Photocuring 3D printing method, 3D printer and 3D printing control system

Abstract

The invention relates to the field of 3D printing, in particular to a photocuring 3D printing method, a 3D printer and a 3D printing control system. The photocuring 3D printing method comprises the following steps that a forming platform of a forming body descends, when the distance between the bottom face of the forming body and the bottom of a charging tray is a preset distance, the forming platform is stopped, and the preset distance is smaller than the thickness of a single-layer printing layer; a forming platform of the forming body is lifted, and when the distance between the bottom face of the forming body and the bottom of the charging tray is equal to the thickness of the single-layer printing layer, the forming platform stops ascending; and the bottom of the tray is irradiated with ultraviolet light, so that the photosensitive resin is cured. According to the invention, bubbles can be broken or squeezed away from the lower part of the forming body, so that the generation rate of the bubbles below the forming body is greatly reduced, and the yield of products is improved.

Description

[0001] This application is a divisional application of the invention patent application with application number 201910712994.2 filed on August 2, 2019. Technical Field

[0002] The present invention relates to the field of 3D printing, and in particular to a light-curing 3D printing method, a 3D printer and a 3D printing control system. Background Art

[0003] The technical principle of the traditional projection light-curing printer is:

[0004] First, 3D modeling is performed to design a three-dimensional solid model of the product. Then, the model is sliced ​​through the software to obtain the data of the light spot shape (light source control). Then, photosensitive resin is placed in the material tray (the photosensitive resin is quickly solidified under light irradiation to form a solid product). The molding platform is placed on the material tray, and the molding end surface of the molding platform will contact the photosensitive resin. Then, the optical machine will emit a light spot shape of the corresponding shape according to the sliced ​​data, and the layer of resin will be solidified. After the layer is printed, the molding platform moves upward a short distance under the drive of the lifting mechanism (for the sinking DLP printer, the molding platform moves downward), and then, on the basis of the previous layer of solidified resin, the shape of the next layer is printed. Finally, the layers are stacked to obtain the desired 3D printed product.

[0005] In the existing bottom projection light-curing 3D printing method, the molding platform is constantly immersed in and exposed from the photosensitive resin liquid. This action is equivalent to constantly stirring the photosensitive resin liquid, which will cause air to mix into the photosensitive resin liquid, resulting in bubbles in the photosensitive resin liquid, and ultimately causing pore defects in the printed molded product, resulting in poor finished product problems. Summary of the invention

[0006] The object of the present invention is to provide a light-curing 3D printing method, which can reduce or avoid the generation of bubbles during the printing process and improve the yield rate.

[0007] Another object of the present invention is to provide a 3D printer, which can reduce or avoid the generation of bubbles during printing and improve the yield rate.

[0008] Another object of the present invention is to provide a 3D printing control system, which can control the generation of bubbles during the printing process and improve the yield rate.

[0009] The embodiment of the present invention is achieved as follows:

[0010] A light-curing 3D printing method comprises the following steps:

[0011] Step S10: the molding platform descends until the distance between the bottom surface of the molding body and the bottom of the material tray is T2, and the molding platform stops descending, and T2 is less than the single-layer printing thickness T1;

[0012] Step S20: the molding platform rises until the distance between the bottom surface of the molding body and the bottom of the tray is T1, and then the molding platform stops rising;

[0013] Step S30: light-curing printing.

[0014] When printing, the molded body is first lowered to a small distance T2 between its bottom surface and the bottom of the material tray, and T2 is less than the single-layer printing thickness T1, so that during the lowering process of the molded body, the bubbles can be squeezed or squeezed out from the bottom of the molded body, thereby greatly reducing the bubble generation rate under the molded body and improving the product yield.

[0015] In a preferred embodiment of the present invention, after step S30, step S40 is performed: separating the molded body and the tray.

[0016] In a preferred embodiment of the present invention, after step S30, step S10 is performed again, and the process loops until the workpiece printing is completed.

[0017] In a preferred embodiment of the present invention, in step S30, the light curing operation mode is to turn on the light source to irradiate the bottom of the material tray to cure the photosensitive resin.

[0018] In a preferred embodiment of the present invention, the light source is an ultraviolet laser.

[0019] In a preferred embodiment of the present invention, after step S10, a delay operation is performed.

