A three-dimensional printing method

Abstract

The present application discloses a three-dimensional printing method, which detects the appearance and disappearance of dead zones during the three-dimensional printing process; if it is determined that a dead zone has appeared, all first parts to be formed that have been affected by the dead zone and will be affected by the dead zone, as well as all second parts to be formed that are not affected by the dead zone, are determined, and are printed according to a first scheme; the first scheme is to cancel the printing of all first parts to be formed and continue to print all second parts to be formed in situ; if it is determined that the dead zone has disappeared, all third parts to be formed that have been affected by the dead zone and all fourth parts to be formed that are not affected by the dead zone are determined, and are printed according to a second scheme; the second scheme is to cancel the printing of all third parts to be formed and continue to print all fourth parts to be formed in situ. The above technical solution provides another dead zone coping method, and can better avoid the waste of printing materials and flux than the existing technology, or prevent the three-dimensional printed parts from becoming waste due to severe shrinkage during cooling.

Description

Technical Field

[0001] The present application relates to the field of three-dimensional printing, and in particular to a three-dimensional printing method. Background Art

[0002] In the prior art, one 3D printing method forms a 3D printed object by selectively sintering powdered printing material layer by layer. A 3D printing system generally includes a 3D printer and a build unit. The build unit is fixed relative to the 3D printer during the printing process. The build unit is used to store and transport printing material. The build unit also has a build platform that rises and falls along the Z-axis. A 3D printer generally includes a preheating unit, a powder spreading unit, and a printing unit. The powder spreading unit has a powder spreading roller that reciprocates relative to the build unit along the Y-axis to spread the printing material delivered by the build unit onto the build platform. The preheating unit is located above the build platform along the Z-axis. The preheating unit has an array of preheating lamps. Each preheating lamp is used to preheat the printing material laid onto the build platform. The printing unit reciprocates relative to the build unit along the X-axis and includes an injection assembly and a fluxing assembly. The injection assembly includes multiple nozzles that selectively spray flux onto the printing material on the build platform according to injection commands from a controller during the movement of the printing unit. The fluxing assembly is used to sinter and melt the printing material to which the flux has been injected. After a layer of printing material is laid and printed, the build platform moves downward to facilitate the powder spreading unit to lay the next layer of printing material onto the build platform. Finally, a printing cavity is formed on the build platform, which accommodates the 3D printed part and the printing material wrapped around it.

[0003] Due to various potential faults during 3D printing, dead zones are prone to appearing during the printing process. A dead zone is primarily a projected range on the build platform, with different faults having different projections. Once a dead zone appears, defects will inevitably appear in the parts being printed within it. Furthermore, if the fault cannot be corrected or the dead zone does not disappear on its own, the dead zone will affect a cylindrical area extending above the projected range along the Z-axis as printing progresses. All parts within this cylindrical area will be defective. If the fault is corrected or the dead zone disappears on its own, it will no longer affect other parts above it along the Z-axis.

[0004] To detect dead zones or faults that could cause them, conventional technology uses a thermopile sensor in the preheating unit to sense the temperature of the 3D printing material applied to the build platform. Conventional technology also uses distributed optical sensors around the jetting assembly of the printing unit, with each optical sensor corresponding to a nozzle, to detect any abnormalities. Conventional technology also uses an imaging device on the side of the build platform to detect the surface morphology of the 3D printing material applied to the build platform.

[0005] Once a dead zone appears, some existing technologies do not respond and continue printing according to the predetermined printing plan; some stop the printing process and issue an alarm while waiting for maintenance and troubleshooting; some respond by rearranging the remaining part of the part to be molded in the printing cavity and printing according to the new plan. Summary of the Invention

[0006] The purpose of this application is to provide a three-dimensional printing method, which provides another dead zone coping method outside the existing technology.

[0007] In order to achieve the above objectives, the following technical solutions are adopted:

[0008] The first technical solution relates to a three-dimensional printing method, which detects the occurrence and disappearance of dead zones during the three-dimensional printing process; if it is determined that a dead zone occurs, all first parts to be formed that have been affected by the dead zone and will be affected by the dead zone, as well as all second parts to be formed that are not affected by the dead zone, are determined and printed according to the first solution; the first solution is to cancel the printing of all first parts to be formed and continue to print all second parts to be formed in situ; if it is determined that the dead zone disappears, all third parts to be formed that have been affected by the dead zone and all fourth parts to be formed that are not affected by the dead zone are determined and printed according to the second solution; the second solution is to cancel the printing of all third parts to be formed and continue to print all fourth parts to be formed in situ.

