Device for Processing Photopolymerizable Material in Order to Construct a Shaped Body Layer by Layer

Patent metadata

Field	Value
Publication number	US-2016288412-A1
Application number	US-201415038148-A
Country	US
Kind code	A1
Filing date	Nov 20, 2014
Priority date	Nov 22, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

The method for processing photopolymerizable material for the layered construction of a shaped body comprises
a) providing a tank having a bottom transparent at least in some region, in which the photopolymerizable material is contained; b) moving a construction platform to such a height that a layer of the photopolymerizable material with a specified thickness is defined between the lower side of the construction platform or, if already present, the lowermost cured layer of the part of the shaped body formed thereon and the tank bottom; c) exposing the layer from below through the tank bottom by position-specific exposure so as to cure the material layer in the desired shape; d) repeating steps b) and c) until the last layer of the shaped body is formed.

The photopolymerizable material has a viscosity of at least 20 Pa·s at room temperature (20° C.), and the layer of the photopolymerizable material is heated in the tank to a temperature of at least 30° C. so as to lower its viscosity.

First claim

1 - 23 . (canceled)

24 . A method for processing photopolymerizable material for the layered construction of a shaped body, comprising
a) providing a tank having a bottom transparent at least in some region thereof, in which the photopolymerizable material is contained, wherein the photopolymerizable material has a viscosity of at least 20 Pa·s at room temperature (20° C.), and the photopolymerizable material forming a layer in the tank; b) moving a construction platform to such a height that a layer of the photopolymerizable material with a specified thickness is defined between the lower side of the construction platform or, if already present, the lowermost cured layer of the part of the shaped body formed thereon and the tank bottom; c) exposing the layer from below through the tank bottom by position-specific exposure to light so as to cure the material layer in the desired shape; and d) repeating steps b) and c) until the last layer of the shaped body is formed, wherein before b) the method includes heating the layer of the photopolymerizable material ( 6 ) in the tank to a temperature of at least 30° C. so as to lower its viscosity, characterized in that heating of the layer of the photopolymerizable material ( 6 ), and optionally maintaining of the temperature, is effected by the input of heat over a large area and directly on the tank bottom ( 2 ) and only in a process zone, in particular by at least one heating element disposed on or in the tank bottom ( 2 ), e.g. heating films, the process zone comprising the region between the transparent tank bottom ( 2 ) and the shaped body being constructed.

25 . A method according to claim 24 , characterized in that the temperature of the photopolymerizable material ( 6 ) is maintained at a temperature of at least 30° C. during steps b), c), and d).

26 . A method according to claim 24 , characterized in that the photopolymerizable material ( 6 ) has a molecular weight of at least 5000.

27 . A method according to claim 24 , characterized in that uncured photopolymerizable material ( 6 ) adhering to the part of the shaped body formed on the construction platform ( 5 ) is allowed to solidify by cooling.

28 . A method according to claim 24 , characterized in that the photopolymerizable material ( 6 ) further comprises filler particles.

29 . A method according to claim 24 , characterized in that the photopolymerizable material ( 6 ), prior to step b), is distributed in the tank with the aid of a doctor knife ( 11 ) moved through below the construction platform ( 5 ) so as to achieve a uniform layer thickness, wherein the doctor knife ( 11 ) comprises at least two doctor blades ( 16 , 17 ) spaced-apart in the direction of movement and moved over the tank bottom ( 2 ) at a constant distance thereto.

30 . A method according to claim 29 , characterized in that the photopolymerizable material ( 6 ) is pressed into a chamber ( 18 ) formed between the two doctor blades ( 16 , 17 ) through overflow channels ( 19 ) during the distribution step.

31 . A method according to claim 29 , characterized in that the method further comprises introducing fresh photopolymerizable material ( 6 ) to refill, in whole or in part, the tank through an upwardly open chamber ( 18 ) formed between the two doctor blades ( 16 , 17 ).

