DE102009048706A1 - Method and device for producing a molded part by means of generative application - Google Patents

Abstract

A method for producing a molded part, comprising the steps: providing a base surface, applying a release layer to the base surface by means of a generative method, the release layer surface corresponding to the inverse molded part surface. Applying the molded part to the separating layer surface by means of a generative process, and detaching the molded part from the separating layer.

Description

The invention relates to methods and an apparatus for producing a molded part by means of a generative application technique.

The prior art knows various generative methods, which are usually summarized under the generic term "rapid prototyping". With these methods according to the prior art, either the desired component can be constructed directly or else a casting mold of the desired component is generated generatively and then poured out. Thus, these known methods are mainly suitable for producing components with the outer dimensions and contours of typical cast parts. For the generative production of components with dimensions and contours comparable to formed sheets, these known methods are unsuitable and inefficient.

It is therefore an object of the present invention to provide methods and a device which enable the production of a molded part in an efficient and cost-effective manner with a generative application method.

This object is solved by the features of the independent claims. The respective dependent claims contain advantageous refinements of the invention.

Thus, in order to achieve the object, the invention provides a first method for producing a molded part comprising the following steps: providing a release surface, applying a release layer to the base surface by means of a generative process, wherein the release liner surface corresponds to the inverse feature surface, applying the liner to the release liner surface a generative process, and releasing the molding from the release liner. The desired molded part is therefore not produced directly by a generative application method, but first the inverse surface of the molded part is reproduced by means of a separating layer. On this interface surface, so the inverse molding surface, then the desired molding can be applied very quickly and effectively by a generative process.

Preferably, the molded part is post-processed prior to dissolution of the release layer by means of machining processes.

The separating layer is preferably 1/10 mm to 2 mm, in particular 1/10 mm to 1 mm, in particular 1/10 mm to 5/10 mm thick.

Advantageously, it is provided that the release layer and the molding are applied by the same generative method. In particular, kinetic compacting of metal powder, for example by thermal spraying or cold gas spraying, is suitable for this purpose. The temperature of the gas at the nozzle inlet is preferably regulated to a constant value. This value is advantageously in an interval of 380 ° C to 650 ° C. Further preferably, the static pressure at the nozzle inlet is controlled to a constant 80 to 120 bar, in particular to 90 to 110 bar. Cold gas spraying is a thermal spraying process based in particular on the high kinetic energy of the powder particles. Preferably, this process is carried out using steam and / or nitrogen and / or air. Particularly suitable as the main gas water vapor or oxygen-reduced air and also as a carrier gas for the powder to be applied also oxygen-reduced air has been found. The oxygen content should be advantageously <3%. Because the applied material is not liquid, d. H. is neither dissolved nor melted, a movement of the molding or the base surface or the release layer during the manufacturing process is possible at any time. Furthermore, due to the use of relatively low temperatures, neither the base surface nor the release layer or the molded part becomes very hot, which has a positive effect on the accuracy and the residual stresses in the molded part. As an alternative to cold gas spraying, additional generative application methods such as layered laminate method, 3D printing method or microcasting deposition are advantageously provided.

In a further advantageous embodiment, the base surface is produced by an erosive method and / or by means of a generative method. The base surface can thus be produced by machining, for example by rotating, milling and / or grinding machining, a plastic or metal base. Alternatively, the base, and thus the base surface, is generated by a generative process. It is of particular advantage to produce the release layer, the molding and the base surface by the same generative method, in particular with cold gas spraying. In a further alternative, the base is provided with a separate device, e.g. B. in a casting process.

In a further advantageous embodiment of the method according to the invention, the base surface deviates from the inverse shaped part surface by a separating layer thickness. Advantageously, the base surface corresponds approximately or almost to the inverse shaped part surface, so that the exact inverse shaped part surface is achieved by applying an advantageously uniformly thin separating layer. Furthermore, advantageously a width and / or Length and / or a diameter of the molding much larger than the separation layer thickness Because the base surface already approximately corresponds to the inverse molding surface, relatively little material is used for the separation layer and also a relatively labile separation layer is supported by the base surface in shape.

The combination of base surface formed on a base with the release layer applied thereon thus advantageously forms a die for the molding. Such a die, for example, is similar in appearance to a die used for pressing sheet metal parts, but according to the present invention, the uppermost layer, namely the release layer and the molded part itself, is produced by a generative process.