[0020] In a preferred embodiment of the present invention, after step S20, a delay operation is performed.

[0021] In a preferred embodiment of the present invention, the molding body comprises a molding platform;

[0022] Alternatively, the molding body further includes a molding piece, and the molding piece is arranged on a side of the molding platform close to the material tray.

[0023] The present invention also provides a 3D printer, which uses any of the above-mentioned light-curing 3D printing methods for printing.

[0024] The present invention also provides a 3D printing control system used to implement the above-mentioned 3D printer, which includes a data processor, a data acquisition module, a molding platform ascending unit, a molding platform descending unit and a light-curing printing unit;

[0025] The data processor is respectively connected to the data acquisition module, the molding platform ascending unit, the molding platform descending unit and the light-curing printing unit through signals.

[0026] The beneficial effects of the embodiments of the present invention are:

[0027] When printing, the molded body is first lowered to a small distance T2 between its bottom surface and the bottom of the material tray, and T2 is less than the single-layer printing thickness T1, so that during the lowering process of the molded body, the bubbles can be squeezed or squeezed out from the bottom of the molded body, thereby greatly reducing the bubble generation rate under the molded body and improving the product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A flow chart of a light-curing 3D printing method provided in an embodiment of the present invention;

[0030] Figure 2 A specific flow chart of the light-curing 3D printing method provided in an embodiment of the present invention;

[0031] Figure 3 A schematic diagram of the structure of a light-curing 3D printer provided in an embodiment of the present invention;

[0032] Figure 4 A schematic diagram of the state of the light-curing 3D printer provided in an embodiment of the present invention before performing step S10;

[0033] Figure 5 A schematic diagram of the state of the light-curing 3D printer provided in an embodiment of the present invention when performing step S10;

[0034] Figure 6 A schematic diagram of the state of the light-curing 3D printer provided in an embodiment of the present invention when performing step S20;

[0035] Figure 7 A schematic diagram of the state of the light-curing 3D printer provided by an embodiment of the present invention when performing step S20.

[0036] In the figure:

[0037] 1-lifting mechanism; 2-lifting arm; 3-molding platform; 4-resin; 5-material tray; 7-molded part; 8-bubble; 9-molded body. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0041] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0042] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0043] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] The following is combined with Figure 1 -Attached Figure 7 , some embodiments of the present invention are described in detail. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0045] The present invention provides a light-curing 3D printing method, which comprises the following steps:

[0046] Step S10: the molding platform 3 descends until the distance between the bottom surface of the molding body 9 and the bottom of the material tray 5 is T2, and then the molding platform stops descending, and T2 is less than the single-layer printing thickness T1;

[0047] Step S20: the molding platform 3 rises until the distance between the bottom surface of the molding body 9 and the bottom of the tray 5 is T1, and then the molding platform stops rising;

[0048] Step S30: light-curing printing.

[0049] Before printing the first layer of molded part 7, liquid photosensitive resin 4 needs to be poured into the material tray 5. During the pouring process, air will be mixed into the resin 4, thereby generating bubbles 8. During the printing process, since the bottom of the molded body 9 is constantly immersed in the resin 4 and floats out of the resin 4, the molded body 9 is equivalent to constantly stirring the photosensitive resin 4, stirring air into the resin 4.

[0050] It can be seen that the bubble problem runs through the entire 3D printing process, and the 3D printing method of the present invention is applicable to all stages of the light-curing 3D printing process.

[0051] In order to solve the bubble problem, in this embodiment, the following 3D printing method is used:

[0052] First, the molding platform 3 is lowered until the distance between the bottom surface of the molding body 9 and the bottom of the material tray 5 is T2, and T2 is less than the single-layer printing thickness T1; then the molding platform 3 is raised until the distance between the bottom surface of the molding body 9 and the bottom of the material tray 5 is T1, and then light-curing printing is performed.

[0053] It should be noted that, when the molding platform 3 descends to the distance T2 between the bottom surface of the molding body 9 and the bottom of the tray 5, the molding platform 3 can be descended in a segmented manner or in a direct manner. The segmented descent means that the movement stroke of the molding platform 3 is composed of multiple segments. The segmented descent can avoid excessive bubbles at the bottom of the molding body due to too fast a descent speed. The direct descent means that the movement stroke of the molding platform 3 is one segment, that is, the descent process of the molding platform 3 is one-step. The direct descent can reduce time and improve efficiency.

