CN114603848B

CN114603848B - Three-dimensional object printing method and device and computer equipment

Info

Publication number: CN114603848B
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: 2023-11-07
Anticipated expiration: 2042-03-14
Also published as: CN114603848A

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 from a powder material, the bottoming powder layer comprising at least one barrier powder layer; adjusting the temperature of at least part of the underlying powder layer to a preset temperature; forming a shaped powder layer on a surface of the at least one underlying powder layer with a powder material; applying a liquid material on the shaped powder layer according to layer print data; and adjusting the temperature of the molding powder layer to a preset temperature to form a printing layer, wherein the temperature rising rate of the isolation powder layer is larger than that of the molding powder layer. The three-dimensional object printing method provided by the application can avoid the phenomenon of overshoot of the temperature of the powder layer in the three-dimensional object printing process, and improve the printing quality of the three-dimensional object.

Description

Three-dimensional object printing method and device and computer equipment

Technical Field

The present application relates to the field of three-dimensional printing technologies, and in particular, to a method and apparatus for printing a three-dimensional object, and a computer device.

Background

In a three-dimensional printing process that produces an object by curing based on layer-by-layer build material, the quality of the final formed 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 three-dimensional object formed.

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 a powder bed, however, in a printing and forming stage, the temperature of a powder laying roller is greatly lower than the temperature of the powder bed due to the fact that the temperature difference between the powder laying roller and the powder bed is large and the influence of smooth reflection of the surface of the powder laying roller is added. The detected temperature is lower in the printing forming stage, so that the power of a heat source is increased at a constant speed, the temperature of a powder bed is finally higher than the target temperature, and overshoot is possibly caused, so that the powder material is hardened, and the quality and the precision of a formed three-dimensional object are affected.

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 bedding powder layer with a powder material, the bedding powder layer comprising at least one barrier powder layer;

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

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

Applying a liquid material on the shaped powder layer according to layer print data;

and adjusting the temperature of the molding 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 larger than that of the molding powder layer.

With reference to the first aspect, in a possible implementation manner, the adjusting the temperature of at least part of the bottom-laying powder layer to a preset temperature specifically includes: and adjusting the temperature of at least the last isolating 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 bottom-laying powder layer to a preset temperature specifically includes:

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

the adjusting the temperature of the molding 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 molding powder layer, wherein the second heating power is smaller than the first heating power.

Setting control coefficients of a PID controller as a first group of PID coefficients, wherein the PID controller controls a heat source to heat the isolation powder layer based on the first group of PID coefficients; and

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

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

acquiring an actual temperature of the isolating powder layer by a temperature detector;

calculating to obtain 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 isolating powder layer and the first group of PID coefficients;

the PID controller controls a heat source to heat the molding powder layer based on the second group of PID coefficients, and specifically comprises the following steps:

acquiring an actual temperature of the molded powder layer by 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 of the formed powder layer and the preset temperature 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 insulating powder layer or the molding powder layer includes:

a temperature within at least one preset area of the insulating powder layer or the shaped powder layer is detected with a thermal image camera.

With reference to the first aspect, in a possible implementation manner, the isolating powder layer or the molding 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 isolating powder layer or the molding powder layer, and the plurality of heating lamp groups of the heat source are respectively configured with corresponding weight distribution coefficients;

adjusting the temperature of the underlying powder layer or the shaped powder layer to a preset temperature, comprising:

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.

With reference to the first aspect, in one possible embodiment, the temperature rise rate of the insulating powder layer is 0.5 ℃/s to 10 ℃/s, and the temperature rise rate of the shaping powder layer is 0.1 ℃/s to 2 ℃/s.

With reference to the first aspect, in a possible implementation, the underlying powder layer further comprises at least one buffer powder layer; the buffer powder layer is formed after the barrier 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 bottom-laying powder layer to a preset temperature specifically includes: adjusting the temperature of at least the last layer of the barrier 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 a possible implementation, the temperature rise rate of the insulating powder layer is greater than the temperature rise rate of the buffer powder layer.

In a second aspect, the application provides a three-dimensional object printing device, which comprises a construction platform, a powder supply module, a spraying module, a temperature adjusting module and a control module, wherein the control module is respectively connected with the construction platform, the powder supply module, the spraying module and the temperature adjusting module; 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 barrier powder layer;

controlling the temperature regulating module to regulate the temperature of at least part of the bottoming powder layer to a preset temperature;

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

controlling the jetting module to apply a liquid material on the layer of shaped powder according to layer print data;

and controlling the temperature regulating module to regulate the temperature of the molding powder layer to a preset temperature so as to form a printing layer, wherein the temperature rising rate of the isolation powder layer is larger than that of the molding powder layer.

With reference to the second aspect, in a possible implementation manner, the temperature adjusting module includes a heat source, a temperature detector, and a PID controller, where the PID controller is communicatively connected to the control module, 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 a possible implementation manner, the control module is configured to:

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

After the controlling the powder supply module to form a shaped powder layer on the surface of the at least one underlying powder layer, setting the control coefficients of the PID controller to a second set of PID coefficients, wherein the values of at least one coefficient of the first set of PID coefficients and the second set of PID coefficients are different.