[0009] The second technical solution is based on the first technical solution. During the three-dimensional printing process, it also detects faults that will inevitably lead to the appearance of dead zones and eliminates the faults. If the fault occurs, it is determined that a dead zone appears. If the fault is eliminated, it is determined that the dead zone disappears.

[0010] The third technical solution is based on the first technical solution. After determining that a dead zone appears, it prompts all first parts to be formed to be cancelled; after determining that the dead zone disappears, it prompts all third parts to be formed to be cancelled.

[0011] The fourth technical solution is based on the second technical solution. During the three-dimensional printing process, a light sensor is used to detect whether the nozzle is abnormal. If the nozzle is determined to be abnormal, the nozzle is controlled to flash at a position away from the building unit. After the nozzle flashes, the light sensor is used to detect whether the nozzle is abnormal again. If the result of the re-detection is still that the nozzle is abnormal, a dead zone is determined to appear, and the range of the dead zone is determined according to the position of the nozzle perpendicular to the movement direction of the printing unit; if the result of the re-detection is that the nozzle is normal, the dead zone is determined to disappear, and the range of the dead zone is determined according to the position of the nozzle perpendicular to the movement direction of the printing unit.

[0012] The fifth technical solution is based on the first technical solution. During the three-dimensional printing process, the surface of the printed material after powder spreading is detected by an imaging device. If at least two depressions or protrusions extending along the powder spreading direction are found on the surface of the printed material, it is determined that a dead zone appears. The dead zone range occupies the entire surface of the printed material along the powder spreading direction, and the width perpendicular to the powder spreading direction is the width of the depression or protrusion; if the surface of the printed material is found to be restored to flatness, it is determined that the dead zone disappears.

[0013] The sixth technical solution is based on the first technical solution. During the three-dimensional printing process, the surface of the printed material after powder coating is detected by an imaging device. If irregular micro-depressions or protrusions are found on the surface of the printed material, it is determined that a dead zone appears, and the dead zone range is the range where the irregular depressions or protrusions are located; if the surface of the printed material is found to be flat again, it is determined that the dead zone disappears.

[0014] The seventh technical solution is based on the first technical solution. During the three-dimensional printing process, the surface of the printed material after powder coating is detected by a thermopile sensor located above the surface of the printed material. If irregular temperature mutation areas are found on the surface of the printed material, it is determined that a dead zone appears, and the dead zone range is the range corresponding to the irregular temperature mutation area; if the irregular temperature mutation area on the surface of the printed material disappears, it is determined that the dead zone disappears.

[0015] The eighth technical solution is based on the first technical solution. During the three-dimensional printing process, a thermopile sensor located above the surface of the printed material is used to detect the surface of the printed material before the flux is applied. If regular areas with temperatures higher or lower than a threshold are found on the surface of the printed material, it is determined that a dead zone has occurred. The dead zone range is the range corresponding to the area with a temperature higher or lower than the threshold.

[0016] The ninth technical solution is based on the first technical solution. During the three-dimensional printing process, the surface of the printed material after powder spreading is detected by an imaging device. If depressions or protrusions are found on the surface of the printed material that are not distributed along the powder spreading direction but extend along the powder spreading direction, it is determined that a dead zone appears, and the dead zone range is the range where the depressions or protrusions are located.

[0017] The tenth technical solution is based on the first technical solution. During the three-dimensional printing process, the surface of the printed material after the flux is applied is detected by an imaging device. If lumps are found on the surface of the printed material, it is determined that a dead zone has appeared. The dead zone range is the range enclosed by all lumps.

[0018] Compared with the prior art, the above solution has the following beneficial effects:

[0019] In the prior art, if no response is taken after the dead zone appears and printing is still performed according to the predetermined printing plan, it will cause a waste of printing materials and flux. If the printing process is stopped after the dead zone appears, the three-dimensional printed parts that have been printed and formed in the printing cavity may become waste due to the insufficient thickness of the printing material covering them, which causes drastic shrinkage during cooling, which also causes waste. There will still be problems when rearranging the parts to be formed in the remaining part of the printing cavity. This is because the arrangement of the three-dimensional printed parts in the printing cavity often takes into account the maximum packing rate. Once the packing is rearranged, the distance between the three-dimensional printed part and the wall of the printing cavity will inevitably become smaller, or the distance between the three-dimensional printed part and the upper surface of the printing material after printing is completed will become shorter, which will still cause the three-dimensional printed part to shrink drastically during cooling and become waste.

