Abstract:
An additive manufacturing deposition tool and cartridge system and method that allows for a preassembled cartridge to be dropped into a deposition tool, pressurized once, locked into place using a combination of a locating feature and tapered valve catch, where the deposition tool can deposit pressurized material by opening and closing a valve. The deposition tool can move up and down to avoid obstacles on the work surface, with the accuracy of the tool head height governed by physical hard stop devices, which allow an inexpensive motor to exert a force against a stop to precisely locate the tool head using inexpensive, low-precision motors.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 62/108,644, filed Jan. 28, 2015, which is incorporated by reference as if fully set forth herein. 
         [0002]    U.S. application Ser. No. 13/761,272, published on Aug. 15, 2013 as U.S. Patent Publication No. 2013/0209600 A1, is incorporated by reference as if fully set forth herein. 
         [0003]    PCT Application No. PCT/US2013/050792, published on Jan. 23, 2014 as WO 2014/014977 A2, is incorporated by reference as if fully set forth herein. 
         [0004]    U.S. application Ser. No. 13/356,194, issued on Jul. 14, 2015 as U.S. Pat. No. 9,079,337, is incorporated by reference as if fully set forth herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    This invention relates primarily to additive manufacturing (3-D printing) devices, also known as three dimensional fabricators. 
         [0007]    2. Background 
         [0008]    In recent years, with the proliferation of additive manufacturing (3-D printing) technology, shortcomings in the technology have become increasingly apparent. As users have sought out new materials for printing, alternatives to traditional fused deposition modeling (FDM) technology have led to the continuing development of syringe-based extrusion systems. These systems expand the capabilities of affordable 3-D printers—many of which would have otherwise been limited to filament extrusion—and allow for the deposition of nontraditional materials. In the past, such systems were saddled with design limitations that proved cumbersome and inefficient, though not inoperative. In particular, (i) the process of pressurizing and depressurizing syringe tools that utilize air pressure to extrude, and (ii) even state-of-the-art mechanisms for installation of material canisters into the deposition tool, are both slow and labor intensive. Further, deposition tool heads of all types for 3-D printing—and more generally tool heads applicable to similar gantry-based devices—share severe limitations when the layering process is discontinuous. For example, a 3-D printer may be used to extrude material onto an irregular surface, perhaps one comprising previously-printed material (e.g., an object), with additional material. In such a case it is often critical that the newly extruded material not interfere with an object already on the surface, such as previously-printed material. Likewise, where a 3-D printer with a multi-tool head is used to deposit material into a cavity, it is critical that the non-functional tool head (i.e., the one not in current use) does not come into contact or otherwise interfere with an object onto which the new material is being deposited. 
         [0009]    One solution to this problem is to actuate the non-functioning tool head, such that it is at a different height from the functioning head, thereby avoiding any obstacles on the work surface. However, accomplishing this task generally requires high-precision equipment, given the great sensitivity that 3-D printing processes have to the relative height of the deposition tool head tip and the work surface. As will be described below, embodiments of the present invention can eliminate the need for such precision equipment by exploiting novel designs. Further, embodiments of the present invention also offer a more effective means of loading syringe extrusion cartridges into a 3-D printer. Although exemplary embodiments may utilize air pressure-driven printers, other embodiments of the present invention could be applied to piston-riven systems, filament driven, or other 3-D printing systems. 
       SUMMARY OF THE INVENTION 
       [0010]    The shortcomings of the prior art can be overcome and additional advantages can be provided with the additive manufacturing systems and methods described herein. The present invention can thereby make additive manufacturing more practical, more economical, and capable of higher quality products. Some of the features provided by the system of the present disclosure are described as follows. 