[0054] When the bottom of the molded body 9 moves to a position at a distance T2 from the bottom wall of the tray 5, the bottom of the molded body 9 will further squeeze the bubbles 8 out of the molding area, that is, the area between the bottom of the molded body 9 and the bottom wall of the tray 5, thereby reducing hole defects.

[0055] During the printing process, the amount of change between layers is relatively small. In other words, the printing area of ​​the previous layer is similar to the printing area of ​​the next layer. Therefore, by controlling the molding body 9 to descend, the bubbles 8 below the molding body 9 can be squeezed out or broken, thereby greatly reducing the bubbles 8 below the molding body 9. This is equivalent to reducing the bubbles 8 in the molding area when the next layer is printed.

[0056] In addition, when the molded body 9 descends, a positive error will be generated due to the descending movement, and then when the molded body 9 rises, a negative error will be generated due to the rising movement. These two errors offset each other, which can further improve the position accuracy of the molded body 9 relative to the material tray 5 and improve the molding quality of 3D printing.

[0057] At the same time, during the rising process of the molding body 9, the molding area between the molding body 9 and the bottom of the material tray 5 will increase instantly, thereby generating negative pressure, so that the photosensitive resin 4 can be quickly filled, thereby improving the density of the printed product.

[0058] In addition, since the values ​​of T2 and T1 are very small, the time spent by the molded body 9 in the above-mentioned movement process is very small and can be almost ignored.

[0059] The specific operation of the light-curing printing in step S30 is as follows:

[0060] The light source is turned on, and ultraviolet light is irradiated to the bottom of the material tray 5 , so that the photosensitive resin 4 is cured and becomes a part of the molded part 7 .

[0061] Before step S10, a pre-processing step S00 is also included. The pre-processing step S00 includes 3D printing modeling, slicing processing, printing parameter determination, etc., wherein the printing parameter determination includes determining the setting of a single-layer printing thickness T1, etc. The value of T1 is determined based on factors such as the printing material, the shape of the model, and user needs.

[0062] In this embodiment, the range of T2 is 0≤T2≤T1. When T2 is too small, the time required for the resin 4 to reflow will be longer, which will extend the printing time, reduce efficiency, and even cause incomplete reflow of the resin 4; when T2 is too large, the defoaming effect will be reduced.

[0063] Therefore, it is necessary to select a maximum value of T2 that can meet the defoaming effect through testing.

[0064] In a preferred embodiment of the present invention, after step S30, step S40 is performed: separating the molded body and the tray.

[0065] The operation of "separating the molded body and the material tray" in step S40 is specifically as follows: after completing the single-layer light-curing printing operation, the bottom of the molded body 9 will be close to the bottom wall of the material tray 5, that is, the bottom of the molded part 7 will be close to the bottom wall of the material tray 5. In order to separate the molded part 7 from the material tray 5, the molded body 9 rises to a specified height when necessary.

[0066] The designated height can be set according to user needs, as long as the molded part 7 and the tray 5 are completely separated.

[0067] In a preferred embodiment of the present invention, after step S40, step S10 is performed again, and the process loops until the workpiece printing is completed.

[0068] That is to say, when printing each layer, it first descends, and the bottom surface of the molded part 7 after descending is at a distance T2 from the bottom of the material tray 5, and then rises a distance T1, performing a cycle of descending and ascending, so that no bubbles 8 are generated when each layer is printed, ensuring the yield rate.

[0069] In a preferred embodiment of the present invention, the light source is an ultraviolet laser.

[0070] It should be pointed out that, in the present embodiment, the light source is an ultraviolet laser, but it is not limited to ultraviolet laser, and it can also be other light sources as long as it can achieve photocuring of the printed material.

[0071] In a preferred embodiment of the present invention, after step S10, a delay operation is performed.

[0072] Between step S10 and step S20, a delayed operation may be performed, which is step S11, that is, after performing step S10, the operation is stopped for a certain period of time, and then the operation of step S20 is performed.

[0073] The function of step S11 is to wait for the air bubbles 8 to be discharged, so as to avoid the molded part 7 from rising when the air bubbles 8 are not completely discharged, thereby causing the air bubbles 8 to flow back along with the resin 4, thereby ensuring the yield rate of the product.

