CN114603848A

CN114603848A - Three-dimensional object printing method and device and computer equipment

Info

Publication number: CN114603848A
Application number: CN202210247189.9A
Authority: CN
Inventors: 吕如松; 陈伟; 梁澳徽
Original assignee: Zhuhai Sailner 3D Technology Co Ltd
Current assignee: Zhuhai Sailner 3D Technology Co Ltd
Priority date: 2022-03-14
Filing date: 2022-03-14
Publication date: 2022-06-10
Anticipated expiration: 2042-03-14
Also published as: CN114603848B

Abstract

The application provides a three-dimensional object printing method and device and computer equipment, wherein the printing method comprises the following steps: forming a bottoming powder layer using a powder material, the bottoming powder layer including at least one isolated powder layer; adjusting the temperature of at least part of the bottoming powder layer to a preset temperature; forming a shaped powder layer on a surface of the at least one priming powder layer with a powder material; applying a liquid material on the profiled powder layer in accordance with layer print data; and adjusting the temperature of the formed powder layer to a preset temperature to form a printing layer, wherein the temperature rise rate of the isolation powder layer is greater than that of the formed powder layer. The three-dimensional object printing method can avoid the phenomenon that the temperature of the powder layer is over-adjusted in the three-dimensional object printing process, and improves the printing quality of the three-dimensional object.

Description

Three-dimensional object printing method and device and computer equipment

Technical Field

The application relates to the technical field of three-dimensional printing, in particular to a three-dimensional object printing method and device and computer equipment.

Background

In three-dimensional printing processes of objects produced by layer-by-layer build material-based solidification, the quality of the resulting three-dimensional object depends at least in part on the temperature distribution across each layer. Maintaining a stable and uniform temperature distribution helps to improve the quality and accuracy of the formed three-dimensional object.

In the current three-dimensional printing equipment, a temperature detection module (taking a thermal imager as an example) is mainly used for detecting the temperature of the powder bed, however, in the printing and forming stage, because the temperature difference between the powder spreading roller and the powder bed is large at the moment, and the influence of smooth reflection of the surface of the powder spreading roller is added, the temperature of the powder spreading roller is greatly lower than the temperature of the powder bed. In the printing and forming stage, the detected temperature is lower, and the power of the heat source is rapidly increased at a constant speed, so that the temperature of the powder bed is finally higher than the target temperature, and the phenomenon of overshoot can occur, so that the powder material is hardened, and the quality and the precision of the formed three-dimensional object are influenced.

Disclosure of Invention

The embodiment of the application provides a three-dimensional object printing method and device and computer equipment, which can avoid the phenomenon of temperature overshoot in the three-dimensional object printing process and improve the quality and precision of the three-dimensional object.

In a first aspect, the present application provides a method of printing a three-dimensional object, the method comprising:

forming a bottoming powder layer from a powder material, the bottoming powder layer comprising at least one isolated powder layer;

adjusting the temperature of at least part of the bottoming powder layer to a preset temperature;

forming a shaped powder layer on a surface of the at least one layer of priming powder layer with a powder material;

applying a liquid material on the profiled powder layer in accordance with layer print data;

and adjusting the temperature of the formed powder layer to a preset temperature to form a printing layer, wherein the temperature rising rate of at least part of the isolation powder layer is greater than that of the formed powder layer.

With reference to the first aspect, in a possible implementation manner, the adjusting the temperature of at least part of the bottoming powder layer to a preset temperature specifically includes: and adjusting the temperature of at least the last layer of the isolation powder layer to a preset temperature.

With reference to the first aspect, in a possible implementation manner, the adjusting the temperature of at least part of the bottoming powder layer to a preset temperature specifically includes:

controlling the heating power of a heat source to be adjusted to a first heating power and heating the isolated powder layer;

adjusting the temperature of the formed powder layer to a preset temperature specifically comprises:

and controlling the heating power of the heat source to be adjusted to a second heating power and heating the formed powder layer, wherein the second heating power is smaller than the first heating power.

With reference to the first aspect, in a possible embodiment, the adjusting the temperature of at least part of the bottoming powder layer to a preset temperature specifically includes:

setting the control coefficient of a PID controller to be a first set of PID coefficients, the PID controller controlling a heat source to heat the isolated powder layer based on the first set of PID coefficients; and

setting the control coefficient of the PID controller as a second PID coefficient, wherein the PID controller controls the heat source to heat the formed powder layer based on the second PID coefficient, and the value of at least one coefficient in the first PID coefficient and the second PID coefficient is different.

With reference to the first aspect, in a possible implementation manner, the PID controller controls the heat source to heat the isolated powder layer based on the first set of PID coefficients, specifically including:

acquiring the actual temperature of the isolated powder layer through a temperature detector;

calculating the adjustment rate of the heating power of the heat source according to the error value between the actual temperature and the preset temperature of the isolated powder layer and the first group of PID coefficients;

the PID controller controls the heat source to heat the formed powder layer based on the second group of PID coefficients, and specifically includes:

acquiring the actual temperature of the formed powder layer through a temperature detector;

and calculating the adjustment rate of the heating power of the heat source according to the error value between the actual temperature and the preset temperature of the formed powder layer and the second group of PID coefficients.

With reference to the first aspect, in a possible implementation manner, the obtaining, by a temperature detector, an actual temperature of the isolated powder layer or the formed powder layer includes:

detecting a temperature within at least one preset area of the isolated powder layer or the shaped powder layer with a thermal image camera.

With reference to the first aspect, in a possible implementation manner, the isolated powder layer or the formed powder layer includes a plurality of preset areas, the heat source includes a plurality of heating lamp sets, each heating lamp set is used for heating a corresponding preset area of the isolated powder layer or the formed powder layer, and the plurality of heating lamp sets of the heat source are respectively configured with corresponding weight distribution coefficients;

adjusting the temperature of the bottoming powder layer or the forming powder layer to a preset temperature, including:

the PID controller adjusts the heating power of at least one heating lamp group in the heat source based on the adjustment rate of the heating power of the heat source and the weight distribution coefficient of the heating lamp group.

In a possible embodiment in combination with the first aspect, the temperature increase rate of the isolating powder layer is 0.5 ℃/s to 10 ℃/s, and the temperature increase rate of the shaping powder layer is 0.1 ℃/s to 2 ℃/s.

In combination with the first aspect, in a possible embodiment, the priming powder layer further comprises at least one buffer powder layer; the buffer powder layer is formed after the isolation powder layer and before the shaping powder layer.

With reference to the first aspect, in a possible implementation manner, the adjusting the temperature of at least part of the bottoming powder layer to a preset temperature specifically includes: and adjusting the temperature of at least the last layer of the isolation powder layer to a preset temperature, and adjusting the temperature of the buffer powder layer to a preset temperature.

With reference to the first aspect, in one possible embodiment, the temperature increase rate of the isolated powder layer is greater than the temperature increase rate of the buffer powder layer.

In a second aspect, the present application provides a three-dimensional object printing apparatus, where the printing apparatus includes a construction platform, a powder supply module, an injection module, a temperature adjustment module, and a control module, where the control module is connected to the construction platform, the powder supply module, the injection module, and the temperature adjustment module, respectively; the control module is configured to:

controlling the powder supply module to provide powder material to the build platform to form a bottoming powder layer, the bottoming powder layer comprising at least one isolated powder layer;

controlling the temperature adjusting module to adjust the temperature of at least part of the bottom-paved powder layer to a preset temperature;

controlling the powder supply module to form a formed powder layer on the surface of the at least one bottoming powder layer;

controlling the jetting module to apply a liquid material on the formed powder layer according to layer printing data;

and controlling the temperature adjusting module to adjust the temperature of the formed powder layer to a preset temperature so as to form a printing layer, wherein the heating rate of the isolation powder layer is greater than that of the formed powder layer.

