Disclosure of Invention
The technical problem to be solved by the invention is to provide a 3D printing system aiming at the defects of the prior art, wherein the light-emitting unit is used as a curing light source, and the wavelength conversion unit is additionally arranged so that the laser wavelength of the curing light source can be adjusted.
The technical problem to be solved by the invention is realized by the following technical scheme:
the invention provides a 3D printing system, the 3D printing system comprises:
a light emitting unit for emitting excitation light;
a wavelength conversion unit for receiving the excitation light and outputting curing light;
the combined lens unit is used for refracting the curing light onto the DMD digital micromirror unit and guiding the curing light reflected by the DMD digital micromirror unit to a photocuring material to be cured;
the DMD digital micromirror unit is used for receiving the curing light refracted by the combined lens unit and selectively reflecting the curing light; and
and the control unit is electrically connected with the light-emitting unit, the wavelength conversion unit, the combined lens unit and the DMD digital micromirror unit.
In order to ensure the quality of 3D printing, the control unit adjusts the working parameters of the 3D printing system according to the type and the curing state of the light-cured material.
Preferably, the operating parameters include output power of the light emitting unit, wavelength of the curing light output by the wavelength conversion unit, optical power density of a pattern directed to the surface of the photocurable material to be cured, and curing time.
Specifically, the output power of the light emitting unit is 0W-4W. The pattern directed to the surface of the photocurable material to be cured has an optical power density of 10mW/cm2-100mW/cm 2.
Preferably, the wavelength conversion unit outputs curing light of different wavelengths by adjusting a position of receiving the excitation light.
In order to fully cure the light-cured material, the curing time is 0.1s-100 s.
In order to enable the wavelength conversion unit to receive the exciting light and output curing light with different wavelengths, the wavelength conversion unit comprises a control part, and a fluorescent powder color wheel or a fluorescent powder hollow color barrel driven by the control part.
Preferably, the phosphor color wheel is a reflective color wheel or a transmissive color wheel.
Preferably, the phosphor wheel is provided with a plurality of annular phosphor ring areas, and the colors of the plurality of phosphor ring areas are different.
Preferably, the phosphor wheel includes a non-phosphor ring area, a green phosphor ring area and a red phosphor ring area sequentially arranged from inside to outside.
Preferably, the phosphor barrel is provided with a plurality of annular phosphor ring areas, wherein the plurality of phosphor ring areas are different in color and are sequentially arranged along the axis of the phosphor barrel.
In order to enable the 3D printing system to print products with more sizes, a lens unit is further disposed between the combined lens unit and the light-curing material to be cured, and the lens unit is used for expanding and focusing curing light on the light-curing material.
In summary, the light emitting unit is used as the curing light source, and the wavelength conversion unit is additionally arranged to enable the laser wavelength of the curing light source to be adjustable, compared with the traditional ultraviolet 3D printing, the 3D printing system provided by the invention avoids the harm caused by ultraviolet light, breaks through the limitation of monochromatic light curing materials, has the advantages of safety, environmental protection, high light emitting efficiency, good light beam quality and the like, and can realize multicolor 3D printing.
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
Detailed Description
Fig. 1 is a schematic structural diagram of a 3D printing system according to the present invention. As shown in fig. 1, the present invention provides a 3D printing system, the 3D printing system includes a light emitting unit 10, a wavelength converting unit 20, a combined lens unit 30, a DMD (Digital Micromirror Device) Digital Micromirror unit 31 and a control unit 50, wherein the control unit 50 is electrically connected to the light emitting unit 10, the wavelength converting unit 20, the combined lens unit 30 and the DMD Digital Micromirror unit 31 for controlling the operation thereof. Preferably, the control unit 50 adjusts operating parameters of the light emitting unit 10, the wavelength conversion unit 20, the combined lens unit 30, and the DMD digital micromirror unit 31 according to the type and curing state of the light-curing material, thereby performing 3D printing.
The light emitting unit 10 is a light source in the prior art, and is used for emitting exciting light, such as an LED light source, a laser diode light source, a laser light source, and the like. Further, the light emitting unit 10 may be a blue light source emitting blue excitation light, and it is understood that the light emitting unit 10 is not limited to the blue light source, and the light emitting unit may also be a violet light source, a red light source, a green light source, a white light source, or the like. In this embodiment, the light emitting unit 10 includes a blue laser for emitting blue laser as the excitation light, and it can be understood that the light emitting unit 10 may include one, two or more blue lasers, the number of the lasers may be selected according to actual needs, preferably, each laser includes 1 to 200 laser tubes, and the output optical power of each laser tube is adjustable.