32 . A method according to claim 29 , characterized in that at least a third doctor blade ( 27 ) is provided, disposed between the at least two doctor blades ( 16 , 17 ) and moved in such a position that unused material is lifted from the tank bottom ( 2 ).

33 . A method according to claim 24 , characterized in that a thermal insulation is arranged between the bath of the photopolymerizable material ( 6 ) and the construction platform ( 5 ), or the shaped body formed thereon, so as to provide two temperature zones.

34 . The method according to claim 24 , characterized in that in the method, the heating directly over a large surface area of the tank bottom is provided by at least one heating element disposed on or in the tank bottom ( 2 ), the heating element comprising heating films; and the photopolymerizable material ( 6 ) further comprising, as filler particles, particles of ceramic or a metal.

35 . A device for carrying out the method according to claim 24 , comprising
a tank having a bottom transparent at least in some region, into which photopolymerizable material can be filled; a construction platform, which is held at an adjustable height above the tank bottom; an exposure unit capable of being controlled from below through the tank bottom for the position-selective exposure of a material layer formed between the lower side of the construction platform and the tank bottom; a control unit arranged to polymerize in successive exposure steps superimposed layers on the construction platform each with a specified geometry by controlling the exposure device, and to adapt the relative position of the construction platform relative to the tank bottom after each exposure step for a layer so as to successively construct the shaped body in the desired shape; and a stationary heating device for heating a layer of the photopolymerizable material in the tank to a temperature of at least 30° C., characterized in that the heating device comprises at least one heating element disposed on or in the tank bottom ( 2 ) and that is configured such that the input of heat occurs over a large area and directly on the tank bottom ( 2 ) and only in a process zone of the plant, the process zone comprising the region between the transparent tank bottom ( 2 ) and the shaped body being constructed.

36 . A device according to claim 35 , characterized in that the heating device is disposed outside the transparent bottom region of the tank ( 1 ).

37 . A device according to claim 35 , characterized in that the heating device extends at least partially over the transparent bottom region of the tank ( 1 ) and is designed to be transparent.

38 . A device according to claim 35 , characterized in that a temperature sensor ( 15 ) is provided, which interacts with the control unit for controlling the heating power of the heating device in such a manner as to allow a specified temperature of the photopolymerizable material ( 6 ) to be attained and/or maintained.

39 . A device according to claim 35 , characterized in that the construction platform ( 5 ) is associated with a cooling device for cooling, and allowing to solidify, uncured photopolymerizable material ( 6 ) adhering to the part of the shaped body formed on the construction platform ( 5 ).

40 . A device according to claim 35 , characterized in that a movably guided doctor knife ( 11 ) and a drive unit for the reciprocating movement of the doctor knife ( 11 ) through below the construction platform ( 5 ) are provided, said doctor knife ( 11 ) preferably comprising two doctor blades ( 16 , 17 ) spaced apart in the direction of movement and movable over the tank bottom ( 2 ) at a constant distance thereto.

41 . A device according to claim 40 , characterized in that a preferably downwardly open chamber ( 18 ) is formed between the two preferably parallel doctor blades ( 16 , 17 ), at least one wall of which chamber comprises at least one opening ( 19 ) passing through said wall in the moving direction of the doctor knife ( 11 ) for forming an overflow channel.

42 . A device according to claim 41 , characterized in that at least one opening ( 21 ) is each formed in two oppositely located walls of the chamber ( 18 ).

Assignees

• Univ Wien Tech

Inventors

• Stampfl Jürgen
• Gruber Simon

Classifications

• B29C64/25

  Housings, e.g. machine housings · CPC title

• B29C64/135

  the energy source being concentrated, e.g. scanning lasers or focused light sources · CPC title

• B33Y30/00

  Apparatus for additive manufacturing; Details thereof or accessories therefor · CPC title

• B29C64/245

  Platforms or substrates (support structures intended to be sacrificed after manufacture B29C64/40) · CPC title

• B33Y10/00

  Processes of additive manufacturing · CPC title