With reference to the second aspect, in a possible implementation manner, the temperature adjustment module includes a heat source, a temperature detector, and a PID controller, the PID controller is connected to the control module in a communication manner, and the PID controller controls the heating power of the heat source according to information fed back by the temperature detector.

With reference to the second aspect, in one possible implementation, the control module is configured to:

setting the control coefficients of the PID controller to a first set of PID coefficients after the controlling the powder supply module to provide powder material to the build platform to form at least one layer of a bottomed powder layer;

setting the control coefficient of the PID controller to be a second set of PID coefficients after the powder supply module is controlled to form a formed powder layer on the surface of the at least one layer of bottoming powder layer, wherein the first set of PID coefficients is different from at least one coefficient of the second set of PID coefficients in value.

In combination with the second aspect, in one possible embodiment, the heat source is selected from at least one of an ultraviolet lamp, an infrared lamp, a microwave emitter, a heating wire, a heating sheet, and a heating plate.

In combination with the second aspect, in a possible embodiment, the powder layer includes a plurality of preset areas, the powder layer is the formed powder layer or the bottom-laid powder layer, and the heat source includes a plurality of heating lamp sets, each of which is used for heating a corresponding one of the preset areas of the powder layer.

In combination with the second aspect, in one possible embodiment, the heat source is an array of heating lamps.

In a third aspect, the present application provides a non-transitory computer-readable storage medium, where the storage medium includes a stored program, and when the program runs, the storage medium controls an apparatus to execute the above-mentioned three-dimensional object printing method.

In a fourth aspect, the present application provides a computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the three-dimensional object printing method described above when executing the computer program.

The technical scheme of the application has at least the following beneficial effects:

according to the three-dimensional object printing method, the three-dimensional object printing device and the computer equipment, the temperature of at least part of the bottoming powder layer and the temperature of the forming powder layer are respectively adjusted to preset temperatures, and the temperature rise rate of at least part of the bottoming powder layer is controlled to be larger than that of the forming powder layer, so that the temperature of the bottoming powder layer can reach the preset temperature as quickly as possible; and in the printing and forming stage, the heating rate of the forming powder layer is slower, the phenomenon of temperature overshoot of the printing layer is avoided, and the temperature of the printing layer is ensured to be about the preset temperature, so that the quality of the printing layer is ensured, and the quality and the precision of the formed three-dimensional object are improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a schematic structural diagram of a three-dimensional object printing apparatus according to an embodiment of the present application;

fig. 2 is a schematic flow chart of a three-dimensional object printing method according to an embodiment of the present disclosure;

fig. 3 is another schematic flow chart of a three-dimensional object printing method according to an embodiment of the present disclosure;

fig. 4 is a state diagram of temperature change of a printing method in a process of forming a bottoming powder layer according to an embodiment of the present application;

fig. 5 is a state diagram of temperature change of a printing method in a process of forming a formed powder layer according to an embodiment of the present application;

FIG. 6 is a schematic structural diagram of a non-transitory computer-readable storage medium provided in an embodiment of the present application;

fig. 7 is a schematic structural diagram of a computer device according to an embodiment of the present application.

Detailed Description

For better understanding of the technical solutions of the present application, the following detailed descriptions of the embodiments of the present application are provided with reference to the accompanying drawings.

It should be understood that the embodiments described are only a few embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

It should be noted that, in the X-Y-Z coordinate system indicated in the drawings, in the non-rotational printing mode of the support platform relative to the print head, the X axis is parallel to the printing direction, the Y axis is perpendicular to the printing direction and is parallel to the slice layer, that is, the X-Y plane is parallel to the slice layer, and the Z axis is parallel to the stacking direction of the slice layer and is perpendicular to the X-Y plane.

Fig. 1 is a schematic structural diagram of a three-dimensional object printing apparatus provided in an embodiment of the present application, and as shown in fig. 1, the printing apparatus includes a construction platform 1, a powder supply module 2, an injection module 3, a temperature adjustment module 4, and a control module 5, where the control module 5 is connected to the construction platform 1, the powder supply module 2, the injection module 3, and the temperature adjustment module 4, respectively. In this embodiment, the printing apparatus is an inkjet three-dimensional printer.

A build platform 1 is provided for carrying a layer of powder formed of a powder material. In particular, the build platform 1 is disposed within a build chamber. Optionally, the building chamber further comprises a lifting mechanism, and the lifting mechanism is connected with the building platform 1 and used for driving the building platform 1 to ascend or descend along the vertical direction.

And the powder supply module 2 is used for supplying powder materials to the building platform 1 to form powder layers, wherein the powder layers comprise a bottom laying powder layer and a forming powder layer. By way of example, the powder supply module 2 may include a powder storage chamber for storing a powder material, a powder feeder, a powder storage tank, and a powder spreader, wherein the powder material in the powder storage chamber is conveyed into the powder storage tank located on one side of the construction platform 1 by the powder feeder; the powder spreader is used for spreading the powder material in the powder storage tank onto the build platform 1 to form at least one bottoming powder layer 11 or at least one shaping powder layer, and the commonly used powder spreader may be a powder spreading roller and/or a scraper.

A spray module 3 for applying liquid material to the profiled powder layer on the build platform 1. In particular, the ejection module 3 may be an inkjet print head, which may be a single-channel print head or a multi-channel print head, the number of print heads in this embodiment being dependent on the type of liquid material used and the amount of liquid material that needs to be applied. For example, when the liquid material includes functional materials of different colors, the liquid materials of different colors are ejected through different print heads or different channels of the same print head. For example, when the amount of liquid material that needs to be applied is large and the volume of a single drop is insufficient to meet the demand, multiple printheads or multiple channels of the same printhead may be used simultaneously to eject the same type of material in order to increase printing efficiency.

A temperature adjustment module 4 for adjusting the temperature of the powder layer on the build platform 1. Specifically, the temperature adjustment module 4 may include a heat source, a temperature detector, and a controller. The heat source may be arranged above the build platform 1, in particular the heat source may be arranged at the top of the build chamber, and the energy provided by the heat source may cover the entire area of the build platform 1.

The heat source provides radiant energy or heat energy, and the heat source may be at least one selected from the group consisting of an infrared lamp, an ultraviolet lamp, a microwave emitter, a heating wire, a heating sheet, a heating plate, and a heating lamp. In some embodiments, the heat source comprises an array of heating lamps comprising a first set of heating lamps located in a center region of the array of heating lamps, a second set of heating lamps located in an edge region of the array of heating lamps, and a third set of heating lamps located in a corner region of the array of heating lamps; the first heating lamp group, the second heating lamp group and the third heating lamp group are different in heating power, so that regional regulation and control according to heating requirements are achieved.

A temperature detector for monitoring the actual temperature of the uppermost powder layer on the build platform 1. The powder layer may be a bottoming powder layer or a formed powder layer. The temperature detector may be selected from at least one of a thermal image camera, a pyrometer, and a temperature sensor. In this embodiment, the temperature detector is located above the build platform and is disposed at the top of the build chamber along with the heat source arrangement. In other embodiments, the temperature detector may be located outside the construction chamber, and is not limited herein.

