Device and method for forming three-dimensional object, and non-volatile storage medium

Abstract

The present disclosure relates to the technical field of 3D printing, and provides a device and method for forming a three-dimensional object, and a non-volatile storage medium. The device comprises: a forming platform on which a three-dimensional object is formed; a tray, a printing area being formed between the forming platform and a construction surface of the tray; an optical module, used for irradiating the printing area; a controller, used for controlling the forming platform to move during printing, so that the forming platform is in contact with a polymerizable liquid; and a detection assembly, used for acquiring a liquid change state during the contact between the forming platform and the polymerizable liquid. The controller is used for determining, on the basis of the liquid change state, whether the thickness of a liquid layer tends to be stable, and when the thickness of the liquid layer tends to be stable, controlling the optical module to irradiate the printing area. The present disclosure solves the technical problem in the related art of easy occurrence of a void or uneven printing layer thickness due to poor applicability of pre-exposure waiting time caused by whether to end pre-exposure waiting and enter an exposure stage in 3D printing being determined on the basis of an empirical value.

Description

Apparatus, method and non-transitory storage medium for forming a three-dimensional object

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 2024108875611, filed on July 3, 2024, entitled “Apparatus, method and non-transitory storage medium for forming a three-dimensional object”, the disclosure of which is hereby incorporated by reference in its entirety as part of, or an alternative to, this application. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of 3D printing, and in particular, to an apparatus, method and non-transitory storage medium for forming a three-dimensional object. BACKGROUND

[0004] The pre-exposure waiting time in 3D printing refers to a period of time before each layer is exposed, during which the printing platform is stationary for excess liquid resin to drain out of the platform and for the resin to flow back. The purpose of the pre-exposure waiting time is to ensure that the light-cured material uniformly covers the entire printing platform and adheres to the previously printed layer, thereby maintaining the stability of the printing layer thickness. In the 3D printing process, the pre-exposure waiting time needs to be controlled. However, in the related art, whether the 3D printing ends the pre-exposure waiting and enters the exposure phase is mainly determined based on an empirical value. Setting the empirical value may not ensure that the thickness of each layer of the three-dimensional object is uniform, and may easily cause hollow or uneven printing problems. Moreover, the empirical value setting may not take into account changes in material properties or device performance, resulting in the pre-exposure waiting time no longer being applicable.

[0005] To address the above problems, no effective solutions have been proposed so far. SUMMARY

[0006] The embodiments of the present disclosure provide an apparatus, method and non-transitory storage medium for forming a three-dimensional object, to at least solve the technical problem of poor applicability of the pre-exposure waiting time, which is caused by determining whether the 3D printing ends the pre-exposure waiting and enters the exposure phase based on an empirical value in the related art, and easily causing hollow or uneven printing layer thickness.

[0007] According to an aspect of an embodiment of the present disclosure, there is provided an apparatus for forming a three-dimensional object, comprising: a forming platform configured to carry the three-dimensional object; a tray configured to carry a polymerizable liquid and having a build surface, a printing area being formed between the forming platform and the build surface; an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; a controller configured to be connected with the forming platform, for controlling movement of the forming platform to make the forming platform contact the polymerizable liquid during a printing process; a detection assembly configured to acquire a liquid change state during the forming platform contacting the polymerizable liquid; the controller is further configured to be connected in communication with the detection assembly and the optical module, to determine whether a liquid layer thickness is stable according to the liquid change state, and to send an exposure instruction to the optical module to make the optical module irradiate the printing area when it is determined that the liquid layer thickness is stable.

[0008] In some embodiments, the controller is further configured to: control the forming platform to wait or adjust a waiting time of the forming platform or adjust a movement speed of the forming platform when it is determined that the liquid layer thickness is not stable.

[0009] In some embodiments, the detection assembly comprises at least one of a force sensor, a displacement sensor, a flow rate sensor, an ultrasonic sensor, a laser radar sensor, a photoelectric sensor, and a strain gauge sensor; and the liquid change state is obtained from at least one of a force value, a displacement change amount, a liquid flow rate, a liquid level height, and a tray deformation amount.

[0010] In some embodiments, the detection assembly comprises a force sensor, and the controller is further configured to: acquire a plurality of force values detected by the force sensor at different times, wherein the force sensor is configured to acquire a force value applied to the forming platform during the forming platform contacting the polymerizable liquid; and determine whether the liquid layer thickness is stable according to the plurality of force values.

[0011] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of force values comprises: performing a difference operation on force values respectively received by the forming platform at two adjacent times to obtain a force value change amount; calculating a time interval between the two adjacent times; performing a division operation on the force value change amount and the time interval to obtain a force value change rate; determining whether the force value change rate is less than a preset change rate threshold; and determining that the liquid layer thickness is stable in a case where the force value change rate is less than the preset change rate threshold.

[0012] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of force values comprises: determining whether a currently collected force value is within a preset force value threshold range; and determining that the liquid layer thickness is stable in a case where the currently collected force value is within the preset force value threshold range.

[0013] In some embodiments, the detection component comprises a displacement sensor, and the controller is further configured to: acquire a plurality of distance values detected by the displacement sensor, wherein the displacement sensor is arranged on the forming platform and configured to collect distance values between the forming platform and the build surface; and determine whether the liquid layer thickness is stable according to the plurality of distance values.

[0014] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of distance values comprises: determining whether the currently collected distance value is within a preset distance threshold range; and determining that the liquid layer thickness is stable in a case where the currently collected distance value is within the preset distance threshold range.

[0015] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of distance values comprises: performing difference operation on distance values between the forming platform and the build surface at two adjacent time instants to obtain a distance change amount; calculating a time interval between the two adjacent time instants; performing division operation on the distance change amount and the time interval to obtain a distance change rate; determining whether the distance change rate is less than a preset change rate threshold; and determining that the liquid layer thickness is stable in a case where the distance change rate is less than the preset change rate threshold.

[0016] In some embodiments, the detection component comprises a flow rate sensor, and the controller is further configured to: acquire a liquid flow rate detected by the flow rate sensor, wherein the flow rate sensor is configured to collect the liquid flow rate of a liquid in a liquid-free region after peeling off the bottom of the tray during contact between the forming platform and the polymerizable liquid; and determine that the liquid layer thickness is stable in a case where the liquid flow rate is less than or equal to a preset speed threshold.

[0017] In some embodiments, the detection component comprises an ultrasonic sensor or a laser radar sensor, and the controller is further configured to: acquire a liquid level height of a liquid in a liquid-free region after peeling off in the tray detected by the ultrasonic sensor or the laser radar sensor, wherein the ultrasonic sensor or the laser radar sensor is configured to collect the liquid level height of the liquid in the liquid-free region after peeling off in the tray during contact between the forming platform and the polymerizable liquid; and determine whether the liquid layer thickness is stable according to the liquid level height.

[0018] In some embodiments, determining whether the liquid layer thickness is stable according to the liquid level height comprises: performing difference operation on liquid level heights corresponding to two adjacent time instants to obtain a liquid level difference; calculating a time interval between the two adjacent time instants; performing division operation on the liquid level difference and the time interval to obtain a liquid level height change rate of the tray; determining whether the liquid level height change rate is less than or equal to a preset height change rate; and determining that the liquid layer thickness is stable in a case where the liquid level height change rate is less than or equal to the preset height change rate.

[0019] In some embodiments, determining whether the liquid layer thickness is stable according to the liquid level height comprises: determining whether the liquid level height is continuously stable within a preset height threshold range; and determining that the liquid layer thickness is stable when the liquid level height is continuously within the preset height threshold range for a preset time.

[0020] In some embodiments, the detection assembly comprises a photoelectric sensor or a strain sensor, and the controller is configured to: acquire a deformation amount of the construction surface detected by the photoelectric sensor or the strain sensor, wherein the photoelectric sensor or the strain sensor is configured to collect the deformation amount of the construction surface during the contact between the forming platform and the polymerizable liquid; and determine that the liquid layer thickness is stable when the deformation amount is greater than or equal to a preset deformation amount threshold.

[0021] In some embodiments, the controller is further configured to: acquire a waiting time period from a starting time point when the forming platform moves to the preset position to a time point when it is determined that the liquid layer thickness is stable; detect whether the waiting time period is greater than or equal to a preset waiting time period; and send an exposure instruction to the optical module when the waiting time period is greater than or equal to the preset waiting time period.

[0022] In some embodiments, the controller is further configured to: control the forming platform to continue waiting until the waiting time period is greater than or equal to the preset waiting time period, or slow down the movement speed of the forming platform until the waiting time period is greater than or equal to the preset waiting time period, when the waiting time period is less than the preset waiting time period.

[0023] In some embodiments, the controller is further configured to: detect whether a current printing layer is a first set of slice layers of the three-dimensional object during the printing of the three-dimensional object; and control the detection assembly to acquire the liquid change state caused by the movement of the forming platform when the current printing layer is not the first set of slice layers.

[0024] In some embodiments, during the printing of the three-dimensional object, the controller is further configured to: acquire a material type corresponding to the polymerizable liquid, and an actual waiting time of each slice layer corresponding to the three-dimensional object; wherein the actual waiting time is a waiting time of the forming platform before printing of each slice layer; and generate a printing parameter data packet according to the three-dimensional object, the material type corresponding to the polymerizable liquid, and the actual waiting time.

[0025] According to an aspect of an embodiment of the present disclosure, there is also provided an apparatus for forming a three-dimensional object, comprising: a forming platform configured to carry a three-dimensional printed object; a tray configured to carry a polymerizable liquid and having a build surface, a printing area being formed between the forming platform and the build surface; an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; a controller configured to control movement of the forming platform; a detection assembly configured to determine whether a liquid layer thickness of the polymerizable liquid on the build surface is stable; the controller is further configured to be communicatively connected with the detection assembly and the optical module, and when it is determined by the detection assembly that the liquid layer thickness is stable, the controller sends an exposure instruction to the optical module to cause the optical module to irradiate the printing area.

[0026] In some embodiments, the controller is further configured to: when it is determined that the liquid layer thickness is not stable, control the forming platform to wait or extend a waiting time of the forming platform or reduce a movement speed of the forming platform.

[0027] In some embodiments, the detection assembly comprises at least one of a force sensor, a displacement sensor, a flow rate sensor, an ultrasonic sensor, a laser radar sensor, a photoelectric sensor, and a strain sensor; whether the liquid layer thickness is stable is determined by at least one of a force value, a displacement change amount, a liquid flow rate, a liquid level height, and a deformation amount of the build surface of the tray.

[0028] In some embodiments, the detection assembly comprises a force sensor, and the controller is further configured to: acquire a plurality of force values detected by the force sensor on the forming platform at different times, wherein the force sensor is configured to acquire a force value applied to the forming platform during contact between the forming platform and the polymerizable liquid; and determine whether the liquid layer thickness is stable according to the plurality of force values.

[0029] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of force values comprises: performing a difference operation on force values respectively received by the forming platform at two adjacent times to obtain a force value change amount; calculating a time interval between the two adjacent times; performing a division operation on the force value change amount and the time interval to obtain a force value change rate; determining whether the force value change rate is less than a preset change rate threshold; and in a case where the force value change rate is less than the preset change rate threshold, determining that the liquid layer thickness is stable.

[0030] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of force values comprises: determining whether a currently collected force value is within a preset force value threshold range; and in a case where the currently collected force value is within the preset force value threshold range, determining that the liquid layer thickness is stable.

[0031] In some embodiments, the detection assembly comprises a displacement sensor, the displacement sensor is arranged on the forming platform and configured to collect a deformation amount of the forming platform during liquid discharge; and whether the liquid layer thickness is stable is determined according to the deformation amount.

[0032] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of distance values comprises: determining whether the currently collected distance value is within a preset distance threshold range; and determining that the liquid layer thickness is stable in a case where the currently collected distance value is within the preset distance threshold range.

[0033] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of distance values comprises: performing difference operation on distance values between the forming platform and the build surface at two adjacent time instants to obtain a distance change amount; calculating a time interval between the two adjacent time instants; performing division operation on the distance change amount and the time interval to obtain a distance change rate; determining whether the distance change rate is less than a preset change rate threshold; and determining that the liquid layer thickness is stable in a case where the distance change rate is less than the preset change rate threshold.