With reference to the second aspect, in a 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.

With reference to the second aspect, in a possible embodiment, the powder layer comprises a plurality of preset areas, the powder layer is the profiled powder layer or the bottoming powder layer, and the heat source comprises a plurality of heating lamp sets, each heating lamp set being used for heating a corresponding one of the preset areas of the powder layer.

With reference to the second aspect, in a possible implementation manner, the heat source is a heating lamp array.

In a third aspect, the present application provides a non-transitory computer readable storage medium, the storage medium including a stored program that, when executed, controls a device in which the storage medium is located to perform the above-described 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 and device and the computer equipment, the temperature of at least part of the bottom powder layer and the temperature of the forming powder layer are respectively adjusted to the preset temperature, and the heating rate of at least part of the bottom powder layer is controlled to be larger than that of the forming powder layer, so that the temperature of the bottom powder layer can reach the preset temperature as soon as possible; in the printing and forming stage, the temperature rising rate of the formed powder layer is slower, the phenomenon of temperature overshoot of the printed layer is avoided, the temperature of the printed layer is guaranteed to be about the preset temperature, the quality of the printed layer is guaranteed, and the quality and the accuracy of the formed three-dimensional object are improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.

Fig. 1 is a schematic structural diagram of a three-dimensional object printing device 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 application;

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

FIG. 4 is a graph showing the temperature change of the printing method according to the embodiment of the present application during the formation of the underlying powder layer;

FIG. 5 is a temperature change state diagram of a printing method according to an embodiment of the present application during formation of a molded powder layer;

FIG. 6 is a schematic diagram of a non-transitory computer readable storage medium according to 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 a better understanding of the technical solution of the present application, the following detailed description of the embodiments of the present application refers to the accompanying drawings.

It should be understood that the described embodiments are merely some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in 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 relationship describing the association of the associated objects, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

In the X-Y-Z coordinate system marked in the drawing, in a non-rotating printing mode of the supporting platform relative to the printing head, the X axis is parallel to the printing direction, the Y axis is perpendicular to the printing direction and parallel to the slicing layer, namely, the X-Y plane is parallel to the slicing layer, and the Z axis is parallel to the superposition direction of the slicing layer and perpendicular to the X-Y plane.

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

A build platform 1 for carrying a powder layer of powder material. Specifically, 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 is used for driving the building platform 1 to lift or descend along the vertical direction.

A powder supply module 2 for supplying a build platform 1 with powder material to form a powder layer comprising a bottoming powder layer and a shaping powder layer. Illustratively, the powder supply module 2 may include a powder storage cavity, a powder feeder, a powder storage tank and a powder spreader, wherein the powder storage cavity is used for storing powder materials, and the powder materials in the powder storage cavity are conveyed into the powder storage tank located at one side of the building platform 1 through the powder feeder; the powder spreader is used to spread the powder material in the powder storage tank onto the build platform 1 to form at least one underlying powder layer 11 or at least one profiled powder layer, and a common powder spreader may be a spreading roller and/or a scraper.

A spraying module 3 for applying liquid material to the profiled powder layer on the build platform 1. In particular, the jetting module 3 may be an inkjet printhead, which may be a single-channel printhead or a multi-channel printhead, the number of printheads 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, where the liquid material comprises different colours of functional material, the different colours of liquid material are ejected through different printheads or different channels of the same printhead. For example, when the volume of a single ink droplet to be applied is insufficient in a larger amount of liquid material, a plurality of printheads or a plurality of channels of the same printhead may be simultaneously used to eject the same kind of material in order to improve printing efficiency.

A temperature regulation module 4 for regulating the temperature of the powder layer on the build platform 1. Specifically, the temperature regulation module 4 may include a heat source, a temperature detector, and a controller. The heat source may be arranged above 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 whole area of build platform 1.

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

A temperature detector for monitoring the actual temperature of the uppermost powder layer on the build platform 1. The powder layer may be a backing powder layer or a shaping 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 on top of the build chamber along with the heat source arrangement. In other embodiments, the temperature detector may also be located outside the build chamber, without limitation.

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

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

Further, the three-dimensional object printing device further comprises a preheating assembly for preheating the powder material carried on the build platform 1. The preheating component can provide radiant energy or heat energy, and can 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 choice is not limited. In some embodiments, a preheating assembly is provided on build platform 1 for heating build platform 1 to preheat the powder material carried on build platform 1. In some embodiments, a preheating assembly may also be provided on the four walls of the build chamber to preheat the powder material within the build chamber. In particular, the build chamber may have heating wires on its four walls for insulating the powder material within the build chamber. In other embodiments, a preheating assembly may also be provided on the powder feeder and the powder storage tank in the powder supply module 2 to preheat the conveyed powder material.