In some embodiments, the temperature detector is an infrared imaging camera that detects infrared radiation emitted from the uppermost powder layer on the build platform 1 and determines the temperature of the uppermost powder layer based on the infrared radiation energy.

In some embodiments, the controller is a PID controller (performance Integration Differentiation), the temperature detector feeds back the monitored actual temperature to the PID controller, and the PID controller controls the heating power of the heat source according to the information fed back by the temperature detector.

Further, the three-dimensional object printing apparatus further comprises a preheating assembly for preheating the powder material carried on the build platform 1. The preheating assembly may provide radiant energy or heat energy, and may be at least one selected from an ultraviolet lamp, an infrared lamp, a microwave emitter, a heating wire, a heating sheet, and a heating plate, and the specific selection of which is not limited. In some embodiments, a pre-heating assembly is provided on the build platform 1 for heating the build platform 1 to pre-heat powder material carried on the build platform 1. In some embodiments, a pre-heat assembly may also be provided on the four walls of the build chamber to pre-heat the powder material within the build chamber. In particular, the four walls of the build chamber may have heating wires thereon for keeping the powder material within the build chamber warm. In other embodiments, the preheating assembly may also be disposed on the powder feeder and the powder storage tank in the powder supply module 2 to perform preheating treatment on the conveyed powder material.

The three-dimensional object printing device also comprises a data processing device, a data processing device and a data processing device, wherein the data processing device is used for carrying out slicing processing on the digital model of the object to be printed to obtain a plurality of slice layers and slice layer image data; and generating slice layer printing data according to the slice layer image data, and transmitting the slice layer printing data to the control module 5. The data processing device is, for example, slicing software, and during the slicing process, the slicing software slices and layers the digital model of the three-dimensional object in the vertical direction to obtain a plurality of slice layers and layer image data.

As can be understood, during the printing process, the control module 5 controls the powder supply module 2 to supply the powder material to the build platform 1 to form a bottom powder layer, and controls the temperature adjustment module 4 to heat the bottom powder layer so that at least part of the bottom powder layer reaches a preset temperature; and then controlling the powder supply module 2 to supply powder materials to the bottoming powder layer to form a formed powder layer, controlling the spraying module 3 to spray liquid materials to the formed powder layer based on the layer printing data, and controlling the temperature adjusting module 4 to heat the formed powder layer to reach a preset temperature so as to promote the formation of a printing layer. The control module 5 controls the lifting mechanism to move in the vertical direction, controls the powder supply module 2 and the injection module 3 to repeat the steps to print layer by layer and superposes a plurality of printing layers to form a three-dimensional object. The shape of the three-dimensional object to be printed is not limited in the present application.

In a second aspect, fig. 2 is a schematic flow chart of a three-dimensional object printing method provided in an embodiment of the present application, and as shown in fig. 2, the printing method includes the following steps:

s10, forming a bottoming powder layer by using a powder material, wherein the bottoming powder layer comprises at least one isolation powder layer;

s20, adjusting the temperature of at least part of the bottoming powder layer to a preset temperature;

s30, forming a formed powder layer on the surface of the at least one bottom-laid powder layer by using a powder material;

s40, applying a liquid material on the formed powder layer according to the layer print data;

and S50, adjusting the temperature of the formed powder layer to a preset temperature to form a printing layer, wherein the temperature rise rate of the isolation powder layer is greater than that of the formed powder layer.

In the scheme, the temperature of at least part of the bottoming powder layer and the temperature of the forming powder layer are respectively adjusted to preset temperatures, and the temperature rise rate of the isolation powder layer is controlled to be greater than that of the forming powder layer, so that the temperature of the bottoming powder layer can reach the preset temperature as quickly as possible; and in the printing and forming stage, the heating rate of the forming powder layer is slower, the phenomenon of temperature overshoot of the printing layer is avoided, and the temperature of the printing layer is ensured to be about the preset temperature, so that the quality of the printing layer is ensured, and the quality and the precision of the formed three-dimensional object are improved.

Referring to fig. 1 and 3, the following description is made in detail with reference to the specific embodiments:

prior to step S10, the method further comprises:

step S01, acquiring a digital model of the three-dimensional object, slicing and layering the digital model of the three-dimensional object to obtain a plurality of sliced layers and sliced layer image data, and generating layer print data according to the sliced layer image data.

In a specific implementation manner, the original data of the three-dimensional object may be obtained by a scanning manner and subjected to three-dimensional modeling to obtain a digital model of the three-dimensional object, or the digital model of the three-dimensional object may be obtained by designing and constructing a three-dimensional object model, and the digital model may be subjected to data format conversion, for example, converted into a format that can be recognized by slicing software, such as an STL format, a PLY format, a WRL format, and the like, and then sliced and layered by using the slicing software to obtain sliced layer image data, and the layer image data may be processed to obtain layer print data representing the object. In the present application, the shape of the three-dimensional object to be printed is not limited, and may be an object of any shape.

And S10, forming a bottom powder layer by using the powder material, wherein the bottom powder layer comprises at least one isolated powder layer.

In this embodiment, the powder material is a material particle in a powder form. The powder material includes a powdery granular material, a powder-based material, and a particulate material. The powder material may be selected from a powdered metal material, a powdered composite material, a powdered ceramic material, a powdered glass material, a powdered resin material, a powdered polymer material, etc., without limitation. In the embodiment, the powder material does not have polymerization reaction with the liquid material, and the powder material does not have polymerization reaction; the powder material can also be subjected to polymerization reaction with the liquid material, and the powder material can also be subjected to polymerization reaction and can be selected according to actual requirements.

Optionally, the powder material is selected from at least one of Polystyrene (PS), polyvinyl chloride (PVC), polyacrylonitrile, acrylonitrile-styrene-acrylate copolymer (ASA), Polyamide (PA), polyester, Polyurethane (PU), polylactic acid, poly (meth) acrylate, poly (methyl (meth) acrylate), polyvinyl fluoride, chlorinated polyolefin, polyvinyl alcohol (PVA) containing hydroxyl groups, cellulose, modified cellulose.

The melting point or melting temperature of the powder material in this embodiment may be 60 ℃ to 300 ℃. Specifically, the temperature may be 60 ℃, 70 ℃, 80 ℃, 100 ℃, 120 ℃, 150 ℃, 180 ℃, 200 ℃, 240 ℃, 280 ℃ or 300 ℃, or the like, or may be other values within the above range, and is not limited herein. When the powder material provided by the embodiment forms the formed powder layer, the flowability of the powder material can meet the use requirement, the gap formed between the powder materials can be filled with the applied liquid material, and the applied liquid material can wet the surface of the powder material.

In the examples of the present application, the particle shape and particle size of the powder material are not particularly limited. Alternatively, the powder material may be in the shape of spheres, dendrites, flakes, discs, needles, rods, and the like. The powder material has an average particle diameter of 1 μm to 400. mu.m, and may be, for example, 1 μm, 5 μm, 10 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm or 400 μm, or may have other values within the above range. The particle size of the powder material is too small, and the liquid material is difficult to permeate to the bottom of the current powder material layer in a short time, so that the liquid material is not in contact with the powder material. The particle size of the powder material is too large, and the gaps between the powder particles are too large, which affects the forming precision of the three-dimensional object. The average particle diameter of the powder material is preferably 30 to 200. mu.m. The particle spacing in the powder material is approximately 5nm to 100. mu.m, and may be, for example, 5nm, 10nm, 100nm, 250nm, 500nm, 1 μm, 5 μm, 10 μm, 25 μm, 50 μm, 75 μm or 100 μm, but is not limited thereto. The powder material in the embodiments of the present application has a particle gap in the range of 5nm to 100 μm, which facilitates rapid penetration of the liquid material through the gap into the powder layer and retention of portions on the surface layer, even wetting of the surface of the powder material in selected areas.