[0034] In some embodiments, the detection assembly comprises a flow rate sensor, and the controller is further configured to: obtain a liquid flow rate detected by the flow rate sensor, wherein the flow rate sensor is configured to collect the liquid flow rate of the liquid in the liquid- free region after the stripping of the bottom of the tray during the contact between the forming platform and the polymerizable liquid; and determine that the liquid layer thickness is stable in a case where the liquid flow rate is less than or equal to a preset speed threshold.

[0035] In some embodiments, the detection assembly comprises an ultrasonic sensor or a laser radar sensor, and the controller is further configured to: obtain a liquid level height of the liquid in the tray detected by the ultrasonic sensor or the laser radar sensor, wherein the ultrasonic sensor or the laser radar sensor is configured to collect the liquid level height in the tray during the contact between the forming platform and the polymerizable liquid; and determine whether the liquid layer thickness is stable according to the liquid level height.

[0036] In some embodiments, determining whether the liquid layer thickness is stable according to the liquid level height comprises: performing difference operation on liquid level heights corresponding to two adjacent time instants to obtain a liquid level difference; calculating a time interval between the two adjacent time instants; performing division operation on the liquid level difference and the time interval to obtain a liquid level height change rate of the tray; determining whether the liquid level height change rate is less than or equal to a preset height change rate; and determining that the liquid layer thickness is stable in a case where the liquid level height change rate is less than or equal to the preset height change rate.

[0037] In some embodiments, determining whether the liquid layer thickness is stable according to the liquid level height comprises: determining whether the liquid level height is continuously stable within a preset height threshold range; and determining that the liquid layer thickness is stable in a case where the liquid level height is continuously within the preset height threshold range for a preset time.

[0038] In some embodiments, the detection component comprises a photoelectric sensor or a strain gauge sensor, and the controller is configured to: acquire a deformation amount of the build surface detected by the photoelectric sensor or the strain gauge sensor, wherein the photoelectric sensor or the strain gauge sensor is configured to collect the deformation amount of the build surface during the contact between the forming platform and the polymerizable liquid; and determine that the liquid layer thickness is stable when the deformation amount is greater than or equal to a preset deformation amount threshold.

[0039] In some embodiments, the controller is further configured to: acquire a waiting time period from a starting time point when the forming platform moves to the preset position to a time point when it is determined that the liquid layer thickness is stable; detect whether the waiting time period is greater than or equal to a preset waiting time period; and issue an exposure instruction to the optical module when the waiting time period is greater than or equal to the preset waiting time period.

[0040] In some embodiments, the controller is further configured to: control the forming platform to continue waiting until the waiting time period is greater than or equal to the preset waiting time period, or slow down the movement speed of the forming platform until the waiting time period is greater than or equal to the preset waiting time period, when the waiting time period is less than the preset waiting time period.

[0041] In some embodiments, the controller is further configured to: detect whether a current printing layer is a first set of slice layers of the three-dimensional object during printing of the three-dimensional object; and control the detection component to acquire the movement of the forming platform to determine whether the liquid layer thickness is stable, when the current printing layer is or is not the first set of slice layers.

[0042] In some embodiments, during printing of the three-dimensional object, the controller is further configured to: acquire a material type corresponding to the polymerizable liquid, and an actual waiting time of each slice layer corresponding to the three-dimensional object; wherein the actual waiting time is a waiting time of the forming platform before printing of each slice layer; and generate a printing parameter data packet according to the three-dimensional object, the material type corresponding to the polymerizable liquid, and the actual waiting time.

[0043] According to an aspect of some embodiments of the present disclosure, a method for forming a three-dimensional object is also provided, which is implemented by a three-dimensional printing device, the three-dimensional printing device comprising: a forming platform configured to carry the three-dimensional object; a tray configured to carry a polymerizable liquid, the tray having a build surface, and a printing area being formed between the forming platform and the build surface; and an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; the method comprising: controlling movement of the forming platform to make the forming platform contact the polymerizable liquid; acquiring a liquid change state during the contact between the forming platform and the polymerizable liquid; determining whether the liquid layer thickness is stable according to the liquid change state; and issuing an exposure instruction to the optical module to make the optical module irradiate the printing area when it is determined that the liquid layer thickness is stable.

[0044] According to a further aspect of the embodiments of the present disclosure, a method for forming a three-dimensional object is also provided, which is implemented by a three-dimensional printing device, the three-dimensional printing device comprising: a forming platform configured to carry the three-dimensional object; a tray configured to carry a polymerizable liquid and having a build surface, a printing area being formed between the forming platform and the build surface; and an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; the method comprising: controlling movement of the forming platform to make the forming platform contact the polymerizable liquid; detecting whether a liquid layer thickness of the polymerizable liquid on the build surface is stable; and when the liquid layer thickness is stable, issuing an exposure instruction to the optical module to make the optical module irradiate the printing area to form the three-dimensional object from the polymerizable liquid.

[0045] According to a further aspect of the embodiments of the present disclosure, a non-volatile storage medium is also provided, which stores a plurality of instructions adapted to be loaded and executed by a processor to perform any one of the methods for forming a three-dimensional object.

[0046] In the embodiments of the present disclosure, the forming platform is configured to carry the three-dimensional object; the tray is configured to carry the polymerizable liquid and has a build surface, a printing area being formed between the forming platform and the build surface; the optical module is configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; the controller is configured to control movement of the forming platform to make the forming platform contact the polymerizable liquid; the detection assembly is configured to acquire a liquid change state during the process that the forming platform contacts the polymerizable liquid; and the controller is further configured to be in communication connection with the detection assembly and the optical module, to determine whether the liquid layer thickness is stable according to the liquid change state, and when the liquid layer thickness is determined to be stable, to issue an exposure instruction to the optical module to make the optical module irradiate the printing area, so as to achieve the technical effects of improving the accuracy and applicability of the pre-exposure waiting setting of 3D printing by determining whether the liquid layer thickness is stable according to the liquid change state detected by the detection assembly in real time, and timely and accurately determining whether to end the pre-exposure waiting, and avoiding the problems of voids or uneven printing layer thickness. BRIEF DESCRIPTION OF DRAWINGS

[0047] The accompanying drawings, which are included to provide a further understanding of the present disclosure and constitute a part of this application, illustrate certain illustrative embodiments of the present disclosure and are used to explain the present disclosure, but should not be construed as limiting the present disclosure. In the drawings:

[0048] FIG. 1 is a structural schematic diagram of a device for forming a three-dimensional object according to an embodiment of the present disclosure;

[0049] FIG. 2 is a hardware structure block diagram of a computer terminal for a method for forming a three-dimensional object according to an embodiment of the present disclosure;

[0050] FIG. 3 is a flow chart of a method for forming a three-dimensional object according to some embodiments of the present disclosure;

[0051] FIG. 4 is a flow chart of a method for forming a three-dimensional object according to some embodiments of the present disclosure;

[0052] FIG. 5 is a flow chart of a method for forming a three-dimensional object according to some embodiments of the present disclosure;

[0053] FIG. 6 is a flow chart of a method for forming a three-dimensional object according to some embodiments of the present disclosure;

[0054] FIGS. 7A-7E are schematic diagrams of a method for forming a three-dimensional object according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0055] In order to make the person skilled in the art better understand the present disclosure scheme, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by a person skilled in the art without creative labor should be within the scope of protection of the present disclosure.

[0056] It should be noted that the terms "first", "second" and the like in the specification and claims of the present disclosure and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0057] First, for the convenience of understanding the embodiments of the present disclosure, the following will explain some terms or nouns involved in the present disclosure:

[0058] 3D printing technology based on light curing principle, which uses liquid photosensitive material (light curing resin) as raw material, through ultraviolet irradiation on photosensitive resin, liquid material is solidified layer by layer into solid state, and the required object is constructed. In this process, after starting printing, the 3D printer will uniformly coat / apply liquid photosensitive resin on the workbench or construction surface. Then, through the projection system at the bottom, using a specific wavelength of light source to irradiate the photosensitive resin, so that it is cured in a short time.

[0059] Layer by layer stacking: once the first layer is solidified, the forming platform or printing platform will rise after each layer is solidified, so that the printed object is gradually extracted from the liquid material. Then the forming platform will be lowered by a fixed distance in order to print the next slice layer. Then, the photosensitive resin is coated again and solidified. This process will be repeated layer by layer until the entire three-dimensional object or model is printed.

[0060] The pre-exposure waiting time in 3D printing refers to the time before each layer is exposed, the printing platform is stationary for a period of time to wait for the excess liquid resin to drain out of the forming platform and the backflow of the resin until the resin fills / applies on the construction surface. The purpose of this waiting time is to ensure that the light-cured material can uniformly cover the entire printing platform and adhere to the previously printed layer, thereby maintaining the stability of the printing layer thickness.

[0061] In the 3D printing process, the pre-exposure waiting time needs to be controlled. The related technology provides a 3D printing pre-exposure waiting time prediction method, which includes obtaining a slice image of a model to be printed, determining the maximum distance of the pixel points to be exposed from the model boundary based on an image processing algorithm; based on the maximum distance and the pre-constructed fitting curve of the liquid discharge radius and the waiting time, the predicted pre-exposure waiting time is obtained; wherein the pre-constructed fitting curve of the liquid discharge radius and the waiting time is: real-time acquisition of the liquid discharge force data of the printing platform descending when printing a specific model; wherein the specific model needs to meet the condition that the liquid discharge radius gradually changes during printing; using the obtained liquid discharge force data, the time variation curve of the deformation recovery amount of the cartridge is fitted based on the linear elastic theory; based on the time variation curve, the waiting time when the deformation recovery amount of each liquid discharge radius is less than a preset threshold is obtained, and then the fitting curve of the liquid discharge radius and the waiting time is obtained.

[0062] It can be seen that the related technology needs to fit the curve according to the liquid discharge force data of the printing platform descending of the characteristic model. However, the empirical value setting cannot ensure that the thickness of each layer of the three-dimensional object is uniform, and the problem of hollow or uneven printing is prone to occur. And the empirical value setting may not take into account the change of material characteristics or device performance, resulting in that the pre-exposure waiting time is no longer applicable.

[0063] To solve the above problems, according to an embodiment of the present disclosure, a device for forming a three-dimensional object is provided, comprising: a forming platform configured to carry the three-dimensional object; a tray configured to carry a polymerizable liquid, having a build surface, a printing area being formed between the forming platform and the build surface; an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; a controller configured to control the movement of the forming platform to make the forming platform contact the polymerizable liquid; a detection assembly configured to acquire a liquid change state during the contact between the forming platform and the polymerizable liquid; the controller is further configured to be in communication connection with the detection assembly and the optical module, to determine whether the liquid layer thickness tends to be stable according to the liquid change state, and to send an exposure instruction to the optical module to make the optical module irradiate the printing area when it is determined that the liquid layer thickness tends to be stable.

[0064] When performing 3D printing, a 3D model of a three-dimensional object (or a printed part) to be printed can be established first, and then the 3D model of the printed part is sliced layer by layer, and when printing, the printing can start from the first slice layer, and each slice layer is printed in turn based on the successfully printed previous slice layers, and finally a complete 3D model of the printed part is obtained, that is, the three-dimensional object formed finally. Fig. 1 is a structural schematic diagram of a device for forming a three-dimensional object according to an embodiment of the present disclosure. As shown in Fig. 1, the device configured to form a three-dimensional object provided by the present disclosure can generate a projection image according to the shape of each slice model when printing each slice model; the optical module 13 can be a light emitting mechanism, which can irradiate the projection image on the printing area in the tray 12 filled with the polymerizable liquid; the controller can control the movement of the forming platform during printing to make the forming platform 11 contact the polymerizable liquid; the detection assembly can collect the corresponding liquid change state of the polymerizable liquid in real time during the contact between the forming platform 11 and the polymerizable liquid; the controller can determine whether the liquid layer thickness of the current slice model tends to be stable according to the liquid change state, and send an exposure instruction to the optical module for the current printing layer in time when the liquid layer thickness tends to be stable; through the exposure instruction, the optical module 13 can be controlled to irradiate the printing area formed between the forming platform 11 and the build surface, and the polymerizable liquid will be solidified between the forming platform 11 and the build surface to form a solid or semi-solid polymer matching the projection image under the irradiation of the light emitted by the optical module, thereby completing the printing and forming of the slice model.