The three-dimensional object printing device further comprises a data processing device, a printing device and a printing device, wherein the data processing device is used for slicing the digital model of the object to be printed to obtain a plurality of slice layers and slice layer image data; slice layer print data is generated from the slice layer image data and transferred to the control module 5. The data processing device is, for example, slicing software, and in 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 will be appreciated, during printing, the control module 5 controls the powder supply module 2 to supply powder material to the build platform 1 to form a layer of base powder, and controls the temperature adjustment module 4 to heat the layer of base powder to bring at least part of the layer of base powder to a preset temperature; the powder supply module 2 is controlled to supply powder material to the underlying powder layer to form a molded powder layer, and the jetting module 3 is controlled to jet liquid material to the molded powder layer based on the layer printing data, and the temperature adjusting module 4 is controlled to heat the molded powder layer to a preset temperature to promote the formation of a printed layer. The control module 5 controls the lifting mechanism to move in the vertical direction, and controls the powder supply module 2 and the injection module 3 to repeat the steps to print layer by layer and to stack 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 according to an embodiment of the present application, as shown in fig. 2, where the printing method includes the following steps:

s10, forming a bottom powder layer by using a powder material, wherein the bottom 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 molding powder layer on the surface of the at least one bottoming powder layer by using a powder material;

s40, applying liquid material on the molding powder layer according to layer printing data;

s50, adjusting the temperature of the molding powder layer to a preset temperature to form a printing layer, wherein the temperature rising rate of the isolation powder layer is larger than that of the molding powder layer.

In the scheme, the temperature of at least part of the bottom powder layer and the temperature of the forming powder layer are respectively adjusted to the preset temperature, and the temperature rising rate of the isolation powder layer is controlled to be larger than that of the forming powder layer, so that the temperature of the bottom powder layer can reach the preset temperature as soon as possible; in the printing and forming stage, the temperature rising rate of the formed powder layer is slower, the phenomenon of temperature overshoot of the printed layer is avoided, the temperature of the printed layer is guaranteed to be about the preset temperature, the quality of the printed layer is guaranteed, and the quality and the accuracy of the formed three-dimensional object are improved.

Referring to fig. 1 and 3, the following details are described in conjunction with the specific embodiments:

prior to step S10, the method further comprises:

step S01, a digital model of the three-dimensional object is obtained, slicing and layering are carried out on the digital model of the three-dimensional object, a plurality of slice layers and slice layer image data are obtained, and layer printing data are generated according to the slice layer image data.

In a specific implementation manner, original data of a three-dimensional object can be obtained through a scanning mode and three-dimensional modeling is carried out to obtain a digital model of the three-dimensional object, or the three-dimensional object model is designed and built to obtain the digital model of the three-dimensional object, data format conversion is carried out on the digital model, for example, the digital model is converted into a format which can be identified by slicing software, such as an STL format, a PLY format, a WRL format and the like, then slicing and layering are carried out on the model through the slicing software to obtain slice layer image data, and layer image data are processed to obtain layer printing data representing the object. In the present application, the shape of the three-dimensional object to be printed is not limited, and may be any shape.

S10, forming a bottom-paved powder layer by using a powder material, wherein the bottom-paved powder layer comprises at least one isolation powder layer.

In this embodiment, the powder material is a material particle in a powder form. The powder material includes powdery particulate material, powder-based material, and particulate material. The powder material may be selected from a powder metal material, a powder synthetic material, a powder ceramic material, a powder glass material, a powder resin material, a powder polymer material, and the like, without limitation. In this embodiment, the powder material may not undergo polymerization reaction with the liquid material, and the powder material itself may not undergo polymerization reaction; the powder material can also be polymerized with the liquid material, and the powder material can also be polymerized 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 (meth) methyl 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 deg.c to 300 deg.c. Specifically, the temperature may be 60 ℃, 70 ℃, 80 ℃, 100 ℃, 120 ℃, 150 ℃, 180 ℃, 200 ℃, 240 ℃, 280 ℃, or 300 ℃, or the like, but other values within the above range are also possible, and the temperature is not limited thereto. The powder material provided in this embodiment can satisfy the use requirement when forming the molded powder layer, 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 embodiments of the present application, the particle shape and particle size of the powder material are not particularly limited. Alternatively, the powder material may be spherical, dendritic, sheet-like, disk-like, needle-like, rod-like, or the like. The average particle diameter of the powder material is 1 μm to 400. Mu.m, 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, and other values within the above range are also possible. The particle size of the powder material is too small, so that the liquid material is difficult to permeate to the bottom of the current powder material layer in a short time, and the contact of the liquid material with the powder material is not facilitated. The particle size of the powder material is too large, and gaps among powder particles are too large, so that the molding accuracy of the three-dimensional object can be affected. The average particle diameter of the powder material is preferably 30 μm to 200. Mu.m. The particle gap in the powder material is approximately 5nm to 100. Mu.m, and may be, for example, 5nm, 10nm, 100nm, 250nm, 500nm, 1. Mu.m, 5. Mu.m, 10. Mu.m, 25. Mu.m, 50. Mu.m, 75. Mu.m, or 100. Mu.m, without limitation. The particle gaps of the powder material in the embodiments of the application are in the range of 5nm to 100 μm, which facilitates the rapid penetration of the liquid material through the gaps into the powder layer and the retention of portions of the powder material in the surface layer, even wetting 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. As can be appreciated, 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 increases; when the thickness of the powder layer is thick, the time for the liquid material to infiltrate the powder material is prolonged, and the resolution of the object to be manufactured is lowered, which is difficult to expect.

