Patent Publication Number: US-2021178690-A1

Title: Printing system guide rail cleaning assembly

Description:
BACKGROUND 
     In three-dimensional (3D) printing, an additive printing process is often used to make three-dimensional solid parts from a digital model. Some 3D printing techniques are considered additive processes because they involve the application of successive layers or volumes of a build material, such as a powder or powder-like build material, to an existing surface (or previous layer). Particulates of the build material may contaminate various surfaces of components, which may cause defects in the printing of 3D objects. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features of the present disclosure are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements, in which: 
         FIG. 1A  shows a front view of an example printing system that may include example cleaning assemblies; 
         FIGS. 1B and 1C , respectively, show side views of the example printing system depicted in  FIG. 1A  having other example cleaning assemblies; 
         FIG. 1D  depicts an enlarged view of a scraper and a mounting member of the scraper assemblies depicted in  FIGS. 1A-1C  according to one example; 
         FIG. 2  shows a side perspective view of an example cleaning assembly and a rotatable member shown in  FIGS. 1A and 1B , 
         FIG. 3A  shows a top perspective view of another cleaning assembly that may be mounted to a portion of a chassis of a carriage in a printing system according to one example; and 
         FIG. 3B  shows a bottom perspective view of the example cleaning assembly depicted in  FIG. 3A  and a portion of the chassis. 
     
    
    
     DETAILED DESCRIPTION 
     In powder-based three-dimensional (3D) printing systems, successive layers of a build material, such as a powder or powder-type build material, may be formed, for example, on a build platform. Portions of each layer may be selectively solidified, with each portion representing a portion of a 3D object to be formed. In some examples, a build material may include a powdered build material that is composed of particles in the form of fine powder or granules. In addition or in other examples, the build material may include short fibers. In any regard, the powdered build material may include metal particles, plastic particles, polymer particles, ceramic particles, or particles of other materials. 
     The 3D printing systems may include various components that may be moved, for instance, over the build platform to create the successive layers and to selectively solidify the portions of the layers. For instance, a carriage supporting printing components such as a printhead, a recoater, a heat lamp, or the like, may be scanned across the build platform during printing and other operations. The carriage may include rotatable members that are supported on a guide rail or on multiple guide rails such that the rotatable members rotate as the carriage is scanned. In many instances, particulates of the build material powder may become airborne due to environmental and/or printing processes and may contaminate various surfaces of the 3D printing systems, including the rotatable members, the guide rail or rails, upon which the carriage rolls. 
     Contamination of the guide rail or rails may interfere with the contact between the rotatable members and the guide rail(s), which may cause defects in the formation of 3-D objects. For instance, debris on the guide rail(s) and/or the rotatable members may prevent build material particles from being applied in a smooth, level layer. As another example, the debris may interfere with the accurate positioning of the carriage with respect to the build platform, which may result in, for instance, deposition of printing liquid in unintended locations. Similar types of errors due to debris, such as dust, and other airborne particulates, may also occur in two-dimensional (2D) printing systems that employ a carriage and a guide rail or guide rails. 
     Disclosed herein are cleaning assemblies that may be mounted to a carriage of a printing system as well as carriages and printing systems upon which the cleaning assemblies may be mounted. The cleaning assemblies disclosed herein may include a scraper to clean debris off of at least a portion of a guide rail as the carriage is scanned over the guide rail. The cleaning assemblies disclosed herein may also include a brush to further clean debris off at least a portion of the guide rail. In addition, or in other examples, the cleaning assemblies may include a scraper and/or a brush to clear off debris from at least a portion of a rotatable member upon which the carriage is supported on a guide rail. 
     Through implementation of the cleaning assemblies disclosed herein, debris may be cleared off at least a portion of a guide rail and/or a rotatable member simply by moving a carriage over the guide rail. As such, for instance, the guide rail and/or rotatable member may continuously be cleaned during printing operations and thus, a separate cleaning operation may not implemented to clean the guide rail. In one regard, therefore, the number of defects caused by contamination on guide rails and/or rotatable members may be reduced or minimized. 