Alternatively, the powder layer is formed to a thickness of 10 μm to 500 μm, and may be, for example, 10 μm, 25 μm, 50 μm, 75 μm, 100 μm, 125 μm, 150 μm, 200 μm, 300 μm, 400 μm, or 500 μm. The thickness of the powder layer formed is preferably 50 μm to 150 μm. It is understood that when the thickness of the powder layer is thin, an object with higher resolution can be formed, but the time taken to manufacture the object is greatly lengthened, and the manufacturing cost is increased; when the thickness of the powder layer is thick, the time for the liquid material to wet the powder material is lengthened, and the resolution of the object formed by manufacturing is reduced, which is difficult to achieve.

In this application, the powder material may further include a filler, where the filler is used to improve the mechanical strength of the three-dimensional object, and the filler may specifically be at least one of graphene, carbon nanotubes, glass fibers, and kaolin, which is not limited in this embodiment. The mass ratio of the filler in the powder material is 0% to 5%, specifically 0%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, and may be other values within the above range, and is not limited herein. The filler cannot change in volume in the forming process, and when the mass ratio of the filler is higher, the rigidity and tensile strength of the formed three-dimensional object are stronger, but the toughness is reduced; when the mass ratio of the filler is too high, the molded three-dimensional object is easily brittle and easily broken. It can be understood that the toughness of the three-dimensional object can be guaranteed and the mechanical strength of the three-dimensional object can be improved by adding a proper amount of filler into the powder material.

In the present application, the powder material may further include a flow aid, and the flow aid is used to improve the flowability of the powder material, and the flow aid may specifically be silica, talc, and the like, which is not limited in this embodiment. The mass ratio of the flow aid in the powder material may be 0% to 5%, specifically 0%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, and may be other values within the above range, which is not limited herein. It can be understood that the flow aid does not undergo a volume change during the molding process, and a proper amount of flow aid can be beneficial to improving the flowability of the powder material, but when the mass ratio of the flow aid is too high, the original performance characteristics of the powder material can be changed.

Referring to fig. 1 and 3 together, in step S10, the control module 5 controls the powder supply module 2 to supply the powder material to the build platform 1 to form the bottom powder layer 11. Specifically, in step S10, the control module 5 controls the powder supply module 2 to supply and lay down the powder material, and in some embodiments, the control module 5 also controls the build platform 1 to be raised and lowered to cooperate with the powder supply module 2, so that the powder material forms the bottoming powder layer 11 on the build platform 1. Understandably, the bottom powder layer 11 can play a role of isolating and preserving heat, and the bottom powder layer 11 isolates the forming powder layer from the building platform 1, so as to avoid the influence on the temperature of the forming powder layer due to the poor thermal stability of the building platform 1. For better insulation effect, the thicker the laid bottom-laying powder layer 11 is, the better the insulation effect is.

In order to achieve a better insulation effect and avoid excessive consumption of the powder material in the bottom-laying powder layer, the thickness of the bottom-laying powder layer 11 is preferably between 20mm and 50mm, and may be, specifically, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, and the like, which is not limited herein. As shown in fig. 1, in the present embodiment, the sub-bed powder layer includes at least one isolated powder layer 111.

S20, adjusting the temperature of at least part of the bottom powder layer to a preset temperature.

It should be noted that the flowchart in fig. 2 does not necessarily mean that step S20 is performed after step S10, and step S20 may be performed in parallel with step S10.

In step S20, the controller in the temperature adjustment module 4 controls the heat source to adjust the temperature of at least a part of the underlying powder layer 11 to a preset temperature. In one embodiment, the temperature regulating module 4 is always in operation when the powder supply module 2 forms the bottom powder layer 11 on the build platform 1 with powder material, and the temperature regulating module 4 continuously regulates the temperature of the powder material on the build platform 1 to bring at least a portion of the bottom powder layer 11 to a predetermined temperature.

When multiple layers of isolated powder layers 111 are formed on the build platform 1, in some embodiments, the temperature adjustment module 4 may adjust the temperature of each isolated powder layer 111 such that the temperature of each isolated powder layer 111 reaches a preset temperature. In other embodiments, the temperature adjusting module 4 may adjust the temperature of each of the isolation powder layers 111 such that the temperature of at least the last isolation powder layer 111 reaches a preset temperature, or such that the temperature of the isolation powder layers 111 located at the upper layer reaches a preset temperature.

Further, as shown in fig. 1, in the present embodiment, the bottom powder layer 11 further includes a buffer powder layer 112, and the buffer powder layer 112 is formed after the isolation powder layer 111 and before the molding powder layer. Therefore, the buffer powder layer enables the isolation and heat preservation effect of the bottom-laying powder layer to be better and the thermal stability to be stronger. During the actual printing process, the control module 5 may control the powder supply module 2 to supply the powder material to the build platform 1 to form 30 isolated powder layers and 10 buffer powder layers on the isolated powder layers, for example.

For example, the temperature adjusting module 4 adjusts the temperature of the plurality of isolation powder layers 111 first, so that the temperature of the last isolation powder layer 111 reaches a preset temperature; after the temperature of the isolation powder layer 111 reaches the preset temperature, buffer powder layers 112 are continuously formed, and the temperature of each buffer powder layer 112 is adjusted by controlling the temperature adjusting module 4, so that the temperature of each buffer powder layer 112 reaches the preset temperature, wherein the heating rate of the isolation powder layer 111 is greater than that of the formed powder layer; the temperature rising rate of the buffer powder layer 112 may be greater than, equal to, or less than the temperature rising rate of the formed powder layer, which is not limited herein.

Further, in the present embodiment, the temperature increase rate of the isolated powder layer 111 is larger than the temperature increase rate of the buffer powder layer 112. Since the temperature of the isolation powder layer 111 has already reached the preset temperature before the formation of the buffer powder layer 112, the isolation powder layer 111 reaching the preset temperature can achieve thermal diffusion, so that the starting temperature of the buffer powder layer 112 is higher than the starting temperature of the isolation powder layer 111, and the temperature difference between the starting temperature of the buffer powder layer 121 and the preset temperature is smaller, and the temperature rising rate is smaller.

In some embodiments, the heating power of the heat source is controlled to be adjusted to the first heating power and the isolated powder layer 111 is heated.

In other embodiments, the controller is a PID controller (Proportion Integration Differentiation) that uses a PID control algorithm, and the PID controller is composed of a proportional unit (P), an integral unit (I), and a derivative unit (D), and the relationship between the ith temperature measurement point input e (t) and the output u (t) is shown in formula 1:

in equation 1, e (t) is the error of the corresponding ith temperature measurement point,

for the integration of the error corresponding to the ith temperature measurement point,

is the error differential for the corresponding ith temperature measurement point. K_pIs the coefficient of the proportional term, K_dIs a coefficient of differential term, K_iAs integral term coefficient, proportional term coefficient K_pCoefficient of differential term K_iAnd integral term coefficient K_dTogether form a PID coefficient, and K_p、K_i、K_dAre all positive numbers.

