System and method of detecting failed bed adhesion for a three-dimensional printer

A three-dimensional printer includes an enclosure defining a chamber and a print surface disposed within the chamber. The printer further includes a nozzle displaceable relative to the print surface for melting and dispensing a filament on the print surface to form a dielectric part during a printing process. The printer further includes a filament drive system for supplying the filament to the nozzle, and one or more capacitance sensors coupled to the print surface. The printer further includes a controller electrically coupled to the capacitance sensors for measuring a capacitance, with the controller generating an error signal in response to the controller determining a change of capacitance when the dielectric part is displaced relative to the print surface during the printing process. The printer further includes a display device electrically coupled to the controller and displaying an error message in response to the display device receiving the error signal.

TECHNICAL FIELD

The present disclosure relates to three-dimensional printers for printing parts on a print bed, and more particularly to a system and method of detecting failed adhesion between the part and the print bed.

BACKGROUND

Three-dimensional printers (“3D printers”) produce three-dimensional parts from computer generated models. The printers deposit feed stock on a print bed during an additive manufacturing process. In some instances, the filament may be include a printer head that draws the feedstock in the form of thermoplastic filament from a spool contained within a canister. The printer head may move along path while heating and depositing the filament onto the print bed to form the part. For example, the printer head may move within an XY plane and deposit the filament in a first layer, and the printer head and/or the print bed may be moved along a Z-axis to form a successive layer. This process may then be repeated until the entire part is completed.

One exemplary challenge in the additive manufacturing process is that the part may separate from the print bed, and the printer head may drag the part along the print bed before the entire part has been printed. The failed adhesion between the part and the print bed can cause the printed part to deviate from design requirements, which can in turn require the part to be re-printed and waste material.

Thus, while current 3D printers achieve their intended purpose, there is a need for a new and improved 3D printer that addresses these issues.

SUMMARY

The present disclosure provides a three-dimensional printer including an enclosure that defines a chamber and a print surface disposed within the chamber. The printer further includes a nozzle displaceable relative to the print surface for melting and dispensing a filament on the print surface to form a dielectric part during a printing process. The printer further includes a filament drive system for supplying the filament to the nozzle, and one or more capacitance sensors coupled to the print surface. The printer further includes a controller electrically coupled to the capacitance sensors for measuring a capacitance during the print process. The controller determines a change of capacitance in response to the dielectric part being displaced relative to the print surface during the printing process. The controller generates an error signal in response to the controller determining the change of capacitance. The printer further includes a display device electrically coupled to the controller and displaying an error message in response to the display device receiving the error signal from the controller.

The present disclosure also provides a three-dimensional printer including an enclosure that defines a chamber. The printer further includes a print surface disposed within the chamber and having a plurality of sections. The printer further includes a nozzle displaceable relative to the print surface for melting and dispensing a filament on the sections of the print surface to form at least one dielectric part during a printing process. The printer further includes a filament drive system for supplying the filament to the nozzle and a plurality of capacitance sensors coupled to the associated sections of the print surface. The printer further includes a controller electrically coupled to the plurality of capacitance sensors for measuring a capacitance for the associated sections of the print surface during the print process. The controller determines a change of capacitance in response to an associated portion of the dielectric part being displaced relative to the associated section of the print surface during the print process. The controller generates an error signal in response to the controller detecting the change of capacitance. The printer further includes a display device electrically coupled to the controller and displaying an error message in response to the display device receiving the error signal from the controller.

The present disclosure also provides a method of operating a three-dimensional printer having an enclosure, a print surface disposed within the enclosure, a nozzle, a filament drive system, at least one capacitance sensor, a controller electrically coupled to the capacitance sensors, and a display device. The method includes the filament drive system supplying a filament to the nozzle. The nozzle is displaced relative to the print surface for melting and dispensing the filament onto the print surface to form a dielectric part on the print surface during a printing process. The controller and the capacitance sensor measure a capacitance during the print process. The controller determines a change of capacitance in response to the dielectric part being displaced relative to the print surface during the printing process. The controller generates an error signal in response to the controller determining the change of capacitance. The display device displays an error message in response to the display device receiving the error signal from the controller.