         [0011]    A 3-D printer comprising a deposition tool head, a work surface configured to receive material deposited by the deposition tool head, a motor configured to move the deposition tool head vertically to different heights relative to the work surface, and at least one lower hard stop surface referenced absolutely to the gantry that maintains a maximum lowest position for the deposition tool head, wherein the height of the deposition head relative to the work surface is maintained by the application of force from the motor onto the lower hard stop surface. Additionally, the lower hard stop surface of the 3-D printer may be adjustable. Additionally, the 3-D printer may further comprise a locking mechanism to secure the deposition tool head against the lower hard stop, and at least one actuator to engage or disengage the locking mechanism. Additionally, the 3-D printer may further comprise at least one upper hard stop surface referenced absolutely to the gantry that maintains a maximum highest position for the deposition tool head, wherein the height of the deposition head relative to the work surface is maintained by the application of force from the motor onto the upper hard stop surface. Additionally, the upper hard stop surface of the 3-D printer may be adjustable. 
         [0012]    A method of 3-D printing comprising the steps of determining the topography of a substrate on a work surface, depositing a desired material on the work surface using at least one deposition tool, mechanically moving the deposition tool vertically above the work surface as to avoid a collision between the deposition tool and the substrate, maintaining a maximum highest position of the deposition tool head relative to the work surface where required by the application of force from a motor onto an upper hard stop surface, and maintaining a maximum lowest position of the deposition tool head relative to the work surface where required by the application of force from the motor onto a lower hard stop surface. 
         [0013]    A 3-D printing deposition tool comprising an integrated syringe-cartridge assembly comprising a syringe barrel connected to a valve that is connected to a deposition tip, and a syringe tool frame with a guide-lock-and-engaging apparatus that has a slot adapted to receive the valve, wherein the integrated syringe-cartridge can be inserted into the syringe tool frame with the valve in the guide-lock-and-engaging apparatus, and locked into position by automatically engaging the guide-lock-and-engaging apparatus. 
         [0014]    Embodiments of the present invention may include a 3-D printer deposition tool head that is able to receive a preassembled syringe-cartridge that need only be pressurized once upon installation. The preassembled syringe-cartridge can be dropped into the tool head largely using gravity, such that the shape of the tool head and corresponding shape of the syringe-cartridge (valve) cause the cartridge to hit a locating feature, and then become locked in (in some embodiments upon the action of the motor turning the valve open, even if the cartridge was insufficiently pushed in at first). The tool head is capable of moving up and down (in most configurations in the same direction as a movable z-axis of the printer), such that they can be located at precise points using a hard stop physically attached to the apparatus and the force of inexpensive, low accuracy motors. In this way, precision of tool head height is not limited by the accuracy and precision of motors, but only by the accuracy of simple framing elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  shows a perspective view of a 3-D printer. 
           [0016]      FIG. 2  is an embodiment of the invention that shows an actuating deposition tool head. 
           [0017]      FIG. 3  is an embodiment of the invention that shows a cutaway illustration of a syringe tool frame as shown in  FIG. 2 . 
           [0018]      FIG. 4  is an embodiment of the invention that shows a valve guide-lock-and-engaging apparatus that can be secured to the syringe tool frame, and a method for installing a material cartridge. 
           [0019]      FIG. 5  is an embodiment of the invention that shows a syringe-cartridge engaged in a valve guide-lock-and-engaging apparatus, as well as an attachment by which the motor (e.g., servo) turns the valve. 
           [0020]      FIG. 6  is an embodiment of the invention that depicts the illustration of  FIG. 5  with the motor attachment removed. 
           [0021]      FIG. 7  is a front perspective of an embodiment of the invention with two tips at various heights, representing the “lower” position of the tool had depicted in the previous figures. 
           [0022]      FIG. 8  is a front perspective of an embodiment of the invention with two tips at various heights, representing the “higher” position of the tool had depicted in the previous figures. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    A perspective view of exemplary 3-D printing apparatus  101  is shown in  FIG. 1 . As described in the referenced art, and other pertinent references, devices compatible with the invention, including 3-D printers and other multi-axis/gantry systems function wherein it a control unit and command unit, or similar equipment, provide instructions to the apparatus  101 . Exemplary three dimensional fabricating systems and components thereof are described or referenced in U.S. Patent Pub. No. 2013/0209600, entitled “Multi-Axis, Multi-Purpose Robotics Automation and Quality Adaptive Additive Manufacturing” and published on Aug. 15, 2013. 