In the present application, the powder material may further include a filler for improving 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%, etc., but it is needless to say that the filler may be other values within the above range, and the present application is not limited thereto. 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 formed three-dimensional object is easy to become brittle and easy to damage. It can be appreciated that by adding a proper amount of filler to the powder material, the toughness of the three-dimensional object can be ensured and the mechanical strength of the three-dimensional object can be improved.

In the present application, the powder material may further include a flow aid for improving the fluidity of the powder material, and the flow aid may be silica, talc, or the like, and is not limited in this embodiment. The flow aid may be present in the powder material in an amount of 0% to 5% by mass, specifically 0%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, or the like, but may be present in other amounts within the above range, and is not limited thereto. It will be appreciated that the flow aid will not undergo a volume change during the forming process and that a suitable amount of flow aid may be advantageous to improve the flowability of the powder material, but that when the flow aid mass ratio is too high, the original performance characteristics of the powder material will be altered.

Referring to fig. 1 and 3 together, in step S10, the control module 5 controls the powder supply module 2 to supply powder material to the build platform 1 to form a bottom powder layer 11. Specifically, in step S10, the control module 5 controls the powder supply module 2 to supply and lay down powder material, and in some embodiments, the control module 5 also controls the build platform 1 to lift to cooperate with the powder supply module 2 such that the powder material forms a bottomed powder layer 11 on the build platform 1. It will be appreciated that the underlying powder layer 11 may act as an insulating layer, the underlying powder layer 11 insulating the profiled powder layer from the build platform 1, thereby avoiding affecting the temperature of the profiled powder layer due to poor thermal stability of the build platform 1. For better insulation effect, the thicker the paved bottom powder layer 11 is, the better the insulation effect is.

In order to achieve a good insulation effect and avoid excessive consumption of powder material in the underlying powder layer, the thickness of the underlying powder layer 11 preferably ranges from 20mm to 50mm, and specifically may be 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, etc., without limitation. As shown in fig. 1, in this embodiment, the underlying powder layer includes at least one barrier powder layer 111.

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

It should be noted that the flowchart of fig. 2 does not represent that step S20 is necessarily 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 part of the underlying powder layer 11 to a preset temperature. In one embodiment, while the powder supply module 2 forms the underlying powder layer 11 on the build platform 1 with powder material, the temperature adjustment module 4 is constantly in operation, and the temperature adjustment module 4 continuously adjusts the temperature of the powder material on the build platform 1 so that at least a portion of the underlying powder layer 11 reaches a preset temperature.

When forming multiple isolated powder layers 111 on build platform 1, in some embodiments, 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 adjustment module 4 may adjust the temperature of each of the insulating powder layers 111 such that the temperature of at least the last insulating powder layer 111 reaches a preset temperature, or such that the temperatures of the plurality of insulating powder layers 111 located at the upper layer reach a preset temperature.

Further, as shown in fig. 1, in the present embodiment, the underlying powder layer 11 further includes a buffer powder layer 112, the buffer powder layer 112 being formed after the insulating powder layer 111 and before the molding powder layer. Therefore, the buffer powder layer has better isolation and heat preservation effects and stronger thermal stability. During actual printing, control module 5 may illustratively control powder supply module 2 to supply powder material to build platform 1 to form 30 isolated powder layers, and to form 10 buffer powder layers on the isolated powder layers.

Illustratively, the temperature adjustment module 4 adjusts the temperatures of the plurality of insulating powder layers 111 so that the temperature of the last insulating powder layer 111 reaches a preset temperature; after the temperature of the isolation powder layer 111 reaches the preset temperature, continuing to form the buffer powder layers 112, and controlling the temperature adjusting module 4 to adjust the temperature of the buffer powder layers 112 so that the temperature of each buffer powder layer 112 reaches the preset temperature, wherein the temperature rising rate of the isolation powder layer 111 is greater than the temperature rising rate of the molding powder layer; the temperature rise rate of the buffer powder layer 112 may be greater than or equal to the temperature rise rate of the molding powder layer, or may be less than the temperature rise rate of the molding powder layer, and is not limited herein.

Further, in the present embodiment, the temperature rise rate of the insulating powder layer 111 is greater than the temperature rise rate of the buffer powder layer 112. Since the temperature of the insulating powder layer 111 has reached the preset temperature before the formation of the buffer powder layer 112, the insulating 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 insulating powder layer 111, 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 to heat the insulating powder layer 111.

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

in equation 1, e (t) is an error corresponding to the i-th temperature measurement point,for the error integration corresponding to the ith temperature measurement point,/->Is the differential of the error corresponding to the i-th temperature measurement point. K (K) _p As proportional term coefficient, K _d As differential term coefficients, K _i For integral term coefficients, proportional term coefficient K _p Coefficient of differential term K _i Integral term coefficient K _d Together form PID coefficients, and K _p 、K _i 、K _d All are positive numbers.

