Plastic and nonmetallic article shaping or treating: processes – Stereolithographic shaping from liquid precursor
Patent
1998-06-16
2000-08-29
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
Stereolithographic shaping from liquid precursor
264308, 264497, 4251744, 425375, B29C 3508, B29C 4102
Patent
active
061104094
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
It is known to produce industrial components or articles automatically by the transformation of successive layers of raw material from a first state into a second state using computer information representing their shape. Machines using this principle, called Rapid Prototype machines, operate in most cases by repetition of a cycle comprising the following steps: the previous steps is covered by a layer of non-transformed raw material; emits electromagnetic radiation or particles of matter in the direction of that face of the layer which is not in contact with the previous layers.
International Application PCT WO 93/25377, for example, describes a rapid prototyping machine using the action of light radiation to partially solidify successive layers of liquid resin contained in a tank. The transformation-inducing device consists of a light generator and of an optical system which makes it possible to direct the photons emitted by tip light generator onto a portion of the free surface of the liquid corresponding with the section of the component to be produced. After each transformation phase, a support integral with the layers already partially solidified is moved vertically by a motor-driven system in order to reduce the height of the component being created with respect to that of the free surface of the liquid. Very often this movement is not sufficient to cover the parts that have just been solidified with the liquid resin and to ensure sufficient flatness of the free surface of the liquid to be able to carry out the next transformation phase. This is why a mechanical component of elongate shape, called a doctor blade, the lower part of which is in contact with the resin, is moved, in an approximately horizontal movement, by a motor-driven mechanical device, to progressively sweep over the entire surface accessible to the transformation-inducing device and to obtain the desired covering and desired flatness before moving on to new transformations. All the components of the machine are controlled by a computer, using computing data which is generated (by software processing) from the initial data and which determines the shape of the components to be produced.
Document PCT WO 93/25377 proposes various embodiments of the doctor blade; in particular, in FIG. 13 of that document, a doctor blade is described which consists of a rigid support coming into contact with the resin, by means of a plurality of flexible films called moisteners. Application EP-A-0,484,182 also contains a description of a doctor blade: this doctor blade consists of two rigid supports arranged parallel and lying close to each other, to which are fixed brush elements which come into contact with the resin via their lower part.
The type of transformations carried out in the context of rapid prototyping machines is not limited to photopolymerization or photocrosslinking of liquid resins. For example, cutting sheets of paper or agglomerating powders (plastic powders, metal powders, powder blends, etc.) using a laser are techniques commonly used for producing components in rapid prototyping. Rapid prototyping processes also exist which, instead of using light, operate by the addition of material. Mention may be made, for example, of the process developed at M.I.T. and described in the work "Rapid Prototyping & Manufacturing--Fundamentals of Stereolithography (Paul F. Jacobs, published by "Society of Manufacturing Engineers", page 409), in which the local solidification of layers of ceramic powder is carried out by the addition of an aqueous binder in the form of droplets expelled by nozzles.
Despite the wide variety of materials used, of types of transformation, of devices for carrying out the transformations and of devices for carrying out the covering phases, it is possible, however, to identify a few characteristics common to the great majority of currently operational rapid prototyping machines.
This is because material transformations are always induced, for reasons of physical accessibility, via the so-calle
REFERENCES:
patent: 5204124 (1993-04-01), Secretan et al.
patent: 5204823 (1993-04-01), Schlotterbeck
patent: 5780070 (1998-07-01), Yamazawa et al.
Allanic Andre-Luc
Schaeffer Jean-Philippe
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