RU2809581C2 - Method of operating stereolithographic device to prevent sticking of 3d object to container using vibrational excitations - Google Patents

Abstract

FIELD: stereolithographic devices.

SUBSTANCE: invention is related to a method for operating a stereolithographic device for creating a three-dimensional object from a photocurable substance. The stereolithographic device contains: a container; a platform; an optical block; and an oscillating block. The method includes the stages of storing the photocurable substance in the container; supporting the three-dimensional object using a platform that is movable relative to the container; sequentially projecting multi-layer images onto the photocurable substance using the optical unit in order to cure the photocurable substance deposited between the three-dimensional object and the bottom of the container. The method additionally includes the stage of horizontal oscillations of the container using an oscillating unit simultaneously with the projection of multilayer images. The horizontal oscillation of the container is produced with an amplitude that is smaller than the pixel size of the multi-layer images.

EFFECT: preventing the three-dimensional object from sticking to the bottom of the container and reucing the blurring of the three-dimensional object.

4 cl, 1 dwg

Description

Field of technology to which the invention relates

The present invention relates to a stereolithography device for creating three-dimensional objects from a photocurable substance in a container. The present invention particularly relates to means for preventing a three-dimensional object from sticking to the bottom of a container.

BACKGROUND OF THE ART

A stereolithography device is used to produce a 3D object of the desired shape by exposing, stepwise or continuously, to a photocurable substance, such as a liquid monomer in a container, using multi-layer images that can be created, for example, using digital masks or ultraviolet laser beam scanning . The basic principle of stereolithography is also commonly referred to as rapid prototyping or 3D printing. For stereolithographic manufacturing, an alternative can be the use of pixel displays that create digital masks, or laser beams in combination with controllable micromirrors to project multilayer images, in particular pixel multilayer images, onto a base surface in the photocurable substance for its gradual or continuous curing. The base surface is defined as the focal layer in which the photocurable substance cures and forms the cured layer. Depending on the application, the cured layer may have a hard or soft consistency and is usually located at the bottom of the container within the volume of the flowable photocurable substance. The cured layer initially transfers due to adhesion during the polymerization process to a platform that is relatively mobile relative to the container. During exposure, the hardened layer also adheres to the bottom of the container. After exposure, the cured layer must be separated from the bottom of the container so that fresh photocurable material can flow between the last cured layer, that is, the polymerization front and the bottom of the container. The cured layer is typically released from the bottom of the container by tilting or moving the container relative to the platform on which the 3D object rests. The incoming photocurable substance is then cured by subsequent exposure to it. These steps are repeated until a 3D object is created according to the projected multi-layer images. In a well-known technique, the bottom of the container is covered with an elastic film, from which the 3D object is more easily peeled off when the container is tilted or moved. Another well-known method at the bottom of the container uses special oxygen-permeable materials and can prevent the 3D model of the object from sticking to the bottom of the container. However, such oxygen-permeable containers are relatively expensive.

US 2017/0210072 A1 discloses a system for the additive manufacturing of a homogeneous optical element with reduced scattering and diffraction effects through pseudo-random lateral vibration of a digital print projector and resin reservoir. The random amplitude had a size of 1.5 pixels.

WO 2016/172788 A1 discloses a stereolithography system having a resin reservoir with a pair of ultrasonic transducers flexing outward and inward when vibrating to tilt the resin reservoir after exposure to peel off a manufactured object.

US 2018/0243987 A1 discloses an additive manufacturing system having an ultrasonic vibrator connected to a container that vibrates to separate the manufactured object from the container window upon completion of the fragment.

WO 2018/187874 A1 discloses a stereolithography system having tactical transducers located at the corners of a resin reservoir to help release a cured object from the reservoir using vibration amplitude in the direction of the thickness of the printed layer.

EP 3205484 A1 discloses a three-dimensional printing machine having vibrating means to promote separation of the printed object from the bottom of a resin reservoir after printing.

DISCLOSURE OF INVENTION

An object of the present invention is to overcome the shortcomings of the prior art and to provide a method for operating a stereolithography device in which sticking of a 3D object to the bottom of a container can be effectively prevented during exposure in a less complicated manner.

This goal was achieved using the method that is defined in paragraph 1 of the claims. Dependent claims relate to further developments.

The present stereolithography device of the present invention is suitable for creating a three-dimensional object from a photocurable substance, and includes a capacity for storing the photocurable substance; a platform for supporting a three-dimensional object, the platform being movable relative to the container; an optical unit for sequentially projecting multi-layer images onto a photocurable substance for curing the photocurable substance deposited between the three-dimensional object and the bottom of the container; and an oscillating unit that is configured to produce horizontal oscillations of the container while projecting the layered images at a substantially constant amplitude that is smaller than the pixel size of the layered images in the horizontal direction to prevent the three-dimensional object from sticking to the bottom of the container and to reduce blurriness of the three-dimensional object .

