Patent Application
20050279152
1. Field of the Invention
The invention concerns a deforming tool and a process for manufacturing thereof in according with the precharacterizing portion of Patent Claims 1, 2 and 8. One such generic tool and one such process are already known from DE 199 00 597 A1.
2. Related Art of the Invention
The basic sequence in the process of deforming work pieces is comprised therein, that the work piece is introduced into a form determining tool, which is comprised of a lower tool and an upper tool; that an external force is applied to the deforming tool and/or the work piece which brings about a yielding of the work piece material and a plastic deformation into a shape determined by the tool shape.
In the framework of increasingly shorter production cycles it is increasingly necessary to produce such deforming tools more rapidly, wherein their quality must substantially be maintained.
In DE 199 00 597 A1 it is proposed to rapidly produce the tool by means of Laminated Object Manufacturing (LOM), building up of paper or plastic sheets, or by means of laser sintering of plastic powder. In one exemplary embodiment it is besides this disclosed that the tool can comprise a shape determining shell and a filler material supporting the shell.
This type of tool exhibits a limited friction-wear resistance and is thus suitable only for a limited production run.
It is the task of the invention to provide a deforming tool with high friction wear. resistance as well as a process for manufacturing thereof.
With regard to the deforming tool to be provided and the process for manufacturing thereof, the invention is described by the characteristics of Patent Claims 1, 2 and 8. The remaining claims contain advantageous embodiments and further developments of the inventive deforming tool (Patent Claims 3 through 7) and the inventive process (Patent Claims 9 through 11).
The task with regard to the deforming tool to be provided is inventively solved thereby, that it comprises a lower and an upper tool, wherein the lower and/or upper tool includes a shape determining shell and a backfill for supporting thereof, wherein lower and/or upper tool are comprised at least partially of laminated material layers, and wherein the laminated material layers are arranged in such a manner, that there are as many as possible, as small as possible, steps in the direction towards the shape determining shell, such that the laminated material layers support the shell as evenly as possible.
For example, in a conventional basin-shaped deep draw tool the material layers are preferably oriented parallel to the direction of closing of the tool. Thereby the characteristic step-shape effect (that is, little, high steps) occurs essentially in the narrow region of the basin wall, while in the essentially longer area of the basin floor there occur very many, very small step stages, which do not lead to a noticeable step effect and thus support the shell very evenly.
An optimal orientation with as many as possible, as short as possible, step stages in the direction towards the shape determining shell can easily be determined by known optimization programs.
In addition to the conventional joining by adhesive, the joining of the individual laminated layers can be reinforced by through-going reinforcement, in particular in the form of wires or rods.
With regard to the deforming tool to be provided the task is inventively solved in that this includes a lower and an upper tool, wherein lower and/or upper tool comprise a shape determining shell and a backfill supporting this, wherein lower and/or upper tool are comprised at least in part of laminated material layers or powder particles joined to each other, wherein the deforming tool includes an elastic intermediate layer between lower and/or upper tool (lower and/or upper backfill) and the shape determining shell.
The elastic intermediate layer serves to reduce pressure or stress tips in the pressure load in the deforming process or to evenly distribute this, and thus to reduce the friction wear of the tool.
Besides this, the elastic intermediate layer evens out the step effect in the built-up of the tool of laminated material layers, or the graininess of sintered powder surfaces, which otherwise would imprint in the inner side of the shell and, following longer employment, could leave an impression extending through the shell and thus increase on the one hand the friction wear of the shell, respectively the tool, and which would on the other hand reduce the quality of the produced piece surface.
This type of effect can also be reduced by a suitable selection of material for the shape determining shell. The shape materials for the shell are thus, on the one hand, metallic, in particular steel sheets, however may be non-metallic and in particular reinforced plastics, for example carbon fiber reinforced plastic composites (CFC).
The shape determining shell as well as the backfill, as well as both, could be produced by the same or different rapid prototyping processes. For example, the shape determining shell can be laminated sheet metal or carbon-fiber reinforced webs, and the backfill can be of sintered plastic powder. On the basis of the comparatively small load on the backfill, this can also be produced by other rapid processes, for example with 3D-printing or stereo lithography.
In a preferred embodiment the elastic intermediate layer exhibits a thickness of 0.5 to 2 mm. In a thickness of this type the generally available, that is, easily and cost effectively commercially available elastic materials, are capable of reducing in sufficient manner most pressure tips in the pressure load in the conventional deforming process, in order to significantly reduce friction wear.
Suitable elastic materials are, for example plastics, preferably polyolefin or polyurethane.
Therein the elastic intermediate layer can be in the form of a single unitary piece, as well as of a flowable material, for example plastic powder, or also a mass of polyurethane. Depending upon deforming process and shape of the shell, the one or the other may be preferred. An intermediate layer of one single piece would be more easily produced, introduced and either be completely removed or, as the case may be, exchanged or replaced. Flowable material, in particular powder, can more easily conform to complicated geometries of the shell.
With regard to friction wear, it is also advantageous when the shape determining shell and/or the laminated material layers or the powder particles are comprised of metal, in particular steel.
Besides this, it is advantageous when the laminate material layers are oriented in the manner such that as many as possible, as thin or shallow step stages, are oriented in the direction toward the shape determining shell, and support this thereby as evenly as possible. The determining of the optimal orientation and an advantageous supplemental interconnection of the laminate are already described above.