Other features and advantages of the present disclosure will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION

Referring toFIG. 1, one example of a three-dimensional printer100includes an enclosure102defining a chamber104and a print bed106disposed within the chamber104. The print bed106has a print surface108with a section110(FIGS. 2 and 3) upon which a dielectric part130is printed. In this example, the print bed106is a composite panel112(FIGS. 2 and 3) including a substrate114disposed between two composite layers116,118, with one of the composite layers116,118including the print surface108. The substrate114and composite layers116,118can be made of Fiberglass-epoxy laminate material. In other examples, the print bed can be made of other materials and have any number of layers. The printer100further includes a Z-motor system120for linearly moving the print surface108along a Z-axis.

The printer100further includes one or more canisters122for storing a filament124and a filament drive system126for drawing one or more filaments124from the associated canisters122. WhileFIG. 1illustrates the filament drive system126drawing only one filament124from one canister, it is contemplated that the filament drive system126can engage two or more filaments dispensed from any number of canisters122. Other examples of the printer can include other delivery mechanisms for delivering filament or non-filament feedstock from any suitable storage device to the print surface.

The printer100further includes a nozzle128for receiving the filament124from the filament drive system126, heating the filament124, moving relative to the print surface108, and dispensing the filament124on one or more sections110of the print surface108to form one or more dielectric parts130during a printing process. The printer100includes an XY all-linear motor system132for moving the nozzle128within the XY plane to print the dielectric part130on the print surface108. However, it is contemplated that either one or both of the nozzle128and the print surface can be movable in any suitable direction for 3D printing the part130.

Referring again toFIGS. 2 and 3, the printer100further includes one or more capacitance sensors134coupled to the print surface108. In this example, the printer100includes one capacitance sensor134coupled to the section110of the print surface108. The capacitance sensor134is electrically coupled to a voltage source136having a positive terminal138and a negative terminal140. The capacitance sensor134further includes a positive electrode142coupled to the positive terminal138and receiving a positive charge from the positive terminal138. Each capacitance sensor134further includes a negative electrode144coupled to the voltage source136and receiving a negative charge from the voltage source136. It is contemplated that the printer can include more than one capacitance sensor as detailed in the description of the examples illustrated inFIGS. 5 and 6.

As best shown inFIG. 2, each of the positive and negative electrodes142,144includes a plurality of fingers148,150embedded within the substrate114, with the fingers148of the positive electrode142being interdigitated with the fingers150of the negative electrode144. However, it is contemplated that the printer can include any number of capacitors in the form of fingers, in-plane plates, or other suitable structures arranged in series or parallel.

Referring back toFIG. 1, the printer100further includes a controller152electrically coupled to the filament drive system126, the XY-motor system132, the nozzle128, the Z-motor system120for actuating the same to 3D print the dielectric part130. The controller152is further electrically coupled to the capacitance sensors134for measuring a capacitance for the associated sections110of the print surface108during the print process. In this example, the controller152includes an analog-to-digital converter154coupled to the capacitance sensors134for converting the capacitance to a voltage and then converting the voltage to digital. The controller152determines a change of capacitance, in response to the associated portion of the dielectric part130being displaced relative to the associated section110of the print surface108during the print process. The controller152generates an error signal, in response to the controller152detecting the change of capacitance. More specifically, the controller152is configured to generate the error signal, in response to the controller152determining that the change of capacitance is above a predetermined threshold. The threshold can be an empirically determined value. For instance, the threshold can be 20 picofarads where the controller152and associated capacitance sensor134measure a capacitance of 120-140 picofarads when a dielectric part adheres to an associated section110of the print surface108and a capacitance of 100 picofarads when the dielectric part separates from and moves relative to the associated section110of the print surface108. While it is contemplated that the threshold can be above or below 20 picofarads and the feedstock and the print bed can be made of any suitable material with associated capacitance values above or below the range of 120-140 picofarads, the controller152still determines a change of capacitance in response to the part detaching from the print bed. The controller152is configured to not generate the error signal in response to the controller152determining that the change of capacitance is less than the predetermined threshold. The filament drive system126ceases supplying filament to nozzle128, in response to the filament drive system126receiving the error signal from the controller152.

