Search

EP-4737099-A1 - SYSTEM AND METHOD FOR ADDITIVE MANUFACTURING

EP4737099A1EP 4737099 A1EP4737099 A1EP 4737099A1EP-4737099-A1

Abstract

A system and method for additive manufacturing of an object (90) on a substrate (16), comprising a printing unit (10) with a vat (12) for photocurable resin (14) and a semitransparent membrane (18). The optical unit (20) includes light sources (22) emitting light beams (24) through the membrane, a collimator lens (30), an objective lens (32), and a detector (40) for monitoring properties of the object and substrate. XY-actuators (44,46) position the optical unit, while a collimator lens actuator (62) adjusts the focal point (64) along the optical path (26) to cure the resin at specific positions. This system enables precise layer-by-layer construction of objects by moving the optical unit and adjusting the focal point to cure the resin, ensuring high-resolution and accurate manufacturing.

Inventors

  • HWU, EN-TE

Assignees

  • Danmarks Tekniske Universitet

Dates

Publication Date
20260506
Application Date
20241031

Claims (15)

  1. A system for additive manufacturing of an object (90) on a received substrate (16), the system comprising - a printing unit (10), the printing unit comprising: ▪ a vat (12) configured to accommodate a photocurable resin (14), such that the substrate (16) and/or the object (90) can be at least partly submerged within the photocurable resin (14), the vat comprises a semi-transparent membrane (18), and - an optical unit (20), the optical unit comprising: ▪ one, or more, light source(s) (22) capable of emitting a single wavelength or multiple wavelengths emitted light beam (24) along an optical path (26) passing through said membrane (18) towards said substrate (16), ▪ a collimator lens (30) arranged to receive and collimate said emitted light beam along the optical path, ▪ an objective lens (32) adapted to receive, and focus said emitted light beam along the optical path, ▪ a detector (40) configured to detect one, or more, properties of the object (90), the substrate (16), the cured resin (15) and/or the membrane (18) from a reflected light beam (42) from the object, the substrate, the cured resin and/or the membrane, and ▪ XY-actuators (44, 46) configured to position the optical unit (20) at a printing position (63) along a XY-plane substantially parallel to the attachment surface (48) of the substrate or the upper surface (52) of the membrane relative to the printing unit (10); - wherein the system (1) is adapted to receive the substrate (16), the substrate is comprising an attachment surface (48) on which the object is manufactured; - wherein said collimator lens (30) is mechanically displaceable substantially along said optical path (26) by a corresponding collimator lens actuator (62); - wherein, when the optical unit (20) is positioned at said printing position (63), the collimator lens (30) is arranged to be displaced by said collimator lens actuator (62) along the optical path (26) to move a focal point (64) of the emitted light beam (24) along a line (Z) substantially perpendicular to the upper surface (52) of the membrane (18) and/or the attachment surface (48) of the substrate (16) to a curing position (67); and - wherein the photocurable resin (14) is adapted to be cured to cured resin (15) at the focal point (64) of the emitted light beam (24) when the focal point has reached said curing position; and - wherein, to manufacture the object (90) on the received substrate (16), the system (1) is adapted to move the optical unit (20) between different printing positions (63), and at each printing position, to move the focal point (64) of the emitted light beam (24) to the curing position (67), and thereby cure the photocurable resin (14) at the focal point such that the cured resin (15) is attached to the object or the received substrate.
  2. The system according to claim 1, wherein the collimator lens actuator (62) is a stepper motor configured to displace the collimating lens (30).
  3. The system according to claim 2, wherein the stepper motor (62) is configured to displace the collimating lens (30) along a line (Z) by steps less than 200 nm, preferably less than 150 nm and even more preferably less than 100 nm to shift the focal point (64) of the emitted light beam (24).
  4. The system according to any of the preceding claims, wherein the detector (40) is configured to detect from the reflected light beam (24) a focus error signal (FES) indicative of the displacement of the focal point (64) from an optimal focus position.
  5. The system according to any of the preceding claims, wherein the light sources (22) comprise at least one light source, which is a coherent radiation source, such as a laser.
  6. The system according to any of the preceding claims, wherein, upon detection of the at least one property of the object (90), the substrate (16), the cured resin (15) and/or the membrane (18) by the detector (40), the light source(s) (22) emits the emitted light beam (24) at a wavelength or wavelengths that does not cure the resin (14).
  7. The system according to any of the preceding claims, wherein, when the photocurable resin (14) is to be cured, the light source(s) (22) emits the emitted light beam (24) at a wavelength or wavelengths that cures the resin (15).
  8. The system according to any of the preceding claims, wherein the detector (40) is configured to detect one or more of the following properties: the roughness of the substrate (16) or the membrane (18), the topography of the of the object, the cured resin, substrate or the membrane, physical coordinates of the of the object, the cured resin, the substrate and or the membrane, parallelism between the substrate and the membrane, the flatness of the substrate or the membrane, the deformation of the substrate or the membrane, the thickness of the photocurable resin and/or the membrane, the transmission characteristics of the photocurable resin and/or the membrane, and the reflection characteristics of the substrate and/or the photocurable resin and/or the membrane.
  9. The system according to any of the preceding claims, wherein the membrane (18) is located at the bottom of the vat (12).
  10. The system according to any of the preceding claims, wherein the detector (40) is configured to detect the thickness of the membrane 18.
