JP3404306B2 - Stereolithography - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an optical molding apparatus, and more particularly, to a thin-layer photocurable resin which is irradiated with light energy. The present invention relates to an optical shaping apparatus that locally cures a resin to form a desired shape. 2. Description of the Related Art An optical molding method for forming a three-dimensional molded object by irradiating a photocurable resin with light energy is described in, for example, "Optical molding method" published by Nikkan Kogyo Shimbun (Yoji Marutani et al.
(October 30, 1990). [0003] Conventionally, as a general stereolithography method,
There are two methods, a method called a free liquid level method and a method called a regulated liquid level method. [0004] In the free liquid level method, a base plate (modeling table) is arranged at a position near the liquid surface of an uncured photocurable resin stored in an open top storage tank, and the resin free liquid surface on the base plate is placed on the base plate. By irradiating light from above,
A first resin cured layer of a desired pattern is formed on the base plate, and then the base plate is lowered downward in the tank by the thickness of the first layer, so that the uncured resin is free on the first layer. Cover with a liquid surface, irradiate the resin free liquid surface with light similarly from above to form a second resin cured layer, and by repeating this, a plurality of thin resin cured layers are continuously formed. Lamination is performed to perform a desired three-dimensional modeling. In other words, in this method, the base plate in the tank is formed by laminating the cured layers while being sequentially cured from the free liquid level of the uncured resin, and this is the origin of the name. In the regulated liquid level method, an uncured photocurable resin is filled in a storage tank whose bottom is a light-transmitting window, and a base plate is arranged near the bottom of the storage tank. By irradiating the uncured resin layer with light through the transmission window on the bottom from below the storage tank, this resin layer is cured to a desired pattern as a first resin cured layer, and then the first plate is pulled up by pulling up the base plate. The resin cured layer of the layer is peeled upward from the bottom of the tank, and the space between the resin cured tank of the first layer and the bottom of the tank is filled again with the uncured resin in the tank. A second resin cured layer is formed by irradiating light from below the storage tank through a transmission window on the bottom surface, and by repeating this, a plurality of thin resin cured layers are continuously laminated. Perform desired three-dimensional solid modeling. That is, in this method, both sides of the uncured resin layer are regulated between the bottom surface inside the tank and the base plate or the cured layer, and this is the origin of the name. [0006] In either the free liquid level method or the regulated liquid level method described above, the irradiation device used in the stereolithography method appropriately controls light energy in a wavelength range according to the photocuring reaction characteristics of the photocurable resin. It is necessary to irradiate with a predetermined exposure amount, and as a light energy source therefor, a semiconductor laser, a solid-state laser excited by a semiconductor laser, a gas laser such as an argon (Ar) laser or a helium cadmium (He-Cd) laser, or an ultraviolet ray Lamps etc. are used,
In addition, a mechanical shutter, a photoacoustic deflection element (AOM), or the like is generally used for controlling the exposure amount. What is important in terms of molding accuracy in photolithography using a photocurable resin is control of the exposure amount of light energy irradiation according to the resin used, and the photocuring reaction sensitivity. In the case of using a resin having a high curing ratio, an improper exposure amount to a portion to be cured causes an error in the shape and dimensions of the cured portion. In particular, when the light energy irradiation is performed by the drawing method using the scanning of the focused beam, for example, if the rising and / or falling speed of the exposure amount at the scanning start position and / or the scanning end position of the part to be cured is low, the curing is performed. As a result, the dimensional shape error of the portion increases, and therefore, in any of the irradiation methods, high responsiveness is required for controlling the exposure amount in order to improve the molding accuracy. The control of the exposure amount by the photoacoustic deflecting element (AOM) can realize an extremely high-speed response, but the AOM itself is still expensive, and the construction of the laser irradiation optical system and the operation control system are complicated. There is a difficulty. The mechanical shutter is inexpensive as compared with the AOM, but has a shortcoming that the response is too slow to be compared with the mechanical shutter. Therefore, it is impossible to appropriately control the exposure amount, so that the dimensional accuracy of the model to be formed is low. . SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned various problems of the exposure amount control in the conventional stereolithography system, and to provide an expensive AOM