The step S20 specifically includes: the control module 5 sets the control coefficients of the PID controller in the temperature adjustment module 4 to a first set of PID coefficients, and the PID controller controls the heat source to heat the insulating 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 based on the information fed back by the temperature detector. Specifically, the actual temperature of the insulating powder layer is acquired by a temperature detector in the temperature adjustment module 4; and calculating according to the error value between the actual temperature and the preset temperature and the first group of PID coefficients to obtain the adjustment rate of the heating power of the heat source. Illustratively, the PID controller controls the heating power adjustment rate of the heating lamp array to increase by 30%, i.e. 130% of the initial power, e.g. 300W, i.e. 390W, when the actual temperature of the insulating powder layer is less than the preset temperature.

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

The powder layer comprises a plurality of preset areas, and the powder layer can be a bottoming powder layer or a forming powder layer, and each heating lamp group is used for heating a 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 underlying powder layers, buffer powder layers, or shaping powder layers described above.

In this embodiment, the plurality of heating lamp groups of the heat source are respectively configured 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. Illustratively, a first set of heating lamps 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 set of heating lamps 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 set of heating lamps positioned at a corner region of the heating lamp array may be configured with a weight distribution coefficient of 1.0.

It can be appreciated that the PID controller is utilized in the above formula 1 to independently adjust the temperatures of a plurality of preset areas of the powder layer by independently or separately adjusting the powers of the heating lamps in a plurality of areas of the heating lamp array, so that the temperature of the printing layer can be ensured to be about the preset temperature, the quality of the printing 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 coefficients of the corresponding heating lamps or groups of heating lamps in the array of heating lamps can meet the heating energy required by each preset area of the powder layer. More specifically, the number of preset regions of the powder layer is equal to the number of heating lamps, so that the heating lamps can be allocated in one-to-one correspondence according to the preset regions of the powder layer.

In this embodiment, a plurality of heating lamps located in a central region of the heating lamp array are used to heat a first preset region of the powder layer, a plurality of heating lamps located in an edge region of the heating lamp array are used to heat a second preset region of the powder layer, and a plurality of heating lamps located in corner regions of the heating lamp array are used to heat a third preset region of the powder layer.

In other embodiments, the number of the preset regions 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 are respectively in one-to-one correspondence with the preset regions of the powder layer.

It will be appreciated that the temperature T of the underlying powder layer reaching the preset temperature Tc does not mean that the temperature of the underlying powder layer must be exactly equal to the preset temperature, the actual temperature of the underlying powder layer may also be approaching the preset temperature, the difference between the actual temperature and the preset temperature is Δt, the preset range of Δt may be-5 ℃ to 5 ℃; preferably, the preset range of Δt is-1 ℃ to 1 ℃. That is, the temperature of the underlying powder layer is allowed to approach the preset temperature indefinitely.

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

As shown in fig. 4, at t ₀ At the moment, the powder supply module 2 starts to supply powder, and no powder material exists on the construction platform 1 at the moment, and the temperature T at the moment ₀ To build the real-time temperature of the platform 1. In the present embodiment, build platform 1 has heating wires to heat build platform 1, illustratively T ₀ About 150 c.

From t ₁ From this moment on, the powder feed module 2 starts to apply powder material on the build platform 1. As can be appreciated, at time t ₀ And t ₁ In between, the temperature detector does not measure the temperature of the powder material, but rather the temperature of the build platform 1. For simplicity, it is assumed here that at t ₀ And t ₁ The temperature of build platform 1 does not change in the time frame in between.

From time T1, powder feed module 2 begins to apply powder material on build platform 1 to form a first isolated powder layer, the amount of powder material on build platform 1 gradually increases over time, as the temperature of the powder material is lower than build platform 1, as shown in FIG. 4, the temperature T detected by the temperature detector decreases, i.e., from temperature T ₀ Down to a minimum value T _L1 . Controlling the heat source to heat the first isolating powder layer, the temperature of the first isolating powder layer being from the minimum value T _L1 Then rise to T _H1 . Illustratively T _L1 About 110 ℃, T _H1 About 155 deg.c. The temperature is raised again after reaching the minimum value due to the 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 rise so as to raise the temperature of the first isolation powder layer, and the heating rate of the isolation powder layer can be accelerated by raising the heating power of the heat source. That is, in the time frame between t1 and t2, powder feed module 2 forms a first underlying powder layer (i.e., a first barrier powder layer) on build platform 1 with the powder material.

From time t2, powder feed module 2 continues to apply powder material on the first barrier powder layer to form a second barrier powder layer. As the amount of powder material on the first barrier powder layer is related toWith increasing time, since the temperature of the powder material is lower than the temperature of the first insulating powder layer, as shown in FIG. 4, the temperature detected by the temperature detector decreases again, i.e. from the temperature T to a minimum value T _L2 Then the temperature of the second isolation powder layer is increased to T again due to the heating of the heat source _H2 . Wherein T is _L2 Greater than T _L1 ，T _H2 Greater than T _H1 . Illustratively T _L2 About 115 ℃, T _H1 About 159 ℃. That is, in the time range between t2 and t3, the powder supply module 2 forms a second insulating powder layer on the first insulating powder layer with the powder material.