Step S20 specifically includes: the control module 5 sets the control coefficient of the PID controller in the temperature adjusting module 4 as a first set of PID coefficients, and the PID controller controls the heat source to heat the isolated powder layer based on the first set of PID coefficients.

In a specific embodiment, the temperature detector feeds back the monitored actual temperature of the isolated powder layer to the PID controller, which controls the power of the heat source according to the information fed back by the temperature detector. Specifically, the actual temperature of the isolated powder layer is obtained by a temperature detector in the temperature regulation module 4; and calculating the adjustment rate of the heating power of the heat source according to the error value between the actual temperature and the preset temperature and the first group of PID coefficients. Illustratively, when the actual temperature of the isolated powder layer is less than the preset temperature, the PID controller controls the heating power adjustment rate of the heating lamp array to be increased by 30%, i.e., 130% of the initial power, e.g., 300W, i.e., 390W.

In some embodiments, the heat source may include a heating lamp array including a first heating lamp group located at a center region of the heating lamp array, a second heating lamp group located at an edge region of the heating lamp array, and a third heating lamp group located at a corner region of the heating lamp array.

The powder layer comprises a plurality of preset areas, the powder layer can be a bottom-laying powder layer or a formed powder layer, and each heating lamp group is used for heating one corresponding preset area of the powder layer. It should be noted that the preset area is not actually embodied in the powder layer, but the powder layer is divided in a virtual area manner. The powder layer may be any of the above-described bottomed powder layer, buffer powder layer, or formed powder layer.

In this embodiment, the plurality of heating lamp groups of the heat source are respectively provided with corresponding weight distribution coefficients, and the PID controller adjusts the heating power of at least one heating lamp group of the heat source based on the adjustment rate of the heating power of the heat source and the weight distribution coefficients of the heating lamp groups. For example, a first heating lamp group positioned at a center region of the heating lamp array may be configured with a weight distribution coefficient of approximately between 0.2 and 0.4, a second heating lamp group positioned at an edge region of the heating lamp array may be configured with a weight distribution coefficient of approximately between 0.7 and 0.8, and a third heating lamp group positioned at a corner region of the heating lamp array may be configured with a weight distribution coefficient of 1.0.

It can be understood that the PID controller is utilized in the above formula 1 to realize individual adjustment of the temperature of a plurality of preset areas of the powder layer by individually or group-wise adjusting the power of the heating lamps in the plurality of areas of the heating lamp array, so that the temperature of the printed layer can be ensured to be around the preset temperature, the quality of the printed layer is ensured, and the quality of the three-dimensional object formed by printing is improved.

In some embodiments, each preset area of the powder layer corresponds to each area of the array of heating lamps, and the heating energy required to be received by each preset area of the powder layer may be distributed according to logic requirements, so that the weighting factor of the corresponding heating lamp or the group of heating lamps in the array of heating lamps can satisfy the heating energy required by each preset area of the powder layer. More specifically, the number of preset areas of the powder layer is equal to the number of heating lamps, so that the heating lamps can be assigned in a one-to-one correspondence according to the preset areas of the powder layer.

In the present embodiment, a plurality of heating lamps located in a center area of the array of heating lamps are used to heat a first preset area of the powder layer, a plurality of heating lamps located in an edge area of the array of heating lamps are used to heat a second preset area of the powder layer, and a plurality of heating lamps located in a corner area of the array of heating lamps are used to heat a third preset area of the powder layer.

In other embodiments, the number of the preset areas of the powder layer is smaller than the number of the heating lamps, and the heating lamps may be divided into a plurality of heating lamp groups, which correspond to the preset areas of the powder layer one by one, respectively.

It can be understood that the temperature T of the bottoming powder layer reaches the preset temperature Tc, which does not mean that the temperature of the bottoming powder layer is necessarily exactly equal to the preset temperature, the actual temperature of the bottoming powder layer may also approach the preset temperature, the difference between the actual temperature and the preset temperature is Δ T, and the preset range of Δ T may be-5 ℃ to 5 ℃; preferably, the predetermined range of Δ T is from-1 ℃ to 1 ℃. That is, the temperature of the underlying powder layer may be infinitely close to the preset temperature.

Fig. 4 is a temperature change state diagram in the process of forming the bottom powder layer 11 according to an embodiment of the present application, as shown in fig. 4, a temperature detector in the temperature adjustment module 4 obtains a temperature t (in units of ℃) of an i-th temperature measurement point of the bottom powder layer at a predetermined position above the build platform 1, and in practical application, the temperature t of the i-th temperature measurement point of the bottom powder layer may be a temperature value of a certain specified preset measurement point, an average value of temperatures of a plurality of preset measurement points of the bottom powder layer 11 detected by the temperature detector, or an average value of temperatures of all preset measurement points detected by the temperature detector.

As shown in fig. 4, at t₀At that moment, the powder supply module 2 starts to supply powder, no powder material is on the construction platform 1 at that moment, and the temperature T is at that moment₀To build the real-time temperature of the platform 1. In the present embodiment, the build platform 1 has heating wires to heat the build platform 1, illustratively, T₀About 150 c.

From t₁From this moment on, the powder supply module 2 starts applying the powder material on the building platform 1. Understandably, at time t₀And t₁In between, the temperature detector does not measure the temperature of the powder material, but the temperature of the build platform 1. For simplicity, it is assumed here that at t₀And t₁The temperature of the build platform 1 did not change in the time frame in between.

From time T1, the powder supply module 2 starts applying powder material on the build platform 1 to form a first isolated powder layer, the amount of powder material on the build platform 1 gradually increases with time, and since the temperature of the powder material is lower than that of the build platform 1, as shown in fig. 4, the temperature T detected by the temperature detector decreases, i.e. from the temperature T₀Down to oneA minimum value T_L1. Controlling the heat treatment of the heat source on the first isolated powder layer, the temperature of which is again from the minimum value T_L1Then rise to T_H1. Illustratively, T_L1About 110 ℃ and T_H1About 155 deg.c. The temperature re-rising after reaching the minimum is due to an increase in the heating power of the heat source. In the actual printing process, after the PID controller receives the temperature reduction signal sent by the temperature detector, the PID controller controls the heating power of the heat source to be increased so as to increase the temperature of the first isolation powder layer, and the heating rate of the isolation powder layer can be increased by increasing the heating power of the heat source. That is, in the time frame between t1 and t2, powder supply module 2 forms a first layer of a bottom powder (i.e., a first layer of an isolated powder) on build platform 1 with powder material.

From time t2, the powder supply module 2 continues to apply powder material on the first isolated powder layer to form a second isolated powder layer. As the amount of powder material on the first isolating powder layer increases gradually over time, the temperature detected by the temperature detector decreases again, i.e. from the temperature T to a minimum value T, as shown in fig. 4, since the temperature of the powder material is lower than the temperature of the first isolating powder layer_L2Then the temperature of the second barrier powder layer is raised again to T due to the heating of the heat source_H2. Wherein, T_L2Greater than T_L1，T_H2Greater than T_H1. Illustratively, T_L2About 115 ℃ and T_H1And about 159 c. That is, in the time range between t2 and t3, the powder supply module 2 forms a second isolated powder layer on the first isolated powder layer with the powder material.