[0020] It is for the above reasons that, in the first technical solution, after the dead zone appears, on the one hand, the printing of all the first parts to be formed that have been affected by the dead zone and will be affected by the dead zone is canceled, and on the other hand, all the second parts to be formed that are not affected by the dead zone are printed in situ. The "parts to be formed" here refers to the parts to be printed that have not completed the molding process, including not only the parts to be printed that have not started printing, but also the parts to be printed that are only partially formed. The "in situ" here means that the preset positions of all the parts to be formed in the printing cavity are not moved. Since all the first parts to be formed are no longer printed, there is no waste of printing materials and flux. Since the second part to be formed is printed in situ, the gap between the three-dimensional printed part and the wall of the printing cavity or the distance between the three-dimensional printed part and the upper surface of the printed material after printing will not be shortened due to displacement, and there will be no situation where the part becomes waste due to severe shrinkage during cooling.

[0021] In the first technical solution, after the dead zone disappears, the third part to be formed that has been affected by the dead zone and the fourth part to be formed that is not affected by the dead zone are re-determined. This can save as much as possible the parts to be formed that were classified as the first part to be formed after the dead zone appeared but will no longer be affected by the dead zone after the dead zone disappears, thereby improving labor productivity.

[0022] The second technical solution, by detecting faults that inevitably lead to the appearance of dead zones and eliminating such faults, helps identify dead zones whose appearance and disappearance cannot be determined by other detection methods. This helps detect more dead zones that may affect the quality of 3D printed parts.

[0023] In the third technical solution, by prompting the user or operator of the cancelled parts to be formed, it is helpful for the user or operator to intervene in the printing process.

[0024] In the fourth technical solution, after the optical sensor detects that the print head is abnormal, flash spraying can be used to determine whether the print head can return to normal. Because flash spraying has a higher pressure and spray volume than ordinary spraying, it may clear the blockage of the print head. If flash spraying can restore the print head to normal, it will be handled as if the dead zone has disappeared. If flash spraying cannot restore the print head to normal, it will be handled as if a dead zone has appeared. Of course, those skilled in the art know that the existing technology has also suggested that when a print head fails, the dead zone range at this time is the entire size of the build platform in the X-axis direction, that is, the direction of movement of the printing unit, and the size that can be covered by the faulty print head in the Y-axis direction.

[0025] In the fifth technical solution, if the imaging device observes at least two depressions or protrusions extending in the direction of powder spreading on the surface of the printing material after powder spreading, it can be determined that the dead zone has occurred due to damage to the powder spreading roller or contamination. Since the powder spreading roller is cleaned after each powder spreading operation, this dead zone may disappear. If the surface of the printing material is found to be smooth, it can be determined that the dead zone has disappeared.

[0026] In the sixth technical solution, if the imaging device observes irregular depressions or protrusions on the surface of the printed material after applying powder, it can be determined that the dead zone is caused by foreign matter in the printed material. In this case, after a period of printing, as the influence of the foreign matter gradually disappears, the dead zone may disappear. If the printed material surface is found to be smooth, it can be determined that the dead zone has disappeared.

[0027] In the seventh technical solution, if the thermopile sensor detects an irregular temperature change after powder application, it can also be determined that the dead zone is caused by foreign matter in the printing material. In this case, after a period of printing, as the influence of the foreign matter gradually disappears, the dead zone may disappear. If the printed material surface is found to be smooth, the dead zone can be determined to have disappeared.

[0028] In the eighth technical solution, if the thermopile sensor detects regular areas of temperature above or below a threshold on the printed material surface before flux is applied, it can be determined that the dead zone is caused by a preheat lamp failure. In this case, the fault cannot be corrected during the printing process, so the dead zone generally persists.

[0029] In the ninth technical solution, the imaging device examines the surface of the printed material after powder application. If it detects any depressions or protrusions extending in the direction of powder application, but these depressions or protrusions are not aligned in that direction, it can be determined that insufficient preheating by the preheat lamps has resulted in incomplete melting of the printed material, causing smearing during powder application and the resulting dead zone. In this case, the problem cannot generally be corrected during printing, so the dead zone typically persists.