As shown inFIG. 1, the printer100further includes a display device156electrically coupled to the controller152for displaying an error message in response to the display device156receiving the error signal from the controller152. The technician can inspect the part130for any defect associated with the failed bed adhesion and determine whether the defect is repairable.

The printer100further includes a user interface158for generating a continue command signal and a stop command signal. The technician may operate the user interface158to generate the continue command signal in response to the technician determining that the defect of the part130associated with the error signal is repairable. The controller152can receive the continue signal from the user interface158for actuating the filament drive system126, the nozzle, the XY-motor system132, and the Z-motor system to continue printing the part130in response to the controller152receiving the continue command signal from the user interface158. In addition, the technician may operate the user interface158to generate the stop command signal. The controller152can receive the all-stop signal from the user interface158for actuating the filament drive system126, the nozzle, the XY-motor system132, and the Z-motor system120to stop printing all parts.

Referring toFIG. 4, another example of a print bed206is similar to the print bed106ofFIG. 2and includes similar components identified by the same reference numbers increased by 100. However, while the print bed106ofFIG. 2includes the capacitance sensor134with positive and negative electrodes142,144in the form of interdigitated fingers148,150, the print bed206includes a single capacitance sensor234with positive and negative electrodes242,244in the form of in-plane electrode plates that are positioned adjacent to one another within the substrate. The print surface208includes a seam260between the positive and negative electrodes242,244, such that dielectric filament formed across the seam260produces an associated capacitance.

Referring toFIG. 5, another example of a print bed306is similar to the print bed106ofFIG. 2and includes similar components identified by the same reference numbers increased by 200. However, while the print bed106ofFIG. 2has a single section110of the print surface108and a single capacitance sensor134with positive and negative electrodes142,144in the form of interdigitated fingers148,150, the print bed306includes a plurality of sections310with a plurality of capacitance sensors334arranged in a matrix362, with each capacitance sensor334having positive and negative electrodes342,344in the form of adjacent in-plane electrode plates embedded within the substrate. The positive and negative electrodes342,344meet at associated seams360, such that separate parts330a-330dformed on associated seams360produce an associated capacitance. In this example, each capacitance sensor334is electrically coupled directly to the voltage source336in a series circuit, such that the controller can determine the change of capacitance for the associated section of the print surface308and determine the failed bed adhesion of the specific parts. In another example, the capacitance sensors are arranged in a parallel circuit, with the positive electrode of each capacitance sensor connected to the positive terminal, and the negative electrode of each capacitance sensor connected to the negative terminal. For instance, as shown inFIG. 6, the rows of positive electrodes442can be connected in parallel to the voltage source136, and the columns of negative electrodes444can be connected in parallel to the voltage source136. It is contemplated that the matrix of capacitance sensors can be arranged in any suitable circuit.

In this example, the printer includes the user interface158for generating an all-continue command signal, a partial-stop command signal, and an all-stop command signal. The technician may operate the user interface158to generate the all-continue command signal in response to the technician determining that the defect of the part130associated with the error signal is repairable. The controller152can receive the all-continue signal from the user interface158for actuating the filament drive system126, the nozzle, the XY-motor system132, and the Z-motor system to continue printing all parts in response to the controller receiving the all-continue command signal from the user interface158. Furthermore, the technician may also operate the user interface158to generate the partial-stop command signal in response to the technician determining that the defect associated with the error signal is not repairable. The controller152can receive the partial-stop signal from the user interface158and in turn actuate the filament drive system126, the nozzle, the XY-motor system132, and the Z-motor system to stop printing only the part associated with the error signal and continue printing the parts not associated with the error signal. In addition, the technician may operate the user interface158to generate the all-stop command signal. The controller152can receive the all-stop signal from the user interface158for actuating the filament drive system126, the nozzle, the XY-motor system132, and the Z-motor system120to stop printing all parts.