     Before continuing, it is noted that as used herein, the terms “includes” and “including” mean, but are not limited to, “includes” or “including” and “includes at least” or “including at least.” The term “based on” means, but is not limited to, “based on” and “based at least in part on.” 
     Reference is first made to  FIGS. 1A-1C .  FIG. 1A  shows a front view of an example printing system  100  that may include example cleaning assemblies  102 .  FIGS. 1B and 10 , respectively, show side views of the example printing system  100  depicted in  FIG. 1A  having other example cleaning assemblies  102 . It should be understood that the printing system  100  and the cleaning assemblies  102  depicted in  FIGS. 1A-1C  may include additional components and that some of the components described herein may be removed and/or modified without departing from a scope of the printing system  100  disclosed herein. In addition, it should be understood that the components of the printing system  100  may not be drawn to scale and that the components may thus have different respective sizes without departing from a scope of the printing system  100  disclosed herein. 
     The printing system  100  depicted in  FIGS. 1A-1C  may be a portion of a three-dimensional (3D) printing system or a portion of a two-dimensional (2D) printing system. In examples in which the printing system  100  is a 3D printing system, the printing system  100  may form 3D objects from layers of build material particles, which may be in powder or power-like form. The printing system  100  may also form 3D objects from other types of materials in other examples. In examples in which the printing system  100  is a 2D printing system, the printing system  100  may print marking material, such as ink, onto media, such as paper. 
     The printing system  100  may include a first guide rail  104  and a second guide rail  106 , although in some examples, the printing system  100  may include a single guide rail  104  or more than two guide rails  104 ,  106 . The printing system  100  may also include a carriage  110  that may be scanned across a build area (3D printing system) or a print area (2D printing system) along the first and second guide rails  104 ,  106 , which may also be termed herein as rails  104 ,  106 . The build area may generally be defined as an area of the printing system  100  at which 3D objects may be formed from the build material particles. Likewise, the print area may generally be defined as an area of the printing system  100  at which media may be printed upon. 
     The first and second guide rails  104 ,  106  may extend across a portion of or over the entire build/print area of the printing system  100 . The carriage  110  may include a chassis  114  on which rotatable members  116 - 1  to  116 - 3 , which are collectively referenced herein as rotatable members  116  (or equivalently, spinning members  116 ), may rotatably be mounted and which may be supported on the first and second guide rails  104 ,  106 . As shown, a first rotatable member  116 - 1  (which may also be referenced herein as a first spinning member  116 - 1 ), may be rotatably mounted to a first side of the chassis  114 . As also shown, a second rotatable member  116 - 2  and a third rotatable member  116 - 3  may rotatably be mounted to a second side of the chassis  114 . 
     The rotatable members  116 , which may be wheels, bearings, rollers, or the like, may be formed of any suitable material, such as rubber, metal, plastic, or the like. In addition, the rotatable members  116  may rotatably be mounted to the chassis  114  through respective axles. 
     In addition, the carriage  110  may support a printing system component  112  (shown in dashed lines) that may be controlled to perform an action as the carriage  110  is scanned over the build area or print area on the first and second guide rails  104 ,  106 . The printing system component  112  may be any combination of a printhead to deliver a fusing agent and/or a marking material onto the build material particles/media, a heating lamp to apply heat onto the build material particles/media, a recoater to spread layers of build material particles across the build area (e.g., a build platform), multiple ones of these components, etc. In this regard, the actions may include any of the actions that the above-identified printing system components  112  may perform. 