An object of the present invention is to provide an optical shaping apparatus capable of controlling an exposure amount with high response characteristics without using a laser beam. [0011] In order to solve the above-mentioned problems, an optical shaping apparatus according to the present invention provides an irradiation apparatus using a semiconductor laser or a semiconductor laser-excited solid-state laser as an optical energy source; An exposure control device for electrically turning on and off the driving of the semiconductor laser as the light source. According to a preferred aspect of the present invention, the optical shaping apparatus further includes a scanning device for two-dimensionally scanning a focused beam of light energy emitted from the irradiation device on the thin layer of the photocurable resin. In this case, the exposure control device may operate the semiconductor laser at the time when the scanning speed of the focused beam reaches a predetermined set speed at the scanning start point position and / or the scanning end point position of the curing target portion on the photocurable resin. And a speed comparison circuit for electrically controlling the driving of the device to an on or off state. In the optical shaping apparatus of the present invention, the light energy source of the irradiation device is a semiconductor laser or a solid-state laser excited by a semiconductor laser, and the exposure control device electrically turns on and off the driving of the semiconductor laser of the light energy source. Control, so that a faster response than a mechanical shutter can be obtained without using an expensive AOM, and the exposure can be accurately controlled by electrical on / off timing control. A mechanism and an element arrangement for the optical shutter are not required, and the molding of the photocurable resin can be performed with high molding accuracy without generating operation noise as in the case of the mechanical shutter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an optical shaping apparatus using a regulated liquid level method will be described below with reference to the drawings. However, the present invention is not limited to this embodiment. Needless to say, the present invention can be similarly applied to, for example, an optical shaping apparatus using a free liquid surface method. FIG. 1 shows a schematic configuration of an optical shaping apparatus according to the present embodiment. This apparatus has a shaping tank 2 serving as a main working part for stacking and shaping a three-dimensional shaped object 12, and a shaping tank 2 provided below a bottom thereof. A scanning device including an XY plotter 5 disposed therein. The shaping tank 2 is a work tank for storing the photocurable resin 3 and shaping the photocurable resin 3. The shaping tank 2 has a shallow main tank 2 a formed by a flat light-transmitting bottom surface 4 in a central region. The photocurable resin 3 is stored in a thin layer in the region, and a peripheral groove 2b is provided around the main tank 2a. The photocurable resin 3 is sucked from the inside of the circumferential groove 2b by the pump 9 outside the tank, is supplied from the pump 9 into the main tank 2a, and is transparent by the horizontal movement of the skimmer device 10 arranged on the tank. A resin liquid layer 11 having a predetermined thickness corresponding to the lamination slice pitch of the final lamination object is formed on the optical bottom surface 4.
Excess resin scraped off by the skimmer device 10 that moves horizontally on the main tank 2a is returned from the main tank 2a into the peripheral groove 2b, and is then sucked by the pump 9 and sent to the main tank 2a. Used as circulation. Above the main layer 2a, the above-described modeling base plate 1 is disposed substantially in parallel with the translucent bottom surface 4,
The base plate 1 can be moved up and down by a stroke set in advance by an elevator device (not shown). On the other hand, the XY plotter 5 is disposed outside the tank below the light-transmitting bottom surface 4, and the moving head 6 of the XY plotter 5 can scan vertically and horizontally below the light-transmitting bottom surface. Has become. The moving head 6 of the XY plotter 5 has a built-in irradiation optical system connected to an irradiation device 7 by an optical fiber 6a, and the light energy radiation output from the irradiation device 7 is transmitted through the optical fiber 6a to the moving head. 6 is emitted as a focused beam.
The thin resin liquid layer 11 between the light-transmitting bottom surface 4 and the light-transmitting bottom surface 4 is scanned by a focused beam irradiated through the light-transmitting bottom surface 4. These XY plotter 5 and irradiation device 7
Is controlled by a control computer unit 8. When irradiating the resin liquid layer 11 of the photocurable resin with the light energy by the irradiation device 7, the scanning mechanism includes a light energy transmitted from the irradiation device 7 through the optical fiber 6a as shown in FIG. X-
In addition to irradiating as a focused beam from the irradiation optical system built in the moving head 6 of the Y plotter 5, various configurations can be adopted. For example, a method in which a light energy source such as a semiconductor laser is directly mounted on the moving head 6, A method in which a focused beam emitted from the irradiation device is scanned by a reflective optical element such as a galvanometer mirror or a polygon may be used. The computer unit 8 controls the XY plotter 5 and the irradiation device 7 as described above, but also controls the operations of the elevator device for moving the base plate 1 up and down, the pump 9, the skimmer device 10, and the like. Further, based on three-dimensional shape data given in advance, a planar shape pattern of each laminated slice of the final molded product is calculated, and the focused beam is scanned by the moving head 6 so that a desired planar shape pattern is drawn. The calculation of the attribute data such as the beam scanning speed and the scanning pitch is also performed at the same time. Further, the computer unit 8 may have a CAD function or a function of processing CAD data by another terminal. Or a 3D model is designed using another computer terminal and the result is used.
