CN116100802A - Relaxation film-separating type photo-curing three-dimensional printing method and printer thereof - Google Patents

Abstract

A relaxation film-separating type photo-curing three-dimensional printing method and a printer thereof belong to the technical field of machinery. The core components of the device comprise: the printing device comprises a printing platform, a resin liquid tank assembly, a shell, an electric control system, a driving motor, a laser beam scanning system or a DLP (digital light processing) and LCD (liquid crystal display) projector; the core of the resin liquid tank assembly includes: a curved bottom resin liquid tank and a large part of a plane frame 2; the flat state and the curved state of the release film in the effective area are alternately formed by utilizing the relative movement of the planar frame in the curved bottom resin liquid tank, and simultaneously, the controlled loose state of the release film can be alternately performed, so that the physical environment for tearing and stripping between a printed object and the release film is created; the printing speed, the printing quality and the printing yield greatly exceed the industry level; can be widely used in an inverted photo-curing three-dimensional printing method and a printer.

Description

Relaxation film-separating type photo-curing three-dimensional printing method and printer thereof

[ field of the invention ]

The invention belongs to the technical field of machinery. Specifically, the alternating change of the deflection degree of the release film is completed by means of alternating the bilateral frame support of the release film on the bottom surface of the liquid tank, so that the newly cured surface of the printed object and the easily separated photo-curing printing method and device on the bottom surface of the liquid tank are realized.

[ background Art ]

Photo-curing molding is the earliest 3D printing molding technology and is one of the 3D printing technologies which are mature at present. The basic principle of the technology is to utilize accumulated light curing molding of liquid materials, namely, the shape of a three-dimensional target part is divided into a plurality of plane layers, a light beam with a certain wavelength is used for scanning a liquid photosensitive resin liquid tank, so that the liquid photosensitive resin surface layer of the liquid tank is cured, the part which is not irradiated by the light beam is still in a liquid state, then a printing platform ascends or descends by one layer of height, the next layer is scanned and cured, the required target part is finally accumulated after accumulating layer by layer, and the material utilization rate can be close to 100%.

The inverted light-cured 3D printer is developed on the basis of SLA technology, has 3 forms and mainly comprises a DLP light-cured 3D printer, an LCD light-cured 3D printer and a laser scanning light-cured 3D printer.

DLP projector photocuring 3D printer:

the application of digital light processing (Digital Light Processing, abbreviated as DLP) has been developed after more than ten years from the advent of SLA technology, which is also a second generation photo-curing molding technology recognized in the industry, and has been developed for more than 20 years. DLP technology was originally developed by texas instruments, and for reasons of DMD light reflection efficiency, it was decided to cure photopolymer liquid layer by a projector, creating a rapid prototyping technology for 3D printed objects. The forming technology firstly uses slicing software to slice the model, a projector plays slice images, each layer of image generates photopolymerization reaction on the section of a printed object solidified on an inverted printing platform in a thin area of a resin layer, a thin layer of the part is increased, then the printing platform moves upwards by one layer, the projector continues to play the next slice image, and continues to process the next layer on the section of the printed object, and the circulation is performed until the printing is finished, so that the forming precision is high, and the printing speed is very fast.

LCD panel photo-curing 3D printer:

the LCD photo-curing molding technology was only recently developed in 2013. This technique is open-source and the core components are also very inexpensive. Forming principle: compared with DLP molding technology, the LCD light valve has a transmittance of 1-6%, needs to be irradiated by high-power ultraviolet light, and is cured and molded by using a very small amount of transmitted ultraviolet light, so that the projected image on the surface of the panel is directly used for direct exposure. When printing, the LCD panel plays slice images, each layer of image generates photopolymerization reaction in a thin area of the resin layer to be solidified on the section of the printed object on the inverted printing platform, so that one thin layer of part is increased, then the printing platform moves upwards by one layer, the panel continues to play the next slice image, and the next layer is continuously processed on the section of the printed object, so that circulation is performed until printing is finished, and therefore, the molding precision is high, and the printing speed is very high.

The LCD screen is very resistant to ultraviolet rays, and can be aged rapidly after being irradiated, and meanwhile, the core component is subjected to heat resistance and high-temperature heat dissipation, and also subjected to high-strength baking for several hours of a few tens of W405 LED lamp beads, so that the service life is very short. If used frequently, the LCD screen, the core component, tends to be damaged in one to two months.