  11. The system according to any of the preceding claims, wherein the system (1) is configured to adjust the focal point (64) of the emitted light beam (24) to adapt the parallelism and/or the flatness and/or the deformation of the substrate (16) and/or the membrane (18).
  12. The system according to any of the preceding claims, wherein the system (1) comprises a processor (99) configured to control the detector (40), the light source (22), the XY-actuators (44, 46), and the collimator lens actuator (62).
  13. The system according to any of the preceding claims, wherein the additive manufacturing of the object is stereolithographic 3D-printing of the object (90).
  14. A method for additive manufacturing of an object (90) on a substrate (16), the method comprising: - providing a printing unit (10), the printing unit comprising: ▪ a vat (12) accommodating a photocurable resin (14), the vat comprising a semi-transparent membrane (18), and - providing an optical unit (20), the optical unit comprising: ▪ one, or more, light source(s) (22) capable of emitting a single wavelength or a multiple wavelength emitted light beam (24) along an optical path (26) passing through said membrane (18) towards said substrate (16), ▪ a collimator lens (30) receiving and collimating said emitted light beam along the optical path, ▪ an objective lens (32) receiving and focusing said emitted light beam along the optical path, ▪ a detector (40) detecting one, or more, properties of the object (90), substrate (16), cured resin (15) and/or the membrane (18) from a reflected light beam (42) reflected from the object, substrate, cured resin and/or membrane, and ▪ XY-actuators (44, 46) positioning the optical unit at a printing position (63) along a XY-plane substantially parallel to the attachment surface (48) of the substrate or the upper surface (52) of the membrane relative to the printing unit; - wherein the system is adapted to receive the substrate (16), the substrate is comprising an attachment surface on which the object is manufactured, and the substrate and/or the object (90) is at least partly submerged within the photocurable resin (14); - the method is further comprising: ∘ emitting the emitted light beam (24) at one, or more, wavelength(s) that does not cure the resin (14), ∘ detecting properties of the object (90), substrate (16), cured resin (15) and/or the membrane (18), ∘ based on the detected properties, positioning the optical unit (20) at said printing position (63), and mechanically displacing said collimating lens (30) along said optical path (26) by applying a corresponding collimator lens actuator (62), hereby moving a focal point (64) of the emitted light beam (24) along a line (Z)(66) substantially perpendicular to the upper surface (52) of the membrane and/or the attachment surface (48) of the substrate to a curing position (67) by displacing said collimator lens (30) along the optical path (26), ∘ emitting the emitted light beam (24) at a wavelength that cures the resin (15), and ∘ curing the photocurable resin (14) at the focal point (64) of the emitted light beam (24) when the focal point reaches said curing position (67); - wherein, the method further comprising manufacturing the object (90) on the substrate (16) by ∘ moving the optical unit (20) between different printing positions, and ∘ in each printing position (63) moving the focal point (64) of the emitted light beam (24) to the curing position (67), and thereby curing the photocurable resin at the focal point such that the cured resin is attached to the object or substrate.
  15. A system for additive manufacturing of an object (90) on a substrate (16), the system (1) comprising - a printing unit (10), the printing unit comprising: ▪ a vat (12) configured to accommodate a photocurable resin (14), such that the substrate (16) and/or the object (90) can be at least partly submerged within the photocurable resin (14), the vat comprises a semi-transparent membrane (18), and ▪ a substrate (16) comprising an attachment surface on which the object is manufactured; and - an optical unit (20), the optical unit comprising: ▪ one, or more, light source(s) (22) capable of emitting a single wavelength or multiple wavelengths emitted light beam (24) along an optical path (26) passing through said membrane (18) towards said substrate (16), ▪ a collimator lens (30) arranged to receive and collimate said emitted light beam along the optical path, ▪ an objective lens (32) adapted to receive, and focus said emitted light beam along the optical path, ▪ a detector (40) configured to detect one, or more, properties of the object (90), substrate (16), cured resin (15) and/or the membrane (18) from a reflected light beam (42) from the object, substrate, cured resin and/or membrane, and ▪ XY-actuators (44, 46) configured to position the optical unit at a printing position (63) along a XY-plane substantially parallel to the attachment surface (48) of the substrate or the upper surface (52) of the membrane relative to the printing unit (10); - wherein said collimator lens (30) is mechanically displaceable substantially along said optical path (26) by a corresponding collimator lens actuator (62); - wherein, when the optical unit (20) is positioned at said printing position (63), the collimator lens (30) is arranged to be displaced by said collimator lens actuator (62) along the optical path (26) to move a focal point (64) of the emitted light beam (24) along a line (Z) (66) substantially perpendicular to the upper surface (52) of the membrane and/or the attachment surface (48) of the substrate to a curing position (67); and - wherein the photocurable resin (14) is adapted to be cured to cured resin (15) at the focal point (64) of the emitted light beam (24) when the focal point has reached said curing position; and - wherein, to manufacture the object (90) on the substrate (16), the system (1) is adapted to move the optical unit (20) between different printing positions, and at each printing position (63), to move the focal point (64) of the emitted light beam (24) to the curing position (67), and thereby cure the photocurable resin at the focal point such that the cured resin is attached to the object or substrate.