Repeatedly, from times t3, t4 … … t12, the powder supply module 2 continues to form a new underlying powder layer on the previous underlying powder layer with powder material. It can therefore be seen in fig. 4 that, from the times T3, T4 … … T12, the temperature T detected by the temperature detector decreases and, in turn, decreases to a minimum value T_L3、T_L4……T_L12Then rises to T again due to heating of the heat source_H3、T_H4……T_H12. Wherein the content of the first and second substances,T_L12＝T_L11＝T_L10＞……＞T_L4＞T_L3＞T_L2＞T_L1at a predetermined temperature T_A＝T_H12＝T_H11＝T_H10＞……＞T_H4＞T_H3＞T_H2＞T_H1. As can be seen from fig. 4, due to the heat preservation effect of the isolation powder layers, from time t10, the powder supply module 2 continues to form the buffer powder layer on the previous isolation powder layer by using the powder material, and the temperature rise rate of the isolation powder layer is greater than the temperature rise rate of the buffer powder layer, that is, when the temperature difference between the real-time temperature of the powder layer and the preset temperature is larger, the temperature rise rate is larger, and when the temperature difference is smaller, the temperature rise rate is smaller. That is, the 10 th, 11 th and 12 th buffer powder layers are adjusted by the temperature adjusting module 4, and the temperature reaches the preset temperature T_AExemplary, T_AAbout 178 deg.c. It is to be understood that fig. 4 is merely illustrative and that no particular limitation is placed on the number of isolated powder layers, the number of buffer powder layers, and the total number of priming powder layers formed.

In order to make each isolated powder layer reach the preset temperature faster, specifically, step S20 includes:

the PID controller controls the heating source to heat the isolated powder layer based on the first PID control system.

It should be noted that the first PID control coefficient can increase the heating power of the heat source in a shorter time, thereby increasing the heating rate of the isolated powder layer.

In some embodiments, the temperature increase rate of the isolation powder layer is 0.5 ℃/s to 10 ℃/s, and specifically may be 0.5 ℃/s, 0.8 ℃/s, 1 ℃/s, 2 ℃/s, 3 ℃/s, 5 ℃/s, 7 ℃/s, 8 ℃/s, or 10 ℃/s, and the like, without limitation.

And S30, forming a formed powder layer on the surface of the at least one bottom-laid powder layer by using the powder material.

In step S30, the control module 5 controls the powder supply module 2 to form the formed powder layer 121 on the surface of the at least one underlying powder layer 11. It will be appreciated that when multiple layers of the laid-down powder layers are formed on the build platform 1, the profiled powder layer 12 is formed on the one of the laid-down powder layers that is uppermost.

In some embodiments, the thickness of a single shaped powder layer 121 may or may not be the same as the thickness of a single underlying powder layer 11. During the actual printing process, the thickness of the formed profiled powder layer 121 may be adjusted by the control module 5 by adjusting the powder supply module 4 and/or the build platform 1. For example, the single powder supply of the powder supply module 4 may be changed, or the single elevation height of the build platform 1 may be changed, etc.

And S40, applying liquid material on the formed powder layer according to the layer printing data.

In one embodiment, the liquid material dissolves at least a portion of the powder material, and it should be noted that dissolution in this embodiment refers to all possible situations except complete dissolution. For example, when 1g of the powdered material is placed in 100g of the liquid material at least 1% of the powdered material is dissolved. Preferably, the liquid material completely dissolves the powder material. The dissolution is not limited to normal temperature, and the dissolution of the powder material by the liquid material can be realized under the condition of heating and/or stirring; the dissolution is not limited to one dissolution but may be staged, such as slow dissolution occurring when a liquid material is contacted with a powder material, which may be heated to increase the rate of dissolution.

In another embodiment, the liquid material is thermally and/or photopolymerized and/or the liquid material is polymerized with the powder material. The liquid material is not limited in this embodiment as long as it can finally cure and mold the powder material on which the liquid material is ejected.

In one embodiment, the liquid material may contain an energy absorber that converts energy into thermal energy upon absorption of the energy provided, thereby melt-forming the powder material in contact therewith. In another embodiment, the liquid material is a light-curable material, the liquid material contains a light-curable component, and the light-curable component can dissolve the powder material, and the light-curable component is induced by the photoinitiator to perform polymerization reaction under irradiation so as to entangle and cure the dissolved powder molecules. In another embodiment, the liquid material is a thermosetting material, the liquid material contains a thermosetting component, and the thermal initiator initiates polymerization of the thermosetting component under irradiation to form a polymer to encapsulate the powder material. In another embodiment, the liquid material has a reactive component that reacts with the powder material, and the initiator initiates polymerization of the liquid material with the powder material upon irradiation.

In one embodiment, the liquid material melts at least a portion of the powder material, and in particular, the liquid material may be heated to a temperature above the melting point of at least a portion of the powder material, such that the liquid material applied to the powder material melts the powder material, and the formed powder layer cools to form the printed layer.

Further, the liquid material also comprises an auxiliary agent. Specifically, the auxiliary agent is selected from an initiator, a leveling agent, a defoaming agent, a surfactant and the like. The initiator is used for initiating the liquid material to react, and the initiator can be selected from a photoinitiator, a free radical initiator, an anion initiator, a cation initiator and the like according to the type of the liquid material. The leveling agent is used to improve the fluidity of the liquid material and the wettability of the powder material, and adjust the surface tension of the liquid material to enable normal printing, which is not limited in this embodiment. The antifoaming agent is mainly used for preventing foaming of the liquid material, and the antifoaming agent may be, for example, a silicone antifoaming agent, a polyether antifoaming agent, a fatty acid ester antifoaming agent, or the like. Surfactants are mainly used to control the wettability, permeability and surface tension of the liquid material to the powder material, and may be, for example, anionic surfactants, nonionic surfactants and amphoteric surfactants.

The liquid material may also include a colorant, which may be a dye or a pigment, when included therein, to realize a colored 3D object.

As shown in connection with fig. 1, the control module 5 controls the jetting module 3 to apply the liquid material on the formed powder layer according to the layer printing data. The spraying module 3 sprays liquid material onto the formed powder layer 121 according to the layer printing data, and the liquid material penetrates into the formed powder layer 121, so that the formed powder layer 121 forms a patterned region and an unpatterned region. In a particular embodiment, the control module 5 controls the jetting module 3 and the shaped powder layer 121 to move relative to each other in the XY plane to jet the liquid material onto the shaped powder layer 121 in a desired pattern according to the layer printing data.

The patterned areas in the formed powder layer are solidified under the action of the heat source to form a printed layer 131.

And S50, adjusting the temperature of the formed powder layer to a preset temperature to form a printing layer, wherein the temperature rising rate of the isolation powder layer is greater than that of the formed powder layer.

In step S50, the control module 5 controls the temperature adjustment module 4 to adjust the temperature of the formed powder layer to a preset temperature to form a printed layer, wherein the temperature increase rate of the isolated powder layer is greater than the temperature increase rate of the formed powder layer.

It should be noted that the flowchart of fig. 2 does not represent that step S50 is necessarily after steps S30 and S40, and in some embodiments, the temperature adjustment module 4 continuously adjusts the temperature of the powder material on the bottom powder layer 11 during the process of the powder supply module 2 forming the formed powder layer 121 on the bottom powder layer 11 by using the powder material and controlling the spraying module 3 to spray the liquid material on the formed powder layer 121 according to the layer printing data, so that the formed powder layer 121 reaches the preset temperature.