         [0024]    The exemplary 3-D printing apparatus  101  can include a work surface or build tray  102  (which may be vertically moving), and a tool head carriage  103 , which can move on the X and Y axis along the gantry and can comprise or be adjoined to certain tools, such as deposition tools  104  and  105 . In exemplary apparatus  101 , deposition tool heads  104  and  105  can be syringe-based tools, but alternative tools such as plastic deposition (filament) or nonprinting tools could be used in other embodiments. In addition, alternative embodiments of the present invention may function using printing technology different than the preferred embodiments shown herein. 
         [0025]      FIG. 2  is an embodiment of the invention that shows an actuating deposition tool in greater detail. This tool head could, for example, correspond to deposition tool head  105  in  FIG. 1 . In this embodiment, a syringe-based deposition tool head is shown, comprising a syringe barrel  206 , valve  207 , tip  208 , attachment point for a pressure cap  209  (pressure cap not shown), valve guide-lock-and-engaging apparatus  210 , valve servo (as shown in  FIG. 4 ), syringe retaining and guiding rings  211  and  212 , syringe tool frame  213 , tool lift servo  214 , and a tool lift frame  215 . The syringe-based deposition tool head can connect to carriage  103  in  FIG. 1 . 
         [0026]      FIG. 4  is a corresponding embodiment of the invention that shows a valve guide-lock-and-engaging apparatus that can be secured to a syringe tool frame, and a method for installing a material cartridge. Syringe barrel  206 , valve  207  and tip  208  of  FIG. 2  correspond syringe barrel  406 , valve  407  and tip  408  in  FIG. 4  (collectively, syringe-cartridge assembly  423 ). Syringe retaining and guiding rings  211  and  212  of  FIG. 2  correspond to syringe retaining and guiding rings  411  and  412  in  FIG. 4 , respectively. Valve guide-lock-and-engaging apparatus  210  of  FIG. 2  corresponds to valve guide-lock-and-engaging apparatus  410  in  FIG. 4 . Notably, the interior space of valve guide-lock-and-engaging apparatus  210  may be constructed such that valve  207  is guided into a slot, which in the embodiment of  FIG. 2  is a tapered design corresponding to the exterior shape of valve  207 . The same construction is illustrated in  FIG. 4  with respect to the tapered slot within the interior space of valve guide-lock-and-engaging apparatus  410  for valve  407 . 
         [0027]    Valve servo  424  as shown in  FIG. 4  may serve to lock syringe-cartridge  423  into place, such as by turning valve  407 , at the appropriate height for printing, such that valve  407  can be engaged and disengaged in order to allow material to flow for deposition. Syringe-cartridge  423  can be pressurized via a pressure cap, line and source (not shown) at its end (e.g., attachment point for a pressure cap  209  in  FIG. 2 ). 
         [0028]    This embodiment of the present invention provides a number of benefits. First, integrated syringe-cartridge  423  can be pre-assembled, allowing a user to simply insert syringe-cartridge  423  into a 3-D printing apparatus. Without the embodiments described herein, it could be necessary to physically attach syringe barrel  406  to valve  407  and tip  408  after the latter components were affixed to a syringe tool frame, such as syringe tool frame  213  in  FIG. 2 . The described embodiment of the present invention, by contrast, allows a user to easily replenish material supply without disassembling a tool head or using any additional hardware to manually secure syringe-cartridge  423  to the 3-D printing apparatus. Second, pre-assembled syringe-cartridge  423  can be pressurized just once after installation in a 3-D printing apparatus, and kept at pressure, without re-engaging the pressure source. In this manner, a user would no longer need to pressurize and depressurize the syringe barrel each time the user sought to deposit material. Instead, this embodiment of the present invention could allow the user to simply open and close valve  407  to control the flow of deposition material. Printing time and response time to computer instructions can thereby be decreased, and the need to frequently engage often noisy pressure sources can be largely eliminated. 