[0065] In some embodiments, the polymerizable liquid can be, but is not limited to, a liquid resin; the liquid layer thickness is used to indicate the distribution of the polymerizable liquid (e.g., resin) on the current printing layer during the actual printing process. In other words, during the actual printing process, after a layer is printed, the build platform carries the printed object to rise and separate or peel off from the build surface of the vat (e.g., the top surface of the release film at the bottom of the vat), at this time, the build surface of the vat has a “no liquid” area after peeling off, and the liquid layer thickness is used to indicate the distribution of the polymerizable liquid (e.g., resin) in the “no liquid” area of the build surface after backflow filling when the next layer is about to be printed.

[0066] FIGS. 7A-7E show schematic diagrams of a method for forming a three-dimensional object. Referring to FIGS. 7A-7E, the build platform 71 is configured to carry the three-dimensional object 74, the vat 72 is configured to carry the polymerizable liquid (e.g., resin), the bottom of the vat has a build surface 721, and the build surface 721 and the build platform 71 define a printing area. The optical module 73 is used to project light onto the printing area to solidify the polymerizable liquid on the build surface and form the three-dimensional object. Before three-dimensional printing, the data model of the three-dimensional object 74 needs to be sliced into multiple slice layers and transmitted to the three-dimensional printing device for printing. The three-dimensional printing device exposes and solidifies each slice layer by layer to finally form the required three-dimensional object. During the printing process, as shown in FIG. 7B, the build platform 71 is lowered to a position at a layer thickness distance of the slice layer to be printed, and then the light source module (e.g., a light machine) projects light onto the build surface 721 to solidify the slice layer. After solidification, as shown in FIG. 7C, the build platform 71 carries the printed object to move so that the printed object is peeled off / separated from the build surface 721. After separation, the resin in the area of the build surface where the printed object was solidified has been consumed, and at this time, a “no liquid” area 722 is formed. In order to print the next layer, the resin outside the “no liquid” area 722 needs to backflow to fill the area. Referring to FIG. 7D, the resin outside the “no liquid” area in the vat flows towards the “no liquid” area to fill the area. The build platform needs to be lowered again to a position at a layer thickness distance of the slice layer to be printed, and wait for the “no liquid” area to be filled with resin. Referring to FIG. 7E, after the liquid layer thickness of the resin in the “no liquid” area is stable, exposure and solidification can be performed. The above process is repeated to complete the printing of the final three-dimensional object.

[0067] In some embodiments, when the liquid layer thickness is not stable, the build platform can be controlled to wait or adjust the waiting time of the build platform or adjust the movement speed of the build platform, so as to wait for the liquid layer thickness of the resin in the “no liquid” area to be stable before printing, which can optimize the printing time and efficiency.

[0068] It should be noted that the detection assembly includes at least one of a force sensor, a displacement sensor, a flow rate sensor, an ultrasonic sensor, a laser radar sensor, a photoelectric sensor, and a strain gauge sensor. When the detection assembly is of different types of sensors, the installation positions of the corresponding detection assemblies are different. For example, when the detection assembly is a force sensor, the sensor can be installed on the forming platform 11; when the detection assembly is a displacement sensor, the sensor can be installed on the forming platform 11; when the detection assembly is a flow rate sensor, the sensor can be installed at the bottom of the tray 12; when the detection assembly is an ultrasonic sensor or a laser radar sensor, the sensor can be installed on one side of the tray 12 for collecting the liquid level height of the "liquid-free" area in the tray 12 after peeling; when the detection assembly is a photoelectric sensor or a strain gauge sensor, the sensor can be installed at the bottom of the tray 12. In actual application, the number and installation position of the sensor can be set as needed, and details are not described here.

[0069] In the above process, the liquid change state during the contact of the forming platform with the polymerizable liquid is detected in real time by the detection assembly, and the controller can quickly and accurately determine whether the liquid layer thickness tends to be stable based on the liquid change state, and timely and accurately determine whether to end the pre-exposure waiting, so as to improve the accuracy and applicability of the pre-exposure waiting setting of 3D printing, avoid the problems of voids or uneven layer thickness, improve the efficiency and stability of 3D printing, and solve the technical problems of poor applicability of pre-exposure waiting time and easy occurrence of voids or uneven layer thickness in the related art based on experience value to determine whether 3D printing ends the pre-exposure waiting and enters the exposure stage.

[0070] It should be noted that during the contact of the forming platform with the polymerizable liquid, the forming platform moves downward, causing the polymerizable liquid in the tray to overflow to the surrounding, so this process can also be referred to as a liquid discharge process. The equipment for forming a three-dimensional printed object provided by the embodiment of the present disclosure can collect the liquid change state in real time and monitor the stability of the liquid layer thickness in real time during the contact of the forming platform with the polymerizable liquid (i.e., the liquid discharge process), and adaptively determine the pre-exposure waiting time according to the real-time monitored stability of the liquid layer thickness, which can not only shorten the printing time, but also improve the consistency and stability in the 3D printing process. Moreover, since the embodiment of the present disclosure can realize real-time collection of the liquid change state, the pre-exposure waiting time can be adaptively adjusted according to the liquid change state of different printing models and different types of polymerizable liquid (such as different viscosity resins), so as to improve the printing precision and efficiency, and have strong applicability. Since real-time monitoring can be performed, even for a printing model with complex cross-section changes, the liquid layer thickness can be accurately judged, the layer thickness error can be reduced, and the printing surface quality can be improved.

[0071] In some embodiments, the controller is further configured to control the forming platform to wait or adjust the waiting time of the forming platform or adjust the movement speed of the forming platform when the liquid layer thickness is not tending to be stable.

[0072] In some embodiments, when the liquid layer thickness is not tending to be stable, at least one of the following can be performed by controlling the forming platform to wait, adjust the waiting time of the forming platform, adjust the movement speed of the forming platform, so that the forming platform continues to wait or prolongs the waiting time or slows down the platform movement speed or adjusts the platform movement parameters, etc. When the forming platform movement speed is very slow, the influence on the polymerizable liquid is very small, which is approximately equal to waiting. During the waiting process of the forming platform, the polymerizable liquid is allowed to flow properly before light exposure, so as to ensure that the liquid layer thickness is maintained stable after deformation recovery, thereby ensuring the quality and precision of printing.

[0073] In some embodiments, during the printing of each layer of the slice model, when the forming platform of the current layer is lowered, the forming platform can be first lowered to a specified height at a faster speed, and then wait at the specified height before exposure until the liquid layer thickness tends to be stable; or after the forming platform is lowered to the specified height at a faster speed and the liquid layer thickness tends to be stable, the waiting time of the forming platform is adaptively adjusted according to the waiting time. And since the forming platform speed is very slow, the influence on the liquid change state is very small, which is approximately equal to waiting, so the movement speed of the forming platform can be adjusted, for example, the forming platform is first lowered at a faster speed, and then the movement speed of the forming platform is slowed down after being lowered to a specified height, or the forming platform can be controlled to be lowered at a relatively smooth speed during the whole lowering process, so that the liquid change state tends to be as stable as possible and the liquid layer thickness tends to be as stable as possible.

[0074] In some embodiments, the detection assembly includes at least one of a force sensor, a displacement sensor, a flow rate sensor, an ultrasonic sensor, a laser radar sensor, a photoelectric sensor, a strain gauge sensor; and the liquid change state is determined by at least one of the following: force value, displacement change amount, liquid flow rate, liquid level height, material disc deformation amount.

[0075] In some embodiments, the liquid change state can be obtained by detecting corresponding operating parameters in real time during the contact of the forming platform with the polymerizable liquid. For example, the force value borne by the forming platform can be collected by a force sensor during the contact of the forming platform with the polymerizable liquid; the distance value between the forming platform and the construction surface can be detected by a displacement sensor, wherein the displacement change amount can be used to indicate the distance change amount between the forming platform and the construction surface collected at two adjacent time points; the liquid flow rate at the bottom of the tray can be collected by a flow rate sensor; the liquid level height in the tray can be collected by an ultrasonic sensor or a laser radar sensor; and the deformation amount of the construction surface of the tray can be collected by a photoelectric sensor or a strain gauge sensor.

[0076] In some embodiments, the detection of force is mainly to detect the force borne by the forming platform. When the forming platform has not contacted the resin, the forming platform has no force value, at which time the platform can be controlled to accelerate downward or upward, thereby saving the movement time of the forming platform. When the forming platform is lowered to contact the resin and gradually starts to extrude the resin, the resin flows to the “liquid-free” area in the tray to fill the area, and the resin filling is completed after the resin flow is stable. During this process, the force value of the forming platform is gradually reduced, and when the force value of the forming platform approaches 0, it can be determined that the liquid layer thickness of the “liquid-free” area in the tray is stable, and exposure printing can be performed.

[0077] In some embodiments, during the process of lowering the forming platform to contact the resin and gradually extruding the resin to discharge / return the liquid, the forming platform bears the reaction force of the resin, which causes a slight deformation, for example, a deformation of 10-20 μm. The deformation amount of the forming platform can be detected by a strain sensor to determine whether the liquid layer thickness of the “liquid-free” area in the tray is stable. For example, when the deformation amount decreases to 0 or approaches 0, it can be determined that the liquid layer thickness of the “liquid-free” area in the tray is stable.

[0078] In some embodiments, after the forming platform carrying the printed part is peeled off from the construction surface, the printed part peeling position can not be covered with liquid, at which time the surrounding liquid will flow to the liquid-free covering area due to surface tension, and the liquid flow rate can be used to determine the backflow completeness. When the liquid backflow rate decreases to 0 or approaches 0, it can be determined that the liquid layer thickness of the “liquid-free” area in the tray is stable. Similarly, the liquid level height of the “liquid-free” area can be detected to determine whether the liquid layer thickness of the “liquid-free” area in the tray is stable.

[0079] It should be noted that the more comprehensive the liquid change state monitoring is, the more accurate and timely the determination of whether the liquid layer thickness tends to be stable can be. Therefore, multiple parameters such as force value, displacement change amount, liquid flow rate, liquid level height, and tray deformation amount can be used to determine the liquid change state, so as to more accurately and timely determine whether the liquid layer thickness tends to be stable.

[0080] In some embodiments, the detection assembly includes a force sensor, and the controller is further configured to: acquire a plurality of force values detected by the force sensor on the forming platform at different times, wherein the force sensor is configured to acquire the force value applied to the forming platform during the contact between the forming platform and the polymerizable liquid; and determine whether the liquid layer thickness tends to be stable according to the plurality of force values.

[0081] In some embodiments, the force sensor can be installed on the forming platform structure or the bottom structure of the exposure device (tray), and the force sensor can be one or more. In the case of one force sensor, the force sensor can be installed at a middle position of the forming platform to monitor the overall force on the forming platform. In the case of multiple force sensors, the force sensors can be installed at four corners of the forming platform to monitor the force on the forming platform in different directions. In the case of multiple force sensors, the average of the force values collected by the multiple sensors at any time can be taken as the force value on the forming platform at the time. The force sensor in the embodiments of the present disclosure can also monitor the force state of the forming platform and other structures during the printing process, and feed back the real-time force value data to the controller for logical calculation.

[0082] In some embodiments, the force value on the forming platform can also be understood as a liquid discharge force, and the corresponding force value change rate can be understood as a liquid discharge force change rate. The liquid discharge force is an important physical effect in the process of light-curing printing. In the process of light-curing printing, the polymerizable liquid is injected into the tank, and the printing platform is gradually pressed down, so that the polymerizable liquid is subjected to pressure and starts to discharge to the edge of the forming platform. During this process, the polymerizable liquid will generate a reaction force on the forming platform, which is called liquid discharge force (hereinafter referred to as liquid discharge force). The size of the liquid discharge force is related to the pressing speed of the forming platform, the fluidity of the resin, and the geometry of the tank, the consistency of the equipment, the environment, and other factors. The liquid discharge force value change rate during the waiting process can be acquired by monitoring the force sensor installed at the corresponding position (such as the top) of the forming platform or the corresponding position (such as the bottom) of the tray, so as to determine whether the liquid layer thickness is stable. If it is detected that the liquid layer thickness has stabilized, the exposure of the next slice layer is directly entered, so as to save the printing time, improve the printing efficiency, and improve the precision and quality of the printed part. It should be noted that the 3D printing process includes exposure-peeling-descending-waiting-exposure (next layer). When the forming platform stops moving to the specified position according to the process package parameters, the liquid resin is extruded and discharged out of the plane during the descending process of the forming platform until the liquid layer thickness stabilizes. The feedback of the liquid discharge force value and the force value on the forming platform changes all the time during this process.