In a preferred embodiment the shape determining shell exhibits a particular surface treatment. For such a surface treatment the shell is, in comparison to its backfill, a comparatively small component and easier and more economical to access. Suitable surface treatments include for example a surface structuring by micro abrasion, which is suitable for forming micro lubricant pockets in the surface of the workpiece to be deformed. Also possible is a hardening of the shape determining shell by suitable selection of material and temperature during its manufacture.
The task, with regard to the process to be provided for production of a deforming tool, which includes a lower and upper tool, is inventively solved thereby, that beginning with a three dimensional set of data of a volumetric model of the forming tool, the deforming tool or parts thereof are build up in layers by rapid processes, wherein for the lower and/or upper tool a shape determining shell and a backfill for supporting thereof are produced, and wherein the three dimensional data set of a volume model for the shape determining shell is determined and is deduced from the three dimensional data set of the volume model the deforming tool, so that a three dimensional volume model of the supporting backfill results, which is then built up in layers by rapid processes.
According to DE 199 00 597 A1, in contrast, the backfill is produced by back spraying and this must then harden or cure for at least one day.
In contrast thereto the inventive process offers the advantage of a rapid manufacturing and an independence from the prior existence/non-existence of the shape-determining shell—its data set is sufficient for the manufacture of the backfill. The data set can be drawn from repeatedly for manufacturing of new backfills, in comparison to which an actual shape shell is needed in the case of back spraying, and is rigidly connected with the backfill, and thus is only available for a single use.
In a preferred embodiment, as layer building rapid process, Laminate Object Manufacturing is employed, wherein the material layers to be laminated are oriented in such a manner, that as many as possible, and as shallow as possible, step stages facing the direction towards the shape determining shell occur and supports this thereby as evenly as possible.
An optimal orientation with as many as possible, as shallow as possible, step stages in the direction towards the shape determining shell can be easily determined by known optimization programs.
In a further preferred embodiment an elastic intermediate layer is provided for the deforming tool to be produced between the upper and/or lower tool (backfill) and the shape determining shell, wherein the three-dimensional data set of a volumetric module of an elastic intermediate layer is determined and extracted or subtracted from the first three-dimensional data set of the volume model of the supporting backfill, so that a second three-dimensional data set of the volumetric model of the supporting back fill results, which then is built up in layers by rapid processes.
By means of this process the individual parts of the lower and/or upper tool are easily and economically produced and the above described advantages of the elastic intermediate layer are obtained.
In a further preferred embodiment of the inventive process, a flat shell pre-form and a work piece to be deformed in the supporting backfill of the upper or lower tool, optionally with an introduced elastic intermediate layer, are introduced and under the action of the corresponding upper or lower tool are deformed in such a manner that from the flat shell pre-form the shape-providing shell results.
This is a particularly simple, rapid and economical possibility for the manufacturing of the shape determining shell, which makes possible the reproduction or replenishment as often as desired. This is in particular advantageous in cooperation with a backfill which can be produced as often desired and without any pre-existing shell.
In the following the inventive deforming tool and the inventive process for its manufacture are described in greater detail on the basis of an illustrative embodiment and the figure:
First, a 3D-volumetric model of the deforming tool is directly produced, or indirectly via a modeling of the deforming tool to be produced.
The creation of the 3D-model can occur completely virtually by means of a suitable CAD-program, or by plastic modeling and subsequent optical or tactile measurement of the model, so called reverse-engineering.
On the basis of the 3D-model a three dimensional data set of the deforming tool is constructed. This shape determining side is computationally reduced by the thickness of the shape determining shell and the intermediate layer. The resulting data set is input into a commercial type rapid prototyping system for laminated object manufacturing. This is filled with rolled up, self-adhesive metal foil. The metal foil is built up into a massive backfill by the known LOM-process according to an input data set. Therein the metal foils to be joined are oriented in such a manner that as many as possible, as shallow as possible, steps result in the direction towards the deforming shell. The optimal orientation is determined in advance by an optimization program. In this embodiment the optimal orientation runs—as can be seen from the figure—parallel to the closing direction of the deforming tool.
Laid into this backfill are an elastic intermediate layer in the shape of a 1 mm thick polyethylene web and a flat shell pre-form. The flat shell pre-form is comprised of multiple layers or carbon fiber composite webs adhered to each other, however not fully cured. Subsequently the deform piece is introduced and then the deform tool is closed under pressure. Thereby the flat shell pre-form is deformed into a shape determining shell. This is subsequently hardened by a suitable tempering.
The inventive deforming tool and the inventive process for manufacture thereof in the embodiment of the above described example have proven themselves as particularly suited for sheet metal work in the automobile industry, in particular deep drawing. In particular therewith substantial advantages with regard to the time of manufacture of the tools and their wear resistance can be achieved.
The invention is not limited to the above described illustrative embodiment, but rather can be broadly applied.
The shape providing shell can also be directly built by means of rapid processes, or also be milled from a blank, or can be produced from a flat preform by first roughly deforming into a pre-shell and a follow-up processing under force into the final shape determining shell.
A backfill comprised of adhesive laminated thin metal sheets may supplementally be reinforced by pull anchors, which run in the direction of the layers of the individual lamellas and are clamped on the sides of the deforming tool with suitable closing mechanisms, for example threaded fasteners. At the same time one or more pull anchors may serve as positioning elements for an exactness of individual lamella as well as for the backfill and form-determining shell.
In less demanding tools the intermediate layer can be dispensed with, since the optimal orientation of the lamella layers, and the therefore resulting more even supporting of the shell, sufficiently minimizes friction wear.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102004029973.0-14 | Jun 2004 | DE | national |