         [0029]      FIG. 5  is an embodiment of the invention that shows syringe-cartridge  523  engaged in valve guide-lock-and-engaging apparatus  510 , as well as attachment mechanism  527  by which, in this embodiment, a motor (e.g., servo) turns the valve. Other embodiments may include alternative dispensing apparatuses or valve designs (e.g., push-to-open). Tip  508  is shown beneath valve guide-lock-and-engaging apparatus  510 . Corresponding  FIG. 6  depicts tapered guide slot (i.e., channel)  628  in valve guide-lock-and-engaging apparatus  610 . The tapered design allows the valve to be secured in the 3-D printing apparatus and locked in the proper position, even if the valve is not perfectly aligned with channel  628  when inserted (i.e., it is turned somewhat to one side or the other). In particular, the simple force of gravity or the user, combined with the tapered design, will necessarily align a valve so it can be locked in the 3-D printing apparatus of the depicted embodiments. 
         [0030]    Another feature of note is that some embodiments of a syringe-cartridge (e.g., syringe-cartridge  423  in  FIG. 4 ) are constructed such that control of the pressure (release or activation thereof) is governed by the syringe-cartridge itself, as opposed to a pressure line interfacing with the pressure cap. 
         [0031]    Returning to  FIG. 2 , syringe tool frame  213  is shown connected to tool lift frame  215 . Corresponding syringe tool frame  313  in the embodiment illustrated in  FIG. 3  is shown in greater detail. Tool lift frame  315  can support tool lift servo  314 , which need not be a servo and may be any suitable motor type or style. Tool lift servo  314  can be connected to arm mechanism  316 , which can move syringe tool frame attachment component  317  up or down along guide rail  318 . While tool lift motor  314  could provide sufficient accuracy to precisely position tip  208  of  FIG. 2  as needed by the 3-D printing apparatus, embodiments of the present invention offer an alternative to using such high precision equipment. For example, one might choose to practice an embodiment of the invention by creating a multi-function/multi-headed tool. In one scenario, a tool with two syringe-cartridges, such as the one shown in  FIG. 1  might be constructed. A first tool  104  might be at a fixed height and attached immovably to carriage  103 . A second tool  105  might include a tool lift frame  215  and tool lift motor  214  as shown in  FIG. 2 . In this fashion, second tool  105  can be engaged at, for example, three different heights: an intermediate height level with a static first tool  104  (which may or may not be used functionally); a height below static first tool  104 ; and a disengaged height above static first tool  104 . When depositing onto irregular surfaces, it is generally necessary that a non-functioning tool head tip not interfere with an object onto which the functioning tool head is depositing material. As such, it is generally necessary that the non-functioning tool head be raised above the functioning tool in such instances. Achieving this task would normally require the use of precision electronics, such that the motor could precisely locate the functioning tip. (Indeed, the precise localization of the tip is often critical for printing accuracy.) Embodiments of the present invention, however, can utilize hard stops  319 ,  320 ,  321  and  322  as shown in  FIG. 3 , which eliminate the need for precision equipment. Hard stops  319  and  320  create a surface for corresponding syringe tool frame  213  in  FIG. 2  to physically contact tool lift frame  215  at a maximum lowest position. Similarly, hard stops  321  and  322  create a surface for syringe tool frame  213  in  FIG. 2  to physically contact tool lift frame  215  at a maximum highest position. Of course, the number, location and configuration of hard stops and associated connection points may vary depending on the embodiment of the invention, with the present example representing just one potential embodiment. In this way, the physical structure of tool lift frame  215  in  FIG. 2  and the force of the motor pushing against it can be used to replace the need for a highly accurate and precise motor with the ability to correctly locate the position of tip  208 . In other words, the motor is directed to “overshoot” its target and move syringe tool frame attachment component  317  slightly past the appropriate hard stop set of  319  and  320 , or hard stop set of  322  and  321 . In this way, the motor exerts a slight force against the hard stops and ensures that the location of tip  208  is accurate, based on the known locations of the hard stops, which are independent of motor quality or function. 
         [0032]    It should be clearly understood that embodiments of the invention may be applied to various tool configurations, including more than two tools, and combination of tools such as filament extruders, syringe print heads, pipettes, milling blades, scanners, etc. For example, embodiments of the invention could be used to print or pipette material from multiple tool heads (e.g., syringe barrels) into well plates used in molecular biology experiments. Likewise, irregular structures printed or milled by a first tool, could be coated with at least one other deposition head using an embodiment of the present invention to avoid crashing the tools into the substrate structure. 