Various modifications and combinations are possible, such as those that perform arithmetic processing and operation control of additive manufacturing data on the modeling apparatus side by data communication with a scanner, an MRI apparatus, or another three-dimensional three-dimensional shape recognition system. FIG. 2 is a block diagram showing a schematic configuration of a control system of the optical shaping apparatus according to this embodiment. In FIG. 2, the irradiation device 7 uses a semiconductor laser or a semiconductor laser-excited solid laser according to the present invention as an optical energy source. Is shown as a laser unit 7a. As shown in FIG. 2, the control system of the optical shaping apparatus includes two motors 5X and 5Y with encoders for moving the moving head 6 of the XY plotter 5 in the X-axis direction and the Y-axis direction, respectively. A driver unit 21 which receives encoder output pulses from these motors as feedback signals and supplies drive signals to each motor at a set speed based on a motor control signal provided from a computer unit 8;
Receiving the encoder output pulse from the moving head 6
A signal conversion circuit 22 for generating a speed signal corresponding to the moving speed in the X-axis direction and the Y-axis direction of the computer unit 8;
And a speed comparison circuit 23 that compares the set speed signal given by the controller with the speed signal from the signal conversion circuit 22 and provides a shutter timing signal to the laser unit 7a when the two match.
The X and 5Y encoders, the signal conversion circuit 22 and the speed comparison circuit 23 constitute an exposure control device for electrically controlling the driving of the semiconductor laser of the laser unit 7a on / off. In the speed comparison circuit 23, the scanning speed of the moving head 6, that is, the focused beam, is set in the computer unit 8 in advance at the scanning start point position and / or the scanning end point position of the curing target portion on the photocurable resin. When the set speed level is reached, the drive of the semiconductor laser of the laser unit 7a is controlled to be electrically on or off. This will be described below with reference to FIG. That is, when a motor control signal is given from the computer unit 8 to the driver unit 21 during the scanning movement of the focused beam by the moving head 6, the motor 5
X and / or 5Y move the moving head 6 at a set scanning speed by accelerating the moving head 6 from a coordinate position set in advance corresponding to the scan starting point position of the curing target portion at that time, as shown in FIG. Similarly, when the head 6 reaches another coordinate position set in advance corresponding to the scan end point position of the curing target portion, the moving head 6 is decelerated and stopped. The acceleration at the start of the scanning movement and the acceleration at the deceleration at the time of stopping are characteristics peculiar to the XY plotter 5, and are, for example, the time from the start of the movement to the set scanning speed or the stop from the set scanning speed to the stop. Time to several msec to several tens msec
It is about. Thus, the moving head 6, and thus the focused beam, accelerates at a certain acceleration and then reaches the set scanning speed,
In the case of scanning when the moving head 6 is decelerated and stopped at a certain acceleration from the set scanning speed, excessive light energy is applied to the photocurable resin when a focused beam is irradiated from the start to the stop of the movement of the moving head 6. As a result, an excessively hardened portion is formed. According to the present invention, this problem is solved as follows. That is, when a motor control signal is given from the computer unit 8 to the driver unit 21, the motors 5X and / or 5Y move from the coordinate position set in advance corresponding to the scanning start position of the curing target portion at that time. FIG.
The moving head 6 is accelerated and moved at a set scanning speed as shown in FIG. 4. When the moving head 6 reaches another coordinate position set in advance corresponding to the scanning end position of the curing target portion, the moving head 6 is moved. To stop. At this time, the encoder output pulse of each motor is input to the signal conversion circuit 22 every moment. Therefore, the signal conversion circuit 22 outputs a speed signal corresponding to the speed of the moving head 6 from these encoder output pulses every moment. Is converted and output. This speed signal is input to the speed comparison circuit 23, where it is compared with a set speed signal given in advance from the computer unit 8, and when the speed signal matches the set speed signal level, the speed comparison circuit 23 A shutter timing signal is given to the laser unit 7a. The laser unit 7a receives the shutter timing signal after the start of the movement of the movable head 6, and switches the semiconductor laser to an operating state (on state) by an internal electrical switching operation, whereby the laser unit 7a is emitted from the laser unit 7a. The emitted laser light is radiated as a focused beam from the irradiation optical system in the moving head 6 via the optical fiber 6a to the photocurable resin. Thereafter, when the speed signal again coincides with the set speed signal level after deceleration for stopping the moving head 6 is started, another shutter timing signal is given from the speed comparison circuit 23 to the laser unit 7a. Accordingly, the laser unit 7a switches the semiconductor laser to a non-operation state (off state) by an internal electric switching operation, and accordingly, the irradiation of the focused beam is immediately stopped. The level comparison between the speed signal and the set speed signal in the speed comparison circuit 23 described above and the ON / OFF of the emission of the laser beam from the laser unit 7a based on the comparison.