Repeatedly, from time 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 thus be seen in fig. 4 that from the instants 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 _L12 Then rise again to T due to heating by the heat source _H3 、T _H4 ……T _H12 . Wherein T is _L12 ＝T _L11 ＝T _L10 ＞……＞T _L4 ＞T _L3 ＞T _L2 ＞T _L1 Preset 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 insulating powder layer, from time t10, the powder supply module 2 continues to form a buffer powder layer on the previous insulating powder layer by using the powder material, and the heating rate of the insulating powder layer is greater than that of the buffer powder layer, i.e. the greater the temperature difference between the real-time temperature and the preset temperature of the powder layer, the greater the heating rate, and the smaller the temperature difference, the smaller the heating rate. That is, the 10 th, 11 th and 12 th buffer powder layers are regulated by the temperature regulating module 4, and the temperature reaches the preset temperature T _A Exemplary, T _A About 178 c. It will be appreciated that FIG. 4 is only illustrative and is not intended herein to be limiting of the number of insulating powder layers formed, the number of buffer powder layers, and the total number of underlying powder layersBody restriction.

In order to make each insulating powder layer reach the preset temperature more quickly, step S20 specifically includes:

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

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 insulating powder layer.

In some embodiments, the temperature rise rate of the insulating powder layer is 0.5 ℃/s to 10 ℃/s, specifically, may be 0.5 ℃/s, 0.8 ℃/s, 1 ℃/s, 2 ℃/s, 3 ℃/s, 5 ℃/s, 7 ℃/s, 8 ℃/s, 10 ℃/s, etc., without limitation herein.

S30, forming a molding powder layer on the surface of the at least one bottoming powder layer by using a powder material.

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

In some embodiments, the thickness of the single shaping powder layer 121 may be the same as or different from the thickness of the single underlying powder layer 11. During actual printing, the thickness of the formed shaped powder layer 121 may be adjusted by the control module 5 adjusting the powder supply module 4 and/or the build platform 1. Illustratively, the single supply of powder to the powder supply module 4 may be changed, or the single elevation height of the build platform 1 may be changed, or the like.

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

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

In another embodiment, the liquid material undergoes thermal and/or photopolymerization and/or the liquid material undergoes polymerization 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 sprayed with the liquid material.

In one embodiment, the liquid material may contain an energy absorber that converts energy into thermal energy upon absorption of the supplied energy, thereby melt-shaping the powder material in contact therewith. In another embodiment, the liquid material is a photocurable material, the liquid material comprises a photocurable component, and the photocurable component is capable of dissolving the powder material, and the photoinitiator causes polymerization of the photocurable component upon irradiation to entangle and cure the dissolved powder molecules into a shape. In another embodiment, the liquid material is a thermally curable material, the liquid material comprising a thermally curable component, and the thermally curable component is initiated by a thermal initiator to polymerize under irradiation, the polymer formed encapsulating the powder material. In another embodiment, the liquid material has an active component that reacts with the powder material, and the initiator initiates polymerization of the liquid material with the powder material under irradiation.

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

Further, the liquid material also includes 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 a photoinitiator, a free radical initiator, an anionic initiator, a cationic 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 to the powder material, and at the same time, adjust the surface tension of the liquid material so that it can be printed normally, without limitation in this embodiment. The defoamer is mainly used for preventing foaming of the liquid material, and can be, for example, silicone defoamer, polyether defoamer, fatty acid ester defoamer and the like. Surfactants are mainly used to control the wettability, permeability and surface tension of a liquid material to a 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 pigment, when included in the liquid material, may enable a colored 3D object.

As shown in connection with fig. 1, the control module 5 controls the jetting module 3 to apply liquid material on the layer of profiled powder according to layer print data. The jetting module 3 jets a liquid material onto the modeling powder layer 121 according to the layer print data, the liquid material will infiltrate into the modeling powder layer 121, so that the modeling powder layer 121 forms patterned areas and non-patterned areas. In a specific embodiment, the control module 5 controls the relative movement of the jetting module 3 and the modeling powder layer 121 in the XY plane to jet the liquid material onto the modeling powder layer 121 in a desired pattern according to the layer print data.

The patterned areas in the shaped powder layer cure to form the printed layer 131 under the influence of the heat source.

In step S50, the control module 5 controls the temperature adjustment module 4 to adjust the temperature of the molding powder layer to a preset temperature to form a print layer, wherein the temperature rising rate of the insulating powder layer is greater than the temperature rising rate of the molding powder layer.

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

It will be appreciated that the temperature T of the shaped powder layer reaches a preset temperature T _A The temperature of the molded powder layer is not necessarily exactly equal to the preset temperature, the actual temperature of the molded 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 delta T can be-5 ℃ to 5 ℃; preferably, the preset range of Δt is-1 ℃ to 1 ℃. That is, the temperature of the molded powder layer is allowed to approach the preset temperature indefinitely.

In some embodiments, the heating power of the heat source is controlled to be adjusted to a second heating power and to heat the layer of shaped powder. Wherein the second heating power is less than the first heating power. Illustratively, the first heating power when heating the insulating powder layer is 400W and the second heating power when heating the shaping powder layer is 350W.

In this embodiment, at least a portion of the underlying powder layer has a rate of temperature rise greater than the rate of temperature rise of the shaping powder layer. Specifically, the rate of temperature rise of the insulating powder layer is greater than the rate of temperature rise of the shaping powder layer.