         [0033]    In some embodiments of the present invention, a spring can be used to bias the deposition tool head towards a set of hard stops (e.g., lower hard stops) to maintain a first state. Compression of the spring would allow the deposition tool head to reach the other set of hard stops to maintain the other state (e.g., upper hard stops). This type of embodiment may be useful when a deposition tool head is expected to be positioned in the first state the vast majority of the time, and the motor would only have to be engaged to maintain the other state. The frame and other described components in the 3-D printer can be adjustable, allowing for the 3-D printer to have a range of pre-programmable heights for the deposition tool head. This could, for example, enable the 3-D printer to be adjusted depending on the size of different deposition tool heads. These size differences can occur when a deposition tip is added to a syringe tool, or a different heating system and tip is added to a filament-based deposition tool head. 
         [0034]    Some embodiments may use a locking mechanism at a hard stop instead of just applying a constant force from an actuator against the hard stop. Such as locking mechanism could be mechanical, such as requiring force to lock or release the deposition tool head at the hard stop. This could result in use of the motor only for applying force during transitions between hard stops, lengthening the life of the motor and saving energy. The locking mechanism could also be electromechanical, such as being switched on and off to facilitate transitions between the upper and lower hard stop positions. The locking mechanism could also be purely magnetic, which may require force to break contact with a hard stop, but making the engagement process at a hard stop less demanding on the motor. 
         [0035]    Some embodiments may use a bistable mechanism to apply force on the deposition tool head, where the mechanism is only stable in two states, “up” at, e.g., the upper hard stop and “down” at, e.g., the lower hard stop. There are many bistable mechanisms which can be used, such as using a preformed strip of metal anchored into a frame in an excited first mode of a structure. In the up or down states it is applying force on the tool head against the upper or lower hard stops. This locks the tool head against hard stops and locks its position. By applying a force on the bistable mechanism, it can be switched from the up state to the down state or from the down state to the up state. This enables a simple actuator to switch the mechanism from one state to another and thereby switch the position of the tool head from one hard stop to another hard stop without requiring precise control or movements. 
         [0036]      FIGS. 7 and 8  depict different snapshots of a 3-D printer,  701  and  801  respectively, that represents on possible embodiment of the present invention. The 3-D printer has a tool head carriage  703  and  803  respectively, a first static deposition tool head tip  725  and  825  respectively, a second moving deposition tool head tip  710  and  810  respectively, and a work surface or build tray  726  and  826  respectively (which may be vertically moving). 
         [0037]    With respect to  FIG. 7 , moving deposition tool head tip  710  is shown in the lower position, relative to the static deposition tool head tip  725 . In this configuration, the corresponding syringe tool frame would be pushing against lower hard stops (e.g., hard stops  319  and  320  in  FIG. 3 ) and accurately maintained at the lowest position setting. With respect to  FIG. 8 , moving deposition tool head tip  810  has moved up relative to static deposition tool head tip  825  and tool head carriage  803 . In this configuration, the moving deposition tool would be pushing against upper hard stops (e.g., hard stops  322  and  321  in  FIG. 3 ). Note also that in the embodiments of  FIGS. 7 and 8  the work surface can be adjustable. For example, work surface  826  (in  FIG. 8 ) is shown in a lower position than work surface  726  (in  FIG. 7 ) to achieve a larger distance from moving deposition tool head tip  810 . Using the various configurations supported by embodiments of the present invention, the 3-D printer can facilitate choreographed movements of deposition tool head tips and a work surface to accommodate any irregular items on the work surface or an irregularly shaped work surface. One method for practicing the invention is that, upon switching from use of one deposition tool head to another or upon vertical movement of a deposition tool head, also moving the work surface (z-table) by an offset amount, for example, to avoid collision between a deposition tool head and the work surface or an object on the work surface without the need for more complex motion calculations. More sophisticated algorithms are envisioned within the scope of invention, including for example, determining the geometry of the surface and only moving a deposition tool head when absolutely necessary to avoid interference.