[0083] It should be noted that by real-time acquisition of the multiple force values of the forming platform, the change of the liquid layer thickness can be monitored in real time, and the fluctuation degree of the liquid layer thickness can be found in time. Based on the feedback of the force values, the liquid layer thickness during printing can be precisely adjusted to ensure the printing quality and stability. Real-time monitoring of whether the liquid layer thickness tends to be stable based on the force values collected by the force sensor can effectively reduce deformation and defects during printing, improve printing quality, and avoid unnecessary repeated printing and waste of materials, saving cost and time. Determining whether the liquid layer thickness tends to be stable based on the real-time collected force values also has certain adaptability, so that during the printing process, the determination of whether the printing layer thickness tends to be stable can be made in time according to the actual situation during the printing process, so as to better adapt to different printing requirements and material characteristics.

[0084] In some embodiments, determining whether the liquid layer thickness tends to be stable according to the multiple force values comprises: performing difference operation on the force values respectively received by the forming platform at two adjacent time points to obtain a force value change amount; calculating a time interval between the two adjacent time points; performing division operation on the force value change amount and the time interval to obtain a force value change rate; determining whether the force value change rate is less than a preset change rate threshold; and in the case that the force value change rate is less than the preset change rate threshold, determining that the liquid layer thickness tends to be stable.

[0085] In some embodiments, during the printing process of each slice layer, when the descending movement of the forming platform corresponding to the current printing layer is performed, the multiple force values collected by the force sensor at different time points during the contact process of the forming platform with the polymerizable liquid (i.e. the liquid discharge process) are obtained, based on the force value change amount between the force values respectively corresponding to two adjacent time points, the time interval between the two adjacent time points is divided to obtain the force value change rate of the forming platform, which can also be understood as the liquid discharge force change rate of the forming platform; further determining whether the force value change rate is less than the corresponding preset change rate threshold, and after successful determination, it is considered that the liquid discharge of the forming platform tends to be stable, and the liquid layer thickness is stable, at this time it is determined that the waiting time is sufficient, and the next printing process is performed, such as the exposure process of the next slice layer.

[0086] In some embodiments, determining whether the liquid layer thickness tends to be stable according to the multiple force values comprises: determining whether the currently collected force value is within a preset force value threshold range; and in the case that the currently collected force value is within the preset force value threshold range, determining that the liquid layer thickness tends to be stable.

[0087] In some embodiments, the current collected force value can be one or more of a plurality of force values borne by the molding platform at different time instants, and in the case where the current collected force value is one, the liquid layer thickness can be determined to be stable when the one force value is within a preset force value threshold range, wherein the one force value is the latest collected force value in the plurality of force values. In order to avoid inaccurate determination of whether the liquid layer thickness is stable due to the mutation or contingency of a single force value, the current collected force value can be set to be a plurality of force values, and in this case, the liquid layer thickness can be determined to be stable when all the plurality of force values are within the preset force value threshold range, or the liquid layer thickness can be determined to be stable when the average of the plurality of force values is within the preset force value threshold range, thereby determining whether the current liquid layer thickness is stable in a timely and accurate manner. The preset force value threshold is a preset liquid discharge force threshold in the printing process database, which can be set to one threshold based on one printing process, or different thresholds for each slice layer, without limitation. For example, the preset force value threshold can be a preset force value threshold matched with the current printing layer determined from the printing process database.

[0088] In some embodiments, the detection assembly includes a displacement sensor, and the controller is further configured to: acquire a plurality of distance values detected by the displacement sensor, wherein the displacement sensor is arranged on the molding platform and configured to collect distance values between the molding platform and the build surface; and determine whether the liquid layer thickness is stable according to the plurality of distance values.

[0089] In some embodiments, the displacement sensor can be arranged on the main shaft connected to the molding platform, and configured to collect distance values between the molding platform and the build surface during the contact process of the molding platform and the polymerizable liquid (i.e., the liquid discharge process). Since the molding platform and the build surface form a printing area for filling the polymerizable liquid, the distance values between the molding platform and the build surface can reflect the formation of the printing area, such as whether the printing area is formed stably, and thus determine whether the liquid layer thickness is stable. Therefore, by monitoring a plurality of distance values between the molding platform and the build surface at different time instants in real time through the displacement sensor, whether the liquid layer thickness is stable can be determined in a timely and accurate manner. If it is detected based on the plurality of distance values collected by the displacement sensor that the liquid layer thickness has stabilized, the exposure of the next slice layer is directly entered, thereby saving printing time, improving printing efficiency, and improving the accuracy and quality of the printed part.

[0090] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of distance values includes: determining whether a currently collected distance value is within a preset distance threshold range; and determining that the liquid layer thickness is stable in the case where the currently collected distance value is within the preset distance threshold range.

[0091] In some embodiments, the currently collected distance value can be one or more of the plurality of distance values detected by the displacement sensor, and in the case where the currently collected distance value is one, the liquid layer thickness region can be determined to be stable when the one distance value, which is the latest collected distance value among the plurality of force values, is within a preset distance threshold range. To avoid inaccurate determination of whether the liquid layer thickness tends to be stable due to the mutation or contingency of a single distance value, the currently collected distance value can be set to be a plurality of distance values, and in this case, the liquid layer thickness can be determined to tend to be stable when all the plurality of distance values are within a preset distance value threshold range, or the liquid layer thickness can be determined to tend to be stable when the average value of the plurality of distance values is within the preset distance value threshold range. Thus, it can be determined in a timely and accurate manner whether the current liquid layer thickness tends to be stable.

[0092] In some embodiments, determining whether the liquid layer thickness tends to be stable according to the plurality of distance values includes: performing difference operation on distance values between the forming platform and the build surface at two adjacent time instants to obtain a distance change amount; calculating a time interval between the two adjacent time instants; performing division operation on the distance change amount and the time interval to obtain a distance change rate; and determining that the liquid layer thickness tends to be stable when the distance change rate is less than a preset change rate threshold.

[0093] In some embodiments, the distance change amount is used to indicate the distance change between the forming platform and the build surface at two adjacent time instants. During the printing of each slice layer, when the lowering movement of the forming platform corresponding to the current printing layer is performed, a plurality of distance values collected by the displacement sensor at different time instants during the contact process (i.e., the liquid discharge process) of the forming platform and the polymerizable liquid are obtained, and based on the distance change amount between the distance values corresponding to the two adjacent time instants, the distance change rate of the forming platform is obtained by dividing the time interval between the two adjacent time instants. The distance change rate is used to indicate the distance change of the forming platform and the build surface per unit time, i.e., the distance fluctuation between the forming platform and the build surface per unit time. The distance change rate can be used to determine whether the liquid discharge and backflow of the polymerizable liquid (such as the liquid numerical value) are completed. When the distance change rate is less than (or equal to) the corresponding preset change rate threshold, it is considered that the liquid discharge tends to be stable, the liquid layer thickness is stable, and it is determined that the waiting time is sufficient, and the next printing process, such as the exposure process of the next slice layer, is performed.

[0094] In some embodiments, the distance change amount of the forming platform can also be used to determine whether the polymerizable liquid (e.g., liquid level) is completely drained and backflowed. When the distance change amount is less than (or equal to) a preset distance threshold, it is considered that the liquid drainage tends to be stable, and the liquid layer thickness is stable. Therefore, it is determined that the waiting time is sufficient, and the next printing process, such as the exposure process of the next slice layer, is performed. The preset distance threshold can be a preset distance threshold matched with the current printing layer determined from the process database.

[0095] It should be noted that the distance value between the forming platform and the build surface is collected in real time by the displacement sensor, which can accurately monitor the distance change amount between the forming platform and the build surface, thereby determining whether the liquid layer thickness tends to be stable. This helps to timely detect abnormal changes in the liquid layer thickness and avoid printing quality problems caused by unstable liquid layer thickness. By collecting the distance value between the forming platform and the build surface by the displacement sensor and calculating the distance change, the liquid layer thickness change can be monitored in real time, and it can be determined in real time and accurately whether the liquid layer thickness tends to be stable. Therefore, the printing time is reduced, and the printing efficiency, precision and stability are improved.

[0096] In some embodiments, the detection assembly includes a flow rate sensor, and the controller is further configured to: acquire a liquid flow rate detected by the flow rate sensor, wherein the flow rate sensor is configured to collect the liquid flow rate at the bottom of the tray during the contact of the forming platform with the polymerizable liquid; and determine that the liquid layer thickness tends to be stable when the liquid flow rate is less than or equal to a preset speed threshold.

[0097] In some embodiments, the resin flow rate at the bottom of the tray changes greatly during the contact of the forming platform with the polymerizable liquid, which can represent the liquid drainage process. Therefore, the flow rate sensor can be arranged at the position of the build surface (mold at the bottom of the tray) at the bottom of the tray to detect the flow rate (i.e., liquid flow rate) of the polymerizable liquid on the build surface at the bottom of the tray during the contact of the forming platform with the polymerizable liquid (i.e., the liquid drainage process). Since there is a certain relationship between the liquid flow rate and the liquid layer thickness. When the liquid flow rate gradually tends to be stable, it indicates that the flow state of the polymerizable liquid in the tray has reached a certain balance, and the liquid layer thickness also tends to be stable. Therefore, by monitoring the change of the liquid flow rate, it can be indirectly determined whether the liquid layer thickness tends to be stable. During the liquid drainage process, when the flow rate of the polymerizable liquid is less than or equal to a preset speed threshold, it is considered that the liquid drainage tends to be stable, and the liquid layer thickness is stable. Therefore, it is determined that the waiting time is sufficient, and the next printing process, such as the exposure process of the next slice layer, is performed. In the above manner, the liquid flow rate collected in real time by the flow rate sensor can monitor the liquid flow rate change at the bottom of the tray in real time, and timely determine whether the liquid layer thickness tends to be stable. In this way, the downtime during the printing process can be reduced, and the printing efficiency, precision and stability are improved.

[0098] In some embodiments, the detection component includes an ultrasonic sensor or a laser radar sensor, and the controller is further configured to: acquire the liquid level height in the tray detected by the ultrasonic sensor or the laser radar sensor, wherein the ultrasonic sensor or the laser radar sensor is configured to collect the liquid level height in the tray during the contact of the forming platform with the polymerizable liquid; and determine whether the liquid layer thickness tends to be stable according to the liquid level height. In some embodiments, the gap between the structured surface at the bottom of the tray and the mounting substrate is detected by the photoelectric sensor or the strain sensor to detect the deformation amount of the structured surface (e.g., the release film), so as to detect the resin backflow in the "liquid-free" area of the tray, and determine whether the liquid layer thickness is stable.

[0099] In some embodiments, the liquid level height directly reflects the amount of polymerizable liquid in the tray, and the liquid layer thickness can reflect the distribution of the polymerizable liquid on the current printing layer in the actual printing process. By collecting the liquid level height in the tray during the contact of the forming platform with the polymerizable liquid (i.e., the liquid discharge process) by the ultrasonic sensor or the laser radar sensor, the remaining and supply status of the polymerizable liquid in the tray can be known in time. By monitoring the change of the liquid level height in real time, the consumption speed and supply stability of the polymerizable liquid can be determined, and then it can be determined whether the liquid layer thickness tends to be stable. When the polymerizable liquid remains relatively stable for a period of time, it indicates that the supply of the liquid material is stable, so that the liquid layer thickness can be accurately inferred to be stable in time, and then it can be determined that the waiting time is sufficient, and the next printing process, such as the exposure process of the next slice layer, can be performed.

[0100] In some embodiments, the ultrasonic sensor or the laser radar sensor can be installed on the side wall of the tray, or the ultrasonic sensor or the laser radar sensor can be arranged above the tray by a mounting bracket and emit light / waves toward the tray to detect the liquid level height in the tray. During the contact of the forming platform with the polymerizable liquid, the resin in the tray is pressed downward by the forming platform and flows to the periphery, and the change of the liquid level height around the tray with time can be acquired by the ultrasonic sensor or the laser radar sensor, and then it can be determined whether the liquid layer thickness tends to be stable according to the change of the liquid level height.