SLA and bottom laser scanning photocuring 3D printer:

is the earliest and most widely used technology; most of them scan the focused laser beam by a vibrating mirror, including the front and back SLA modes;

advantages and disadvantages: the advantages are longer service life, but the cost and complexity are much higher than those of the DLP and LCD photo-curing molding technology, and the 'scraper' of the SLA is an unavoidable disadvantage; however, as with DLP and LCD, the reliability of release in the inverted form has been a common challenge.

The main defect of the inverted photo-curing 3D printing technology is that:

the defects mainly come from the problems of demolding and adhesion between a printed object and a release film, and difficult liquid return.

Because the surface of the printing object which is just solidified and the release film also has certain bonding strength, the forced postscript release can bring about 2 problems: firstly, the force and the upward moving distance are too large (the printing speed is influenced), and secondly, the surface of a printed object is easy to damage, and part of residues can be adhered to the release film.

There are many ways in the industry today to overcome this problem: oxygen ion and additional laser inhibition release film clinical curing method; shaking, rolling resin vat method, etc. are not satisfactory.

[ summary of the invention ]

The invention aims to solve the defects of the prior art:

overcomes the adhesion problem of a release film and a printed object and the buffer barrier of the upper liquid in the current SLA, DLP, LCD inverted photocuring printing technology; the expression is as follows: the demolding and liquid returning are difficult, and the printed objects are easy to be damaged.

The invention is characterized in that:

the mechanical structure is simple, so that the release film can be switched from a plane to a curved surface and the degree of relaxation is alternately changed, a strong release film tearing effect is generated, the release film is reliable, and the yield is high.

The core component of the relaxation release film type photo-curing three-dimensional printer comprises:

the printing platform, the resin liquid tank assembly, the shell, the electric control system and the mechanical driving system comprise a driving motor, a laser beam scanning system or a DLP (digital light processing) LCD (liquid Crystal display) projector;

basic assembly relation and the operation method of the technology:

basic assembly relationship:

the resin liquid tank assembly is used as a core part, and the structure comprises: a curved bottom resin liquid tank and a large part of a plane frame 2; the lower opening (the ring surface of the end surface of the liquid tank) of the curved bottom resin liquid tank is a curved surface or a plane, and at least one section (the ring surface) of the curved bottom resin liquid tank or the whole area is above the exposure curing surface (namely, one part of the area is contacted with the exposure curing surface, and the other part of the area is 2-100 mm away from the exposure curing surface); when the release film is fixed on the lower frame opening of the flexible frame in a curved bottom state by the frame pressing bar, the local upward protruding curved surface state of the release film is restrained, and also if the trend of the lower opening of the curved bottom resin liquid tank is a plane curve (actually is a non-curved bottom), the lower frame opening of the flexible frame is in a plane state, and the fixed release film is in a plane state; the plane frame is placed in the curved bottom resin liquid tank and is an independently controlled relative movement component, and the position is between the position on the exposure curing surface and the position upwards away from the exposure curing surface, and the position is continuously switched; the plane frame is just positioned at the vacant position clamped between the printing platform and the curved bottom resin liquid tank, so that the lifting of the printing platform is not hindered;

the laser beam scanning system or DLP, LCD projector is placed under the curved bottom resin liquid tank (inside the shell), the projection of projection light is formed by: the surface element of the DLP projector projects or scans a laser beam (generally, the laser beam is focused on the plane of a display window under the focusing of a beam expanding mirror, a vibrating mirror and a field lens) to the exposure surface of the display window; or the LCD display panel is directly placed on the display window part below the release film; the laser beam scanning system or the DLP and LCD projector displays the image on the display window plane at the bottom of the resin liquid tank;

the printing platform is a rooting surface of a printed object and is arranged on a lifting arm under the constraint of a Z-axis guide rail, when printing starts, the printing platform is inversely immersed in a liquid tank filled with resin and is carried by the lifting arm along the Z-axis direction under the constraint of the Z-axis guide rail (vertical direction: a double moment arm system under the constraint of 2 horizontal axes besides the Z-axis guide rail, a delta system, the height of the printing platform is constrained and the like); the plane frame is placed in the curved bottom resin liquid tank, does not obstruct the movement of the printing platform, and moves up and down relative to the curved bottom resin liquid tank under the drive of the motor; the electronic control system is connected with components such as a driving motor, a sensor, a display screen and the like, receives sensor signals and sends instructions to the components such as the sensor, the display screen and the like; after the lifting arm drives the printing platform to descend by one layer (the height of the printing layer), the next new resin liquid level (the new slicing layer) is exposed, so that the height of the printed object is increased by one layer, and the cycle is repeated until the whole printing is finished;

basic operation method:

