of the treatment agent on the article to be treated. As shown schematically in Figures 1 , 2 and 3, an example of a disperser is a gas diffusion plate 200. The gas diffusion plate 200 as depicted in Figure 3 has a generally cylindrical hollow body 210, and a generally round surface plate 220 containing a series of evenly spaced apertures 230 extending through the surface plate 220. As shown in Figures 1 and 2, the gas diffuser plate 200 is disposed inside and is connected to an inner wall of the treatment chamber 1 10, and encloses the inlet(s) 150a, 150b. The evenly spaced apertures 230 are arranged such that any fluid entering the treatment chamber 1 10 through the inlets 150a, 150b will be dispersed evenly throughout the interior 120 of the treatment chamber 1 10. The size and shape of the gas diffuser plate 200, and the apertures 230, can be designed based on the desired fluid dynamics, and could include flaps or nozzles to direct fluid flow.

[0018] Another example of a disperser, as shown for example in Figures 2 and 4, is a fan blade impeller 300. The impeller 300 is rotatably mounted to a shaft 310. The impeller 300 comprises a plurality of fan blades 320 mounted on a wheel 330. The impeller may be rotatable upon contact with a fluid, such as treatment agent within the interior 120 of the treatment chamber 1 10, and rotation of the impeller 300 may cause even dispersal of the treatment agent. Other designs of impeller, such as those with a variety of number and size of blades 320 may be used to optimise fluid dispersal. Furthermore, the number and position of impellers 300 within the treatment chamber 110 may be selected to optimise fluid dispersal.

[0019]The treatment apparatus 100 may include gas diffusion plates 200 or impellers 300, or a combination of the two. Other examples of disperser 130 that can be disposed within the treatment chamber 1 10 to disrupt fluid flow and disperse a treatment agent evenly about the treatment chamber 1 10 may be used in addition to or as an alternative to gas diffusion plates 200 and/or impellers 300. [0020]As shown in Figure 2, an article to be treated, in this example a 3D-printed plastic part 400, may be located in the interior 120 of the treatment chamber 1 10. The plastic part 400 may be seated on a rack or stand 410, or may be suspended from the roof of the treatment chamber 1 10 or otherwise supported to ensure that as much surface area of the article as possible is exposed to the treatment agent.

[0021]The wall of the treatment chamber 1 10 may be provided with a sealable door 420, though in some examples it may be provided with a sealable lid or other sealable orifice through which an article to be treated may be disposed into, and subsequently removed from, the treatment chamber 1 10.

[0022]The treatment apparatus may include a heater 430. An example is shown in Figure 2, in which the heater 430 is disposed beneath the treatment chamber 1 10. One or a plurality of heaters 430, of any type, may be placed at any point around the treatment apparatus 100 in order to heat the treatment agent. The heater could take any known form, such as electrically heated coils, a water bath, recirculated hot air and the like. The walls of the treatment chamber 1 10 may also be heated so that, as used in some examples, vaporised treatment agent does not condense on the walls of the treatment chamber 1 10.

[0023]The pump 140 may be arranged to circulate the treatment agent within the treatment chamber 1 10, and also to create a vacuum within the treatment chamber 1 10. Although not shown, the pump 140 may be configured, for example by a system of valves, to expel fluid from within the treatment chamber 1 10. This role may alternatively be carried out by a second pump 140 in fluidic communication with the treatment chamber 1 10. The pump 140 may expel any fluid, such as air, that is initially present in the treatment apparatus to create a vacuum prior to the insertion of a treatment agent, and may, in addition to or alternatively, be used to flush treatment agent out of the system after the article to be treated 400 has been treated.

[0024]The treatment apparatus 100 may further include a fluid inlet so that treatment agent may be inserted into the system. As shown in Figure 2, a sealable inlet represented by arrow 440 is disposed in the pump 140, and treatment agent may be injected into the inlet 400 or drawn from a treatment agent source. In an example, a series of pipes and valves may connect a source of treatment agent to the apparatus 100, permitting treatment agent to be added to the closed loop.

[0025]As shown in Figure 2, the apparatus may also include a processor 450 to control the operation of the apparatus 100. The processor 450 could be a personal computer (PC), programmable logic controller (PLC) or the like, and could be integral with the apparatus 100, or remote from the apparatus 100 and in cabled or wireless communication with the apparatus. A sensor 460 may also be provided in the apparatus, for example within or adjacent the treatment chamber 1 10 to detect a condition within the treatment chamber. Conditions can, for example, include the temperature and/or pressure within the treatment chamber 1 10.