In a further advantageous embodiment of the method according to the invention, it is provided that the separating layer is constructed with a substantially uniform separating layer thickness. Furthermore, it is advantageously provided that the separating layer is applied to the entire base surface. The moldings advantageously produced by the method according to the invention thus correspond in their appearance and contour of the thin sheet-like moldings, as they are known for example from sheet metal forming.

In a further advantageous embodiment, the release layer is before the application of the molding with a removing process, in particular machining process, reworked. This makes it possible to produce an exact separating layer and thus an exact inverse surface for the production of the molded part.

In a further advantageous embodiment, it is provided that the base surface and / or the separating layer and / or the molded part are constructed in several layers by means of thermal spraying. Advantageously, the base surface and / or the separating layer and / or the molded part are in each case machined after the lamination and / or during the lamination. For all three generatively constructed components, namely the base surface, the release layer and the molded part, it is thus advantageously possible to apply layers of different materials individually or arbitrarily on or next to one another. As a result, areas with different properties can be created. It can, for. Example, the one material used have a particularly high thermal conductivity, while the other material has a particularly high wear resistance or hardness. Advantageously, thus, the base and / or the molding in its core of inexpensive material, such. As iron powder, are built, being further built up only at the contour near areas with tool steel.

Furthermore, when coating in layers, it should be noted that if too much energy is applied to the component to be applied during application, it may be necessary to place reversal points outside the component. This means that the nozzle of the applied method, which builds up a layer line by line, advantageously sets its reversal point outside the component to be built up. Similarly, it advantageously behaves with start and end points, which should also be outside the component to be built. In the case of the advantageously used thermal spraying method, usually layers having a thickness of a few 1/10 mm up to a maximum of a few millimeters are sprayed over one another. For thick layers z. As the surface is uneven, or the residual stresses are too large. Therefore, before applying the next layer, the surface must be processed and, in particular, leveled. This smoothing can z. B. done by a machining process. Alternatively, or in addition to the machining process, it should also be noted that it may be necessary to activate the surface to which the next layer is applied. This can advantageously be done by blasting, laser roughening or chemical methods.

In a further advantageous embodiment of the method according to the invention, it is provided that the two steps of applying the release layer and applying the molded part are used as often as desired alternately during the production of one and the same molded part, in order to produce a molded part with internal cavities and / or undercuts. Furthermore, it is advantageous in each case between the steps of applying the release layer and applying the molding, the release layer and / or the molding eroding, in particular machined to edit. Thus, cavities, undercuts and / or sharp-edged internal geometries can be realized on the molded part.

This invention further provides a second method of making a molded article according to the invention, comprising the steps of: fabricating a template, wherein the die surface corresponds to the inverse molding surface, applying the molding to the die surface by a generative process, and releasing the molding from the template. Instead of the separating layer used, as in the first method according to the invention, in the second method according to the invention, the shaped part is applied directly to a die by means of the generative method.

In an advantageous embodiment of the second method according to the invention, it is provided that the molded part is applied by thermal spraying or cold gas spraying or kinetic spraying. The advantages of this generative application method as well as further advantageous alternative application methods have already been explained in the context of the first method according to the invention and are used correspondingly here.

Furthermore, it is provided for the second method according to the invention that the die, similar to the base in the first method according to the invention, is produced by a removal method and / or by a generative method, in particular by thermal spraying or cold gas spraying or kinetic spraying. Furthermore, it is advantageously proposed that the die and / or the molded part are constructed in multiple layers. Particularly advantageously, the die and / or the molded part are machined in each case after the layering. Instead of the generative application of a release layer, the die or the die surface is thus produced directly by means of a generative process in an advantageous manner here in the second process according to the invention. The advantages and the configurations of the layered structure have been explained analogously already in the context of the first method according to the invention.

Furthermore, it is advantageously provided in the context of the second method according to the invention that the application of the die and the application of the molding during the manufacture of the molding as often as desired are alternately used to produce a molding with internal cavities and undercuts. As already explained for the first method according to the invention, an ablating, in particular chip-removing, method is additionally used between the steps of applying the material for the molding and applying the material for the die in order to provide defined surfaces. Preferably, the application of the molding and / or die can be interrupted for the machining with the erosive method.

