Light-cured resin liquid level control device and method
Technical Field
The invention belongs to the technical field of electromechanical and hydraulic control, and particularly relates to a device and a method for controlling the liquid level of light-cured resin.
Background
In order to increase the printing speed of the resin photocuring three-dimensional printing technology, as shown in fig. 1 in the prior art, an imaging element such as an opto-mechanical device 1 of a DLP projector, a laser scanning imager, etc. is generally used to project an image to be processed onto an upper liquid surface 3 of a liquid tank 2 formed by the action of gravity, so as to realize single-layer curing on a working platform 4, and realize layer-by-layer superposition forming of a three-dimensional object by matching with layer-by-layer projection of the imaging element through stepping descending of a lifter 5. By the technical scheme, the working efficiency of three-dimensional printing can be improved, and the difficult problem of stripping of the large imaging surface and the solid imaging surface can be avoided.
However, in the actual three-dimensional printing process, when the light-cured resin is converted from liquid to solid, a certain proportion of volume shrinkage exists, and the liquid level of the resin is lowered. Therefore, prior to the projection of each layer, it is necessary to replenish the resin level in time to maintain a constant resin level, thereby ensuring uniformity of photocuring of each layer. The prior art introduces a filling block and a scraper to solve the problems cooperatively. As shown in fig. 2, after printing one layer, the working platform descends by the height of one printing layer, at this time, the linear actuator 6 controls the relative depth of the filling block 7 immersed in the liquid tank, the volume of the liquid discharged by the filling block is used for compensating the volume shrinkage caused by the solidification of the liquid level layer, namely, liquid supplementing is carried out, and the liquid level is adjusted to the original position; meanwhile, a scraper 8 scrapes the upper liquid surface to force the liquid surface layer to flow, and the liquid surface is promoted to be flattened.
The use of a filling block and a scraper, while allowing the liquid level to be flattened, introduces new technical problems as well. Firstly, the filling block only acts on a local area of the liquid tank, the immersed volume change quantity of the filling block is diffused to the whole liquid level, longer waiting time is needed, and the waiting time is longer when the liquid viscosity is higher; secondly, the accurate control of the liquid level can be realized only by the negative feedback control by matching an accurate liquid level sensor with a linear actuator, and the accurate measurement of the liquid level of the liquid, particularly the liquid with high transparency, is high in difficulty and cost; and when the scraper works, the scraper is in direct contact with liquid, and foam, ripples and material pollution are easily generated.
Therefore, in order to avoid the technical problems caused by the introduction of the filling block, other means for controlling the resin liquid level or performing liquid replacement must be used. At present, in the technical field of photocuring three-dimensional printing, a technical scheme which is simple and convenient in scheme and simple in structure or does not use a filling block and a scraper is lacked to realize rapid material supplementing and rapid flattening of a printing liquid level.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the liquid tank device which has simple and convenient scheme and simple structure, can realize the liquid level control of the photocuring three-dimensional printing resin and quickly planarize the liquid level.
The technical scheme of the invention is as follows:
a liquid level control device of light-cured resin comprises a communicated liquid tank, a lifting platform, a printing substrate, an imaging element, a constant-pressure controller and a liquid tank cover; the communicated liquid tank comprises a first opening side and a second opening side, and the first opening side and the second opening side are communicated through a communication channel; an imaging element is arranged on the upper part of the first opening side, and the lifting table and the printing substrate are arranged inside the first opening side; the second opening side is provided with a constant pressure controller and a liquid tank cover, and the liquid tank cover is positioned at the upper part of the second opening side; when the liquid level of the liquid material in the communicated liquid tank is higher than the horizontal height of the communicated channel, the space between the imaging element and the liquid level of the liquid material in the first opening side is a first pressure chamber, and the space between the liquid tank cover and the liquid level of the liquid material in the second opening side is a second pressure chamber; a fixed amount of working gas is sealed in the first pressure chamber; the constant pressure controller is connected with an air inlet pipe and an exhaust pipe, and the air inlet pipe and the exhaust pipe are connected with the second pressure chamber; the constant pressure controller controls the air pressure of the working gas in the first pressure chamber by adjusting the air pressure of the second pressure chamber.
Preferably, the image forming element is selected from at least one of an LCD display, an OLED display, a DLP projection device, or a laser beam scanning device.