     Although not shown, the chassis  114  may be attached to a belt, chain, rod, or other implement that may push or pull the chassis  114  across the build/print area of the printing system  100 . The rotatable members  116  may rotate as the carriage  110  is moved over the guide rails  104 ,  106 . During operation, debris, such as build material particles, dust, particulates, etc., may contaminate the guide rails  104 ,  106 , as well as other components in the printing system  100 , such as the rotatable members  116 . The contamination of the guide rails  104 ,  106  (and the rotatable members  116 ) may interfere with the contact between the rotatable members  116  and the guide rails  104 ,  106 , which may cause defects in the formation of 3-D objects, printed media, etc. For instance, debris on the guide rails  104 ,  106  and/or the rotatable members  116  may prevent build material particles from being applied in a smooth, level layer. As another example, the debris may interfere with the accurate positioning of the carriage  110  with respect to the build area/print area, which may result in, for instance, deposition of printing liquid in unintended locations. 
     According to examples, cleaning assemblies  102 - 1  to  102 - 3 , which are collectively referenced herein as cleaning assemblies  102 , may be mounted on opposite sides of the carriage  110  to clean debris off at least portions of the guide rails  104 ,  106  as the carriage  110  is scanned across the guide rales  104 ,  106 . Each of the cleaning assemblies  102  may include a plate  118  and a scraper  120 . The scrapers  120  may be attached to respective plates  118  and the plates  118  may be mounted to respective sides of the chassis  114 . In other examples, the scrapers  120  may be mounted directly to the chassis  114  without the plates  118 . In any regard, a first scraper  120 - 1  may contact a portion of a surface of the first guide rail  104  and a second scraper  120 - 2  may contact a portion of a surface of the second guide rail  106 . The sections of the scrapers  120  that contact the portions of the surfaces of the guide rails  104 ,  106  may be contoured to match or complement the shape of the guide rails  104 ,  106 . 
     The scrapers  120  may be formed of a material that is durable, low friction, able to withstand relatively high temperatures, etc. For instance, the scrapers  120  may be formed of plastic, such as polyimide, metal, such as brass, bronze, stainless steel, etc., or the like. The scrapers  120  may also be formed of a combination of materials. For instance, the scrapers  120  may have base sections and contact sections, in which the base sections may be formed of a relatively more rigid material than the contact sections that are to contact the guide rails  104 ,  106 . In these examples, the base sections may be cantilevered from the plates  118  and the contact sections may extend from the base sections to contact the guide rails  104 ,  106 . 
     The scrapers  120  may be angled with respect to the guide rails  104 ,  106  such that the scrapers function to plow or bulldoze across the guide rails  104 ,  106  as the carriage  110  is moved. By way of example, the chassis  114  may extend along a first axis, e.g., a horizontal axis, and the first scraper  120 - 1  may be angled between about 181 and about 269 degrees with respect to the first axis when in contact with the first support rail  104 . By way of particular example, the first scraper  120 - 1  may be between about 200 and about 230 degrees with respect to the first axis when in contact with the first support rail  104 . In addition, the second scraper  120 - 2  may be between about 271 and about 359 degrees with respect to the first axis when in contact with the second support rail  106 . By way of particular example, the second scraper  120 - 2  may be between about 290 and about 330 degrees with respect to the first axis when in contact with the second support rail  106 . When not in contact with the guide rails  104 ,  106 , the scrapers  120  may have different angles. As such, for instance, placement of the scrapers  120  into contact with the guide rails  104 ,  106  may result in the scrapers  120  bending to a greater extent. 
     In addition, or in other examples, the scrapers  120  may be curved prior to being positioned into contact and/or due to contact with the guide rails  104 ,  106 . The scrapers  120  may maintain the curved shape as the scrapers  120  scrape the surfaces of the guide rails  104 ,  106  to thus remove debris that may have collected on the surfaces of the guide rails  104 ,  106  upon which the rotatable members  116  contact. That is the curvature in the scrapers  120  may facilitate the removal of the debris from the guide rails  104 ,  106 . 