[0030] In the tenth technical solution, the imaging device inspects the surface of the printed material after flux has been applied. If any lumps are detected, it can be determined that the preheat lamps overheated the printed material, causing excessive melting of the printed material, leading to lumps of the surrounding printed material and the resulting dead zone. In this case, the problem cannot generally be corrected during printing, so the dead zone typically persists.

[0031] Combining the fourth to tenth technical solutions, by detecting the appearance and disappearance of the dead zone through various technical means, the impact of the dead zone on the printing process can be minimized as much as possible, avoiding the waste of printing materials and flux. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solution of the embodiment, the following briefly introduces the drawings required for use:

[0033] Figure 1 is a simplified diagram of a three-dimensional printing system in an embodiment;

[0034] Figure 2 This is a photo of the dead zone caused by damage to the powder roller or foreign matter stuck on it;

[0035] Figure 3 This is a photo of a dead zone caused by foreign matter in the printed material;

[0036] Figure 4 This is the reflection of the dead zone caused by foreign matter in the printing material on the data expressed by the thermopile sensor array.

[0037] Description of main reference numerals:

[0038] 1. Preheating unit; 2. Build platform; 3. Printing unit; 4. Powder spreading unit; 5. Imaging device; 6. Printing material; 11. Preheating lamp; 12. Thermopile sensor; 31. Jet assembly; 32. Optical sensor; 33. Fluxing assembly. DETAILED DESCRIPTION

[0039] In the claims and the description, unless otherwise defined, the terms "first", "second" or "third", etc. are intended to distinguish different objects rather than to describe a specific order.

[0040] In the claims and the specification, unless otherwise specified, the terms "center", "transverse", "longitudinal", "horizontal", "vertical", "top", "bottom", "inside", "outside", "up", "down", "front", "back", "left", "right", "clockwise", "counterclockwise" and the like to indicate directions or positional relationships are based on the directions and positional relationships shown in the accompanying drawings and are only for the convenience of simplifying the description, and do not imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction.

[0041] In the claims and description, unless otherwise specified, the term "fixed connection" or "fixed connection" should be understood in a broad sense, that is, any connection method in which there is no displacement relationship or relative rotation relationship between the two parties, that is, including non-detachable fixed connection, detachable fixed connection, integral connection, and fixed connection through other devices or elements.

[0042] In the claims and the description, unless otherwise defined, the terms "include", "have" and their variations mean "including but not limited to".

[0043] In the claims and the description, unless otherwise defined, the term "provided with" means that the technical feature thereafter is part of the technical feature therefor.

[0044] In the claims and description, unless otherwise specified, the term "part to be formed" refers to a part to be printed that has not yet completed the forming process, including not only a part to be printed that has not started printing, but also a part to be printed that has only been partially formed.

[0045] In the claims and description, unless otherwise specified, the term "in situ" means that all parts to be molded are not moved from their preset positions in the printing chamber.

[0046] The technical solutions in the embodiments will be described clearly and completely below with reference to the accompanying drawings.

[0047] See also Figure 1 , Figure 1 3D printing system in the embodiment is shown. Figure 1As shown, the 3D printing system in this embodiment includes a 3D printer and a build unit. The build unit is fixed relative to the 3D printer during the printing process. The build unit is used to store and transport printing material 6. The build unit also has a build platform 2 that rises and falls along the Z-axis. The 3D printer includes a preheating unit 1, a printing unit 3, a powder spreading unit 4, and an imaging device 5. The powder spreading unit 4 includes a powder spreading roller that reciprocates relative to the build unit along the Y-axis to spread the printing material 6 transported by the build unit onto the build platform 2. The preheating unit 1 is located above the build platform 2 along the Z-axis. The preheating unit 1 includes an array of preheating lamps 11 and a thermopile sensor 12 located at the center of each preheating lamp 11. Each preheating lamp 11 is used to preheat the printing material 6 placed on the build platform 2. The thermopile sensor 12 is used to sense the temperature of the 3D printing material 6 placed on the build platform 2. The printing unit 3 reciprocates relative to the build unit along the X-axis and includes an ejection assembly 31, a light sensor 32, and a fluxing assembly 33. The injection assembly 31 is provided with a plurality of nozzles, which selectively spray flux onto the printing material 6 on the building platform 2 according to the injection instructions of the controller during the movement of the printing unit 3. The optical sensor 32 is provided corresponding to the nozzle and is used to detect whether the nozzle is abnormal. This is a prior art, and its structure and layout are known to those skilled in the art and will not be described in detail. The fluxing assembly 33 is used to sinter and melt the printing material 6 sprayed with flux. After a layer of printing material is laid and printed, the building platform 2 moves downward to facilitate the powder laying unit to lay the next layer of printing material 6 onto the building platform 2. Finally, a printing cavity is formed on the building platform 2, which accommodates the three-dimensional printed part and the printing material 6 wrapped around the three-dimensional printed part.