Preferably, the working gas is selected from at least one of air, nitrogen or an inert gas.
Preferably, at least one air pressure detector is arranged in the first pressure chamber, and the air pressure detector measures the air pressure of the working gas.
Preferably, the at least one air pressure detector is electrically connected to the constant pressure controller.
Preferably, the working gas has a constant gas pressure during the photocuring operation.
Preferably, the pressure value of the working gas during the photocuring work is 1.1 to 3 atmospheres.
The invention also provides a method for controlling the liquid level of the light-cured resin, which comprises the following steps:
s01, sealing a fixed amount of working gas in a first pressure chamber;
s02, controlling air pressure in the second pressure chamber, and adjusting the liquid level of the liquid material in the first opening side to a target liquid level;
s03, measuring the air pressure of working gas in the first pressure chamber at the moment, and recording the air pressure as a working air pressure value;
s04, measuring the air pressure of working gas in real time during photocuring work, and comparing the air pressure with a working air pressure value;
and S05, adjusting the real-time air pressure of the first pressure chamber by controlling the air pressure of the second pressure chamber to enable the real-time air pressure to approach the working air pressure value until the working air pressure value is kept constant.
Preferably, the first pressure chamber and the second pressure chamber are located at two ends of the communication type liquid groove.
Preferably, the working air pressure value is 1.1 to 3 atmospheres.
Preferably, the pressure of the gas in the second pressure chamber is controlled by a constant pressure controller.
Preferably, the pressure of the working gas in the first pressure chamber is measured by a gas pressure detector.
Preferably, the constant pressure controller records a working air pressure value and compares the working air pressure value with the air pressure of the working gas measured in real time.
Compared with the prior art, the invention has the beneficial effects that: the technical scheme is simple and convenient, the structure is simple, a filling block and a scraper device are not used, and quick material supplement and quick flattening of the printing liquid level can be effectively realized; and the large-amplitude action of the mechanism is inhibited in the adjusting process, or the adverse effect of the violent liquid flow on the liquid level stability is inhibited, the liquid level control precision is high, and the liquid level stabilizing time is short.
Drawings
FIG. 1 is a schematic structural diagram of an apparatus for three-dimensional printing photocuring process in the prior art;
FIG. 2 is a schematic diagram of the working principle of a filling block and a scraper device in a three-dimensional printing photocuring process in the prior art;
FIG. 3 is a schematic structural view of a liquid level control apparatus for light-curable resin according to an embodiment of the present invention;
FIG. 4 shows an implementation of the method for controlling the level of a light-curable resin according to the present invention;
reference numerals: the device comprises an optical mechanical device 1, a liquid tank 2, an upper liquid level 3, a working platform 4, a lifter 5, a linear actuator 6, a control filling block 7, a scraper 8, a communicated liquid tank 9, a lifting platform 10, a printing substrate 11, an imaging element 12, a constant pressure controller 13, a liquid tank cover 14, a first opening side 15, a second opening side 16, a communicated channel 17, a first pressure chamber 18, a second pressure chamber 19, an air inlet pipe 20, an air outlet pipe 21 and an air pressure detector 22.
Detailed Description
The following describes embodiments of the present invention in detail with reference to the accompanying drawings.
The invention provides a light-cured resin liquid level control device, as shown in fig. 3, the main body is a communication type liquid tank 9, which comprises a first opening side 15 and a second opening side 16, wherein the first opening side 15 is communicated with the second opening side 16 through a communication channel 17. The image forming element 12 is provided on the upper portion of the first opening side 15, and the elevating table 10 and the printing substrate 11 are provided inside the first opening side 15. The second opening side 16 is provided with a constant pressure controller 13 and a tank cover 14, and the tank cover 14 is positioned above the second opening side 16.
After the photo-curable resin is added to the communicating liquid bath 9, the photo-curable resin may flow in the communicating liquid bath 9. When the liquid level of the liquid material in the communication-type liquid tank 9 is higher than the level of the communication channel 17, the space between the imaging element 12 and the liquid level of the liquid material in the first opening side 15 is a first pressure chamber 18; the space between the tank cover 14 and the liquid level of the liquid material in the second opening side 16 is a second pressure chamber 19. Wherein, a certain amount of working gas is sealed in the pressure chamber 18, and the sealing gas is at least one of air, nitrogen or inert gas.