the working characteristics of the resin liquid tank component are as follows: the plane frame is used for flattening the convex release film on the bottom surface of the curved bottom resin liquid groove so as to meet the relaxation release effect between the printed object and the release film; relaxation is referred to as: in each exposure period (comprising exposure of a first layer of priming layer), under the control of an electronic control system, the planar frame moves downwards to press the release film to be attached to an exposure curing surface; after exposure is completed, when the printing platform drives the printed object to rise and leave the film, the plane frame rises along with the rising of the printing platform, the rising speed is less than or equal to (or slightly greater than) the rising speed of the printing platform, the release film has a tendency to recover to a convex shape due to the elasticity of the release film and becomes flexible, and the recovered relaxation also causes the release film to slightly relax; the plane frame is firstly turned into descending before the printing platform, and the release film is forcedly pushed down and gradually turned into straight, namely the release film is completely torn off from the printing object; the printed object is easy to separate from the release film; then the plane frame moves downwards in advance to push the deflected release film to lean against the exposure curing surface, so that preparation is made for curing and printing of the next layer; whereas for the case where the trend of the lower opening of the curved-bottom resin tank is a planar curve: although the curved surface state of the local upward bulge of the release film under the constraint of the flexible frame does not appear in the process, the synchronous upward movement and the advanced downward movement of the planar frame also can make the tension of the release film relaxed to some extent, and the planar frame pushes the periphery of the release film to help separate the printed objects;

principle overview of the operation method of the present invention:

the printing mode of the invention is almost the same as the printing distance of a conventional inverted photo-curing 3D printer: firstly, filling resin raw materials into a resin liquid tank; leveling the printing platform by taking an exposure curing surface (display curing window) as a reference, so that the printing platform and the printing platform are parallel to each other; the invention is different from the prior art in that: when printing starts, the planar frame moves downwards under the drive of the motor and keeps the release film fixed on the flexible frame in a pressing mode, and no matter the lower frame opening of the flexible frame is in a flexible curved surface state (a distance exists between the local release film and an exposure curing surface) or in a planar plane state (a distance exists between the integral release film and the exposure curing surface), the release film in the planar frame is in the same plane with the frame due to the elastic action of the release film; and is abutted against the exposure curing surface; on the other hand, when printing starts, the electric control system controls the distance between the lower plane of the printing platform and the release film flattened by the plane frame to be 10-200 micrometers (the thickness of the priming layer); then, the priming layer is subjected to abundant selective exposure and solidification, then, the printing platform and the plane frame are synchronously lifted, the lifting quantity is generally within 100mm, at the moment, the release film has upward bulge and relaxation tendency, the release film is also enabled to move upward along with the upward movement of the plane frame, a larger tangential angle is formed at the edge of a solidification area between the solidification surface of the printed object and the release film, and tearing and stripping are facilitated; when or before the printing platform is stopped, the plane frame is controlled to stop rising and start descending, and the residual bonding area is stripped by utilizing the tensioning of the release film tending to the plane state until the plane frame presses the release film against the exposure curing surface, and the process of priming curing is finished; the printing of the next layer that follows is also exactly the same: the printing platform starts to descend again until the distance between the new surface of the printing object and the flattened release film is the set layer thickness, and then the above curing exposure, motion stripping and cyclic reciprocation are carried out until the whole printing is finished.

Further: the displacement of the plane frame relative to the curved bottom resin liquid tank is translational or non-translational, comprising: the fixed shaft or the movable shaft of the plane frame is moved away in a rotating way;

further: by means of the planar frame construction of the resin bath assembly, a scraper device for cleaning the release film can be easily added: the blade line of the scraper is flush with the plane frame opening of the bottom surface of the plane frame, the scraper guide rail takes root on the plane frame, and the scraper motor arranged on the resin liquid tank component or the shell can push the scraper to reciprocate along the X or Y direction by driving the screw rod, the screw nut and the belt.

The invention has the beneficial effects that:

the structure is simple, the fluid infusion is abundant, and the finished product rate is improved to a certain extent because the stripping state of the printed objects is good.