As a further advantageous embodiment of the second method according to the invention it is provided that the molding is achieved by a thermal treatment, wherein the materials for the molding and the die differ in their thermal expansion coefficient. Alternatively, dissolution by melting is preferred, with the material for the die having a lower melting point than the material for the molding.

Does the molding substantially on the die facing convexity, d. H. Thus, when the die is substantially concave, it is advantageous if the coefficient of thermal expansion of the die material is greater than that of the molding material to avoid deformation of the molding upon release. In the case of a substantially convex shape of the die, the coefficient of thermal expansion of the molded part is advantageously greater in order to ensure easy detachment.

In the following, still advantageous embodiments are described, as they can be used both in the first method according to the invention and in the second method according to the invention.

Thus, the invention provides that the molding is flat and has a substantially uniform molding thickness. The inventive method can thus be used particularly advantageously for the production of sheet-like moldings, as they are produced by a conventional method by forming sheet metal. This means that the methods according to the invention are advantageously suitable for the production of prototypes of sheet metal formed parts. The molding can be described as two-dimensional insofar as the molding extends flat and has a uniform thin molding thickness. Advantageously, it is thus to be described that the width and / or length and / or a diameter of the molding are much larger than the molding thickness.

In a further advantageous embodiment of the method according to the invention, the molded part is reworked before loosening and / or after loosening with a removing method, in particular machining methods. Furthermore, it is provided according to the invention that the molded part is cured before loosening and / or after loosening. The molding can thus advantageously an aftertreatment, z. Example, a heat treatment such as vacuum annealing, be subjected to when the mechanical properties of the molding to be changed. In order to compensate for a possible distortion as a result of the heat treatment, the component can be provided with an allowance at the locations accessible for further processing in order subsequently to be machined to final size. Advantageously, further post-processing, such. As coating, curing, etc. and other post-treatments, such as heat treatment under pressure provided. Of course, advantageously, the curing can be carried out simultaneously with the triggering, so that at the same time hardens the molding and due to the different thermal coefficients between die and molding, the molding dissolves.

Preferably, material with a low melting point and low strength values is used for the cold gas process. In particular, zinc, aluminum or copper are used for this purpose. Experiments have shown that it is particularly preferable to use copper or aluminum. In addition, magnesium and conventional tool steel in the cold gas process lead to good results. Instead of using the materials in pure form, material mixtures, in particular of zinc and / or aluminum and / or copper and / or tool steel and / or magnesium, are preferably used. Particularly advantageous is an aluminum-iron powder mixture.

The carrier material is an iron-magnesium mixture. Preferably, the carrier material is removed by an electrochemical process.

Furthermore, it is advantageously provided for the method according to the invention that the molding is dissolved by means of water. Advantageously, therefore, the separating layer consists of a water-soluble material. Furthermore, it is also conceivable to manufacture the entire matrix according to the second method according to the invention from a water-soluble material, so that the entire matrix is dissolved in water from the molded part.

In a further advantageous embodiment of this water-soluble variant it is provided that a corrodible material is used for the separating layer or the die, wherein the corrodible material is a mixture or alloy of magnesium and at least one further metal component, which may be a metal or a metal compound, their normal potential under reaction conditions is greater than that of magnesium.

The invention further comprises a processing arrangement for producing a molded part according to one of the two described methods according to the invention. The processing arrangement comprises an application device for the generative application of material, wherein the application device is designed for applying a release layer and / or die and / or the molded part, a removal device designed for abrasive machining, in particular chip removal machining, the release layer and / or die and / or or the molding, and a dissolution device formed for releasing the molding from the separation layer or die. The advantageous embodiments, which were discussed in the context of the first and second inventive method, of course, apply mutatis mutandis application for the processing arrangement according to the invention.

Furthermore, the processing arrangement according to the invention advantageously comprises a process chamber, wherein both the application device and the removal device are arranged in this common process chamber. This is advantageously done by a processing machine with at least five axes of motion for combining the applicator and the removal device, wherein both the structure and the removal take place within this one process chamber. Advantageously, while the nozzle of the applicator, such as the spray gun, and the removal device, such as the milling head, with one and the same movement device movable, so that only relatively little effort for the drives must be applied. In a preferred alternative, the application device and the removal device are designed as two separate systems with separate process chambers.

Furthermore, it may be advantageous in the generative application method to heat the component to be built up or the layer below it. For this purpose, for example, a radiation source or an inductive heating device can be provided in the process chamber. The respective heating of the various components to be built up can be controlled, for example, by means of an advantageous thermal imaging camera.