[0074] It should be pointed out that, in the present embodiment, step S11 is a non-essential step, that is, after ensuring that the bubbles 8 are fully discharged or burst, step S11 can be directly skipped from step S10 to enter step S20.

[0075] In a preferred embodiment of the present invention, after step S20, a delay operation is performed.

[0076] There is also a delay operation between step S20 and step S30, which is step S21. That is, after step S20 is performed, the operation is stopped for a certain period of time, and then the operation of step S30 is performed.

[0077] The purpose of step S21 is to wait for the resin 4 to flow back to ensure that there is enough resin 4 for light-curing 3D printing.

[0078] In a preferred embodiment of the present invention, the forming body 9 includes a forming platform 3 .

[0079] In this embodiment, the molded body 9 at least includes a molding platform 3 and a molded part 7 .

[0080] Specifically, before the 3D printer performs 3D printing, the molding body 9 only includes the molding platform 3, and the bottom of the molding body 9 is the bottom of the molding platform 3.

[0081] After the 3D printer performs the first layer printing, the molding body 9 includes the molding part 7 and the molding platform 3 , and the bottom of the molding body 9 is the bottom of the molding part 7 .

[0082] The present invention also provides a 3D printer, which uses any of the above-mentioned light-curing 3D printing methods for printing.

[0083] The light-curing 3D printer using the method of the present invention comprises:

[0084] light source;

[0085] The material tray 5 is located above the light source and is used to hold the photosensitive resin 4, and the bottom thereof corresponding to the light source is transparent;

[0086] The molding platform 3 is located above the material tray 5 and is used to carry the 3D printed molded part 7. Figure 4-Figure 7 The molded part 7.

[0087] The lifting mechanism 1 is connected to the molding platform 3 via the lifting arm 2, and the lifting mechanism 1 can drive the molding platform 3 to move in the vertical direction.

[0088] The light source can be selected as an ultraviolet laser light source (corresponding to an SLS printer), a DLP light source (corresponding to a DLP printer) or an LCD light source. Preferably, the present solution uses a DLP light source, i.e. a DLP optical machine.

[0089] In addition, in the 3D printer of the present invention, a matching control system is provided to implement the light-curing 3D printing method of the present invention.

[0090] Specifically, in this embodiment, the control system includes the following modules:

[0091] Data processor, the center of the control system, all data exchanges are processed through the data processor;

[0092] A data acquisition module is used to collect the distance between the bottom surface of the molded body and the bottom of the tray, and send the collected data to the data processor;

[0093] The execution module mainly includes a molding platform lifting unit, a molding platform lowering unit, and a light-curing printing unit, which are respectively used for the lifting and lowering of the molding body, and light-curing printing;

[0094] The timer is used to time the delayed operation of the molding body.

[0095] Specifically, during light-curing 3D printing, the control process of the control system is as follows:

[0096] The data processor sends instructions to the molding platform descending unit of the execution module to descend the molding platform, that is, to control the lifting mechanism 1 to start working, driving the molding platform to descend, and at the same time the data acquisition module starts to collect the distance between the bottom surface of the molding platform and the inner bottom of the material tray.

[0097] When the distance reaches the set value T2, the data processor receives feedback from the data acquisition module and sends a stop command to the molding platform descending unit of the execution module to stop the molding platform descending unit from descending. At the same time, the data processor sends a timing command to the timer, and the timer starts working.

[0098] When the time recorded by the timer reaches the set time, the timer feeds back the time data to the data processor. After receiving the data signal from the timer, the data processor sends a start operation instruction to the molding platform lifting unit of the execution module, and the molding platform lifting unit starts the lifting operation, that is, controls the lifting mechanism 1 to start the operation, driving the molding platform to rise. At this time, the data acquisition module continues to operate to collect the distance between the bottom surface of the molding platform and the inner bottom of the tray.

[0099] When the distance collected by the data acquisition module reaches the set value T1, it feeds back the data to the data processor in real time. The data processor receives the data information sent by the data acquisition module and sends a stop command to the molding platform lifting unit to stop the molding platform lifting unit from rising. At the same time, the data processor sends a timing command to the timer, and the timer starts working.