The off state is as shown in FIG. 3 with the moving distance of the moving head 6 on the horizontal axis. In FIG. 3, the scanning set speed means the set level of the scanning speed included in the motor control signal given from the computer unit 8 to the motor driver unit 21, and the shutter on / off set speed is the computer unit 8
Means the set speed signal level given to the speed comparison circuit 23. As shown in FIG. 3, when the speed of the moving head 6 matches the shutter on / off setting speed level set in advance by the computer unit 8, the semiconductor laser of the laser unit 7a is operated by the electronic shutter operation. Since the on / off switching control is performed, the shutter on / off setting speed level is appropriately adjusted according to the curing reaction characteristics of the resin, so that the exposure amount control for the photocurable resin is optimized with high responsiveness. Can be controlled. Therefore, while the exposure amount control and the scanning control are being performed, the uncured resin layer between the base plate 1 and the light-transmitting bottom surface 4 in the tank is transferred from the moving head 6 below the molding tank 2 to the light-transmitting layer. This resin layer is cured to a desired pattern as a first resin cured layer by irradiating a focused beam through the bottom surface 4, and then the first resin cured layer is removed from the bottom surface 4 by pulling up the base plate 1. It is peeled upward to refill the space between the first-layer resin curing tank and the bottom surface 4 with the uncured resin in the tank. A second resin cured layer is formed by irradiating a focused beam through the substrate, and by repeating this, a plurality of thin resin cured layers are continuously laminated to form a desired three-dimensional three-dimensional structure 12. Can be formed. The responsiveness of the semiconductor laser and the semiconductor-pumped solid-state laser to the electronic shutter operation is faster than that of the mechanical shutter but is generally of the order of several hundreds of microseconds. It is preferable to allow for this response time
Similarly, it is preferable to allow for the response time of the moving system of the scanning device. In the above-described embodiment, the operating device is provided with X-
Although a Y plotter was used, the same control can be performed by a scanning method using a galvano mirror or a polygon mirror. It goes without saying that we can do it. As described above, in the present invention, a semiconductor laser is used as a light energy source, and the exposure amount is controlled by an electronic shutter system.
It is possible to optimally control the amount of exposure to the photo-curable resin with high responsiveness without using a laser and without having to add an extra element array to the irradiation optical system. And a harsh shutter sound such as a mechanical shutter can be eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing a schematic configuration of an optical shaping apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the optical shaping apparatus according to the embodiment of the present invention. FIG. 3 is a diagram showing a state of on / off control of laser light by an electronic shutter operation in the optical shaping apparatus according to the embodiment of the present invention. [Description of Signs] 1: Modeling base plate 2: Modeling tank 2a: Main tank 2b: Peripheral groove 3: Photocurable resin 4: Translucent bottom surface 5: XY plotter 5X: Motor with encoder for X-axis movement 5Y : Motor with encoder for Y-axis movement 6: Moving head 6a: Optical fiber 7: Irradiation device 7a: Laser unit 8: Computer unit 9: Pump 10: Skimmer device 11: Resin liquid layer 12: Three-dimensional three-dimensional object 21: Motor driver Unit 22: signal conversion circuit 23: speed comparison circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-108481 (JP, A) JP-A-3-16190 (JP, A) JP-A 8-162699 (JP, A) JP-A-1- 228828 (JP, A) JP-A-3-21432 (JP, A) JP-A-5-508126 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 67/00 H01S 5 / 00-5/50

Claims (1)

(1) Claims 1. In a photolithography tank for irradiating a photocurable resin with light energy to form the resin into a desired shape, a semiconductor laser or a semiconductor laser-excited solid laser is irradiated with light energy. An irradiation device serving as a light source; and an exposure control device for electrically turning on and off a semiconductor laser of the light energy source , wherein the irradiation device emits a focused beam of emitted light energy.
Scanning device for two-dimensional scanning on a thin layer of stereolithography resin
The exposure control device includes a curing target portion on the photocurable resin.
Focusing beam at scan start and / or scan end
When the scanning speed of the system reaches a predetermined set speed,
Turns the drive of the semiconductor laser on or off electrically
An optical shaping device comprising a speed proportional circuit for controlling .