Since the temperature of the underlying powder layer has reached the preset temperature before forming the modeling powder layer 121, the underlying powder layer reaching the preset temperature can provide a better insulation effect, and the underlying powder layer can achieve thermal diffusion when contacting the newly laid powder material, so that the starting temperature of the modeling powder layer 121 is higher than the starting temperature of the insulating powder layer, and the temperature difference between the starting temperature of the modeling powder layer 121 and the preset temperature is smaller.

In the scheme, the temperature rising rate of the isolation powder layer is controlled to be larger than that of the forming powder layer, so that the temperature rising rate of the bottom powder layer is faster, and the temperature of the bottom powder layer 11 can reach the preset temperature as soon as possible; in the printing and forming stage, the temperature rising rate of the forming powder layer 121 is slower, and the phenomenon of overshoot of the temperature of the forming powder layer 121 is avoided, so that the temperature of the forming powder layer 121 is ensured to reach the preset temperature, and the quality of the printing layer 131 is ensured.

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

As shown in fig. 5, at t _B1 From time to time, the powder feed module 2 begins to apply powder material on the underlying powder layer 11. It will be appreciated that at t _B1 At this point in time, the temperature detector does not measure the temperature of the newly applied powder material, but rather the temperature of the underlying powder layer 11 located at the uppermost layer of the build platform. Thus, at time t _B1 The temperature detected by the temperature detector is equal to the preset temperature T _A 。

From time t _B1 Starting, the powder supply module 2 starts to apply powder material on the underlying powder layer 11 to form the first shaped powder layer 121, the amount of powder material on the underlying powder layer 11 gradually increases over time, and since the temperature of the powder material is lower than the temperature of the underlying powder 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 . The heat source is controlled to heat the first molding powder layer 121, and the temperature of the first molding powder layer 121 is controlled from the minimum value T _L Then rise to T _A . Illustratively T _L About 160 ℃, T _A About 178 c. The temperature is raised again after reaching the minimum value due to the increase in the heating power of the heat source.

In the actual printing process, after the PID controller receives the 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 the preset temperature, and by increasing the heating power of the heat source to a maximum value, the heating rate of the molding powder layer 121 can be increased. When the difference delta T between the actual temperature detected by the temperature detector and the preset temperature is within the preset range, the PID controller reduces the heating power again.

Repeatedly from time t _B2 、t _B3 、t _B4 … …, inside the measuring zone, a new applied powder material, which is at a lower temperature, is present in progressively increasing amounts to form a new shaped powder layer. As can be seen in fig. 5, the temperature T determined by the temperature detector decreases, the temperature T decreasing all the way to a minimum value T _L Then is raised again to the target temperature T _A . It will be appreciated 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 rise rate of the shaped powder layer is 0.1 ℃/s to 2 ℃/s, 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, 2 ℃/s, etc., without limitation herein.

Referring to fig. 4 and 5, it can be seen that since the molding powder layer is formed on the underlying powder layer, the underlying powder layer plays a role of insulation, and thus, the minimum value of the temperature of the formed molding powder layer is greater than the minimum value of the temperature of the insulating powder layer, and the rate of temperature rise of the insulating powder layer is controlled to be greater than the rate of temperature rise of the molding powder layer. If the PID controller always uses the first set of PID coefficients to heat the underlying and shaping powder layers, it is easy to cause the temperature of the shaping powder layer to deviate from the preset range, resulting in hardening of the powder affecting the quality of the formed printed layer.

The step S50 specifically includes: the control module 5 firstly sets the control coefficient of the PID controller in the temperature adjusting module 4 as a second set of PID coefficients, and the PID controller controls the heat source to heat the molding powder layer based on the second set of PID coefficients, so that the temperature of the molding powder layer is adjusted to a preset temperature, and a printing layer is formed. Wherein the first set of PID coefficients is different from the value of 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 according to the type of powder layer formed, to achieve independent control of the temperature regulation of the powder layer at different stages.

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

The control adopts two different PID control coefficients to be used for heating isolation powder layer and shaping powder layer respectively to make isolation powder layer's rate of heating up is greater than shaping powder layer's rate of heating up, can avoid shaping powder layer's temperature to deviate from the scope of predetermineeing, guarantees the quality of printing the layer.

Specifically, the time to increase the heating power of the heat source to the maximum power becomes longer with the PID controller provided with the second set of PID coefficients and/or the maximum power to which the heating power of the heat source can be increased becomes smaller with the PID controller provided with the second set of PID coefficients, compared with the PID controller provided with the first set of PID coefficients. Thus, the rate of heating up of the underlying powder layer is made greater than the rate of heating up of the shaping powder layer.

Further, in embodiments where the underlying powder layer further comprises 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 control the heat source to heat the buffer powder layer based on a second set of PID coefficients, and may control the heat source to heat the buffer powder layer based on a third set of PID coefficients, wherein the third set of PID coefficients is different from the value of at least one of the first set of PID coefficients and the second set of PID coefficients.

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

step S60, confirming whether the printing layer of the current three-dimensional object is the last layer, if not, repeating the steps from forming the molding powder layer to forming the printing layer, namely, step S30 to step S50, so that the obtained plurality of printing layers are stacked one by one to form the three-dimensional object.