It will be understood that the temperature T of the formed powder layer reaches the preset temperature T_AThe temperature of the formed powder layer is not necessarily equal to the preset temperature, the actual temperature of the formed powder layer can be close to the preset temperature, the difference between the actual temperature and the preset temperature is delta T, and the preset range of the delta T can be-5 ℃ to 5 ℃; preferably, the predetermined range of Δ T is from-1 ℃ to 1 ℃. That is, the temperature of the formed powder layer is allowed to approach the preset temperature infinitely.

In some embodiments, controlling the heating power of the heat source adjusts to a second heating power and heats the shaped powder layer. Wherein the second heating power is less than the first heating power. Illustratively, the second heating power when heating the formed powder layer is 350W when the first heating power when heating the isolated powder layer is 400W.

In this embodiment, the rate of temperature increase of at least a portion of the layer of the bottomed powder is greater than the rate of temperature increase of the layer of the formed powder. Specifically, the temperature rise rate of the isolation powder layer is greater than that of the molding powder layer.

Because before forming the shaping powder layer 121, the temperature of the bottoming powder layer has already reached the preset temperature, the bottoming powder layer reaching the preset temperature can provide a better heat preservation effect, and when the bottoming powder layer contacts a newly laid powder material, thermal diffusion can be realized, so that the initial temperature of the shaping powder layer 121 is higher than the initial temperature of the isolation powder layer, and the temperature difference between the initial temperature of the shaping powder layer 121 and the preset temperature is smaller.

In the scheme, the temperature rise rate of the bottom-laying powder layer is higher by controlling the temperature rise rate of the isolation powder layer to be larger than that of the forming powder layer, and the temperature of the bottom-laying powder layer 11 can reach the preset temperature as fast as possible; in the printing and forming stage, the temperature rise rate of the forming powder layer 121 is slower, so that the phenomenon of temperature overshoot of the forming powder layer 121 is avoided, the temperature of the forming powder layer 121 is guaranteed to reach the preset temperature, and the quality of the printing layer 131 is guaranteed.

Fig. 5 is a temperature change state diagram in the process of forming a formed powder layer according to an embodiment of the present application, and as shown in fig. 5, a temperature detector in the temperature regulation module 4 obtains a temperature t '(in units of ℃) of the formed powder layer 121 at a predetermined position above the underlying powder layer 11, and in an actual application, the temperature t' of the formed powder layer may be an average value of temperatures of a plurality of preset measurement areas of the formed powder layer detected by the temperature detector, or an average value of temperatures of all the preset measurement areas detected by the temperature detector.

As shown in fig. 5, at t_B1From that moment on, the powder supply module 2 starts applying the powder material on the layer of bottomed powder 11. Understandably, at t_B1At this point in time, the temperature detector does not measure the temperature of the newly applied powder material, but rather the bottoming powder located at the uppermost layer of the build platformThe temperature of layer 11. Thus, at time t_B1The temperature detected by the temperature detector is equal to the preset temperature T_A。

From time t_B1Starting with the application of the powder material by the powder supply module 2 on the layer 11 to form the first formed powder layer 121, the amount of the powder material on the layer 11 gradually increases with time, and since the temperature of the powder material is lower than the temperature of the layer 11, as shown in fig. 5, the temperature T detected by the temperature detector decreases, i.e. decreases from the temperature T to a minimum value T_L. Controlling the heat source to heat the first formed powder layer 121, wherein the temperature of the first formed powder layer 121 is controlled to be from the minimum value T_LThen rise to T_A. Illustratively, T_LAbout 160 ℃ and T_AAbout 178 deg.c. The temperature re-rising after reaching the minimum is due to an increase in the heating power of the heat source.

In an actual printing process, after the PID controller receives a temperature decrease signal sent by the temperature detector, the PID controller controls the heating power of the heat source to increase so that the temperature of the first molding powder layer 121 reaches a preset temperature, and the heating rate of the molding powder layer 121 can be increased by increasing the heating power of the heat source to a maximum value. When the difference value delta T between the actual temperature detected by the temperature detector and the preset temperature is in a preset range, the PID controller enables the heating power to be reduced again.

Repeatedly, from time t_B2、t_B3、t_B4… …, inside the measuring area, the newly applied powder material, which is at a lower temperature, is present in gradually increasing amounts to form a new one of the shaped powder layers. As can be seen in fig. 5, there is a decrease in the temperature T determined by the temperature detector, the temperature T decreasing until a minimum value T_LThen raised again to the target temperature T_A. It is to be understood that fig. 5 is merely illustrative and that the total number of formed shaped powder layers is not particularly limited herein.

In some embodiments, the temperature increase rate of the formed powder layer is 0.1 ℃/s to 2 ℃/s, and specifically may be 0.1 ℃/s, 0.2 ℃/s, 0.3 ℃/s, 0.4 ℃/s, 0.5 ℃/s, 0.6 ℃/s, 1 ℃/s, 1.5 ℃/s, or 2 ℃/s, and the like, which is not limited herein.

As can be seen from fig. 4 and 5, since the molded powder layer is formed on the underlying powder layer, and the underlying powder layer functions as an insulating layer, the minimum value of the temperature of the formed molded powder layer is greater than the minimum value of the temperature of the insulating powder layer, and the temperature increase rate of the insulating powder layer is controlled to be greater than the temperature increase rate of the molded powder layer. If the PID controller always adopts the first group of PID coefficients to heat the bottoming powder layer and the forming powder layer, the temperature of the forming powder layer is easy to deviate from a preset range, and the powder hardening influences the quality of the formed printing layer.

Step S50 specifically includes: the control module 5 sets the control coefficient of the PID controller in the temperature adjusting module 4 as a second group of PID coefficients, and the PID controller controls the heat source to heat the formed powder layer based on the second group of PID coefficients, so that the temperature of the formed powder layer is adjusted to a preset temperature to form a printing layer. Wherein the first set of PID coefficients differs in value from at least one coefficient of the second set of PID coefficients. It will be appreciated that the control module 5 may adjust the control coefficients of the PID controller in accordance with the type of powder layer being formed, to achieve independent control of the temperature regulation of the powder layers at different stages.

In a specific embodiment, the actual temperature of the formed powder layer is obtained by a temperature detector in the temperature regulation module 4; and calculating the adjustment rate of the heating power of the heat source according to the error value between the actual temperature and the preset temperature and the second group of PID coefficients. Illustratively, when the actual temperature of the molding powder layer is lower than the preset temperature, the PID controller controls the heating power adjustment rate of the heating lamp array to be increased by 10%, i.e., 110% of the initial power, e.g., 300W, i.e., 330W.

The control adopts two different PID control coefficients for heating the isolation powder layer and the forming powder layer respectively, and the temperature rise rate of the isolation powder layer is larger than that of the forming powder layer, so that the temperature of the forming powder layer can be prevented from deviating from a preset range, and the quality of a printing layer is ensured.

Specifically, the time for increasing the heating power of the heat source to the maximum power by using the PID controller provided with the second PID coefficient becomes longer and/or the maximum power to which the heating power of the heat source can be increased by using the PID controller provided with the second PID coefficient becomes smaller, as compared with using the PID controller provided with the first PID coefficient. Thus, the temperature rise rate of the bottoming powder layer is made larger than that of the formed powder layer.

Further, in an embodiment where the bottom-laying powder layer further includes a buffer powder layer, the PID controller may control the heat source to heat the buffer powder layer based on a first set of PID coefficients, may also control the heat source to heat the buffer powder layer based on a second set of PID coefficients, and may also control the heat source to heat the buffer powder layer based on a third set of PID coefficients, where the third set of PID coefficients is different from at least one of the first set of PID coefficients and the second set of PID coefficients in value.