[0048] The method for performing three-dimensional printing using the above-mentioned three-dimensional printing system includes: detecting the occurrence and disappearance of dead zones during the three-dimensional printing process; at the same time, detecting faults that inevitably lead to the occurrence of dead zones and eliminating the faults during the three-dimensional printing process; if the fault occurs, it is determined that the dead zone has occurred, and if the fault is eliminated, it is determined that the dead zone has disappeared.

[0049] If a dead zone is determined to exist, all first parts to be formed that have been affected by the dead zone and will be affected by the dead zone, as well as all second parts to be formed that are not affected by the dead zone, are identified and printed according to a first solution. This first solution is to cancel printing of all first parts to be formed and continue printing all second parts to be formed in situ. Here, first parts to be formed that have been affected by the dead zone refer to parts to be formed that have already been printed but are at least partially within the dead zone. Here, first parts to be formed that will be affected by the dead zone refer to parts to be formed that, if the dead zone persists, will at least partially be within the cylindrical space extending along the Z-axis within the dead zone.

[0050] If the dead zone is determined to have disappeared, all third parts to be formed that were affected by the dead zone and all fourth parts to be formed that were not affected by the dead zone are identified and printed according to the second plan. The second plan is to cancel printing of all third parts to be formed and continue printing all fourth parts in situ. Here, the third parts to be formed that were affected by the dead zone are parts to be formed that are at least partially within the dead zone and within a cylindrical space with a predetermined size along the Z-axis from the appearance of the dead zone to its disappearance.

[0051] After determining that the dead zone appears, the operator is prompted that all first parts to be formed are cancelled; after determining that the dead zone disappears, the operator is prompted that all third parts to be formed are cancelled.

[0052] Specifically, during the 3D printing process, this embodiment uses an optical sensor 32 to detect whether the nozzles controlled by the controller are abnormal. If a nozzle abnormality is detected, the printing unit 3 is controlled to move away from the build unit and the nozzles are controlled to flash. After the flash, the optical sensor 32 is used to detect the nozzle abnormality again. If the re-detection result still indicates a nozzle abnormality, a dead zone is determined to have appeared, and the dead zone range is determined based on the position of the nozzle perpendicular to the direction of movement of the printing unit. If the re-detection result indicates that the nozzle is normal, the dead zone is determined to have disappeared, and the dead zone range is determined based on the position of the nozzle perpendicular to the direction of movement of the printing unit. In other embodiments, the optical sensor 32 is not located in the printing unit 3, but is fixed relative to the preheating unit 1 and located to the side of the build unit. The printing unit 3 periodically moves to the position of the optical sensor 32 to detect the nozzles. Of course, the controller can control all nozzles to spray simultaneously or one by one to facilitate detection by the optical sensor 32. In this case, if a nozzle detects an abnormality, the nozzle can be controlled to flash in place to facilitate re-detection by the optical sensor 32. Those skilled in the art will appreciate that, in the above process, the dead zone range is the entire size of the build platform in the X-axis direction, i.e., the direction of movement of the printing unit, and is the size that can be covered by the faulty nozzle in the Y-axis direction.

[0053] In this embodiment, during the three-dimensional printing process, the surface of the printing material 6 after the powder is applied is also detected by the imaging device 5. If the surface of the printing material 6 is found to have the following Figure 2 If at least two depressions or protrusions extending along the powder spreading direction (i.e., the Y-axis) are distributed, it is determined that a dead zone has occurred due to damage to the powder spreading roller or contamination. The dead zone extends along the entire surface of the printing material 6 along the Y-axis, and perpendicular to the X-axis is the width of the depression or protrusion. Since the powder spreading roller is cleaned after each powder spreading operation, this dead zone may disappear. If the surface of the printing material is found to be smooth, it can be determined that the dead zone has disappeared.