[0100] When the time recorded by the timer reaches the set time, the timer feeds back the time data to the data processor, and after receiving the time data signal from the timer, the data processor sends a start printing instruction to the light-curing printing unit to start light-curing 3D printing. That is, after the light source is turned on, 3D printing is performed.

[0101] After the data processor detects that printing is completed, the data processor sends a separation instruction to the molding platform lifting unit, and the molding platform lifting unit starts to work, driving the molding platform to rise. At this time, the rising distance is T3.

[0102] At this point, one layer of printing is completed, that is, one printing cycle is completed, wherein 0≤T2≤T1≤T3, T1 is the single-layer printing thickness in the cycle.

[0103] The data processor performs a second printing cycle based on the modeling and slicing data, and so on, until the product is completely printed.

[0104] In one embodiment of the present invention, the data acquisition module includes a distance sensor for detecting the distance between the bottom surface of the molded body and the bottom of the tray. In another embodiment of the present invention, the data acquisition module detects the motion data of the lifting mechanism, determines the current position of the molding platform according to the motion data of the lifting mechanism, and finally obtains the distance information between the bottom surface of the molded body and the bottom of the tray in combination with the height information of the current molded body.

[0105] The beneficial effects of the embodiments of the present invention are:

[0106] When printing, the molded body 9 is first lowered to a small distance T2 between its bottom surface and the bottom of the material tray 5, and T2 is less than the single-layer printing thickness T1, so that in the process of the molded body 9 being lowered, the bubbles 8 can be squeezed or squeezed out from the bottom of the molded body 9, thereby greatly reducing the generation rate of bubbles 8 under the molded body 9 and improving the product yield.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A light-curing 3D printing method, characterized in that: include: Lowering a molding platform of the molding body, and stopping the molding platform when the distance between the bottom surface of the molding body and the bottom of the material tray is a predetermined distance, wherein the predetermined distance is less than the thickness of a single-layer print; The molding platform of the molding body is lifted, and when the distance between the bottom surface of the molding body and the bottom of the material tray is the thickness of a single printing layer, the molding platform stops rising; and The bottom of the material tray is irradiated with ultraviolet light to cure the photosensitive resin.

2. The light-curing 3D printing method according to claim 1, wherein: The forming platform of the descending forming body comprises: the descending forming platform makes the forming platform consist of one or more strokes.

3. The light-curing 3D printing method according to claim 1, wherein: Stopping the forming platform includes: stopping the forming platform for a first predetermined time.

4. The light-curing 3D printing method according to claim 1, wherein: The stopping of the rising of the molding platform includes: stopping the molding platform for a second predetermined time.

5. The light-curing 3D printing method according to claim 1, further comprising: After the bottom of the tray is irradiated with ultraviolet light, the molded body is separated from the tray.

6. According to the light-curing 3D printing method of claim 1, the molded body also includes a molded part obtained by curing the photosensitive resin, and the molded part is arranged on a side of the molding platform close to the material tray.

7. The light-curing 3D printing method according to claim 1, wherein: Irradiating the bottom of the tray with ultraviolet light includes: irradiating the bottom of the tray with ultraviolet light using an ultraviolet laser.

8. A 3D printer, characterized in that: include: a tray configured to hold a photosensitive resin; A molding platform configured to carry a molded part obtained by curing the photosensitive resin; A lifting mechanism, configured to drive the forming platform to move in a vertical direction; a light source configured to project ultraviolet light toward the bottom of the tray; and Control system, configured as: - Sending an instruction to lower the molding platform of the molding body, and stopping the molding platform when the distance between the bottom surface of the molding body and the bottom of the material tray is a predetermined distance, and the predetermined distance is less than the thickness of a single layer of printing; - The molding platform of the molding body is lifted, and when the distance between the bottom surface of the molding body and the bottom of the material tray is the thickness of a single printing layer, the molding platform stops rising.

9. The 3D printer according to claim 8, wherein: The molding platform is configured to be continuously immersed in and floated out of the photosensitive resin under control.

10. The 3D printer according to claim 8, wherein: The control system includes a data processor, a data acquisition module, a molding platform ascending unit, a molding platform descending unit and a light-curing printing unit, wherein the data processor is respectively connected to the data acquisition module, the molding platform ascending unit, the molding platform descending unit and the light-curing printing unit by signals.

Images