Furthermore, it is advantageously provided for the processing arrangement according to the invention that the dissolution apparatus comprises a curing oven for curing the molded part. This solution device or the curing oven are advantageously in direct connection to the processing machine, which unites in the process chamber application device and removal device. As a result, the molded part with release layer and base or die can be transferred directly to the solution device within the processing arrangement.

In the following, three embodiments of the invention will be explained in more detail with reference to the accompanying drawings. The show

1 to 6 the sequence of the first method according to a first embodiment of the invention,

7 the first inventive method according to a second embodiment, and

8th the first inventive method according to a third embodiment.

1 shows the preparation of a base 1 by means of a cutting process by a milling cutter 3 , By this abrasive editing of the base 1 creates a base surface 2 , It should be noted that as an alternative to pure abrading processing also a base surface 2 would be produced by a generative process.

2 now shows the next step, taking on the base surface 2 a separation layer 4 by means of a thermal spray device 5 is applied. This separation layer 4 is applied with uniform thickness and consists of a water-soluble material. A thermal spraying process using steam is used.

In 3 is shown as the separation layer 4 or the interface surface 7 within the same processing machine with the cutter 3 is reworked. This results in a close contour or surface quality of the separating layer 4 ensured. This now processed interface surface 7 forms the inverse surface of the molding 6 or the molding surface 8th (please refer 6 ).

4 shows, as with the same thermal spray device, which already for applying the release layer 4 was used, the molding 6 is applied. Good to see is that the molding 6 is much stronger than the release layer 4 However, the molding is substantially flat and thus can be referred to as two-dimensional.

5 Now shows how with the cutter 3 the final contour of the molding is produced by machining process.

In 6 the separation of the molding takes place 6 from the release layer 4 and from the base surface 2 by dissolving the separating layer 6 by means of water.

In a further step, not shown, the molded part can now be mechanically reworked or cured, for example, in a curing oven.

7 shows a second embodiment of the first method according to the invention. Identical or functionally identical parts are described in all embodiments with the same reference numerals.

7 shows a cross section through the base 1 , the separating layer 4 and the molding 6 prepared according to the first method of the invention. The final molded part 6 Here is a supernatant 12 added. By this supernatant 12 has the molding 6 a direct connection 9 to the base. After the complete spraying of the molding 6 becomes the supernatant 12 along the milling lines 12 milled. This leaves only the easily detachable connection between the molding 6 and separating layer 4 ,

8th shows a third embodiment of the first method according to the invention. Identical or functionally identical parts are described in all embodiments with the same reference numerals.

The third embodiment shows a large-area molding 6 , formed as a sheet metal. In the edge areas is the molding 6 during its preparation by means of the supernatants 12 directly with the base 1 connected. In addition to the connection 9 in the border areas is a bolt 11 provided that breaks through the separation layer and thus the base 1 and the molding 6 combines. The bolt 11 can be both in the base 1 be used as well as an integral part of the base 1 be.

The adhesion between molding material and base material is much better than the adhesion to the release layer 4 , By the supernatant 12 may be a deformation or a detachment of the molding 4 be largely avoided.

LIST OF REFERENCE NUMBERS

1

Base

2

basic interface

3

milling machine

4

Interface

5

Thermal spray device

6

molding

7

Separating layer

8th

Molding surface

9

Connection to the base

10

milling line

11

bolt

12

Got over

Claims (28)