[0054] In this embodiment, during the three-dimensional printing process, the surface of the printing material 6 after the powder is applied is also detected by the imaging device 5. If the surface of the printing material 6 is found to have the following Figure 3If there are irregular depressions or protrusions as shown, it is determined that the dead zone is caused by foreign matter in the printing material 6. The dead zone range is the range where the irregular depressions or protrusions are located. Therefore, this dead zone may disappear. If it is found that the surface of the printing material 6 has returned to a smooth state, it is determined that the dead zone has disappeared.

[0055] In the present embodiment, during the three-dimensional printing process, the surface of the printing material 6 after the powder is applied is detected by the thermopile sensor 12 located above the surface of the printing material 6. If the surface of the printing material 4 is found to have the following Figure 4 If an irregular temperature change region is observed, it is determined that a dead zone has occurred due to foreign matter in the printed material 6. The dead zone corresponds to the range of the irregular temperature change region. As the influence of the foreign matter gradually disappears, the dead zone may disappear. If the irregular temperature change region on the surface of the printed material 6 disappears, it is determined that the dead zone has disappeared.

[0056] During the 3D printing process, this embodiment also uses a thermopile sensor 12 located above the surface of the printing material 6 to monitor the surface of the printing material 6 before flux is applied. If regular areas with temperatures above or below a threshold are detected on the surface of the printing material 6, it is determined that a dead zone has occurred due to a malfunction of the preheat lamp 11. The dead zone corresponds to the area corresponding to the temperature above or below the threshold. In this case, the fault cannot generally be corrected during the printing process, so the dead zone generally persists.

[0057] In this embodiment, during the 3D printing process, the imaging device 5 is used to detect the surface of the printing material 6 after the powder is spread. If depressions or protrusions are found on the surface of the printing material 6 that are not distributed along the powder spreading direction, i.e., the Y-axis direction, but extend along the Y-axis direction, it is determined that the preheating lamp is not heating enough, resulting in incomplete melting of the printing material 6, and a tailing phenomenon occurs during the powder spreading, resulting in the formation of a dead zone. Such depressions or protrusions are related to the Figure 3 The dead zone is similar to the concavity in the image, but there will not be more than two concavities distributed along the Y axis. The dead zone is the area where the concavity or convexity is located. In this case, the fault cannot be corrected during printing, so the dead zone usually does not disappear.

[0058] During the 3D printing process, this embodiment also uses the imaging device 5 to inspect the surface of the printing material 6 after the flux has been applied. If lumps are detected on the surface of the printing material 6, it is determined that the corresponding preheating lamp 11 has overheated the printing material 6, causing excessive melting of the printing material 6, resulting in surrounding lumps of printing material 6 and the formation of a dead zone. The dead zone is the area enclosed by all the lumps. In this case, the fault cannot generally be corrected during the printing process, so the dead zone generally does not disappear.

[0059] In this embodiment, after a dead zone appears, printing of all first-part molded parts already affected or about to be affected by the dead zone is canceled. Meanwhile, printing of all second-part molded parts not affected by the dead zone is continued in situ. Since all first-part molded parts are no longer printed, no printing material or flux is wasted. Since the second-part molded parts are printed in situ, displacement prevents the gap between the 3D printed part and the print chamber wall, or the distance between the 3D printed part and the top surface of the printed material from decreasing. Consequently, there is no risk of waste due to drastic shrinkage during cooling.

[0060] In this embodiment, after the dead zone disappears, the third part to be formed that has been affected by the dead zone and the fourth part to be formed that is not affected by the dead zone are re-determined. This can save as much as possible the parts to be formed that were classified as the first part to be formed after the dead zone appeared but will no longer be affected by the dead zone after the dead zone disappears, thereby improving labor productivity.

[0061] This embodiment, by detecting faults that inevitably lead to the appearance of dead zones and eliminating such faults, is helpful in identifying dead zones whose appearance and disappearance cannot be determined by other detection methods, and is helpful in detecting more dead zones that may affect the quality of 3D printed parts.

[0062] This embodiment helps the user or operator to intervene in the printing process by prompting the operator of the cancelled parts to be formed.

[0063] This embodiment detects the appearance and disappearance of the dead zone through various technical means, which can minimize the impact of the dead zone on the printing process and avoid waste of printing materials and flux.