[ description of the drawings ]

FIG. 1 is a schematic view 1 of a relaxation film type photo-curing three-dimensional printer

FIG. 2 schematic diagram 2 of a relaxation film type photo-curing three-dimensional printer mechanism

FIG. 3 is a schematic drawing showing the disassembly of a relaxation film type photo-curing three-dimensional printer

FIG. 4 is a schematic diagram of a curved bottom resin bath construction and assembly

FIG. 5 is a schematic diagram of assembly and operation of a curved bottom resin bath and a planar frame

Description of the reference numerals:

(1) Curved bottom resin liquid tank (liquid tank for short)

(2) Flexible frame

(3) Frame layering

(4) Release film

(5) Plane frame

(6) Frame shaft

(7) Frame motor

(8) Convex release film

(9) Concave wire frame mouth

(10) An axis line

(11) Liquid tank assembly before assembly

(12) Steering direction

(13) Direction of ascent

(14) Curved bottom resin liquid tank assembly

(15) Z-axis guide rail

(16) Lifting arm

(17) Printed article

(20) Printing platform

(21) Arrows

(22) Shell body

(23) Exposure curing surface (display window)

(24) Screw rod

(25) Fixing screw

(26) Raised portions of the flexure frame

(27) Z-axis and axis

(28) Liquid level

(29) Screw hole

(30) Connecting terminal

(31) Flattening release film

(32) Shaft hole

Best mode for carrying out the invention

The invention is further described with reference to the preferred embodiments in the following with reference to the accompanying drawings:

as shown in fig. 1, 2 and 3:

under the constraint of a Z-axis guide rail (15), a lifting motor in the shell (22) drives a screw rod (24) to drive a lifting arm (16) to drive a printing platform (20) and a printing object (17) adhered below the printing platform through a connecting end (30), the printing object (17) reciprocates up and down along a Z-axis (27) according to the direction of an arrow (21), and the lower end of the printing object (17) is always immersed below the liquid level (28) of the curved bottom resin liquid tank assembly (14); the exposure curing surface (display window) (23) can be used for placing an LCD display panel (the lower inside of the shell is illuminated by an ultraviolet light source), or laser scanning and DLP projection are projected on the exposure curing surface; the fixing screw (25) is screwed in the screw hole (29) after passing through the through hole on the curved bottom resin liquid tank.

The printing mode is almost the same as that of the conventional inversion type: filling resin raw material into a resin liquid tank, leveling a printing platform (20) to be parallel to an exposure curing surface (display window) (23); when printing starts, the plane frame (5) moves downwards under the torque drive of the frame motor (7) and presses the convex release film (8) which is in a natural state and protrudes upwards, and the release film part in the inner area of the flexible frame (2) is pressed into a plane and leans against an exposure curing surface (a display window, a transparent material plate can be used as the exposure curing surface to fill a cavity) (23) on the upper surface of the shell (22); the distance between the lower plane of the printing platform (20) and the flattened release film is generally kept between 10 and 200 micrometers (the thickness of the priming layer) under the control of the electronic control system; then the bottoming layer is fully exposed and solidified; then lifting synchronously, wherein the printing platform (20) and the plane frame (5) (generally within 10 mm), the release film at the moment is loosened, and the tearing and stripping of the printed object are facilitated; when or before the printing platform is stopped, the planar frame (5) stops rising and starts to descend under the drive of the motor, and the release film gradually tightens towards the planar state, so that the residual bonding area of the printed object is further forcedly stripped; then the printing platform (20) starts to descend again until the distance between the new curing surface of the printed object and the flattened release film is the set layer thickness, and then exposure is performed, and the cycle is repeated until printing is completed.

As shown in fig. 4 and 5:

the curved bottom resin liquid tank (1) is composed of: the flexible frame (2), the release membrane (4) and the frame pressing strip (3); the ports of the deflection frame (2) facing downwards are not on the same plane, and the 4 corner areas are in the same plane; the positions of the 4 corner bending frames (2) are the lowest, and the positions of the central parts of the 4 sides are the highest; when the frame pressing bar (3) is used for pressing the release film (4) against the bending end face of the bending frame (2), the release film (4) is in the shape of a convex release film (8) with the lowest 4-angle area and the highest central area due to the restraining effect of the concave wire frame opening (9) of the boundary.

FIG. 5 shows the parts of the liquid tank assembly (11) before assembly, wherein the frame shaft (6) on the 2 sides of the plane frame (5) is connected with the frame motor (7) and matched with the shaft hole (32), and the constraint state of the frame shaft (6) comprises: the 4 corner areas of the flexible frame (2) are in the same plane with the lower frame opening of the plane frame (5); when the frame motor (7) rotates around the axis (10) along the reverse direction of the rotation direction (12), the lower frame opening of the plane frame (5) descends, and the lower frame opening contacts the upward protruding release film and pushes it flat (due to micro elasticity, the lower frame opening can push down to be abutted against the exposure curing surface or the peripheral shell), as shown in the flattened release film sheet (31); when the frame motor (7) rotates around the axis (10) along the rotation direction (12), each edge of the lower frame opening of the plane frame (5) rises along the rising direction (13) to different degrees; as shown by the raised portions (26) of the flex frame.