When the output power of the light emitting unit 10 is too small, incomplete curing in the layer or poor bonding force between layers may occur in the 3D printing process; when the output power of the light emitting unit 10 is too large, the edge of the cured layer may be diffraction-cured during the 3D printing process, or the bonding force between the newly printed layer and the bottom of the groove may be too large. In order to solve the above problems and enable the light emitting unit 10 to be adapted to the curing requirements of a plurality of different light curing materials, in the present invention, the output power of the light emitting unit 10 is adjustable, and the range is between 0W and 4W. The output power of the light emitting unit 10 can be controlled by a person skilled in the art through the control unit 50.
The wavelength conversion unit 20 is configured to receive the excitation light and output curing light. The wavelength conversion unit 20 includes a control portion, and a phosphor color wheel 201 or a phosphor hollow color barrel 202, etc. driven by the control portion.
Fig. 2 is a schematic structural diagram of the phosphor color wheel of the present invention. As shown in fig. 2, when the wavelength conversion unit is a phosphor color wheel, the phosphor color wheel may be a reflective color wheel or a transmissive color wheel. The reflective color wheel has an advantage of sufficient heat dissipation space, and the heat dissipation effect of the wavelength conversion unit 10 can be improved by adding a heat dissipation component, which can be a heat dissipation blade. The transmissive color wheel has the advantage of simple light path, however, because the space limitation cannot add a heat dissipation component, the heat dissipation effect is poor, so the transmissive color wheel is generally suitable for receiving the excitation light emitted by the low-power light emitting unit 10. Specifically, the phosphor color wheel 201 is provided with a plurality of annular phosphor ring areas, wherein the colors of the plurality of phosphor ring areas are different. Preferably, the phosphor ring region comprises a phosphor-free ring region.
At the moment, the control part is a motor arranged on the sliding track, a rotating shaft of the motor is fixedly connected with the center of the fluorescent powder color wheel, the motor can drive the fluorescent powder color wheel to rotate around the rotating shaft, and the motor can drive the fluorescent powder color wheel to translate on the plane where the fluorescent powder color wheel is located when sliding on the sliding track, so that curing light can penetrate through different fluorescent powder ring areas. In other words, the wavelength conversion unit 20 may output curing light of different wavelengths by adjusting the position of receiving the excitation light.
As shown in fig. 1, in the present embodiment, a transmissive phosphor color wheel is taken as an example, when different visible light curable resins are selected as the light curable material, such as a blue light curable resin (a light curable material suitable for blue light curing), a green light curable resin, and a red light curable resin, the plurality of phosphor ring regions may include a non-phosphor ring region 2011, a green phosphor ring region 2012, and a red phosphor ring region 2013 that are sequentially arranged from inside to outside, and when the excitation light emitted by the light emitting unit 10 is guided to the non-phosphor ring region 2011, the output laser (curing light) is still blue and the same as the original laser wavelength, so that the 3D printing system can print and cure the blue light curable resin under the condition of minimum energy consumption; when the blue laser is guided to the green phosphor ring area 2012, the output laser is green light with a wavelength between 490nm and 580nm, so that the 3D printing system can print and cure the green light cured resin under the condition of minimum energy consumption; when the blue laser is guided to the red phosphor ring area 2013, the output light is red light, and the wavelength is 650nm-760nm, so that the 3D printing system can print and cure the red light curing resin under the condition of minimum energy consumption. Preferably, in order to obtain a purer output light, a filter layer may be disposed on the light emitting surface of the phosphor color wheel ring region, where the filter layer is configured to filter each output light and obtain light within a specified wavelength range. The invention can lead the blue laser to be guided to different fluorescent powder ring areas by changing the position of the fluorescent powder color wheel, thereby converting the blue laser emitted by the light-emitting unit 10 into the laser with other colors, improving the application range of the 3D printing system and improving the quality of printed products.