Method for producing a molded part ( 6 ), comprising the steps: - providing a base surface ( 2 ), - applying a release layer ( 4 ) on the base surface ( 2 ) by a generative process, wherein the interface surface ( 7 ) corresponds to the inverse molding surface, - application of the molding ( 6 ) on the release layer surface ( 7 ) by means of a generative method, and - releasing the molded part ( 6 ) from the release layer ( 4 ). Method according to claim 1, characterized in that the separating layer ( 4 ) and the molded part ( 6 ) are applied by the same generative method, in particular by thermal spraying or cold gas spraying or kinetic spraying. Method according to one of the preceding claims, characterized in that the base surface ( 2 ) is produced with an erosive method and / or by means of a generative method, in particular by means of thermal spraying or cold gas spraying or kinetic spraying Method according to one of the preceding claims, characterized in that the base surface ( 2 ) differs by a separation layer thickness of the inverse molding surface. Method according to one of the preceding claims, characterized in that the base surface ( 2 ) together with the separating layer ( 4 ) a die for the molding ( 6 ). Method according to one of the preceding claims, characterized in that the separating layer ( 4 ) is applied with substantially uniform interface thickness. Method according to one of the preceding claims, characterized in that the separating layer ( 4 ) is applied to the entire base surface. Method according to one of the preceding claims, characterized in that the separating layer ( 4 ) before applying the molding ( 6 ) is processed with a removing process, in particular machining process. Method according to one of the preceding claims, characterized in that a width and / or length and / or a diameter of the molded part ( 6 ) is much larger than the interface thickness. Method according to one of the preceding claims, characterized in that the base surface ( 2 ) and / or the separating layer ( 4 ) and / or the molded part ( 6 ) are built up in several layers by means of thermal spraying, wherein in each case after and / or during the layering the base surface ( 2 ) and / or the separating layer ( 4 ) and / or the molded part ( 6 ) is machined. Method according to one of the preceding claims, characterized in that the two steps of applying the release layer ( 4 ) and applying the molding ( 6 ) during the production of the molded part ( 6 ) are used as often as desired alternately to a molding ( 6 ) with internal cavities and / or undercuts. Method according to one of the preceding claims, characterized in that the molded part ( 6 ) with a supernatant ( 12 ) via the separating layer ( 4 ), so that partially a direct contact between the molding ( 6 ) and base surface ( 2 ) arises. Process according to claim 12, characterized in that the supernatant ( 12 ) is removed by a machining process. Method for producing a molded part ( 6 ), comprising the steps of: - producing a die, wherein the die surface corresponds to the inverse shaped part surface, - applying the molding ( 6 ) on the die surface by means of a generative process, and - releasing the molding ( 6 ) from the matrix. A method according to claim 14, characterized in that the molded part ( 6 ) is applied by thermal spraying or cold gas spraying or kinetic spraying. Method according to one of claims 14 or 15, characterized in that the die is produced with a removing method and / or by means of a generative method, in particular by means of thermal spraying or cold gas spraying or kinetic spraying. A method according to claim 16, characterized in that the die and / or the molded part ( 6 ) are constructed in several layers, wherein in each case after and / or during the layering the die and / or the molded part ( 6 ) is machined. Method according to one of claims 14 or 15, characterized in that the application of the die and the application of the molding ( 6 ) during the production of the molded part ( 6 ) are used as often as desired alternately to a molding ( 6 ) with internal cavities and undercuts. Method according to one of claims 14 to 18, characterized in that the molded part is dissolved by a thermal treatment, wherein the materials for the molded part ( 6 ) and the template differ in their thermal expansion coefficient. Method according to one of the preceding claims, characterized in that the molded part ( 6 ) is flat and has substantially a uniform molding thickness. Method according to one of the preceding claims, characterized in that a width and / or length and / or a diameter of the molded part ( 6 ) is much larger than the molding thickness. Method according to one of the preceding claims, characterized in that the molded part ( 6 ) is post-processed before loosening and / or after loosening with an erosive method, in particular machining method. Method according to one of the preceding claims, characterized in that the molded part ( 6 ) is hardened before loosening and / or after loosening. Method according to one of the preceding claims, characterized in that the molded part ( 6 ) is dissolved by means of water. Method according to one of the preceding claims, characterized in that for the separating layer ( 4 ) or the matrix is a corrodible material, wherein the corrodible material is a mixture or alloy of magnesium and at least one other metal component, which may be a metal or a metal compound, whose normal potential under reaction conditions is greater than that of magnesium. Processing arrangement for producing a molded part ( 6 ) according to one of the preceding claims, comprising - an applicator device for the generative application of material, wherein the applicator device is designed to apply a release layer ( 4 ) and / or die and / or the molded part ( 6 ), - a removal device designed for abrading the release layer ( 4 ) and / or die and / or the molded part ( 6 ), and - a dissolving device, which is used for releasing the flat shaped part ( 6 ) from the release layer ( 4 ) or die is formed. Machining arrangement according to claim 26, characterized in that the application device and the removal device are arranged in a common process chamber. Machining arrangement according to one of claims 26 or 27, characterized in that the dissolving device comprises a curing oven for curing the molded part ( 6 ).

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