Description

FIELD OF THE INVENTION The present invention relates to a system for additive manufacturing of objects, particularly for 3D-printing applications. BACKGROUND OF THE INVENTION Additive manufacturing, commonly known as 3D printing, has revolutionized the production of complex objects by enabling the layer-by-layer construction of three-dimensional structures from digital models. Among the various techniques of additive manufacturing, stereolithographic 3D printing stands out for its precision and ability to produce high-resolution objects. This method involves the use of a photocurable resin that solidifies upon exposure to a specific light source, typically a laser or UV light. Traditional stereolithographic systems, however, face several challenges, including the precise control of the light beam's focal point and the accurate positioning of the optical components relative to the substrate on which an object is printed. These challenges can lead to inaccuracies in the printed object, affecting its structural integrity and overall quality. The resolution of the print may also depend on the size of the steps made by the stepper motor used to adjust the focal point position. Additionally, traditional systems are often expensive due to the high cost of precision components and the complexity of the required control mechanisms. Hence, an improved system and method for additive manufacturing would be advantageous, and in particular a more efficient, reliable, and cost-effective system and method with lower resolution would be advantageous. OBJECT OF THE INVENTION The object of the present invention is to provide a system and method for additive manufacturing that enhances the precision and efficiency of the printing process. It is a further object of the present invention to provide an alternative to the prior art. In particular, it may be seen as an object of the present invention to provide a system and a method that solves the above mentioned problems of the prior art with inaccuracies in the printed object. SUMMARY OF THE INVENTION Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing a system for additive manufacturing of an object on a received substrate, the system comprising a printing unit, the printing unit comprising: ▪ a vat configured to accommodate a photocurable resin, such that the substrate and/or the object can be at least partly submerged within the photocurable resin, the vat comprises a semi-transparent membrane, andan optical unit, the optical unit comprising: ▪ one, or more, light source(s) capable of emitting a single wavelength or multiple wavelengths emitted light beam along an optical path passing through said membrane towards said su bstrate,▪ a collimator lens arranged to receive and collimate said emitted light beam along the optical path,▪ an objective lens adapted to receive, and focus said emitted light beam along the optical path,▪ a detector configured to detect one, or more, properties of the object, the substrate, the cured resin, and/or the membrane from a reflected light beam from the object, the substrate, the cured resin, and/or the membrane, and▪ XY-actuators configured to position the optical unit at a printing position along a XY-plane substantially parallel to the attachment surface of the substrate or the upper surface of the membrane relative to the printing unit;wherein the system is adapted to receive the substrate, the substrate is comprising an attachment surface on which the object is manufactured, and the substrate and/or the object is at least partly submerged within the photocurable resin;wherein said collimator lens is mechanically displaceable substantially along said optical path by a corresponding collimator lens actuator;wherein, when the optical unit is positioned at said printing position, the collimator lens is arranged to be displaced by said collimator lens actuator along the optical path to move a focal point of the emitted light beam along a line (Z) substantially perpendicular to the upper surface of the membrane and/or the attachment surface of the substrate to a curing position; andwherein the photocurable resin is adapted to be cured to cured resin at the focal point of the emitted light beam when the focal point has reached said curing position; andwherein, to manufacture the object on the received substrate, the system is adapted to move the optical unit between different printing positions, and at each printing position, to move the focal point of the emitted light beam to the curing position, and thereby cure the photocurable resin at the focal point such that the cured resin is attached to the object or the received substrate. The present invention introduces a novel system for additive manufacturing, specifically designed to enhance the precision and efficiency of 3D printing processes, specifically designed for stereolithographic 3D printing. This system ai