FIG. 3 is a schematic structural diagram of a hollow color barrel of the phosphor of the present invention. As shown in fig. 3, when the wavelength conversion unit 20 includes a phosphor hollow color barrel, the excitation light of the light emitting unit 10 is guided to a reflective mirror 2020 within the phosphor hollow color barrel, and the reflective mirror 2020 causes it to be emitted outside the barrel in the phosphor hollow color barrel diameter direction. The fluorescent powder hollow color barrel is provided with a plurality of annular fluorescent powder ring areas, wherein the colors of the plurality of fluorescent powder ring areas are different and are sequentially arranged along the axis of the fluorescent powder hollow color barrel, and preferably, the fluorescent powder ring areas comprise a non-powder ring area. Specifically, the control portion can control the phosphor hollow color barrel to rotate and translate along the axis direction thereof, or the control portion can control the position of the reflective mirror 2020 within the phosphor hollow color barrel to translate along the axis of the phosphor hollow color barrel, so that the blue laser light can be guided onto the phosphor ring regions of different colors to adjust the excitation light emitted by the light emitting unit 10 to a suitable wavelength to be the curing light. For example, the plurality of phosphor ring zones may include a non-phosphor ring zone 2021, a green phosphor ring zone 2022, and a red phosphor ring zone 2023 arranged in sequence along the axis of the phosphor hollow color barrel.
The curing state of the light-cured material is affected by the wavelength of the curing light, and specifically, when different light-cured materials are cured by different wavelengths of the curing light, parameters such as the curing depth and the curing speed are different, for example, when blue light and green light with the same power are used for curing blue light-cured resin, since the blue light-cured resin has a higher absorption rate to the blue light, the curing efficiency is higher, the curing time is short, the curing reliability is strong, if a 3D printing system can only emit the green light, and in order to shorten the curing time and increase the bonding force of the cured materials, the power of the green light must be increased. The wavelength conversion unit 20 is arranged, so that when a user selects different light curing materials, the wavelength of curing light is adjusted to be in a range suitable for the used light curing materials. It should be added that if the wavelength conversion unit 20 is not provided with the non-phosphor ring region, but only the green-phosphor ring region and the red-phosphor ring region, the user can pass the excitation light through the green-phosphor ring region through the control unit 50, and increase the output power (e.g. 250mW) to cure the green curing light to the blue curing resin.
The combined lens unit 30 is used for refracting the curing light onto the DMD digital micromirror unit 31 and guiding the curing light reflected by the DMD digital micromirror unit 31 onto the photo-curing material to be cured.
The DMD digital micromirror unit 31 is used to receive the curing light refracted by the combined lens unit 30 and selectively reflect the curing light. The resolution of the DMD digital micromirror unit 31 may be 720P, 1080P, 2K, 4K, 8K, etc., depending on the printing precision requirements. The operation principle of the DMD digital micromirror unit is the prior art and is not described herein.
In order to enable the 3D printing system of the present invention to print products of more sizes, a lens unit 32 for expanding and focusing the curing light on the light-curing material is further disposed between the combined lens unit 30 and the light-curing material to be cured.
In the case where the output power of the light emitting unit 10 is determined, the lens unit 32 can change the optical power density of the pattern directed to the surface of the photocurable material to be cured, which is also an important factor affecting the curing state of the photocurable material, by controlling the size of the pattern of curing light focused on the photocurable material. In addition, the optical power density is also affected by the power of the excitation light emitted from the light emitting unit and the curing light reflected by the DMD digital micromirror unit 31. In other words, by controlling the output power of the light emitting unit 10 and the size of the pattern, the optical power density of the pattern directed to the surface of the photocurable material to be cured can be directly controlled.
Under the same conditions, when the optical power density is high, the curing depth and speed of the same light-cured material are increased; when the optical power density is small, the curing depth and speed are reduced. Preferably, in the present invention, the optical power density is 10mW/cm2-100mW/cm2。
It should be added that the curing time is obviously an important factor for determining the curing state of the light-cured material, and under the same condition, for the same light-cured material, the curing depth increases with the increase of the curing time; as the curing time decreases, the depth of cure also decreases. Preferably, the curing time is from 0.1s to 100 s.
In summary, the curing efficiency of the photo-curing material is influenced by various factors, such as the type of the photo-curing material, the output power of the light emitting unit 10, the optical power density of the pattern directed to the surface of the photo-curing material to be cured, the curing time, and the wavelength of the curing light. The user may adjust the above-mentioned operating parameters of the 3D printing system by the control unit according to the type of the light-curable material, including, but not limited to, the output power of the light-emitting unit 10, the wavelength of the curing light output by the wavelength conversion unit 20, the optical power density of the pattern directed to the surface of the light-curable material to be cured, and the curing time.