[0026]As shown in Figure 5, in an example of use of the apparatus as shown in Figure 2, a user may place the article to be treated, for example a 3D-printed plastic part 400, into the interior 120 of the treatment chamber 110. To do so, the user may open the door 420 (shown in Figure 2 but not in Figure 5) of the treatment chamber 1 10 and place the part 400 onto the rack 410, and then close the door 420. Closing the door 420 hermetically seals the treatment chamber 1 10, pump 140 and tubing 170 into a closed loop. The pump 140 may then be initiated to evacuate any fluidic contents, for example air, that may be within the closed loop to create a vacuum of the desired pressure. Treatment agent, the flow thereof being indicated by arrows 500 in Figure 5, which in an example is a solvent chosen to be a solvent for the 3D-printed plastic part 400, is then introduced to the pump 140 through the inlet 440. The heater 430 then heats the interior 120 of the treatment chamber 1 10 to the desired temperature. In the example of a solvent, the temperature and pressure may be suitable to vaporise the solvent. The pump 140 is then initiated to circulate the vaporised solvent 500 around the closed loop. Vaporised solvent 500 is pumped from the pump 140 at the two outlets 190a, 190b of the pump 140 through the tubes 170, and to the two inlets 150a, 150b at the top and bottom surface of the treatment chamber 1 10. The vaporised solvent then enters the interior 120 of the treatment chamber 1 10 through the apertures 220 of the gas diffusion plates 200. The passage of the vaporised solvent 500 through the gas diffusion plates 200 causes the vaporised solvent to disperse evenly within the interior 120 of the treatment chamber 1 10 and contact the outer surface of the 3D-printed plastic part 400 evenly. The contact of the vaporised solvent 500 on the 3D-printed plastic part 400 partly dissolves the outer surface thereof, and polishes it.

[0027] Movement of the vaporised solvent 400 within the interior 120 causes rotation of the impeller 300, which further acts to disperse and homogenise the vaporised solvent 500.

[0028]The vaporised solvent 500 may also be drawn out of the interior 120 of the treatment chamber 1 10 through the outlet 160 back to the pump 140. It is the constant recirculation of the vaporised solvent around the closed loop and through the gas diffusion plates 200 and/or the impellers 300 that homogenises the vaporised solvent 500 and enables the even treatment of the 3D-printed part.

[0029] Once the 3D-printed part has been processed, the pump 140 (or, in an example, another pump 140) may then draw the treatment agent out of the treatment chamber 110. The used treatment agent may then be collected for recycling or disposal.

[0030] In an example, a system may be provided, which for example may include treatment apparatus 100 as previously described and shown, such as in Figure 2. The system, as also shown in Figures 6 and 7, comprises a pump 140, a sensor 460 to detect a condition in the treatment chamber, and a processor 450 to control the operation of the apparatus 100. The processor 450 may be arranged to receive input from the sensor 460 and control the condition within the treatment chamber 1 10 to a desired level, and control the pump 140 to circulate the treatment agent around the closed loop. [0031]A plurality of sensors 460 may be provided, which detect a range of different conditions such as temperature and pressure.

[0032] Referring to Figure 7, the sensor 460, for example, could be disposed to detect the temperature within the treatment chamber 1 10. The sensor 460 may feed the temperature back to the processor 450, which could act to regulate the temperature. For example, the system could comprise a heater 430 and the processor 450 could act to control the heater 430 to regulate the temperature. Alternatively, the system could comprise a thermostat to control the temperature within the treatment chamber 1 10. In examples where the article to be treated is a 3D-printed plastic part, and/or the treatment agent is a solvent, the temperature of the solvent could be held at the dew point, so that the solvent is vaporised in the treatment chamber 1 10 and condenses on the 3D printed part in order to treat it.

[0033]The sensor may also detect pressure. In some examples, including examples where the article to be treated is a 3D-printed plastic piece and the treatment agent is a solvent, the treatment chamber 1 10 may be kept at a negative pressure in order to vaporise the solvent. A pressure sensor will be able to detect a change in pressure. The sensor may feed the change in pressure to the processor, which may act to control the pressure.

[0034]The processor 450 may also initiate the pump 140 to circulate the treatment agent. Further the processor 450 may be programmed to cease the pump 140 when a predetermined treatment time has been reached.

[0035]There may also be provided a non-transitory machine-readable storage medium which may be encoded with instructions executable by a processor 450. As shown in Figure 8 the machine-readable storage medium comprises: instructions to initiate circulation of a treatment agent about a closed loop, the closed loop comprising a pump 140, a treatment chamber 1 10 having an interior 120 in fluidic communication with the pump 140, and at least one disperser 130 wholly disposed within the closed loop; receive information related to an internal condition in the closed loop; and adjust the internal condition based on the received information. The information may be temperature. The machine readable storage may be any electronic, magnetic, optical or other physical storage device that stores executable instructions. Thus, machine-readable storage medium may be, for example, Random Access Memory (RAM), an Electrically-Erasable Programmable Read-Only Memory (EEPROM), a storage drive, and optical disc, and the like.