[0101] In some embodiments, determining whether the liquid layer thickness tends to be stable according to the liquid level height includes: performing difference operation on the liquid level heights corresponding to two adjacent time instants respectively to obtain a liquid level difference; calculating a time interval between the two adjacent time instants; performing division operation on the liquid level difference and the time interval to obtain a liquid level height change rate of the tray; and determining that the liquid layer thickness tends to be stable when the liquid level height change rate is less than or equal to a preset height change rate.

[0102] In some embodiments, in the process of determining whether the liquid layer thickness tends to be stable according to the change of the tray liquid level height, the change of the liquid level height around the tray over time can be obtained by the ultrasonic sensor or the laser radar sensor, and the liquid level height change rate is calculated. When the liquid level height change rate is less than or equal to the preset height change rate, it is considered that the liquid discharge tends to be stable at this time, the liquid layer thickness is stable, and it is determined that the waiting time is sufficient, and the next slice layer printing process is performed.

[0103] In some embodiments, in the printing process of each slice layer model, when the current layer corresponding forming platform descending motion is performed, a plurality of liquid levels in the tray collected by the ultrasonic sensor or the laser radar sensor at different time points during the contact of the forming platform and the polymerizable liquid are obtained, and based on the liquid level difference between the liquid levels corresponding to two adjacent time points, the liquid level height change rate in the tray is obtained by dividing the time interval between the two adjacent time points. According to the liquid level height change rate, it is determined whether the polymerizable liquid is discharged and backflowed. When the liquid level height change rate is less than or equal to the preset height change rate, it is considered that the liquid discharge tends to be stable, the liquid layer thickness is stable, and it is determined that the waiting time is sufficient, and the next printing process is performed, such as the exposure process of the next slice layer.

[0104] In some embodiments, according to the liquid level height, it is determined whether the liquid layer thickness tends to be stable, including: determining whether the liquid level height continues to tend to be stable within the preset height threshold range; in the case that the liquid level height continues to be stable within the preset height threshold range for a preset time, it is determined that the liquid layer thickness tends to be stable.

[0105] In some embodiments, the currently collected liquid level height can be one or more of the liquid levels of the tray at different time points. In the case that the currently collected liquid level height is one, the liquid layer thickness can be determined to tend to be stable when the one liquid level is within the preset liquid level height threshold range, wherein the one liquid level is the latest collected liquid level among the plurality of liquid levels. In order to avoid inaccurate determination of whether the liquid layer thickness tends to be stable due to the mutation or accident of a single liquid level, the currently collected liquid level height can be set to be a plurality of liquid levels. At this time, the liquid layer thickness can be determined to tend to be stable when the plurality of liquid levels are within the preset liquid level height threshold range, or the liquid layer thickness can be determined to tend to be stable when the average of the plurality of liquid levels is within the preset liquid level height threshold range. Thus, it can be determined in time and accurately whether the current liquid layer thickness tends to be stable.

[0106] In some embodiments, the detection component comprises a photoelectric sensor or a strain gauge sensor, and the controller is configured to: acquire a deformation amount of the build surface detected by the photoelectric sensor or the strain gauge sensor, wherein the photoelectric sensor or the strain gauge sensor is configured to collect the deformation amount of the build surface during the contact of the forming platform with the polymerizable liquid; and determine that the liquid layer thickness tends to be stable when the deformation amount is less than or equal to a preset deformation amount threshold.

[0107] In some embodiments, the deformation amount of the build surface refers to the change in the shape of the build surface of the tray due to the solidification, shrinkage or external factors (such as temperature, humidity, etc.) of the polymerizable liquid during the 3D printing process, which can be collected by the photoelectric sensor or the strain gauge sensor. The liquid layer thickness can reflect the distribution of the polymerizable liquid on the current printing layer during the actual printing process. When the liquid layer thickness is unstable, it may cause the printed product to have uneven surface, size deviation and other problems. When the deformation amount of the build surface is large, it means that the build surface has large fluctuations or is uneven. The polymerizable liquid laid on the build surface will cause the liquid layer thickness to be uneven due to the uneven build surface, thereby affecting the printing quality. Conversely, when the deformation amount of the build surface is small, it means that the build surface is relatively flat, and the polymerizable liquid can form a relatively uniform liquid layer when laid, thereby ensuring the stability of the liquid layer thickness.

[0108] Based on this, by collecting the deformation amount of the build surface on the tray in real time by the photoelectric sensor or the strain gauge sensor during the contact of the forming platform with the polymerizable liquid (i.e. the liquid discharge process), the distribution and solidification of the polymerizable liquid corresponding to the current printing layer during the printing process can be understood in time. When the deformation amount remains relatively stable, i.e. the deformation amount is less than or equal to a preset deformation amount threshold, it indicates that the distribution and solidification of the polymerizable liquid corresponding to the current printing layer are relatively uniform, and it can be inferred that the liquid layer thickness also tends to be stable, so that the liquid layer thickness can be inferred to be stable in time, and then it is determined that the waiting time is sufficient, and the next printing process, such as the exposure process of the next slice layer, is performed.

[0109] It should be noted that during the contact of the forming platform with the polymerizable liquid, the forming platform is pressed down, and the resin in the tray flows to the periphery. The build surface (release film) at the bottom of the tray will have a certain deformation amount. The real-time deformation amount of the build surface at the bottom of the tray is acquired by the photoelectric sensor or the strain gauge sensor. When the deformation amount is greater than or equal to a preset deformation amount threshold, it is considered that the liquid discharge tends to be stable, the liquid layer thickness is stable, and it is determined that the waiting time is sufficient, and the next slice layer printing process is performed.

[0110] In some embodiments, the photoelectric sensor (infrared sensor) can be arranged at the bottom of the tray (for example, in the middle of two sides of the bottom), one side emits an optical signal, and the other side receives the optical signal. When the release film of the tray deforms, the optical signal emitted by the optical sensor will be blocked by the release film, and vice versa, when the release film does not exceed the position where the optical sensor is arranged, the optical signal will not be blocked by the release film. Therefore, the deformation amount of the release film of the tray can be determined according to the optical signal of the optical sensor, and then the waiting time and the movement of the forming platform can be adjusted. The strain gauge sensor can be arranged on the side of the tray to sense the deformation amount of the release film.

[0111] In some embodiments, the controller is further configured to: obtain a waiting time period between a starting time when the forming platform moves to a preset position and a time when it is determined that the liquid layer thickness tends to be stable; detect whether the waiting time period is greater than a preset waiting time period; and issue an exposure instruction to the optical module in the case that the waiting time period is greater than or equal to the preset waiting time period. The preset position can be a layer thickness waiting position, that is, the forming platform is lowered to the position for the next printing. If the resin in the "no liquid" area has not yet flowed flat at this time, the liquid needs to be waited to flow flat. The time for waiting for the resin to flow flat is the waiting time.

[0112] In some embodiments, from the start of the movement of the forming platform to the preset position to the process of the forming platform contacting the polymerizable liquid, that is, to the process of draining the liquid, the time period between the starting time when the forming platform moves to the preset position and the time when it is determined that the liquid layer thickness tends to be stable is determined as the waiting time t in the process of draining the liquid. The waiting time t is compared with the preset waiting time period t0. If t is greater than t0, it is determined that the liquid layer thickness has stabilized, and the exposure of the next slice layer is entered. If t is less than t0, the waiting continues until t0. The preset waiting time period t0 can be understood as a safety waiting time period. The preset waiting time period can be obtained by querying a process database or can be set artificially.

[0113] It should be noted that in the pull-up 3D printing scenario, the single-layer printing process is: exposure → peeling → lowering → waiting. The waiting time before exposure in the pull-up 3D printing is that after the printing platform is lowered to contact the resin, a draining force is generated, which causes the forming platform and the tray to deform. A certain waiting time period is set as a preset waiting time period before the exposure of the next slice layer. The preset waiting time period allows the polymerizable liquid to flow appropriately before exposure, so as to ensure that the stable liquid layer thickness is maintained after the deformation is recovered, so as to ensure the quality and precision of printing. The setting of the preset waiting time period usually depends on the type of the polymerizable liquid used (such as the type of resin), the printing area, the printing layer thickness, the properties of the printer, and other factors.

[0114] In some embodiments, since the printing characteristics (such as printing difficulty, printing size, etc.) of each slice layer are different, the determination of the preset waiting time can be targeted according to the characteristics of each slice layer. For example, for a slice layer with complex structure and / or large coverage area, a longer preset waiting time can be set; for a slice layer with simple structure and / or small coverage area, a shorter preset waiting time can be set. In this way, not only can the polymerizable liquid form a relatively uniform liquid layer during laying, ensuring the stability of the liquid layer thickness and the printing accuracy, but also the waiting time before exposure can be reduced, improving the printing efficiency.

[0115] In some embodiments, the determination of whether the current liquid layer thickness tends to be stable and the determination of the waiting time can be performed simultaneously for the printing process of a complex model with varying cross-section. Taking a force sensor as an example, first, it is detected whether the rate of change of the liquid discharge force is less than the corresponding preset change rate threshold, and then the waiting time is compared with the preset waiting time obtained from the process database until the waiting time reaches the preset waiting time. The above two conditions are met to determine the adaptive waiting time, which improves the printing stability and printing accuracy of complex models. For a simple model with varying cross-section, the waiting can be ended directly after detecting that the current liquid layer thickness tends to be stable and entering the exposure process of the next slice layer. For any slice layer, whether it belongs to a simple model or a complex model can be preset. Through the above distinction, the printing efficiency can be improved, and the polymerizable liquid can form a relatively uniform liquid layer during laying of each slice layer.

[0116] In some embodiments, the controller is further configured to, in the case that the waiting time is less than the preset waiting time, control the forming platform to continue waiting until the waiting time is greater than or equal to the preset waiting time, or slow down the movement speed of the forming platform until the waiting time is greater than or equal to the preset waiting time.

[0117] In some embodiments, the preset waiting time can be understood as a safety waiting time, that is, the shortest time that can make the polymerizable liquid form a relatively uniform liquid layer during laying. If the waiting time does not reach the preset waiting time, the waiting continues until the preset waiting time is reached, thereby ensuring that the polymerizable liquid can form a relatively uniform liquid layer during laying, ensuring the stability of the liquid layer thickness and the printing accuracy.

[0118] In some embodiments, the controller is further configured to, during the printing of the three-dimensional object, detect whether the current printing layer is the first group of slice layers of the three-dimensional object; and in the case that the current printing layer is not the first group of slice layers, control the detection assembly to obtain the liquid change state caused by the movement of the forming platform.

[0119] In some embodiments, during the printing of the three-dimensional object, it is detected whether the current printing layer is the first set of slice layers of the three-dimensional object, the first set of slice layers representing the bottom layer of the three-dimensional object, which can be the first or first few layers printed, such as the first 1 layer or the first 1 to 10 layers, etc. If so, no adaptive waiting is performed, and the slice layer exposure process is directly entered; if not, adaptive waiting is needed, and the controller controls the detection assembly to collect the liquid change state obtained by the forming platform movement. In other words, to ensure the forming quality of the bottom layer and avoid the occurrence of a dropped plate during printing, the bottom layer does not perform adaptive waiting.

[0120] In some embodiments, during the printing of the three-dimensional object, the controller is further configured to: obtain the material type corresponding to the polymerizable liquid, the actual waiting time of each slice layer corresponding to the three-dimensional object; wherein the actual waiting time is the waiting time of the forming platform before printing of each slice layer; and generate a printing parameter data packet according to the three-dimensional object, the material type corresponding to the polymerizable liquid, and the actual waiting time.

[0121] In some embodiments, the actual waiting time of each slice layer corresponding to the printing product (i.e., the three-dimensional object) and the printing material during the entire printing process is recorded; and a printing parameter data packet is generated according to the three-dimensional object, the material type corresponding to the polymerizable liquid, and the actual waiting time, which is directly called when printing the same type of printing product next time. The process data packet can also include exposure parameters (exposure time) and stripping parameters, etc., wherein the stripping parameters refer to the stripping speed, Z-axis lifting speed, etc. during the printing process.

[0122] In some embodiments, the exposure parameters corresponding to the three-dimensional object can be obtained, but are not limited to, by the following method: slicing a test model corresponding to the three-dimensional object to obtain a slice data; when printing each slice layer, different area models in the slice data are printed according to different exposure times to obtain physical models printed at different exposure times, for example, a plurality of (such as 4) different exposure time parameters can be selected to obtain a plurality of physical models; a model with the best printing quality is selected from the physical models, and the exposure time corresponding to the model with the best quality is determined as the exposure parameter; and the recorded exposure parameter is generated into a printing process data packet, which is directly called when printing next time.