     As shown in  FIGS. 1B and 10 , the scrapers  120  may be parts of respective scraper assemblies  122 , which may also include mounting members  124  to which the scrapers  120  are respectively attached and/or inserted. In addition, the mounting member  126  may be mounted to the plates  118  or directly to the chassis  114 . As shown, the mounting members  124  may house or support respective complementary scrapers  126  that may be positioned on opposite sides of the mounting members  124  with respect to the scrapers  120 . The complementary scrapers  126  may be positioned adjacent to a respective scraper  120  and the angles of the complementary scrapers  126  may have angles that are opposite the angles of the scrapers  120  attached to the respective mounting members  124 . In this regard, the complementary scrapers  126  may scrape the guide rails  104 ,  106  to remove debris as the carriage  110  is moved in a direction opposite the direction at which the scrapers  120  scrape the guide rails  104 ,  106  to remove debris. The complementary scrapers  126  may be formed of the same materials as the scrapers  120 . In some examples, the complementary scrapers  126  may be formed of respective unitary pieces of material with the scrapers  120 . In these examples, for instance, a unitary piece of material may be formed into a V-shape to form a scraper  120  and a complementary scraper  126  and may be inserted into a mounting member  124 , for instance, as shown in  FIG. 1D . 
     With particular reference to  FIG. 1D , which depicts an enlarged view of a scraper  120  and a mounting member  124  of the scraper assemblies  122  according to an example, the scraper  120  may have an unsupported (or exposed) length, l, and a thickness, t. According to examples, the length, l, and/or the thickness, t, of the scraper  120  may be varied to adjust the force and contact angle of the scraper  120  on a guide rail  104 ,  106 . In this regard, by selecting scrapers  120  with different unsupported lengths and/or thicknesses, the amount of force and the contact angle of the scrapers  120  may be optimized for particular applications. 
     The scraper assemblies  122  may also include brushes  128  attached to the mounting members  124 . The brushes  128  may be formed of a material similar to those discussed above with respect to the scrapers  120 . In addition, the brushes  128  may be positioned to be in contact with the guide rails  104 ,  106  to also brush debris off at least portions of the guide rails  104 ,  106 . As shown, the brushes  128  may be positioned between respective sets of scrapers  120  and complementary scrapers  126 . However, in other examples, the brushes  128  may be positioned outside of the scrapers  120  and/or the complementary scrapers  126 . 
     As also shown in  FIGS. 1B and 10 , additional scraper assemblies  122  may be positioned at multiple locations with respect to the rotatable members  116 . For instance, scraper assemblies  122  may be positioned on opposite sides of the first rotatable member  116 - 1 , on opposite sides of the second rotatable member  116 - 2 , and on opposite sides of the third rotatable member  116 - 3 . Scraper assemblies  122  may additionally be positioned at other locations with respect to the rotatable members  116 . For instance, scraper assemblies  122  may be positioned to scrape the surfaces of the rotatable members  116  that contact the guide rails  104 ,  106 . In this regard, some of the scraper assemblies  122  may include rotatable member scrapers  120  and/or rotatable member brushes  128  to be implemented to remove debris from the rotatable members  116 . 
     Although particular reference is made herein to the printing system  100  including both the first guide rail  104  and the second guide rail  106 , in some examples, the printing system  100  may include a single guide rail  104  without departing from a scope of the printing system  100  disclosed herein. In these examples, the carriage  110  may be supported on the single guide rail  104 , on the guide rail  104  and another surface, on the guide rail  104  and another structure, or the like. In other examples, the printing system  100  may include both guide rails  104 ,  106 , but the carriage  110  may be supported on one of the guide rails  104  and/or the carriage  110  may be supported on both guide rails  104 ,  106 , but a cleaning assembly  102  may be provided to clean one of the guide rails  104 . 