Claims (4)

1. The relaxation film-releasing type photo-curing three-dimensional printing method comprises the following core components: the printing device comprises a printing platform, a resin liquid tank assembly, a shell, an electric control system, a mechanical driving system, a laser beam scanning system or DLP, an LCD projector or an LCD display panel; basic assembly relationship: a laser beam scanning system or DLP, an LCD projector or an LCD display panel is arranged in a shell below the curved bottom resin liquid tank, and a window is formed on the upper surface of the shell at a position opposite to the lower surface of the resin liquid tank, which is used as an exposure curing surface position; the DLP projection optical machine or the scanning laser beam directly forms a focused projection image on the exposure curing surface, or an LCD display panel is directly placed on the exposure curing surface to display the image, and the projection image and the display image are both in ultraviolet light wave bands; the lower surface of the printing platform is used for bonding the printing object, the printing object is rooted on the table surface in an inverted mode, and the height of the printing platform is controlled by a vertical mechanical driving system;

the method is characterized in that: the resin tank assembly structure of the core component comprises: a curved bottom resin liquid tank and a large part of a plane frame 2; when the lower opening of the curved bottom resin liquid tank has a plane curve, the lower frame opening of the flexible frame is in a plane state, and the fixed release film is in a plane state; the lower opening of the curved bottom resin liquid tank is a curved surface or a plane, and at least one section of area or all the areas are above the exposure curing surface, namely, one part of area is contacted with the exposure curing surface, and the other part of area is 2-100 mm away from the exposure curing surface; the plane frame is placed in the curved bottom resin liquid tank and is just positioned at the vacant position clamped between the printing platform and the curved bottom resin liquid tank, so that the lifting of the printing platform is not hindered; the plane frame is controlled by a mechanical driving system to control the height of the release film relative to the bottom surface of the curved bottom resin liquid tank; when printing starts, the plane frame is driven by a mechanical driving system (comprising a motor) to downwards hold and press the release film on the bottom surface of the curved bottom resin liquid tank, and the plane frame can be attached to the exposure curing surface (and keep the flat state of the film in the frame) due to the elastic action of the release film; on the other hand, when printing starts, the electric control system controls the distance between the lower surface of the printing platform and the release film flattened by the planar frame to be 10-200 micrometers; then, the priming layer is subjected to abundant selective exposure and solidification, and the printing platform and the plane frame are synchronously lifted after exposure, wherein the lifting quantity is generally within 100 mm; when or before the printing platform is stopped, the plane frame is controlled to stop rising and start descending, the residual bonding area is stripped by utilizing the tensioning displacement of the release film towards the plane state until the plane frame presses the release film against the exposure curing surface, and the process of priming curing is finished; the printing mode of the next layer is also exactly the same: the printing platform starts to descend again until the distance between the new surface of the printing object and the flattened release film is the set layer thickness, and then the above curing exposure, motion stripping and cyclic reciprocation are carried out until the whole printing is finished.

2. A relaxation film-releasing type photo-curing three-dimensional printer comprises the following core components: the printing device comprises a printing platform, a resin liquid tank assembly, a shell, an electric control system, a driving motor, a laser beam scanning system or a DLP (digital light processing) and LCD (liquid crystal display) projector; basic assembly relationship: the laser beam scanning system or DLP, LCD projector is placed under the curved bottom resin liquid tank, the projection of projection light is formed by DLP projector or scanning laser beam or placing LCD display panel directly on the exposure solidifying surface position under the release film; the printing platform is controlled by a vertical position control system to be at a height position, and the lower surface of the printing platform is used for bonding a printed object; the method is characterized in that: structurally, the resin liquid tank assembly is used as a core part, and the relaxation film type photocuring three-dimensional printing method is used in a 3D printing method.

3. The relaxation film type photo-curing three-dimensional printing method according to claim 1, wherein the displacement of the plane frame relative to the curved bottom resin liquid tank is as follows: translational or non-translational, including: and (3) moving away the fixed shaft or the movable shaft of the plane frame in a rotating way.

4. The relaxation film type photo-curing three-dimensional printing method according to claim 1, wherein the resin liquid tank assembly is additionally provided with a scraper device for cleaning the release film by using a planar frame structure: the blade line of the scraper is flush with the plane frame opening of the bottom surface of the plane frame, the scraper guide rail takes root on the plane frame, and the scraper motor arranged on the resin liquid tank component or the shell can push the scraper to reciprocate along the X or Y direction by driving the screw rod, the screw nut and the belt.

Images