Fig. 1 only schematically illustrates the second shaped powder layer 122, and the second printed layer 132 formed, it being understood that the three-dimensional object may be formed from more than two printed layers stacked one upon the other. If the judgment result is yes, the process is finished, and the construction of the three-dimensional object is completed.

It can be understood that slicing and layering are performed on the digital model of the three-dimensional object to obtain at least one slice layer, in the process of printing the three-dimensional object, each print layer is stacked layer by layer until all slice layers are printed to form the target three-dimensional object, otherwise, the process of repeatedly forming a molding powder layer and spraying liquid material to form the print layer according to layer printing data is needed, and the three-dimensional object is formed by stacking layer by layer.

In summary, the embodiment of the application respectively adjusts the temperature of at least part of the bottom-laying powder layer and the temperature of the forming powder layer to the preset temperature, and controls the temperature rising rate of the isolation powder layer in the bottom-laying powder layer to be larger than the temperature rising rate of the forming powder layer, so that the temperature of the bottom-laying powder layer can reach the preset temperature as soon as possible; in the printing and forming stage, the temperature rising rate of the formed powder layer is slower, the phenomenon of temperature overshoot of the printed layer is avoided, the temperature of the printed layer is guaranteed to be about the preset temperature, the quality of the printed layer is guaranteed, and the quality of the formed three-dimensional object is improved.

The 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 device where the storage medium 91 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, where 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, when the processor 101 executes the computer program 103, the three-dimensional object printing method in the embodiment is implemented, and in order to avoid repetition, details are not described herein.

The computer device may be a desktop computer, a notebook computer, a palm computer, a cloud server, or the like. Computer devices may include, but are not limited to, processors, memory. Those skilled in the art will appreciate that a computer device may include more or less components than those illustrated, or may combine certain components, or different components, e.g., a computer device may also include input and output devices, network access devices, buses, etc.

The processor may be a central processing unit (Central Processing Unit, CPU), other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), field programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory 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 provided on the computer device, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), or the like. Further, the memory may also include both internal storage units and external storage devices of the computer device. The memory is used to store 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 foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the application.

Claims

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

Forming a shaped powder layer on a surface of the underlying powder layer with a powder material;

and adjusting the temperature of the molding powder layer to a preset temperature to form a printing layer, wherein the temperature rising rate of the isolation powder layer is larger than that of the molding powder layer.

2. Printing method according to claim 1, wherein said adjusting the temperature of at least part of said underlying powder layer to a preset temperature comprises in particular: and adjusting the temperature of at least the last isolating powder layer to a preset temperature.

3. Printing method according to claim 1, wherein said adjusting the temperature of at least part of said underlying powder layer to a preset temperature comprises in particular:

4. Printing method according to claim 1, wherein said adjusting the temperature of at least part of said underlying powder layer to a preset temperature comprises in particular:

5. The printing method of claim 4 wherein the PID controller controls a heat source to heat the insulating powder layer based on the first set of PID coefficients, comprising in particular:

6. The printing method according to claim 5, wherein the obtaining the actual temperature of the insulating powder layer or the molded powder layer by a temperature detector includes:

7. The printing method according to claim 5, wherein the insulating powder layer or the molding powder layer includes a plurality of preset regions, the heat source includes a plurality of heating lamp groups each for heating a corresponding one of the preset regions of the insulating powder layer or the molding 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 a temperature rise rate of the insulating powder layer is 0.5 ℃/s to 10 ℃/s, and a temperature rise rate of the molding powder layer is 0.1 ℃/s to 2 ℃/s.

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

10. Printing method according to claim 9, wherein said adjusting the temperature of at least part of said underlying powder layer to a preset temperature comprises in particular: adjusting the temperature of at least the last layer of the barrier 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 the rate of rise of the barrier powder layer is greater than the rate of rise of the buffer powder layer.

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

controlling the powder supply module to form a molding powder layer on the surface of the bottoming powder layer;

controlling the temperature adjusting module to adjust the temperature of the molding powder layer to a preset temperature so as to form a printing layer, wherein,

the rate of rise of the temperature of the insulating powder layer is greater than the rate of rise of the shaped powder layer.

13. The printing device of claim 12, wherein the temperature regulation module comprises a heat source, a temperature detector, and a PID controller communicatively coupled to the control module, the PID controller controlling the heating power of the heat source based on 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 isolating powder layer;

Setting control coefficients of the PID controller to a second set of PID coefficients, and controlling the temperature adjustment module to adjust the temperature of the molded 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.

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

16. The printing apparatus of claim 13, wherein the powder layer comprises a plurality of predetermined areas, the powder layer being either the profiled powder layer or the underlying powder layer, the heat source comprising a plurality of heating light sets, each heating light set for heating a corresponding one of the predetermined areas of the powder layer.

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

18. A non-transitory computer-readable storage medium, characterized in that the storage medium includes a stored program that, when executed, controls a device in which the storage medium is located to perform the three-dimensional object printing method 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, characterized in that the processor implements the three-dimensional object printing method according to any one of claims 1 to 11 when executing the computer program.