[0064] The above description of the specification and embodiments is used to explain the scope of protection of the present application, but does not constitute a limitation on the scope of protection of the present application.

Claims

1. A three-dimensional printing method, characterized by: Detect the appearance and disappearance of dead zones during 3D printing; If it is determined that a dead zone occurs, all first parts to be formed that have been affected by the dead zone and will be affected by the dead zone and all second parts to be formed that are not affected by the dead zone are determined and printed according to the first plan; The first solution is to cancel the printing of all first parts to be formed and continue to print all second parts to be formed in situ; If it is determined that the dead zone disappears, all third parts to be formed that have been affected by the dead zone and all fourth parts to be formed that are not affected by the dead zone are determined and printed according to the second scheme; the second scheme is to cancel printing of all third parts to be formed and continue to print all fourth parts to be formed in situ.

2. A three-dimensional printing method according to claim 1, characterized in that: During the 3D printing process, it also detects faults that inevitably lead to dead zones and eliminates these faults; If the fault occurs, it is determined that the dead zone occurs; if the fault is eliminated, it is determined that the dead zone disappears.

3. A three-dimensional printing method according to claim 1, characterized in that: After it is determined that the dead zone appears, it is prompted that all the first parts to be formed are cancelled; after it is determined that the dead zone disappears, it is prompted that all the third parts to be formed are cancelled.

4. A three-dimensional printing method according to claim 2, characterized in that: During the 3D printing process, an optical sensor is used to detect whether the nozzle is abnormal. If the nozzle is determined to be abnormal, the nozzle is controlled to flash at a position away from the building unit. After the nozzle flashes, the optical sensor is used to detect whether the nozzle is abnormal again. If the result of the second detection is still that the nozzle is abnormal, a dead zone is determined to have appeared, and the range of the dead zone is determined according to the position of the nozzle perpendicular to the movement direction of the printing unit. If the result of the second detection is that the nozzle is normal, the dead zone is determined to have disappeared, and the range of the dead zone is determined according to the position of the nozzle perpendicular to the movement direction of the printing unit.

5. A three-dimensional printing method according to claim 1, characterized in that: During the 3D printing process, the surface of the printed material after powder spreading is detected by an imaging device. If at least two depressions or protrusions extending in the powder spreading direction are found on the surface of the printed material, a dead zone is determined to exist. The dead zone covers the entire surface of the printed material along the powder spreading direction, and the width perpendicular to the powder spreading direction is the width of the depression or protrusion. If the printed material surface is found to be flat again, it is determined that the dead zone has disappeared.

6. A three-dimensional printing method according to claim 1, characterized in that: During the 3D printing process, the surface of the printed material after powder coating is detected by an imaging device. If irregular depressions or protrusions are found on the surface of the printed material, a dead zone is determined to be present. The dead zone range is the area where the irregular depressions or protrusions are located. If the printed material surface is found to be flat again, it is determined that the dead zone has disappeared.

7. A three-dimensional printing method according to claim 1, characterized in that: During the 3D printing process, a thermopile sensor located above the surface of the printing material detects the surface of the printing material after powder coating. If an irregular temperature change area is found on the surface of the printing material, a dead zone is determined to exist. The dead zone range is the range corresponding to the irregular temperature change area. If it is found that the irregular temperature mutation area on the surface of the printing material disappears, it is determined that the dead zone disappears.

8. A three-dimensional printing method according to claim 1, characterized in that: During the 3D printing process, a thermopile sensor located above the surface of the printed material detects the surface of the printed material before the flux is applied. If regular areas with temperatures above or below a threshold are found on the surface of the printed material, a dead zone is determined to have occurred. The dead zone range corresponds to the area where the temperature is above or below the threshold.

9. A three-dimensional printing method according to claim 1, characterized in that: During the 3D printing process, an imaging device is used to detect the surface of the printed material after powder spreading. If depressions or protrusions are found on the surface of the printed material that are not distributed along the powder spreading direction but extend along the powder spreading direction, a dead zone is determined to exist. The dead zone range is the range where the depressions or protrusions are located.

10. A three-dimensional printing method according to claim 1, characterized in that: During the 3D printing process, the surface of the printed material after the flux is applied is detected by an imaging device. If lumps are found on the surface of the printed material, a dead zone is determined to be present. The dead zone range is the range enclosed by all the lumps.

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