Referring toFIG. 6, another example of a print bed406is similar to the print bed306ofFIG. 5and includes similar components identified by the same reference numbers increased by 100. However, while the print bed306ofFIG. 5includes the plurality of capacitance sensors334for detecting a capacitance of multiple separate parts330adhered to associated sections310of the print surface308, the plurality of capacitance sensors434for detecting a capacitance of single part430adhered to multiple sections410of the print surface CC.

Referring now toFIG. 7, one example of a method500for operating the printer100ofFIG. 1with the print bed406ofFIG. 6is illustrated. The method500commences at block502with the filament drive system126supplying the filament124to the nozzle128. In this example, the filament drive system126draws one or more filaments124from associated canisters122and supplying the filament124to the nozzle128. In other examples, other devices can draw feedstock in any form from any suitable storage container to the nozzle.

At block504, the XY-motor system132displaces the nozzle128along an X-axis and a Y-axis relative to the print surface108for melting and dispensing each layer of the filament124onto one or more sections of the print surface108, and the Z-motor system120moves the print bed106along a Z-axis relative to the nozzle128when each layer is completed to form a dielectric part130on the print surface108. In this example (FIG. 6), a single dielectric part430is formed on the print bed406and includes first and second portions431a,431bprinted on associated first and second sections410a,410bof the print surface408. In another example (FIG. 5), separate dielectric parts330can be formed on associated sections310a,310bof the print surface308. Furthermore, it is contemplated that the print bed can be held in a fixed position, and the nozzle can be movable along the X, Y, and Z axes. It is also contemplated that the nozzle and print bed can be movable relative to one another with either one of the nozzle and print bed be movable in any suitable direction or held in a fixed position.

At block506, the controller152and the capacitance sensors measure a capacitance for associated sections of the print surface during the print process. In one example (FIG. 6), a first capacitance sensor434ameasures the capacitance associated with the first section410aof the print surface408, and a second capacitance sensor434bmeasures the capacitance associated with the second section410bof the print surface408. At each section410a,410b, the capacitance between the positive and negative electrodes442,444when the dielectric part430is adhered to the seam460is higher than the capacitance when the dielectric part430is separated or spaced from the seam460. For instance, the measured capacitance can be 120-140 picofarads when the portions431a,431bof the dielectric part430are adhered to the associated seams460, and the measured capacitance can be 100 picofarads when the portions431a,431bof the dielectric part430is separated or spaced from the associated seams460. It is contemplated that the measured capacitance can be above or below 120-140 picofarads when the dielectric part is adhered to the seam, and the measured capacitance can be above or below 100 picofarads when the dielectric part is separated or spaced from the seam460.

At block508, the controller152compares the measured capacitance at each section410a,410bof the print surface408to a previously measured capacitance at the same section to detect a change of capacitance when the associated portion431a,431bof the dielectric part430is displaced relative to the associated section410a,410bof the print surface408. If the controller152determines that there is a change in capacitance for each of the first and second sections410a,410b, the method proceeds to block510. Continuing with the previous example, if the controller152determines that the change of capacitance for each of the first and second sections410a,410b(FIG. 6) is equal to one another and above a threshold change of capacitance, the controller152determines that the single entire dielectric part430is displaced relative to the first and second sections410a,410bof print surface408, and the method proceeds to block510. In another example, the controller152can determine that two separate parts330a,330b(FIG. 5) are displaced relative to associated first and second sections310a,310bduring the printing process, and the method proceeds to block510. If the controller152determines that there is no change in capacitance for both of the first and second sections of the print surface, the method proceeds to block522. Continuing with the previous example, if the controller152determines that the change of capacitance for at least one of the first and second sections410a,410bis below a threshold change of capacitance, the method can proceed to block516.