In one or more embodiments, the imaging element 12 is selected from at least one of an LCD display, an OLED display, a DLP projection device, or a laser beam scanning device. During photocuring, the imaging element 12 projects a laser image or an ultraviolet image to the liquid level of the liquid material in the first opening side 15; the projected image is irradiated to the surface of the liquid material in the first opening side 15 via the working gas 18; further, the region irradiated with light is photocured; the lift table 10 then controls the printing substrate 11 to descend by the height of one printing layer in preparation for printing of the next printing layer.
In one or more embodiments, as shown in FIG. 3, the working gas 18 is sealed between the liquid level in the first open side 15 and the imaging member 12. The working gas 18 is in a sealed state and the total amount of gas remains constant during printing. In the photocuring process, the pressure value of the working gas 18 is 1.1 to 3 atmospheres, which is beneficial to improving the uniformity and the flatness of the liquid level of the liquid material in the first opening side 15. Meanwhile, the existence of the working gas 18 can also prevent the liquid material from being adhered to the lower surface of the imaging element during photocuring in the printing process, so that the printing efficiency and the printing effect are improved.
As shown in fig. 3, at the second opening side 16, an intake pipe 20 and an exhaust pipe 21 are connected to the constant pressure controller 13. An inlet pipe 20 and an outlet pipe 21 are connected with the second pressure chamber 19; the constant pressure controller 13 controls the air pressure in the second pressure chamber 19 by controlling the intake or exhaust of the intake pipe 20 and the exhaust pipe 21.
According to the principle of the communicating vessel, the pressure of the working gas in the first pressure chamber 18 is equal to the sum of the pressure in the second pressure chamber 19 and the pressure due to the difference in the liquid level in the first and second opening sides. And, since the total amount of the working gas is not changed, the pressure of the working gas is inversely proportional to the volume according to the ideal gas state equation under the condition of constant temperature. Thus, the constant pressure controller 13 can control the pressure of the working gas in the first pressure chamber 18 by adjusting the pressure of the second pressure chamber 19. Because the inner diameter or the sectional area of the first opening side can be measured and calculated, the volume of the working gas can be quantitatively controlled while the pressure of the working gas is adjusted, and the liquid level of the liquid material in the first opening side 15 is further controlled.
In one or more embodiments, as shown in fig. 3, the constant pressure controller 13 supplies air to the second pressure chamber 19 through an intake pipe 20; and push the liquid material to flow toward the first open side 15; the working gas pressure increases and decreases in volume while the liquid level of the liquid material in the first open side 15 rises. In other embodiments, the constant pressure controller 13 exhausts the second pressure chamber 19 through the exhaust pipe 21; and pulls the liquid material toward the second open side 16; the working gas pressure decreases and the volume increases while the liquid level of the liquid material in the first open side 15 decreases.
In the above embodiment, the constant pressure controller 13 controls the pressure of the working gas in the first pressure chamber 18 by adjusting the pressure of the second pressure chamber 19, so that the liquid filling operation of the light-cured resin can be completed in the process of controlling the liquid level of the liquid material, thereby eliminating devices such as filling blocks and the like and also eliminating the technical problems caused by using the filling block devices; the liquid level of the liquid material in the first opening side 15 can be adjusted in time according to different light curing working liquid level heights in the continuous light curing working process.
In order to accurately adjust the level of the liquid material in the first open side 15, at least one air pressure detector 22 may be provided within the first pressure chamber 18. In one or more embodiments, the gas pressure detector 22 measures the gas pressure value of the working gas and is electrically connected to the constant pressure controller 13; in the light curing work project, the air pressure detector 22 transmits the air pressure data of the working gas to the constant pressure controller 13, the constant pressure controller 13 converts the volume of the working gas and the liquid level height data of the liquid material in the first opening side 15 according to the real-time air pressure data of the working gas, and controls the air pressure of the second pressure chamber 19 in real time, so that the liquid level of the liquid material in the first opening side 15 is controlled to reach the light curing work liquid level height.