[0123] According to an aspect of an embodiment of the present disclosure, there is also provided an apparatus for forming a three-dimensional object, comprising: a forming platform configured to carry a three-dimensional printed object; a tray configured to carry a polymerizable liquid and having a build surface, a printing area being formed between the forming platform and the build surface; an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; a controller configured to control movement of the forming platform; a detection assembly configured to determine whether a liquid layer thickness of the polymerizable liquid on the build surface is stable; the controller is further configured to be in communication connection with the detection assembly and the optical module, and when it is determined by the detection assembly that the liquid layer thickness is stable, the controller sends an exposure instruction to the optical module to cause the optical module to irradiate the printing area.

[0124] In some embodiments, the controller is further configured to: when it is determined that the liquid layer thickness is not stable, control the forming platform to wait or extend a waiting time of the forming platform or reduce a movement speed of the forming platform.

[0125] In some embodiments, the detection assembly comprises at least one of a force sensor, a displacement sensor, a flow rate sensor, an ultrasonic sensor, a laser radar sensor, a photoelectric sensor, and a strain sensor; whether the liquid layer thickness is stable is determined by at least one of a force value, a displacement change amount, a liquid flow rate, a liquid level height, and a deformation amount of the build surface of the tray.

[0126] In some embodiments, the detection assembly comprises a force sensor, and the controller is further configured to: acquire a plurality of force values detected by the force sensor on the forming platform at different times, wherein the force sensor is configured to acquire a force value applied to the forming platform during contact between the forming platform and the polymerizable liquid; and determine whether the liquid layer thickness is stable according to the plurality of force values.

[0127] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of force values comprises: performing a difference operation on force values respectively received by the forming platform at two adjacent times to obtain a force value change amount; calculating a time interval between the two adjacent times; performing a division operation on the force value change amount and the time interval to obtain a force value change rate; determining whether the force value change rate is less than a preset change rate threshold; and in a case where the force value change rate is less than the preset change rate threshold, determining that the liquid layer thickness is stable.

[0128] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of force values comprises: determining whether a currently collected force value is within a preset force value threshold range; and in a case where the currently collected force value is within the preset force value threshold range, determining that the liquid layer thickness is stable.

[0129] In some embodiments, the detection assembly comprises a displacement sensor, the displacement sensor is arranged on the forming platform and configured to collect a deformation amount of the forming platform during liquid discharge; and whether the liquid layer thickness is stable is determined according to the deformation amount.

[0130] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of distance values comprises: determining whether the currently collected distance value is within a preset distance threshold range; and determining that the liquid layer thickness is stable in a case where the currently collected distance value is within the preset distance threshold range.

[0131] In some embodiments, determining whether the liquid layer thickness is stable according to the plurality of distance values comprises: performing difference operation on distance values between the forming platform and the build surface at two adjacent time instants to obtain a distance change amount; calculating a time interval between the two adjacent time instants; performing division operation on the distance change amount and the time interval to obtain a distance change rate; determining whether the distance change rate is less than a preset change rate threshold; and determining that the liquid layer thickness is stable in a case where the distance change rate is less than the preset change rate threshold.

[0132] In some embodiments, the detection assembly comprises a flow rate sensor, and the controller is further configured to: acquire a liquid flow rate detected by the flow rate sensor, wherein the flow rate sensor is configured to collect the liquid flow rate of the liquid in the liquid- free region after stripping of the material tray bottom during the contact between the forming platform and the polymerizable liquid; and determine that the liquid layer thickness is stable in a case where the liquid flow rate is less than or equal to a preset speed threshold.

[0133] In some embodiments, the detection assembly comprises an ultrasonic sensor or a laser radar sensor, and the controller is further configured to: acquire a liquid level height of the liquid in the material tray in the liquid-free region after stripping detected by the ultrasonic sensor or the laser radar sensor, wherein the ultrasonic sensor or the laser radar sensor is configured to collect the liquid level height in the material tray during the contact between the forming platform and the polymerizable liquid; and determine whether the liquid layer thickness is stable according to the liquid level height.

[0134] In some embodiments, determining whether the liquid layer thickness is stable according to the liquid level height comprises: performing difference operation on liquid level heights corresponding to two adjacent time instants to obtain a liquid level difference; calculating a time interval between the two adjacent time instants; performing division operation on the liquid level difference and the time interval to obtain a liquid level height change rate of the material tray; determining whether the liquid level height change rate is less than or equal to a preset height change rate; and determining that the liquid layer thickness is stable in a case where the liquid level height change rate is less than or equal to the preset height change rate.

[0135] In some embodiments, determining whether the liquid layer thickness is stable according to the liquid level height comprises: determining whether the liquid level height is continuously stable within a preset height threshold range; and determining that the liquid layer thickness is stable in a case where the liquid level height is continuously within the preset height threshold range for a preset time.

[0136] In some embodiments, the detection component comprises a photoelectric sensor or a strain gauge sensor, and the controller is configured to: acquire a deformation amount of the build surface detected by the photoelectric sensor or the strain gauge sensor, wherein the photoelectric sensor or the strain gauge sensor is configured to collect the deformation amount of the build surface during the contact of the forming platform with the polymerizable liquid; and determine that the liquid layer thickness is stable when the deformation amount is greater than or equal to a preset deformation amount threshold.

[0137] In some embodiments, the controller is further configured to: acquire a waiting time period from a starting time point when the forming platform moves to the preset position to a time point when it is determined that the liquid layer thickness is stable; detect whether the waiting time period is greater than or equal to a preset waiting time period; and send an exposure instruction to the optical module when the waiting time period is greater than or equal to the preset waiting time period.

[0138] In some embodiments, the controller is further configured to: control the forming platform to continue to wait until the waiting time period is greater than or equal to the preset waiting time period, or to slow down the movement speed of the forming platform until the waiting time period is greater than or equal to the preset waiting time period, when the waiting time period is less than the preset waiting time period.

[0139] In some embodiments, the controller is further configured to: detect whether a current printing layer is a first set of slice layers of the three-dimensional object during the printing of the three-dimensional object; and control the detection component to acquire the movement of the forming platform to determine whether the liquid layer thickness is stable when the current printing layer is or is not the first set of slice layers.

[0140] In some embodiments, during the printing of the three-dimensional object, the controller is further configured to: acquire a material type corresponding to the polymerizable liquid, and an actual waiting time of each slice layer corresponding to the three-dimensional object; wherein the actual waiting time is a waiting time of the forming platform before printing of each slice layer; and generate a printing parameter data packet according to the three-dimensional object, the material type corresponding to the polymerizable liquid, and the actual waiting time.

[0141] According to the embodiments of the present disclosure, a method for forming a three-dimensional printed object is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in a different order.

[0142] The method provided in the embodiment one of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. FIG. 2 shows a hardware structure block diagram of a computer terminal for forming a three-dimensional printed object. As shown in FIG. 2, the computer terminal 10 can include one or more processors (the processor can include but is not limited to a microprocessor MCU or a programmable logic device FPGA processing device, etc.), a memory 104 for storing data. In addition, it can also include a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which can be included as one of the ports of the BUS bus), a network interface, a power supply and / or a camera. Those skilled in the art can understand that the structure shown in FIG. 2 is only schematic, which does not limit the structure of the above-mentioned electronic device. For example, the computer terminal 10 can also include more or fewer components than those shown in FIG. 2, or have a different configuration from that shown in FIG. 2.

[0143] It should be noted that the one or more processors and / or other data processing circuits described above can be referred to as "data processing circuits" herein. The data processing circuit can be embodied in whole or in part as software, hardware, firmware or any other combination. In addition, the data processing circuit can be a single independent processing module, or all or part of any one of the other elements combined into the computer terminal 10. As referred to in the embodiments of the present application, the data processing circuit controls as a processor (for example, the selection of the variable resistance terminal path connected with the interface).

[0144] The memory 104 can be used to store software programs and modules of application software, such as program instructions / data storage devices corresponding to the method for forming a three-dimensional printed object in the embodiments of the present disclosure. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory 104, that is, implements the above-mentioned application program method for forming a three-dimensional printed object. The memory 104 can include a high-speed random access memory, and can also include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some examples, the memory 104 can further include a memory remotely arranged with respect to the processor, which can be connected to the computer terminal 10 through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0145] The display can be, for example, a touch screen type liquid crystal display (LCD), which can enable a user to interact with the user interface of the computer terminal 10.

[0146] FIG. 3 is a flowchart of a method for forming a three-dimensional printed object, according to an embodiment of the present disclosure. As shown in FIG. 3, the method is implemented by a three-dimensional printing device, which includes a forming platform configured to carry a three-dimensional printed object, a tray configured to carry a polymerizable liquid, having a build surface, a printing area being formed between the forming platform and the build surface, and an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid. The method includes:

[0147] In step S202, the forming platform is controlled to move to contact the polymerizable liquid.

[0148] In step S204, a liquid change state during the contact between the forming platform and the polymerizable liquid is acquired.

[0149] In step S206, it is determined whether the liquid layer thickness tends to be stable according to the liquid change state, and an exposure instruction is sent to the optical module to irradiate the printing area when it is determined that the liquid layer thickness tends to be stable.

[0150] In the embodiments of the present disclosure, the detection assembly detects the liquid change state during the contact between the forming platform and the polymerizable liquid in real time, and quickly and accurately determines whether the liquid layer thickness tends to be stable based on the liquid change state, so as to accurately determine whether to end the pre-exposure waiting, thereby improving the accuracy and applicability of the pre-exposure waiting setting of 3D printing, avoiding the problems of voids or uneven printing layer thickness, improving the efficiency and stability of 3D printing, and solving the technical problems of poor applicability of pre-exposure waiting time and easy occurrence of voids or uneven printing layer thickness in the related art.

[0151] Based on the above embodiments and optional embodiments, an optional implementation of the present disclosure is provided. FIG. 4 is a flowchart of an optional method for forming a three-dimensional printed object, according to an embodiment of the present disclosure. As shown in FIG. 4, the method is a method for forming a three-dimensional printed object when the detection assembly is a force sensor, and the method includes:

[0152] In S11, during the printing of each layer of the slice model, when the forming platform starts to move downward for the current printing layer, the forming platform is lowered to a specified position according to the process package parameters.

[0153] In S12, according to the printing slice data, it is determined whether the current printing layer is the first group of slice layers, i.e., whether it is a bottom layer. If yes, no adaptive waiting is performed; otherwise, adaptive waiting is performed, and step S13 is entered.

[0154] S13, the force sensor is used to collect the force value of the forming platform at different time points during the contact process between the forming platform and the polymerizable liquid (i.e. the liquid discharge process), and the controller calculates the force value change between the force values corresponding to two adjacent time points, wherein the force sensor can be installed on the forming platform structure or the bottom structure of the exposure device (tray), and the force sensor can measure multiple force values at different time points. Then, the force value change is divided by the time interval between the two adjacent time points to obtain the force value change rate. The formula can be expressed as: force value change rate = (Δ force value) / (Δ time). Based on the force values collected at different time points, the above method is used to calculate the liquid discharge force change rate in real time.

[0155] S14, the force value change rate is determined in real time whether it is less than a certain threshold value within a certain time, i.e. whether the force value change rate is within the preset force value threshold range, if yes, it is determined that the liquid layer thickness has been stabilized, and then the exposure of the next slice layer is directly entered. If not, continue to wait and collect the force value of the forming platform by the force sensor.

[0156] It should be noted that in the pull-up 3D printing scenario, the 3D printing process is briefly described as exposure → stripping → lowering → waiting (lowering the next slice layer). When the forming platform moves to the specified position according to the process package parameters and stops, the polymerizable liquid (such as liquid resin) is extruded and discharged out of the plane during the lowering process of the forming platform until the liquid layer thickness is stabilized. The liquid discharge force value and the force value of the platform are changing all the time during this process.

