Method for producing mechanical parts from an assembly of layers which are turned over during machining, and the elemental laminations and assembled parts produced

[0002] The present invention generally relates to an improved method for producing mechanical parts and objects, particularly prototypes, from a specific computer-aided design, to the elemental laminations produced by such a method, and to the prototypes obtained by assembling such elemental laminations.

[0003] Known methods for producing a mechanical part or object, including prototypes, from a specific computer-aided design generally include the successive steps of manufacturing the part in elemental layers or laminations, building up the collection of layers and assembling the layers. The laminations result from a prior breakdown of the part along plural planes, and one or more defined steps.

[0004] A rapid prototyping method of this general type is described in European Patent EP-0 585 502-B1, the content of which is incorporated herein by reference, and is known by the trademark “STRATOCONCEPTION”.

[0005] The method of the present invention is fully compatible with the applications specified in European Patent EP-0 585 502. In practice, however, the disclosed rapid prototyping method has been found to have limits in the production of parts with complex shapes. This is particularly so when the micromachining tool which is used to perform the method has to, or should produce contours on one face of a lamination and then on the other face of the lamination being machined.

[0006] The object of the present invention is to provide a method which permits the machining of laminations having such complex shapes.

[0007] In accordance with the present invention, this is achieved with an improved method for producing mechanical parts and objects from a specific computer-aided design. The method generally includes the successive steps of manufacturing the parts in elemental layers or laminations, building up the collection of layers, and assembling the layers to form the part. The elemental layers or laminations result from a prior breakdown of the part along a plurality of planes, and one or more defined steps. At least portions of a lamination are turned through 180° (i.e., turned over) after one of its faces has been machined, so that the other face of the lamination can be machined after the lamination has been turned over. In an alternative implementation of the method of the present invention, the entire lamination will be subjected to the foregoing operation.

[0008] In yet another alternative implementation of the method of the present invention, the lamination is cut into two or more sub-laminations, along one or more cutting planes which are roughly vertical. Only those sub-laminations which contain a portion which cannot be machined in the customary way are turned over.

[0009] The present invention will be better understood with reference to the description which is provided hereafter, together with the following drawings.

[0010] FIG. 1 is a schematic representation of the general steps for implementing the method of the present invention.

[0011] FIG. 2 is a perspective view of a theoretical part having complex shapes which can be broken down into laminations in accordance with the method of the present invention.

[0012] FIGS. 2A to 2G are perspective views of the various laminations which collectively form the part of FIG. 2.

[0013] FIG. 1 generally illustrates a process for producing a mechanical part, in the illustrated case, a prototype, from a specific computer-aided design. Using specific software (1), the part that is to be prototyped is cut into laminations. The laminations are machined by rapid micromachining (2), which is controlled by the software (1), from a material (3) in sheet form. The various laminations are assembled into a collection (4) of inserts (5) to finally obtain the prototype (6), after finishing.

[0014] The software (1) governs selection of the planes for the slicing/stratification of the laminations, the lamination profiling step, any scaling ratios, the precision and the position for the inserts. Once the various sheet parameters (i.e, dimensions, material, choice of direction, clearance, etc.) and the machining parameters (i.e., cutting rate, cutter diameter, etc.) have been input, the entire machining program is transmitted by the software (1), which controls the cutting robot (i.e., the apparatus (2) which performs the micromachining).

[0015] Such methods have been found to be limited when producing parts having complex shapes, such as the theoretical part (7) shown in FIG. 2, for example. The part (7) can be broken down into subassemblies. In practice, however, machining of the resulting laminations will exhibit difficulties of different kinds.

[0016] FIG. 2A shows a section (8) of the part (7) which is of the classical type, and which can be machined from sheet stock by micromachining from the top of the sheet (i.e., as shown in FIG. 1).

[0017] FIGS. 2B and 2C show a more complex section (9) of the part (7). The section (9) is produced by machining (2) areas of the section (9) from above (see, FIG. 2B). In accordance with the present invention, the section (9) is turned over (see, FIG. 2C) so that areas of the section (9), such as the outside and the shoulder areas (10), can then be machined. FIGS. 2D and 2E similarly illustrate another section of the part (7), which is turned over to machine areas which respectively have a positive clearance (11) and a negative clearance (12).

[0018] For sections such as the section shown in FIG. 2F, the cutter cannot work either from above or from the underside of the section. In such cases, it is necessary to subject the section to a sub-lamination step. As an example, for the section illustrated in FIG. 2F, such sub-lamination is performed along the cutting planes (13, 14), so as to obtain three laminations. One of the resulting sub-laminations can then be produced in accordance with the present invention, by turning the sub-lamination over.

[0019] An alternative to the sub-lamination step shown in FIG. 2F is shown in FIG. 2G. Of greatest significance in this case is that the elemental lamination is cut, for example, into the two portions (15, 16) shown. Each of the portions (15, 16) can then be machined separately, with a turn-over step in accordance with the present invention, and finally assembled along the cutting plane (17), which is generally vertical.

[0020] In general, the following is noted. To make the second face easier to machine after a lamination, a sub-lamination, or a half-lamination has been turned over, holding areas will be formed during the first cut. These areas will be eliminated by machining during the second machining phase (i.e., after the turning-over step), so as to completely free the part. Positioning of the laminations during the turning-over operation is taken into consideration by the method of manufacture and by the software (1). The holes intended for the inserts provided according to the method described by European Patent EP 0 585 502 can be used for positioning, as can the positioning and assembly apparatus provided according to the method which forms the subject of a patent application filed simultaneously by the applicant. As an alternative, the positioning of the laminations during machining can be taken into consideration via inserts determined by the software (1), or by a holding array. In general, all of the foregoing operations entail recognition of the contours of the part beforehand, by computer processing involving the specific software which is used.