Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1994-05-25
1996-07-09
Simmons, David A.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156290, 1563071, 264401, 264308, 264DIG59, 427510, 427581, 427586, B29C 3508, B29C 4102
Patent
active
055341047
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method and to an apparatus for production of three-dimensional objects.
An example for such a method is described in the paper of H. Kodama, "Automatic method for fabricating a three-dimensional plastic model with photo-hardening polymer", Rev. Sci. Instrum. 52(11), Nov. 1982L, pages 1770 to 1773. With such a method the problem is encountered that an accuracy to size of the object is not guaranteed. This is in particular caused by the fact that during production the individual layers shrink when solidifying and therefore cause stresses and deformations of the entire layered structure.
In order to solve this problem the EP-A-0,362,982 proposes either to begin with solidifying individual strips only which are connected to adjacent or underlying strips only by means of a support structure or to solidify only regions of the layer whereby gaps are generated between those regions.
The above first mentioned solution is, however, disadvantageous because of the difficult control of the solidification to avoid an adhesion of a strip to the underlying strip. Both solutions have the common disadvantage that the solidity of the object before a possible post-curing is very low and the object may therefore be deformed or broken by action of outer forces.
It is therefore the object of the invention to improve the the accuracy in producing the object while avoiding the above-mentioned drawbacks of the prior art.
According to the invention this object is achieved by a method characterized in claim 1 and by the apparatus characterized in claim 11, resp.
In the following the invention will be described in connection with an embodiment with reference to the figures. In the figures:
FIG. 1 is a top view of a layer of an object solidified according to the invention;
FIG. 2 is a sectional view of the object taken along the line II--II of FIG. 1; and
FIG. 3 is a schematic representation of an embodiment of the inventive apparatus.
FIG. 1 is a top view of a part of an object 1 of which a section is shown in FIG. 2. The object is produced in the form of individual superposed layers 2a, 2b, 2c, 2d and 2e for example by subsequent solidification of the layers on a support 3 in a bath of liquid resin which can be polymerized by action of electromagnetic radiation. Such a method is known and a detailed description thereof is therefore omitted at this place.
The first layer 2a adjacent to the support 3 is produced in a known manner by complete solidification of the layer within the contour or boundary surface 5 of the object.
FIG. 1 shows the top view of the top face 4 of the uppermost layer 2e which is outwardly defined by the contour 5 of the object 1. The respective further layers 2b . . . 2e are produced according to the same rules and the production of those layers of the object is therefore described in the following by reference to the top view of layer 2e shown in FIG. 1.
First of all a liquid layer formed on the first layer 2a is not solidified everywhere within the contour 5 but only at partial regions 6a . . . 6k spaced from each other at all sides. Those partial regions are shown in FIG. 1 as being substantially square-shaped but may have any other shape. The size of the partial regions is free but preferably a linear dimension of 1-20 mm, in particular 2-10 mm is chosen.
As a consequence narrow liquid intermediate regions referenced in the figure by the sign 7 remain between the partial regions 6a . . . 6k. The width of those intermediate regions, i.e. the clearance between the partial regions 6a . . . 6k, is about 1/20 to 1/500, preferably about 1/50 to 1/200 and particularly preferred about 1/100 of the dimension of the partial regions, i.e. about 0.05 to 0.2 mm, preferably about 0.1 mm.
The partial regions shrink during and after the solidification and the width of the intermediate regions 7 is thereby enlarged. The shrinkage rate is particularly high in the first seconds after the irradiation and for example about 80% of the shrinkage occurs within 10 seconds. Considering the conventional produ
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Langer Hans J.
Reichle Johannes
EOS GmbH Electro Optical Systems
Neuner George W.
Sells J.
Simmons David A.
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