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EP-4132769-B1 - BUILDING PLATE ASSEMBLY FOR USE IN AN ADDITIVE MANUFACTURING APPARATUS

EP4132769B1EP 4132769 B1EP4132769 B1EP 4132769B1EP-4132769-B1

Inventors

  • STAHL, CHRISTIAN
  • Brandes, Christoph

Dates

Publication Date
20260513
Application Date
20210326

Claims (20)

  1. A building plate assembly (1) for use in an additive manufacturing apparatus comprising means for additively manufacturing a component (2), namely a printed object through curing liquid photocurable resin in a vat, the building plate assembly (1) comprising: a building plate (3) having a front surface (3a) on which said component (2) can be printed layer-by-layer through light-based curing of the liquid photocurable resin during the additive manufacturing and for pulling, said attached component (2) upside-down out of the photocurable resin filled in the vat; a plurality of through holes (3b) formed between the rear surface (3c) and the front surface (3a) of the building plate (3); characterized by further comprising: a detachment means (4) having one or more projections (4a) which can be relatively moved towards the rear surface (3c) and into the through-holes (3b) to detach the component (2) from the front surface (3a) and retracted to at least partly clear the through-holes (3b), wherein the detachment means (4) comprises a detachment plate (4b), and wherein the through-holes (3b) and the corresponding projections (4a) are arranged in a two-dimensional array which extends over the entire building plate (3) and the detachment plate (4b), and wherein the through-holes (3b) and the corresponding projections (4a) form a honeycomb-like structure or the like.
  2. The building plate assembly (1) according to claim 1, wherein the detachment plate (4b) is arranged relatively movable within a gap behind the rear surface (3c) of the building plate (3), wherein the projections ( 4a) are arranged on the detachment plate ( 4b) at a plurality of positions corresponding to the through-holes (3b) respectively.
  3. The building plate assembly (1) according to claim 2, characterized in that the detachment plate (4b) and the building plate (3) are substantially parallel and separated through the gap.
  4. The building plate assembly (1) according to any one of claims 2 or 3, characterized in that the detachment plate (4b) and the building plate (3) have substantially the same size.
  5. The building plate assembly (1) according to any one of claims 1 to 4, characterized in that the projections (4a) are outside or partially inside the through holes (3b) in the retracted position, and wherein the tips of the projections (4a) are either partially inside the through holes (3b), leveled with the front surface (3a) or protruded from the front surface (3a) in the furthest moved position.
  6. The building plate assembly (1) according to any one of claims 2 to 5, characterized in that the detachment means (4) comprises: a resilient means (4c) for biasing the detachment plate (4b) away from the rear surface (3c) of the building plate (3).
  7. The building plate assembly (1) according to claim 6, characterized in that the resilient means (4c) comprises one or more compression springs (4d) arranged between the detachment plate (4b) and the building plate (3).
  8. The building plate assembly (1) according to any one of claims 2 to 7, characterized in that the detachment means (4) comprises: a guiding means (4e) for stably guiding the detachment plate (4b) relative to the building plate (3) and limiting their relative positions.
  9. The building plate assembly (1) according to any one of claims 1 to 8, characterized by further comprising: a mounting means (5) for releasably mounting the building plate (3) into the additive manufacturing apparatus.
  10. The building plate assembly (1) according to claim 9, characterized in that the mounting means (5) is disposed on the detachment means (4).
  11. The building plate assembly (1) according to claim 10, where dependent on claim 2, characterized in that the mounting means (5) is disposed on the detachment plate (4b).
  12. The building plate assembly (1) according to claim 9, characterized in that the mounting means (5) is disposed on the rear side of the building plate (3).
  13. The building plate assembly (1) according to any one of claims 1 to 12, characterized in that the through-holes (3b) and the corresponding projections (4a) have complementary shapes with sufficiently small clearance for allowing the relative movement.
  14. The building plate assembly (1) according to any one of claims 1 to 13, characterized in that the through-holes (3b) and the corresponding projections (4a) have circular, oval or polygonal cross sections.
  15. The building plate assembly (1) according to any one of claims 1 to 14, characterized in that the through-holes (3b) are tapered towards the rear surface (3c) and/or the corresponding projections (4a) are tapered towards the front surface (3a).
  16. The building plate assembly (1) according to any one of claims 1 to 15, characterized in that the detachment means (4) has a motorized actuator which is adapted to move the projections (4a) relatively into the through holes (3b) so as to detach the component (2).
  17. The building plate assembly (1) according to any one of claims 1 to 16, characterized in that detachment means (4) can be solely hand-driven by the user.