[0157] The force value of the forming platform can also be understood as the liquid discharge force, and the corresponding force value change rate can be understood as the liquid discharge force change rate. The liquid discharge force is an important physical effect in the process of photocuring printing. In the process of photocuring printing, the polymerizable liquid is injected into the tank, and the printing platform is gradually pressed down, so that the polymerizable liquid is subjected to pressure and begins to discharge to the edge of the forming platform. During this process, the polymerizable liquid will generate a reaction force on the forming platform, which is called the liquid discharge force (hereinafter referred to as the liquid discharge force). The size of the liquid discharge force is related to the pressing speed of the forming platform, the fluidity of the resin, the geometry of the tank, the consistency of the equipment, the environment and other factors. The liquid discharge force value change rate during the waiting process can be obtained by monitoring the force sensor arranged at the corresponding position (such as the top) of the forming platform, and the liquid layer thickness is determined whether it is stable. If it is detected that the liquid layer thickness has been stabilized, the exposure of the next slice layer is directly entered, so as to save the printing time, improve the printing efficiency, and improve the precision and quality of the printed parts.

[0158] Based on the above embodiments and optional embodiments, the present disclosure proposes an optional implementation. FIG. 5 is a flowchart of another optional method for forming a three-dimensional printed object according to an embodiment of the present disclosure. As shown in FIG. 5, the method is also a method for forming a three-dimensional printed object in the case where the detection component is a force sensor. The method comprises the following steps:

[0159] S21, in the printing process of each layer of the sliced model, when starting the descending movement of the forming platform corresponding to the current printing layer, the forming platform is lowered to a specified position according to the process package parameters.

[0160] S22, according to the printing slice data, it is judged whether the current printing layer is the first group of slice layers, i.e., whether it is the bottom layer. If yes, no adaptive waiting is performed; otherwise, adaptive waiting is performed, and step S13 is entered.

[0161] S23, the force values received by the forming platform at different times in the process of the forming platform contacting the polymerizable liquid (i.e., the liquid draining process) are collected in real time by the force sensor, and the current collected force value is obtained.

[0162] S24, the current collected force value is compared with a preset force value threshold range corresponding to the current printing layer. The preset force value threshold range is a preset force value threshold range corresponding to the current printing layer in the process database. When it is detected that the current collected force value is between the preset threshold range [a, b], it is determined that the liquid layer thickness is stable, and the exposure of the next slice layer is entered.

[0163] Based on the above embodiments and optional embodiments, the present disclosure proposes an optional implementation. FIG. 6 is a flowchart of another optional method for forming a three-dimensional printed object according to an embodiment of the present disclosure. As shown in FIG. 6, the method is also a method for forming a three-dimensional printed object in the case where the detection component is a force sensor. The method comprises the following steps:

[0164] S31, in the printing process of each layer of the sliced model, when starting the descending movement of the forming platform corresponding to the current printing layer, the forming platform is lowered to a specified position according to the process package parameters.

[0165] S32, according to the printing slice data, it is judged whether the current printing layer is the first group of slice layers, i.e., whether it is the bottom layer. If yes, no adaptive waiting is performed; otherwise, adaptive waiting is performed, and step S3 is entered.

[0166] S33, the force sensor is used to collect the force value of the forming platform at different time points during the process of the forming platform contacting with the polymerizable liquid (i.e. the liquid discharge process), and the controller calculates the force value change between the force values corresponding to two adjacent time points. Then, the force value change is divided by the time interval between the two adjacent time points, and the force value change rate is obtained. The formula can be expressed as: force value change rate = (Δ force value) / (Δ time). Based on the force values collected at different time points, the above method is used to calculate the liquid discharge force change rate in real time.

[0167] S34, it is judged whether the liquid discharge force change rate is less than a certain threshold value within a certain time, if yes, the forming platform position is kept, and the waiting time t is compared with the preset waiting time t0 in the process database, if t is greater than or equal to t0, it is judged that the liquid layer thickness has been stabilized, and the exposure of the next slice layer is entered. If t is less than t0, the waiting continues.

[0168] Further, the preset waiting time t0 is obtained by querying the process database, which can be set artificially. In the pull-up 3D printing scenario, the single layer printing process is: exposure → stripping → lowering → waiting. After the printing platform is lowered to contact the resin, the platform assembly and the tray will be deformed due to the liquid discharge force, and a certain waiting time is set as the preset waiting time before the exposure of the next slice layer. This preset waiting time allows the liquid resin to flow properly before exposure, so as to ensure that the deformation is recovered and the stable liquid layer thickness is maintained, so as to ensure the quality and precision of printing. The setting of the preset waiting time usually depends on the type of resin used, the printing area, the printing layer thickness, the properties of the printer, etc.

[0169] Further, the parameter for determining the preset waiting time in the process database can be the printing complexity. For example, for the printing process of a complex model with varying cross sections, the liquid discharge force value detected by the detection sensor and the preset waiting time t0 in the process database are compared at the same time. First, it is judged whether the liquid discharge force change rate is less than the corresponding preset change rate threshold value, and then the waiting time is compared with the preset waiting time t0 obtained from the process database until the waiting time reaches the preset waiting time t0. If the above conditions are met, the adaptive waiting time can be determined, which improves the printing stability and precision of complex models.

[0170] It should be noted that the above embodiments in FIGS. 4 to 6 are only the processing flow when the detection assembly is a force sensor. For the processing flow of the detection assembly being a displacement sensor, a flow rate sensor, an ultrasonic sensor, a laser radar sensor, a photoelectric sensor, a strain gauge sensor, etc., the specific processing mode is consistent with the processing flow when the detection assembly is a force sensor, and the difference is only in the detected operating parameters (or liquid change state) during the process of the forming platform contacting with the polymerizable liquid and the judgment condition of whether the liquid layer thickness tends to be stable. Therefore, the details are not described here.

[0171] According to a further aspect of the embodiments of the present disclosure, a method for forming a three-dimensional object is also provided, which is implemented by a three-dimensional printing device, the three-dimensional printing device comprising: a forming platform configured to carry the three-dimensional object; a tray configured to carry a polymerizable liquid and having a build surface, a printing area being formed between the forming platform and the build surface; and an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; the method comprising: controlling the forming platform to move so as to make the forming platform contact the polymerizable liquid; detecting whether a liquid layer thickness of the polymerizable liquid on the build surface is stable; and when the liquid layer thickness is stable, issuing an exposure instruction to the optical module to make the optical module irradiate the printing area to form the three-dimensional object from the polymerizable liquid.

[0172] The above embodiments can achieve at least the following effects: 1) According to the value of the sensor, the liquid change state in the liquid discharge process is updated in real time, and when the liquid change state meets the preset condition, it can be quickly and accurately judged whether the liquid layer thickness of the current layer slice model is stable, thereby improving the efficiency and stability of 3D printing. The adaptive determination of the pre-exposure waiting time can improve the consistency and stability of the printing process. According to different printing models and different viscosity resins at different fluid discharge rates, the pre-exposure waiting time is automatically adjusted to achieve higher printing precision and efficiency. 2) For printing models with complex cross-section changes, the liquid layer thickness is accurately judged by detecting the change rate of the discharge force in real time, thereby reducing the layer thickness error and improving the printing surface quality. 3) The printing process is optimized by using model slicing, real-time force value change and device state monitoring to achieve better liquid discharge behavior and implement real-time adjustment of the waiting time, thereby improving the printing quality. 4) The printing time is shortened, the printing surface quality and printing precision are improved, and users have a better experience.

[0173] It should be noted that, for the above-mentioned method embodiments, in order to simply describe, they are all described as a series of action combinations, but those skilled in the art should know that the present disclosure is not limited to the action sequence described, because according to the present disclosure, certain steps can be performed in other sequences or at the same time. Secondly, those skilled in the art should know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present disclosure.

[0174] Those skilled in the art can clearly understand that the method for forming a three-dimensional object according to the above-mentioned embodiments can be implemented by means of software on a general hardware platform as necessary, and of course, can also be implemented by hardware, but in many cases, the former is a better implementation. Based on such understanding, the technical solutions of the present disclosure can be embodied in the form of a software product, which is stored in a storage medium (such as a ROM / RAM, a magnetic disk, or an optical disk) and includes a plurality of instructions for causing a terminal device (which can be a mobile phone, a computer, a server, or a network device) to execute the method of each embodiment of the present disclosure.

[0175] Those skilled in the art can understand that all or part of the steps of the various methods of the above-mentioned embodiments can be completed by programs instructing the relevant hardware of the terminal device, and the programs can be stored in a non-volatile storage medium, which can include a flash disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0176] The embodiments of the present disclosure also provide a non-volatile storage medium. Optionally, in the present embodiment, the above-mentioned non-volatile storage medium can be used to save the program code executed by the method for forming a three-dimensional object provided by the above-mentioned embodiments.

[0177] Optionally, in the present embodiment, the above-mentioned non-volatile storage medium can be located in any one of the computer terminals in a computer terminal group in a computer network, or in any one of the mobile terminals in a mobile terminal group.

[0178] Optionally, in the present embodiment, the non-volatile storage medium is configured to store program code for performing the following steps: controlling the forming platform to move away from the build surface or controlling the forming platform to reciprocate relative to the build surface to form a three-dimensional object from the solid or semi-solid polymer, and: obtaining the changing state of the solid or semi-solid polymer detected by the detection assembly during the separation of the solid or semi-solid polymer from the build surface; and controlling the movement of the forming platform according to the changing state.

[0179] The above-mentioned serial numbers of the embodiments of the present disclosure are only for description, and do not represent the advantages or disadvantages of the embodiments.

[0180] In the above-mentioned embodiments of the present disclosure, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0181] In several embodiments provided in the present application, it should be understood that the disclosed technical contents can be implemented by other manners. Among them, the above-described device embodiments are only illustrative, for example, the division of the units can be a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units or modules shown or discussed can be indirect coupling or communication connection between the units or modules through some interfaces, and can be electrical or other forms.

[0182] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place or distributed to multiple units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0183] In addition, each functional unit in each embodiment of the present disclosure can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0184] When the integrated unit is realized in the form of a software functional unit and sold or used as an independent product, it can be stored in a non-volatile storage medium. Based on this understanding, the technical solutions of the present disclosure essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, including a plurality of instructions for causing a computer device (which can be a personal computer, a server or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present disclosure. The foregoing storage medium includes: a U disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a mobile hard disk, a magnetic disk or an optical disk, and various media that can store program codes.

[0185] The above description is only the preferred embodiment of the present disclosure, and it should be pointed out that for ordinary skilled persons in the art, without departing from the principles of the present disclosure, a number of improvements and refinements can be made, and these improvements and refinements should be regarded as the protection scope of the present disclosure. Industrial applicability:

[0186] The scheme provided by the embodiments of the present disclosure can be applied to the field of 3D printing technology. In the embodiments of the present disclosure, the forming platform is configured to carry a three-dimensional printed object; the tray is configured to carry a polymerizable liquid, and has a build surface, and a printing area is formed between the forming platform and the build surface; the optical module is configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; the controller is configured to control the movement of the forming platform to make the forming platform contact the polymerizable liquid; the detection assembly is configured to obtain the liquid change state during the contact between the forming platform and the polymerizable liquid; the controller is further configured to be in communication connection with the detection assembly and the optical module, so as to determine whether the liquid layer thickness tends to be stable according to the liquid change state, and when it is determined that the liquid layer thickness tends to be stable, an exposure instruction is sent to the optical module to make the optical module irradiate the printing area. The purpose of timely and accurately determining whether to end the pre-exposure waiting is achieved by judging whether the liquid layer thickness tends to be stable through the liquid change state detected by the detection assembly, so as to improve the accuracy and applicability of the pre-exposure waiting setting of 3D printing, and the technical effect of avoiding the problems of voids or uneven printing layer thickness is achieved, and thus the technical problems of poor applicability of the pre-exposure waiting time and easy occurrence of voids or uneven printing layer thickness caused by determining whether to end the pre-exposure waiting and enter the exposure stage based on the experience value in the related art are solved.

Claims

1. An apparatus for forming a three-dimensional object, comprising: a forming platform configured to carry a three-dimensional object; a tray configured to carry a polymerizable liquid and having a build surface, a printing area being formed between the forming platform and the build surface; an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; a controller configured to connect with the forming platform for controlling the forming platform movement in a printing process to make the forming platform contact with the polymerizable liquid; a detection assembly configured to acquire a liquid change state during the forming platform contacting with the polymerizable liquid; the controller is further configured to connect with the detection assembly and the optical module to determine whether a liquid layer thickness is stable according to the liquid change state, and to send an exposure instruction to the optical module to make the optical module irradiate the printing area when determining that the liquid layer thickness is stable.