At block510, the controller152generates an error signal, indicating that the dielectric part or parts have entirely separated from the print surface. More specifically, the error signal may indicate that the part430(FIG. 6) previously printed on both of the first and second sections410a,410bhas detached from or been displaced relative to the first and second sections410a,410bof the print surface408. In another example, the error signal may indicate that two separate dielectric parts330a,330b(FIG. 5) previously printed on associated ones of the first and second sections310a,310bof the print surface308have detached from and been displaced relative to the first and second sections310a,310b.

At block512, the filament drive system126ceases a supply of the filament124to the nozzle128in response to the filament drive system126receiving the error signal from the controller152.

At block514, the display device156displays an error message to notify a technician of the entire separation of the single dielectric part430(FIG. 6) from the first and second sections410a,410bof the print surface408, or the separation of multiple separate parts330(FIG. 5) from the associated sections310a,310bof the print surface308.

At block516, the technician inspects the part associated with the notification displayed on the display device156. If the technician determines that the part associated with the error signal has a defect that is repairable, the method proceeds to block518. If the technician determines that the part associated with the error signal has defect that is not repairable, the method proceeds to block520.

At block518, the technician operates the user interface158to continue the printing process for the single part430associated with the error signal. In another example where the printer100is concurrently printing multiple parts, the technician operates the user interface158to continue the printing process for all parts330a,330b, including parts with repairable defects associated with the error signal and parts not associated with the error signal.

At block520, the technician operates the user interface158to terminate the printing process for the single part430associated with the error signal. In another example where the printer100is printing concurrently printing multiple parts330a,330b, the technician operates the user interface158to terminate the printing process for the parts associated with the error signal and resume the printing process for the parts not associated with the error signal.

At block522, the controller152determines that one of the first and second changes of capacitance associated with the first and second portions431a,431bof the print surface408is above a threshold change of capacitance when one of the first and second portions431a,431bof the dielectric part430is displaced relative to the print surface108during the printing process, and the method proceeds to block518. If the controller152determines that the change of capacitance for each of the first and second sections410a,410bis below the threshold change of capacitance, the method returns to block502.

At block524, the controller152generates an error signal, indicating a partial separation of the portion of the single dielectric part130from the sections110a,110bof the print surface408associated with the error signal. In another example where multiple parts330a,330bare being printed, the error signal can indicate that multiple parts330a,330bhave separated from the associated sections410a,410bof the print surface408.

At block526, the filament drive system126ceases a supply of the filament124to the nozzle128in response to the filament drive system126receiving the error signal from the controller152.

At block528, the display device156displays an error message to notify the technician of the partial separation of the single dielectric part430from the print surface408or, in another example, to indicate the separation of multiple separate parts330a,330bfrom associated sections410a,410bof the print surface408.

At block530, the technician inspects the part associated with the notification displayed on the display device156. If the technician determines that the part associated with the error signal has a defect that is repairable, the method proceeds to block532. If the technician determines that the part associated with the error signal has defect that is not repairable, the method proceeds to block534.

At block532, the technician operates the user interface158to continue the printing process for the single part430associated with the error signal. In another example where the printer100is concurrently printing multiple parts, the technician operates the user interface158to continue the printing process for all parts330a,330b, including parts with repairable defects associated with the error signal and parts not associated with the error signal.

At block532, the technician operates the user interface158to terminate the printing process for the single part430associated with the error signal. In another example where the printer100is printing concurrently printing multiple parts330a,330b, the technician operates the user interface158to terminate the printing process for the parts associated with the error signal and resume the printing process for the parts not associated with the error signal.

The description of the present disclosure is merely exemplary in nature and variations that do not depart from the general sense of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.