     In addition or in other examples, although the guide rails  104 ,  106  have been depicted as having circular cross-sections, it should be understood that the guide rails  104 ,  106  may have cross-sections having other geometrical shapes. For instance, the guide rails  104 ,  106  may have square, rectangular, triangular, combinations thereof, etc., shaped cross sections. Moreover, the first guide rail  104  may have a different cross-section and/or size than the second guide rail  106 . 
     Turning now to  FIG. 2 , there is shown a side perspective view of an example cleaning assembly  102 - 1  and a rotatable member  116 - 1  shown in  FIGS. 1A and 1B . The cleaning assemblies  102 - 2  and  102 - 3  may have similar configurations. As shown, the scrapers  120 - 1 ,  126  and the brushes  128  may be mounted to the scraper assemblies  122  and the scraper assemblies  122  may be mounted to the plate  118 - 1  via mechanical fasteners  200 . In addition, the plate  118 - 1  may be mounted to the chassis  114  of the carriage  110  via mechanical fasteners  202 . In other examples, however, the scraper assemblies  122  may be mounted to the plate  118 - 1  and the plate  118 - 1  may be mounted to the chassis  114  via other mechanisms, such as welds, glue, etc. 
     Reference is now made to  FIGS. 3A and 3B .  FIG. 3A  shows a top perspective view of another cleaning assembly  300  that may be mounted to a portion of a chassis  114  of a carriage  110  in a printing system  100 .  FIG. 3B  shows a bottom perspective view of the example cleaning assembly  300  depicted in  FIG. 3A  and a portion of the chassis  114 . It should be understood that the cleaning assembly  300  depicted in  FIGS. 3A and 3B  may include additional components and that some of the components described herein may be removed and/or modified without departing from a scope of the cleaning assembly  300  disclosed herein. In addition, it should be understood that the components of the cleaning assembly  300  may not be drawn to scale and that the components may thus have different respective sizes without departing from a scope of the cleaning assembly  300  disclosed herein. 
     The cleaning assembly  300  may include a plate  302  that may be attached to a chassis  114 . The cleaning assembly  300  may also include a plurality of scrapers  304  attached to the plate  302 . Each of the scrapers  304  may be formed of a base portion  306  and a contact portion  308 , in which the base portion  306  may be formed of a relatively more rigid material as compared with the contact portion  308 . In addition, the scrapers  304  may be formed of materials similar to those discussed above with respect to the scrapers  120 . 
     As shown, the scrapers  304  may contact different sections of a guide rail  104  and may be aligned with respective rotatable members  310 . In addition, each of the contact portions  308  of the scrapers  304  may extend toward a common position with respect to the cleaning assembly  300 , e.g., a central axis of the guide rail. The rotatable members  310  may be similar to the rotatable members  116  discussed above with respect to  FIGS. 1A-1C  and may be rotatably mounted to a chassis  114 . In addition, similarly to the rotatable members  116 , the rotatable members  306  may rotate as the carriage  110  is moved with respect to the guide rail  104 . 
     In any regard, the scrapers  304 , and more particularly, the contact portions  308  may contact different sections of the guide rail  104  and may scrape debris off or remove debris from at least a portion of the guide rail  104  as the carriage  110  is moved with respect to the guide rail  104 . The scraper assembly  300  may also include brushes  312  that may additionally clean debris off at least a portion of the guide rail  104 . Although the brushes  312  are depicted as being mounted to the chassis  114 , it should be understood that the brushes  312  may instead be attached to the plate  302  without departing from a scope of the cleaning assembly  300 . Additionally, scrapers and/or brushes may be positioned to clear debris from the rotatable members  310 . 
     Although described specifically throughout the entirety of the instant disclosure, representative examples of the present disclosure have utility over a wide range of applications, and the above discussion is not intended and should not be construed to be limiting, but is offered as an illustrative discussion of aspects of the disclosure. 
     What has been described and illustrated herein is an example of the disclosure along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the spirit and scope of the disclosure, which is intended to be defined by the following claims—and their equivalents—in which all terms are meant in their broadest reasonable sense unless otherwise indicated.