It should be added that the control unit 50 of the 3D printing system of the present invention can also adjust the above-mentioned operating parameters according to the curing state of the light-curable material. Specifically, the 3D printing system further includes a detection unit, where the detection unit is configured to detect a curing state of the photo-curing material when the photo-curing material is cured, for example, the detection unit may monitor a surface change of each layer of the photo-curing material when the photo-curing material is cured in real time, and the fully cured photo-curing material has a bright surface, no whisker phenomenon, and no ghost at an edge. When the detection unit detects that the light-cured material has an incomplete in-layer curing phenomenon, the detection unit sends a detection signal to the control unit, and the control unit controls the interlayer bonding force of the light-cured material by adjusting working parameters, for example, the output power of the light-emitting unit 10 is improved or/and the curing time is prolonged; when the detection unit detects that the light-cured material has the phenomenon that the edges of the cured layer are diffraction cured, the detection unit sends a detection signal to the control unit, and the control unit controls the interlayer bonding force of the light-cured material by adjusting the working parameters, for example, the output power of the light-emitting unit 10 is reduced or/and the curing time is increased. For example, when the light curing material is a blue light curing resin, the user adjusts the position of the phosphor color wheel 201 or the phosphor hollow color barrel 202 in the wavelength conversion unit 20 through the control unit 50 to allow the excitation light to pass through the non-powder-ring region thereof, and then adjusts the output power of the light emitting unit 10 to an optimal value, such as an output power of 200mW, before starting printing. In the printing process, if the curing of the light-cured material is found to be abnormal, the control unit further adjusts the working parameters so as to ensure the printing quality.
In order to guide the excitation light and the curing light to the correct positions and meet different focusing or diffusion requirements, the 3D printing system further comprises an optical shaping unit 40, wherein the optical shaping unit 40 comprises a focusing lens 41, a beam expander 42 and a zooming system 43, wherein the focusing lens 41 is used for focusing the excitation light beam emitted by the light emitting unit 10 to the wavelength conversion unit 20, and the beam expander is used for reducing the diffusion angle of the curing light beam after passing through the wavelength conversion unit 20; the zoom system is used to adjust the beam quality of the curing light so that it can be precisely projected onto the combined lens unit 30.
The invention also provides a using method of the 3D printing system, which comprises the following steps: selecting a light-cured material; adjusting the wavelength of curing light according to the type and the curing state of the light curing material; adjusting the output power of the light emitting unit 10, the optical power density of the pattern directed to the surface of the photo-curing material to be cured, and the curing time according to the type of the photo-curing material; printing is started.
When the wavelength of the curing light is adjusted, the adjusted curing light is required to be suitable for curing a corresponding light-curing material, namely, the wavelength-adjusted curing light can still rapidly cure the light-curing material under the condition of ensuring that the output power is low, and the reliability after curing is ensured; after the wavelength of the curing light is adjusted, the output power of the light emitting unit 10 is adjusted to avoid the phenomena of incomplete curing in the layer, poor bonding force between layers, diffraction curing of the edges of the cured layer, and excessive bonding force between the newly printed layer and the bottom of the resin groove during printing.
The 3D printing system and the using method thereof can be used for DLP (digital light processing) lower projection 3D forming and can also be used for DLP upper projection 3D forming (as shown in FIG. 1).
The technical solutions of the present invention will be described in detail and fully with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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 invention.
Example one
In this embodiment, the light emitting unit 10 of the 3D printing system is a blue semiconductor laser, the wavelength conversion unit 20 includes a control portion and a phosphor color wheel driven by the control portion, and the phosphor color wheel includes a non-phosphor ring area 2011, a green phosphor ring area 2012 and a red phosphor ring area 2013 which are sequentially arranged from inside to outside.
And loading the 3D printing system on the 3D printing equipment, and adding blue light curing resin into the 3D printing equipment. Setting a pattern to be directed to a surface of a photocurable material to be curedThe optical power density of the table is 10mW/cm2The print layer thickness was 0.05mm and the monolayer curing time was 2 s.
When printing is started, the blue semiconductor laser emits 445nm blue excitation light after current is applied to the control unit 40, the excitation light is guided to the phosphor color wheel non-powder ring area 2011 through the focusing mirror 41, the wavelength of the curing light after passing through the phosphor color wheel is still 445nm, then the divergence angle of the light beam is reduced through the beam expanding mirror 42, then the laser beam with good directivity is obtained through the zooming system, the laser beam is firstly refracted to the DMD digital micro-mirror unit 31 through the combined lens unit 30, then is selectively reflected through the DMD digital micro-mirror unit 31, passes through the combined lens unit 30, is then expanded into a pattern with a certain size through the lens unit 32, after the pattern is guided to the upper surface of the light curing material (blue light curing resin), the light curing material is selectively cured under the irradiation of the projected pattern, one layer of curing is finished, the workpiece moves upwards by one layer thickness, and the new, and (5) laminating the layers to a workpiece for forming.
