Patent Publication Number: US-2021187852-A1

Title: Treatment of articles

Description:
BACKGROUND 
     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 
         FIG. 1  is a schematic representation of an example of treatment apparatus; 
         FIG. 2  is a schematic representation of another example of treatment apparatus; 
         FIG. 3  is a perspective view of an example of a diffusion plate; 
         FIG. 4  is a perspective view of an example of an impeller; 
         FIG. 5  is a schematic representation of the apparatus of  FIG. 2  in use; 
         FIG. 6  is a flow diagram of an example of a system; 
         FIG. 7  is a flow diagram of an example of a system; and 
         FIG. 8  is block diagram of example instructions executable by a processor. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     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. 
     As shown in  FIG. 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  110 . The pump  140  is connected to an inlet  150  and outlet  160  of the treatment chamber  110  with tubing  170 , so the interior  120  of the treatment chamber  110  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  110 , where in use it may be exposed to a treatment agent. 
     The treatment chamber  110  can be of any size or shape, depending on the size or quantity of articles to be treated. The treatment chamber  110  may be made of a material such as plastic, metal or glass, or a combination thereof. The treatment chamber  110  may be subject to strong negative pressure, and exposed to highly reactive treatment agents, so the design of the treatment chamber  110  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  110  in order to evenly cover the outer surface of the article to be treated. 
     The tubing may have a fluid-proof seal with the treatment chamber  110  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  110 , suitable unreactive, fluid-proof and strong materials may be chosen. 
     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  110 . 
     In the example shown in  FIG. 2 , the hermetically sealable treatment chamber  110  is provided with two inlets  150   a ,  150   b  and one outlet  160 , all connected to the pump  140  via tubing  170 , effectively forming two closed loops. A treatment chamber  110  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  110  and also of the article to be treated. 
     One or more disperser  130  is disposed within the treatment chamber  110 . In another example, not shown in  FIG. 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  110  to ensure even coverage of the treatment agent on the article to be treated. As shown schematically in  FIGS. 1, 2 and 3 , an example of a disperser is a gas diffusion plate  200 . The gas diffusion plate  200  as depicted in  FIG. 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  FIGS. 1 and 2 , the gas diffuser plate  200  is disposed inside and is connected to an inner wall of the treatment chamber  110 , and encloses the inlet(s)  150   a ,  150   b . The evenly spaced apertures  230  are arranged such that any fluid entering the treatment chamber  110  through the inlets  150   a ,  150   b  will be dispersed evenly throughout the interior  120  of the treatment chamber  110 . 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. 
     Another example of a disperser, as shown for example in  FIGS. 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  110 , 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. 
     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  110  to disrupt fluid flow and disperse a treatment agent evenly about the treatment chamber  110  may be used in addition to or as an alternative to gas diffusion plates  200  and/or impellers  300 . 
     As shown in  FIG. 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  110 . The plastic part  400  may be seated on a rack or stand  410 , or may be suspended from the roof of the treatment chamber  110  or otherwise supported to ensure that as much surface area of the article as possible is exposed to the treatment agent. 
     The wall of the treatment chamber  110  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  110 . 
     The treatment apparatus may include a heater  430 . An example is shown in  FIG. 2 , in which the heater  430  is disposed beneath the treatment chamber  110 . 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  110  may also be heated so that, as used in some examples, vaporised treatment agent does not condense on the walls of the treatment chamber  110 . 
     The pump  140  may be arranged to circulate the treatment agent within the treatment chamber  110 , and also to create a vacuum within the treatment chamber  110 . Although not shown, the pump  140  may be configured, for example by a system of valves, to expel fluid from within the treatment chamber  110 . This role may alternatively be carried out by a second pump  140  in fluidic communication with the treatment chamber  110 . 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. 
     The treatment apparatus  100  may further include a fluid inlet so that treatment agent may be inserted into the system. As shown in  FIG. 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. 
     As shown in  FIG. 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  110  to detect a condition within the treatment chamber. Conditions can, for example, include the temperature and/or pressure within the treatment chamber  110 . 
     As shown in  FIG. 5 , in an example of use of the apparatus as shown in  FIG. 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  FIG. 2  but not in  FIG. 5 ) of the treatment chamber  110  and place the part  400  onto the rack  410 , and then close the door  420 . Closing the door  420  hermetically seals the treatment chamber  110 , 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  FIG. 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  110  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  190   a ,  190   b  of the pump  140  through the tubes  170 , and to the two inlets  150   a ,  150   b  at the top and bottom surface of the treatment chamber  110 . 
     The vaporised solvent then enters the interior  120  of the treatment chamber  110  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  110  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. 
     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 . 
     The vaporised solvent  500  may also be drawn out of the interior  120  of the treatment chamber  110  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. 
     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. 
     In an example, a system may be provided, which for example may include treatment apparatus  100  as previously described and shown, such as in  FIG. 2 . The system, as also shown in  FIGS. 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  110  to a desired level, and control the pump  140  to circulate the treatment agent around the closed loop. 
     A plurality of sensors  460  may be provided, which detect a range of different conditions such as temperature and pressure. 
     Referring to  FIG. 7 , the sensor  460 , for example, could be disposed to detect the temperature within the treatment chamber  110 . 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  110 . 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  110  and condenses on the 3D printed part in order to treat it. 
     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  110  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. 
     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. 
     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  FIG. 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  110  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.