Abstract: When producing an object by subsequent solidification of material layers 1 at places corresponding to the object there is a problem of limited production speed because the scanning speed or laser power of the light beam scanning the material layer 1 cannot be increased at will, if the light beam 4 used for solidification is focused as required for exact resolution. According to the invention this problem is solved by providing a variable focusing device 8 in the light beam 4, whereby the focus of the light beam 4 can be varied during the solidification of the layer 1. Thus, a different focus, laser power and scanning speed can be used in different regions of the layer 1.

Abstract: In a method for producing a three-dimensional object wherein the object is produced layer by layer by applying a layer of a material which can be solidified by irradiation with electromagnetic radiation and subsequently solidifying the layer at the points corresponding to the object by irradiation the problem is encountered that the production process is considerably delayed by long heating and cooldown times within the apparatus used for the production. According to the invention this problem is solved by irradiating and thereby solidifying in each layer a region of the material surrounding the object so as to produce a container wall (26) for the material (21).

Abstract: In a method and an apparatus for producing three-dimensional objects by layerwise solidification of a material the problem is encountered that, in particular when using powdery or pasty material, a material layer having an exactly adjusted thickness can not be generated in a sufficiently fast manner. In order to solve this problem, it is proposed to scrape the material by means of a vibrating wiper member (21, 22) when applying the material or to provide a movable container (13) used for applying the material with such wiper members (21, 22) at the lower side thereof.

Abstract: An apparatus for producing an object using stereography is disclosed. The apparatus has a bath of liquid material in a container, the bath having a free surface. A support in the container supports and positions the object relative to the surface. A means for applying electromagnetic radiation solidifies a layer having solidified sections of the material. A wiper extends across the surface in a first direction. The wiper is at least partly formed of a flexible material and has a substantially horizontal lower edge, and it is positioned below the free surface of the bath in a working position. Displacement means displaces the wiper in the working position in a second direction substantially transversely to the first direction to move a portion of the liquid material in the bath. The lower edge of the wiper is flexibly yielding so as to apply a thin film of liquid material on a surface of the solidified layer and liquid material between solidified sections when displacing the wiper in the second direction.

Abstract: A method for producing an object by layerwise solidification of the object by means of electromagnetic radiation is expedited by simultaneously solidifying the material of a layer at a plurality of places.An apparatus for carrying out the method comprises an irradiation device (11, 12, 14, 15, 16) generating a plurality of beams (20, 21, 22) as well as a control device (7, 17, 18, 19) directing each of the plurality of beams independently to different regions of the layer (8a . . . 8d).

Abstract: In a method for producing a three-dimensional object by successive solidification of superposed layers of the object a deformation of the object caused by shrinkage during the solidification shall be reduced. To this end first of all respective partial regions (6a . . . 6k) of a layer are solidified and simultaneously connected with underlying partial regions of the previously solidified layer to form multilayered cells and thereafter adjacent partial regions of the same layer are interconnected by solidifying narrow connecting regions (8a . . . 8p). The intermediate regions (7) between the individual partial regions are solidified by post-curing.

Abstract: An exhaust gas filter, such as a soot filter for a diesel engine, is provided with a filter body disposed in a housing. The exhaust gases flow through the filter body to be cleaned. The filter also has an inlet duct and an outlet duct. Between the inlet duct and the outlet duct, there is disposed one or several lateral lines for passing gases along the outside of the filter body. Both ends of the lateral lines are connected via apertures to the inlet duct and the outlet duct, respectively. The cross sections of the inlet duct, outlet duct and the lateral lines are selected so that in the unloaded condition of the filter body a return flow in the lateral lines is produced, while a bypass flow is produced when a preselected loading condition of the filter body is reached.

Abstract: A process is described for the determination of the aging condition of an exhaust-gas catalyst for an internal combustion engine which is fitted with .lambda.-controlled regulation of the fuel/air ratio. In the process, the switching of the fuel/air ratio from rich to lean and vice versa is delayed and the content of the combustibles in the exhaust gas downstream of the catalyst is measured. With delayed switching, complete conversion of the exhaust gas only occurs when the catalyst still possesses its full oxygen-storage capability. Since the oxygen-storage capability decreases with increasing age of the catalyst, the degree of conversion or the proportion of combustible components arising in the exhaust gas when conversion is no longer complete is a direct measure of the aging condition of the catalyst. A catalyst can thus be replaced in good time before it is completely destroyed and before undesired components of the exhaust gas reach the atmosphere.