  18. An additive manufacturing apparatus comprising: the building plate assembly (1) according to any one of the preceding claims; and a control means for controlling the building plate assembly (1), wherein the control means has at least a printing mode and one or more detachment modes; the control means is adapted to control the building plate assembly (1) such that in the printing mode the tips of the projections (4a) are leveled with the front surface (3a) of the building plate (3) during printing of the object, in a first detachment mode the tips of the projections (4a) are first protruded through the front surface (3a) so as to detach the printed object from the front surface (3a), and subsequently retracted from the front surface (3a) of the building plate (3) in order to detach the tips of the projections (4a) from the printed object, or alternatively in a second detachment mode the tips of the projections (4a) are first retracted from the front surface (3a) of the building plate (3) in order to detach the tips of the projections (4a) from the printed object, and subsequently protruded through the front surface (3a) so as to detach the printed object from the front surface (3a).
  19. The additive manufacturing apparatus according to claim 18, characterized by further comprising: a measurement means for sensing the force exerted on the projections (4a), wherein the control means is further adapted to control the building plate assembly (1) based on the sensed force (4).
  20. A method of controlling an additive manufacturing apparatus, wherein the additive manufacturing apparatus is according to claim 18 or 19.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an additive manufacturing apparatus. The present invention also relates to a method of controlling the additive manufacturing apparatus. The present invention more particularly relates to the building plate of the additive manufacturing apparatus. BACKGROUND ART OF THE INVENTION In additive manufacturing techniques, such as stereolithography (SLA) or digital light processing (DLP), a three dimensional component is printed layer-by-layer through light-based curing of a liquid printing medium i.e., a liquid photocurable resin, which is selectively cured under the influence of UV radiation. In a commonly known variation of additive manufacturing, the 3D components are preferably pulled by means of a building plate, upside-down out of the liquid photocurable material filled in a vat. Other variations of additive manufacturing are also known to those skilled in the art. A commonly known problem in the additive manufacturing is that after 3D printing, the printed 3D component (hereinafter referred to as component) must be removed from the building plate. This is typically done with a spatula. Thus, the removal process is not very comfortable to handle and can cause injury to the user if the sharp-edged spatula slips off. Another commonly known problem in the additive manufacturing is that the adhesion between the printing film, the resin and the building plate may create large forces, especially for a building plate with large surface area, when pulling the building plate away from the printing film in the vat. Building plates with honeycomb like structure are commonly used to reduce the surface area of the building plate and thus the resulting adhesion. However, the open honeycombs are usually partially filled with resin during the 3D printing, which hardens in the honeycombs, making it even more difficult to remove the component. Moreover, the honeycombs must then be laboriously cleaned. Reference is made to US2020001524A1 which discloses a system and method for manufacturing a three-dimensional object. Reference is further made to WO2019012103A1 discloses sacrificial additively manufactured molds for use in injection molding processes. Reference is further made to WO2016172805A1 which discloses a building plate assembly according to the preamble of claim 1. DISCLOSURE OF THE INVENTION An objective of the present invention is to overcome the problems of the prior art and provide a building plate assembly for use in an additive manufacturing apparatus. This objective has been achieved through the building plate assembly as defined in claim 1, the additive manufacturing apparatus as defined in claim 18, and the method of controlling the additive manufacturing apparatus as defined in claim 20. The dependent claims relate to further embodiments and developments. The present invention provides a building plate assembly for use in an additive manufacturing apparatus comprising means for additively manufacturing a component through curing photocurable resin. The building plate assembly comprises: a building plate having a front surface on which said component can be attached during the additive manufacturing; a plurality of through holes formed between the rear surface and the front surface of the building plate; and a detachment means having one or more projections which can be relatively moved towards the rear surface and into the through-holes to detach the component from the front surface and, retracted to at least partly clear/evacuate the through-holes. A major advantageous effect of the present invention is that through the detachment means the component can be easily detached from the front surface of the building plate, without the need of using a spatula or the like and thus the risk of injury can be eliminated. Another major advantageous effect of the present invention is that through the detachment means the through holes in the building plate can be simultaneously pierced free from resin during the detachment of the component, and thus the user can immediately obtain a clean building plate again after completion of the detachment. Thus, the detachment of the component and the cleaning of the honeycomb structure can be safely and easily achieved in a single step by pressing the projections into the through holes. Another major advantageous effect of the present invention is that thanks to the through-holes of the building plate the adhesion can be reduced during the pulling of the building plate away from the printing film, and thus the 3D printing can be improved. According to the present invention, the detachment means is provided like a negative form of the building plate to allow pressing the resin out of the through-holes. Therefore, in an embodiment, the detachment means has a detachment plate which is arranged relatively movable within a gap behind the rear surface of the building plate. And the projections are arranged on the detachm