The main advantageous effect of the present invention is that the 3D object can be prevented from sticking to the bottom of the container during exposure due to the accompanying oscillatory excitations. In this way, the need to tilt or move the container after exposure can be avoided, and thus the manufacturing process can be further accelerated. In addition, the need to use oxygen-permeable containers, elastic films can be eliminated and production costs can be comparatively reduced.

In accordance with the present invention, the container can also be continuously oscillated between successive exposures, that is, during pauses in production, so that the flowable photocurable substance, namely the resin, quickly fills the gap between the last cured layer and the bottom of the container. In this way, pause periods during production can be comparatively shortened and the production process can be further accelerated.

According to one embodiment of the present invention, the oscillating unit oscillates the capacitance horizontally during the production process and/or during pauses in production. In this way, the flowable photocurable substance can be more effectively prevented from sticking to the container. Also, the gap can be more effectively filled with a flowable photocurable substance.

In accordance with one embodiment of the present invention, the oscillator unit produces capacitance oscillations with an amplitude that is smaller than the pixel size of the multilayer images and a frequency that is higher than the exposure frequency of the multilayer images. In this way, the blur of a three-dimensional object can be effectively reduced.

In accordance with one embodiment of the present invention, the oscillating unit has at least one drive that produces oscillations of the capacitance. The drive may be directly connected to the container or container support. Preferably, the container is mounted on a support and can be replaced. The drive is controlled by the control unit of the stereolithography device based on multilayer images, pixel size, exposure time, viscosity of the photocurable substance, etc. The actuator may be piezoelectric. Alternatively, other types of actuators known to those skilled in the art may be used.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following description, additional aspects and beneficial effects of the present invention will be described in more detail using exemplary embodiments and with reference to the drawings, in which

Figure 1 shows a stereolithography device in accordance with one embodiment of the present invention.

Reference numerals shown in the drawings indicate the elements listed below and will be indicated in the following description of exemplary embodiments:

1. Stereolithographic device

2. 3D object

3. Photocurable substance

4. Capacity

5. Platform

6. Optical block

7. Oscillatory block

8. drive

9. Control unit

10. Drive unit

Figure 1 shows a stereolithography device (1) for creating a three-dimensional object (2) from a photocurable substance (3). All processes in the stereolithographic device (1) are controlled by the control unit (9). The photocurable substance (3) is stored in a container (4). The container (4) is placed on the support. The optical unit (6) sequentially projects multi-layer images onto the photocurable substance (3) to cure the photocurable substance (3) deposited between the three-dimensional object (2) and the bottom of the container (4). The oscillating unit (7) oscillates the container (4) simultaneously with the projection of multi-layer images to prevent the three-dimensional object (2) from sticking to the bottom of the container (4). The three-dimensional object (2) is supported by the platform (5). The platform (5) can be moved relative to the container (4) by means of a drive unit (10).

The oscillating unit (7) oscillates the container (4) in the horizontal direction, preferably in the X and/or Y direction. The amplitude and frequency of oscillations are controlled by the control unit (9) depending on the type of photocurable substance (3) and multilayer images, in particular pixel size and exposure frequency. It is preferable that the vibration amplitude be smaller than the pixel size of multilayer images. It is preferable that the oscillation frequency be higher than the exposure frequency of multilayer images. The exposure frequency is inversely proportional to the exposure time of each image layer.

In accordance with one of the embodiments of the present invention, the oscillating unit (7) contains at least a drive (8), which produces oscillations of the capacitance (4). The drive (8) can be connected directly to the container (4). Alternatively, the drive (8) can be connected to the container support (4).

According to one embodiment of the present invention, the drive (8) may comprise an electromechanical drive. A piezoelectric actuator can be used. Alternatively, an electroactive polymer actuator can be used. Alternatively, a magnetic restriction drive is possible.

Claims (10)

1. A method of operating a stereolithography device (1) to create a three-dimensional object (2) from a photocurable substance (3), where the stereolithography device (1) contains: a container (4); platform (5); optical block (6); and an oscillating unit (7), wherein the method includes the steps: storing the photocurable substance (3) in a container (4); supporting a three-dimensional object (2) using a platform (5), which is movable relative to the container (4); sequentially projecting multilayer images onto the photocurable substance (3) using an optical unit (6) in order to cure the photocurable substance (3) deposited between the three-dimensional object (2) and the bottom of the container (4); And additionally includes the stage: horizontal oscillations of the capacitance (4) using an oscillating unit (7) simultaneously with the projection of multilayer images, characterized in that the horizontal oscillation of the container (4) is produced with an amplitude that is smaller than the pixel size of the multi-layer images to prevent the three-dimensional object (2) from sticking to the bottom of the container (4) and to reduce the blur of the three-dimensional object (2). 2. The method according to claim 1, characterized in that the capacitance (4) oscillates with the help of an oscillating unit (7) at a frequency exceeding the exposure frequency of multilayer images. 3. Method according to any one of claims 1, 2, characterized in that the oscillating unit (7) contains at least one drive (8) configured to produce oscillations of the capacitance (4), and the drive (8) is either directly connected to container (4), or with container support. 4. Method according to claim 3, characterized in that the drive (8) is piezoelectric.

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