In the three-dimensional object printing process, after step S50, the printing method further includes:

step S60, determining whether the current printing layer of the three-dimensional object is the last layer, if not, repeating the steps from forming the molding powder layer to forming the printing layer, i.e. steps S30 to S50, so that the obtained multiple printing layers are overlapped layer by layer to form the three-dimensional object.

While fig. 1 schematically illustrates the second formed powder layer 122, and the resulting second printed layer 132, it is to be understood that a three-dimensional object may be formed from more than two printed layers, one on top of the other. If the judgment result is 'yes', the process is ended, and the construction of the three-dimensional object is completed.

The method includes the steps that a digital model of a three-dimensional object is sliced and layered to obtain at least one sliced layer, and in the process of printing the three-dimensional object, every printing layer is formed and overlapped layer by layer until all the sliced layers are printed to form the target three-dimensional object, otherwise, a forming powder layer and a liquid material are repeatedly formed according to layer printing data to form the printing layers, and the three-dimensional object is formed by layer.

In summary, in the embodiment of the present application, the temperature of at least part of the bottoming powder layer and the temperature of the forming powder layer are respectively adjusted to the preset temperatures, and the temperature rise rate of the isolation powder layer in the bottoming powder layer is controlled to be greater than the temperature rise rate of the forming powder layer, so that it can be ensured that the temperature of the bottoming powder layer can reach the preset temperature as quickly as possible; and in the printing and forming stage, the heating rate of the forming powder layer is slower, the phenomenon of temperature overshoot of the printing layer is avoided, and the temperature of the printing layer is ensured to be about the preset temperature, so that the quality of the printing layer is ensured, and the quality of the formed three-dimensional object is improved.

An embodiment of the present application further provides a non-transitory computer-readable storage medium, as shown in fig. 6, where the storage medium 91 includes a stored program 911, and when the program runs, the apparatus where the storage medium 91 is located is controlled to execute the above-mentioned three-dimensional object printing method.

An embodiment of the present application further provides a computer device, as shown in fig. 7, the computer device of the embodiment includes: the processor 101, the memory 102, and the computer program 103 stored in the memory 102 and capable of running on the processor 101, where the processor 101 implements the three-dimensional object printing method in the embodiment when executing the computer program 103, and details are not repeated here to avoid repetition.

The computer device may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The computer device may include, but is not limited to, a processor, a memory. Those skilled in the art will appreciate that a computing device may include more or fewer components than those shown, or some of the components may be combined, or different components, e.g., a computing device may also include input output devices, network access devices, buses, etc.

The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The storage may be an internal storage unit of the computer device, such as a hard disk or a memory of the computer device. The memory may also be an external storage device of the computer device, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like provided on the computer device. Further, the memory may also include both internal and external storage units of the computer device. The memory is used for storing computer programs and other programs and data required by the computer device. The memory may also be used to temporarily store data that has been output or is to be output.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed.

Claims

1. A method of printing a three-dimensional object, the method comprising:

and adjusting the temperature of the forming powder layer to a preset temperature to form a printing layer, wherein the temperature rise rate of the isolation powder layer is greater than that of the forming powder layer.

2. The printing method according to claim 1, wherein the adjusting the temperature of at least part of the layer of bottomed powder to a preset temperature comprises: and adjusting the temperature of at least the last layer of the isolation powder layer to a preset temperature.

3. The printing method according to claim 1, wherein the adjusting the temperature of at least part of the layer of bottomed powder to a preset temperature comprises:

4. The printing method according to claim 1,

the adjusting of the temperature of at least part of the bottom-laying powder layer to a preset temperature specifically comprises:

setting the control coefficient of the PID controller to be a second set of PID coefficients, and controlling a heat source to heat the formed powder layer by the PID controller based on the second set of PID coefficients, wherein the value of at least one coefficient in the first set of PID coefficients and the second set of PID coefficients is different.

5. The printing method according to claim 4, wherein the PID controller controls the heat source to heat the isolated powder layer based on the first set of PID coefficients, specifically comprising:

calculating the adjustment rate of the heating power of the heat source according to the error value between the actual temperature and the preset temperature of the isolation powder layer and the first group of PID coefficients;

6. The printing method according to claim 5, wherein said obtaining an actual temperature of said isolated powder layer or said shaped powder layer by a temperature detector comprises:

7. The printing method according to claim 5, wherein the isolated powder layer or the formed powder layer includes a plurality of preset areas, the heat source includes a plurality of heating lamp groups, each heating lamp group is used for heating a corresponding preset area of the isolated powder layer or the formed powder layer, and the plurality of heating lamp groups of the heat source are respectively configured with corresponding weight distribution coefficients;

8. The printing method according to claim 1, wherein the temperature increase rate of the isolated powder layer is 0.5 ℃/s to 10 ℃/s and the temperature increase rate of the shaped powder layer is 0.1 ℃/s to 2 ℃/s.

9. The printing method of claim 1, wherein the priming powder layer further comprises at least one buffer powder layer; the buffer powder layer is formed after the isolation powder layer and before the shaping powder layer.

10. The printing method according to claim 9, wherein said adjusting the temperature of at least part of said layer of underlayment powder to a preset temperature comprises: and adjusting the temperature of at least the last layer of the isolation powder layer to a preset temperature, and adjusting the temperature of the buffer powder layer to a preset temperature.

11. The printing method of claim 9, wherein a rate of temperature rise of the isolated powder layer is greater than a rate of temperature rise of the buffer powder layer.

12. The three-dimensional object printing device is characterized by comprising a construction platform, a powder supply module, an injection module, a temperature regulation module and a control module, wherein the control module is respectively connected with the construction platform, the powder supply module, the injection module and the temperature regulation module; the control module is configured to:

13. The printing device according to claim 12, wherein the temperature adjustment module comprises a heat source, a temperature detector and a PID controller, the PID controller is connected to the control module in a communication manner, and the PID controller controls the heating power of the heat source according to the information fed back by the temperature detector.

14. The printing apparatus of claim 13, wherein the control module is configured to:

setting the control coefficient of the PID controller as a first group of PID coefficients, and controlling the temperature adjusting module to adjust the temperature of the isolation powder layer;

setting the control coefficient of the PID controller as a second group of PID coefficients, and controlling the temperature adjusting module to adjust the temperature of the formed powder layer, wherein the value of at least one coefficient in the first group of PID coefficients and the second group of PID coefficients is different.

15. The printing apparatus of claim 13, wherein the heat source is selected from at least one of an ultraviolet lamp, an infrared lamp, a microwave emitter, a heating wire, a heating sheet, and a heating plate.

16. The printing apparatus of claim 13, wherein a powder layer comprises a plurality of predetermined areas, the powder layer is the formed powder layer or the bottomed powder layer, and the heat source comprises a plurality of heating lamp groups, each heating lamp group being for heating a corresponding one of the predetermined areas of the powder layer.

17. The printing apparatus of claim 13, wherein the heat source is an array of heat lamps.

18. A non-transitory computer-readable storage medium, wherein the storage medium includes a stored program, and when the program runs, the apparatus on which the storage medium is controlled to execute the method for printing a three-dimensional object according to any one of claims 1 to 11.

19. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the method of printing a three-dimensional object according to any one of claims 1 to 11 when executing the computer program.