Similarly, the liquid material decreases in volume after photocuring, and causes a decrease in the liquid level near the print substrate 11 and a decrease in the pressure of the working gas in the first pressure chamber 18. Therefore, in the fluid infusion operation, in order to ensure that the light-cured working fluid level of the fluid material in the first opening side 15 is kept constant in the working process, the pressure of the working gas can be measured in real time, and the constant pressure of the working gas can be controlled to be constant in real time through the constant pressure controller 13.
In one or more embodiments, as shown in fig. 3, at least one gas pressure detector 22 is disposed inside the first pressure chamber 18, and the gas pressure detector 22 measures a gas pressure value of the working gas. Preferably, the air pressure detector 22 is electrically connected to the constant voltage controller 13. In the light curing work process, the air pressure detector 22 transmits the air pressure data of the working gas to the constant pressure controller 13, and the constant pressure controller 13 controls the air pressure of the second pressure chamber 19 in real time according to the real-time air pressure data of the working gas, so as to control the air pressure of the working gas to be constant in the light curing work process.
In the above-mentioned embodiment, the adjustment of photocuring working liquid level is realized through the flow of photocuring resin self, not only can effectively realize quick feed supplement, and along with the flow of liquid material, the action of gravity to and working gas's pressure, can also make the liquid material liquid level in the first opening side 15 realize quick flattening, save and use scraper device promptly relevant step, promoted printing efficiency.
The invention also provides a method for controlling the liquid level of the light-cured resin, which comprises the following steps:
s01, sealing a fixed amount of working gas in a first pressure chamber;
s02, controlling air pressure in the second pressure chamber, and adjusting the liquid level of the liquid material in the first opening side to a target liquid level;
s03, measuring the air pressure of working gas in the first pressure chamber at the moment, and recording the air pressure as a working air pressure value;
s04, measuring the air pressure of working gas in real time during photocuring work, and comparing the air pressure with a working air pressure value;
and S05, adjusting the real-time air pressure of the first pressure chamber by controlling the air pressure of the second pressure chamber to enable the real-time air pressure to approach the working air pressure value until the working air pressure value is kept constant.
Specifically, as shown in fig. 3, the first pressure chamber 18 and the second pressure chamber 19 are located at both ends of the communicating liquid tank 9; the air pressure in the second pressure chamber 19 is controlled by the constant pressure controller 13; the gas pressure of the working gas in the first pressure chamber 18 is measured by the gas pressure detector 22; the constant pressure controller 13 records the working air pressure value and compares the working air pressure value with the working gas pressure measured in real time.
In one or more embodiments, as shown in fig. 3, the method for controlling the level of a light-curable resin includes the steps of:
S01, adding a proper amount of light-cured resin into the communicated liquid tank 9, and sealing a fixed amount of working gas 18 at the upper part of the first opening side 15, namely in the first pressure chamber 18;
s02, after the liquid tank cover 14 is closed, the constant pressure controller 13 adjusts the liquid level of the liquid material in the first opening side 15 to a target liquid level by air intake or air exhaust to the second pressure chamber 19;
s03, measuring the air pressure of the working gas by an air pressure detector 22 in the first pressure chamber 18, transmitting the air pressure value to the constant pressure controller 13, and recording the air pressure of the working gas as the working air pressure value by the constant pressure controller 13;
s04, during photocuring work, the air pressure detector 22 measures the air pressure of the working gas in real time and transmits an air pressure value to the constant pressure controller 13, and the constant pressure controller 13 compares the received real-time air pressure value of the working gas with the working air pressure value and converts the pressure difference into air inflow;
and S05, the constant pressure controller 13 feeds a proper amount of gas into the second pressure chamber 19 through the gas inlet pipe 20 to control the gas pressure of the second pressure chamber 19, so that the real-time gas pressure of the first pressure chamber 18 is adjusted and is close to the working gas pressure value until the working gas pressure value is kept constant.
Preferably, the working air pressure is 1.1 to 3 atmospheres. Because the light-cured resin has certain viscosity, the working air pressure value is improved, and the uniformity and the smoothness of the liquid level of the liquid material in the first opening side 15 are improved.
After the printing is completed, the constant pressure controller 13 slowly releases the gas in the second pressure chamber 19 by controlling the exhaust pipe 21 until the liquid material level in the first opening side 15 and the second opening side 16 reaches a natural balance.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the technical solution of the present invention in any way. Any simple modification, form change and modification of the above embodiments according to the technical spirit of the present invention fall within the scope of the present invention.