2. The apparatus of claim 1, wherein, the controller is further configured to: control the forming platform to wait or adjust a waiting time of the forming platform or adjust a movement speed of the forming platform when determining that the liquid layer thickness is not stable.

3. The apparatus of any preceding claim, wherein, the detection assembly comprises at least one of a force sensor, a displacement sensor, a flow rate sensor, an ultrasonic sensor, a laser radar sensor, a photoelectric sensor, and a strain gauge sensor; the liquid change state is obtained from at least one of a force value, a displacement change amount, a liquid flow rate, a liquid level height, and a tray deformation amount.

4. The apparatus of any preceding claim, wherein, the detection assembly comprises a force sensor, and the controller is further configured to: acquire a plurality of force values detected by the force sensor at different times, wherein the force sensor is configured to acquire a force value applied to the forming platform during the forming platform contacting with the polymerizable liquid; determine whether the liquid layer thickness is stable according to the plurality of force values.

5. The apparatus of any preceding claim, wherein, determining whether the liquid layer thickness is stable according to the plurality of force values comprises: performing a difference operation on force values respectively received by the forming platform at two adjacent times to obtain a force value change amount; calculating a time interval between the two adjacent times; performing a division operation on the force value change amount and the time interval to obtain a force value change rate; determining whether the force value change rate is less than a preset change rate threshold; determining that the liquid layer thickness is stable in a case where the force value change rate is less than the preset change rate threshold.

6. The apparatus of any preceding claim, wherein, determining whether the liquid layer thickness is stable according to the plurality of force values comprises: determining whether a currently collected force value is within a preset force value threshold range; determining that the liquid layer thickness is stable in a case where the currently collected force value is within the preset force value threshold range.

7. The apparatus of any preceding claim, wherein, the detection assembly comprises a displacement sensor, and the controller is further configured to: acquire a plurality of distance values detected by the displacement sensor, wherein the displacement sensor is arranged on the forming platform and configured to collect distance values between the forming platform and the build surface; determine whether the liquid layer thickness is stable according to the plurality of distance values.

8. The apparatus of any preceding claim, wherein, determining whether the liquid layer thickness is stable according to the plurality of distance values comprises: determine whether the current collected distance value is within a preset distance threshold range; in a case where the current collected distance value is within the preset distance threshold range, determine that the liquid layer thickness is stable.

9. The apparatus of any preceding claim, wherein, determine whether the liquid layer thickness is stable according to the plurality of distance values, comprising: performing difference operation on distance values between the forming platform and the construction surface at two adjacent time instants, to obtain a distance change amount; calculating a time interval between the two adjacent time instants; performing division operation on the distance change amount and the time interval, to obtain a distance change rate; determine whether the distance change rate is less than a preset change rate threshold; in a case where the distance change rate is less than the preset change rate threshold, determine that the liquid layer thickness is stable.

10. The apparatus of any preceding claim, wherein, The detection assembly includes a flow rate sensor, and the controller is further configured to: obtain a liquid flow rate detected by the flow rate sensor, wherein the flow rate sensor is configured to collect the liquid flow rate of the liquid in the liquid-free area after peeling off at the bottom of the tray during the contact between the forming platform and the polymerizable liquid; in a case where the liquid flow rate is less than or equal to a preset speed threshold, determine that the liquid layer thickness is stable.

11. The apparatus of any preceding claim, wherein, The detection assembly includes an ultrasonic sensor or a laser radar sensor, and the controller is further configured to: obtain a liquid level height of the liquid in the liquid-free area after peeling off in the tray detected by the ultrasonic sensor or the laser radar sensor, wherein the ultrasonic sensor or the laser radar sensor is configured to collect the liquid level height of the liquid in the liquid-free area after peeling off in the tray during the contact between the forming platform and the polymerizable liquid; determine whether the liquid layer thickness is stable according to the liquid level height.

12. The apparatus of any preceding claim, wherein, determine whether the liquid layer thickness is stable according to the liquid level height, comprising: performing difference operation on liquid level heights corresponding to two adjacent time instants respectively, to obtain a liquid level difference; calculating a time interval between the two adjacent time instants; performing division operation on the liquid level difference and the time interval, to obtain a liquid level height change rate of the tray; determine whether the liquid level height change rate is less than or equal to a preset height change rate; in a case where the liquid level height change rate is less than or equal to the preset height change rate, determine that the liquid layer thickness is stable.

13. The apparatus of any preceding claim, wherein, determine whether the liquid layer thickness is stable according to the liquid level height, comprising: determine whether the liquid level height is continuously stable within a preset height threshold range; in a case where the liquid level height is continuously within the preset height threshold range for a preset time, determine that the liquid layer thickness is stable.

14. The apparatus of any preceding claim, wherein, The detection assembly includes a photoelectric sensor or a strain sensor, and the controller is configured to: obtain a deformation amount of the construction surface detected by the photoelectric sensor or the strain sensor, wherein the photoelectric sensor or the strain sensor is configured to collect the deformation amount of the construction surface during the contact between the forming platform and the polymerizable liquid; in a case where the deformation amount is greater than or equal to a preset deformation amount threshold, determine that the liquid layer thickness is stable.

15. The apparatus of any preceding claim, wherein, The controller is further configured to: obtain a time length between a starting time instant when the forming platform moves to a preset position and a time instant when it is determined that the liquid layer thickness is stable, to obtain a waiting timing; detecting whether the waiting time is greater than a preset waiting time length; in a case where the waiting time is greater than or equal to the preset waiting time length, issuing the exposure instruction to the optical module.

16. The apparatus of any preceding claim, wherein, The controller is further configured to: in a case where the waiting time is less than the preset waiting time length, controlling the forming platform to continue waiting until the waiting time is greater than or equal to the preset waiting time length, or slowing down the movement speed of the forming platform until the waiting time is greater than or equal to the preset waiting time length.

17. The apparatus of any preceding claim, wherein, The controller is further configured to: in the process of printing the three-dimensional object, detecting whether a current printing layer is a first group of slice layers of the three-dimensional object; in a case where the current printing layer is not the first group of slice layers, controlling the detection component to acquire the liquid change state caused by the movement of the forming platform.

18. The apparatus of any preceding claim, wherein, In the process of printing the three-dimensional object, the controller is further configured to: acquire a material type corresponding to the polymerizable liquid, and an actual waiting time of each slice layer corresponding to the three-dimensional object; wherein the actual waiting time is the waiting time of the forming platform before printing of each slice layer; generate a printing parameter data packet according to the three-dimensional object, the material type corresponding to the polymerizable liquid, and the actual waiting time.

19. An apparatus for forming a three-dimensional object, comprising: a forming platform configured to carry a three-dimensional object; a tray configured to carry a polymerizable liquid and having a build surface, the forming platform and the build surface forming a printing area therebetween; an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; a controller configured to control the movement of the forming platform; a detection component configured to determine whether the liquid layer thickness of the polymerizable liquid on the build surface is stable; the controller is further configured to be in communication connection with the detection component and the optical module, and when it is determined by the detection component that the liquid layer thickness is stable, the controller issues an exposure instruction to the optical module to cause the optical module to irradiate the printing area.

20. The apparatus of any preceding claim, wherein, The controller is further configured to: when it is determined that the liquid layer thickness is not stable, control the forming platform to wait or extend the waiting time of the forming platform or reduce the movement speed of the forming platform.

21. The apparatus of any preceding claim, wherein, The detection component includes at least one of a force sensor, a displacement sensor, a flow rate sensor, an ultrasonic sensor, a laser radar sensor, a photoelectric sensor, and a strain sensor; whether the liquid layer thickness is stable is determined by at least one of a force value, a displacement change amount, a liquid flow rate, a liquid level height, and a deformation amount of the build surface of the tray.

22. The apparatus of any preceding claim, wherein, The detection component includes a force sensor, and the controller is further configured to: acquire a plurality of force values detected by the force sensor at different times, wherein the force sensor is configured to acquire the force value applied to the forming platform during the contact between the forming platform and the polymerizable liquid; determine whether the liquid layer thickness tends to be stable according to the plurality of force values.

23. The apparatus of any preceding claim, wherein, The detection component includes a displacement sensor disposed on the forming platform and configured to collect a deformation amount of the forming platform during the liquid draining process. The controller determines whether the liquid layer thickness is stable according to the deformation amount.

24. The apparatus of any preceding claim, wherein, The detection component includes a flow rate sensor, and the controller is further configured to: acquire a liquid flow rate detected by the flow rate sensor, wherein the flow rate sensor is configured to collect the liquid flow rate of a liquid area without liquid after the peeling of the bottom of the tray during the contact of the forming platform with the polymerizable liquid; determine that the liquid layer thickness is stable when the liquid flow rate is less than or equal to a preset speed threshold.

25. The apparatus of any preceding claim, wherein, The detection component includes an ultrasonic sensor or a laser radar sensor, and the controller is further configured to: acquire a liquid level height of a liquid area without liquid after the peeling in the tray detected by the ultrasonic sensor or the laser radar sensor, wherein the ultrasonic sensor or the laser radar sensor is configured to collect the liquid level height in the tray during the contact of the forming platform with the polymerizable liquid; determine whether the liquid layer thickness is stable according to the liquid level height.

26. The apparatus of any preceding claim, wherein, The detection component includes a photoelectric sensor or a strain gauge sensor, and the controller is configured to: acquire a deformation amount of the construction surface detected by the photoelectric sensor or the strain gauge sensor, wherein the photoelectric sensor or the strain gauge sensor is configured to collect the deformation amount of the construction surface during the contact of the forming platform with the polymerizable liquid; determine that the liquid layer thickness is stable when the deformation amount is greater than or equal to a preset deformation amount threshold.

27. The apparatus of any preceding claim, wherein, The controller is further configured to: acquire a waiting time from a starting time when the forming platform moves to a preset position to a time when it is determined that the liquid layer thickness is stable, to obtain a waiting timing; detect whether the waiting timing is greater than a preset waiting time; issue the exposure instruction to the optical module when the waiting timing is greater than or equal to the preset waiting time.

28. The apparatus of any preceding claim, wherein, The controller is further configured to: detect whether a current printing layer is a first set of slice layers of the three-dimensional object during the printing of the three-dimensional object; control the detection component to acquire whether the liquid layer thickness is stable when the forming platform moves in the case that the current printing layer is or is not the first set of slice layers.

29. The apparatus of any preceding claim, wherein, During the printing of the three-dimensional object, the controller is further configured to: acquire a material type corresponding to the polymerizable liquid and an actual waiting time of each slice layer corresponding to the three-dimensional object, wherein the actual waiting time is a waiting time of the forming platform before printing of each slice layer; generate a printing parameter data packet according to the three-dimensional object, the material type corresponding to the polymerizable liquid, and the actual waiting time.

30. A method for forming a three-dimensional object, implemented by a three-dimensional printing device, the three-dimensional printing device comprising: a forming platform configured to carry a three-dimensional printed object; a tray configured to carry a polymerizable liquid and having a construction surface, a printing area being formed between the forming platform and the construction surface; an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; the method comprising: controlling movement of the build platform to bring the build platform into contact with the polymerizable liquid; acquiring a liquid change state during the build platform being in contact with the polymerizable liquid; determining whether the liquid layer thickness is stable according to the liquid change state, and issuing an exposure instruction to the optical module to cause the optical module to irradiate the printing area when the liquid layer thickness is determined to be stable.

31. A method for forming a three-dimensional object, implemented by a three-dimensional printing device, the three-dimensional printing device comprising: a build platform configured to carry a three-dimensional object; a tray configured to carry a polymerizable liquid and having a build surface, the build platform and the build surface forming a printing area therebetween; an optical module configured to irradiate the printing area to form a solid or semi-solid polymer from the polymerizable liquid; the method comprising: controlling movement of the build platform to bring the build platform into contact with the polymerizable liquid; detecting whether a liquid layer thickness of the polymerizable liquid on the build surface is stable; issuing an exposure instruction to the optical module to cause the optical module to irradiate the printing area to form a three-dimensional object from the polymerizable liquid when the liquid layer thickness is stable.

32. A non-transitory storage medium storing a plurality of instructions adapted to be loaded and executed by a processor to perform the method for forming a three-dimensional object according to claim 30 or 31.

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