Example two
In this embodiment, the light emitting unit 10 of the 3D printing system is a blue semiconductor laser, the wavelength conversion unit 20 includes a control portion and a phosphor color wheel driven by the control portion, and the phosphor color wheel includes a non-phosphor ring area 2011, a green phosphor ring area 2012 and a red phosphor ring area 2013 which are sequentially arranged from inside to outside.
And loading the 3D printing system on a 3D printing device, and adding green light curing resin into the 3D printing device. Compared with the first embodiment, in the present embodiment, the type of the light-cured resin is changed, and the control unit needs to adjust the working parameters of the 3D printing system to perform 3D printing. Specifically, the optical power density of the pattern to be guided to the surface of the photocurable material to be cured was from 10mW/cm2Adjusting to 15mW/cm2And the position of the phosphor color wheel 201 is shifted so that the excitation light is directed to the green phosphor ring field 2012.
When printing starts, the blue semiconductor laser emits 445nm blue excitation light after current is applied to the control unit 40, the excitation light is guided to the phosphor powder green wheel phosphor powder ring area 2012 through the focusing mirror 41, the excitation light is changed into curing light with the wavelength of 520nm to 540nm after passing through the phosphor powder color wheel, then the beam divergence angle is reduced after passing through the beam expander 42, then a laser beam with good directivity is obtained through the zoom system, the laser beam is firstly refracted to the DMD digital micromirror unit 31 through the combined lens unit 30, then is selectively reflected through the DMD digital micromirror unit 31, passes through the combined lens unit 30, is then expanded into a pattern with a certain size through the lens unit 32, the pattern is guided to the upper surface of the light-curing material (green light-curing resin), the light-curing material is selectively cured under the irradiation of the projected pattern, one layer of curing is finished, and the workpiece moves upwards by one layer thickness, and re-curing the new resin layer, and laminating the new resin layer on the workpiece layer by layer for forming.
EXAMPLE III
In this embodiment, the light emitting unit 10 of the 3D printing system is a blue semiconductor laser, the wavelength conversion unit 20 includes a control portion and a phosphor color wheel driven by the control portion, and the phosphor color wheel includes a non-phosphor ring area 2011, a green phosphor ring area 2012 and a red phosphor ring area 2013 which are sequentially arranged from inside to outside.
And loading the 3D printing system on a 3D printing device, and adding red light curing resin into the 3D printing device. Compared with the first embodiment, in the present embodiment, the type of the light-cured resin is changed, and the control unit needs to adjust the working parameters of the 3D printing system to perform 3D printing. Specifically, the optical power density of the pattern to be guided to the surface of the photocurable material to be cured was from 10mW/cm2Adjusting to 30mW/cm2The single layer cure time is adjusted from 2s to 3s and the position of the phosphor wheel 201 is moved so that the excitation light is directed to the red phosphor ring area 2013.
When printing starts, the blue semiconductor laser emits 445nm blue excitation light after current is applied to the control unit 40, the excitation light is guided to the phosphor powder wheel red phosphor powder ring area 2013 through the focusing mirror 41, the excitation light is changed into curing light with the wavelength of 650nm-680nm after passing through the phosphor powder wheel, then the beam divergence angle is reduced after passing through the beam expander 42, then a laser beam with good directivity is obtained through the zoom system, the laser beam is firstly refracted to the DMD digital micromirror unit 31 through the combined lens unit 30, is selectively reflected through the DMD digital micromirror unit 31, passes through the combined lens unit 30, is expanded into a pattern with a certain size through the lens unit 32, the pattern is guided to the upper surface of the light-curing material (red light-curing resin), the light-curing material is selectively cured under the irradiation of the projected pattern, one layer of curing is finished, and the workpiece moves upwards by one layer thickness, and re-curing the new resin layer, and laminating the new resin layer on the workpiece layer by layer for forming.
In summary, the light emitting unit is used as the curing light source, and the wavelength conversion unit is additionally arranged to enable the laser wavelength of the curing light source to be adjustable, compared with the traditional ultraviolet 3D printing, the 3D printing system provided by the invention avoids the harm caused by ultraviolet light, breaks through the limitation of monochromatic light curing materials, has the advantages of safety, environmental protection, high light emitting efficiency, good light beam quality and the like, and can realize multicolor 3D printing.