DE102010047082A1 - Method for producing e.g. die utilized for producing ultra-high-strength structural components in passenger car body, has optimizing contact surfaces, and producing tool with optimized tool geometry by machining process - Google Patents

Abstract

The method involves performing computer-aided construction of a sheet metal component (6) to be produced and tool geometry that corresponds to the component. Contact pressures between the tool geometry and component are computed, and contact surfaces are optimized so that uniform contact pressure arises between the tool geometry and component. The tool geometry is formed by tool inner surfaces (5) that are optimized by simulation of thinning and thickness increase at the component. A shaping tool (1) is produced with the optimized tool geometry by a machining process.

Description

The present invention relates to a method for producing a forming tool, in particular a hot forming tool with the features according to claim 1.

In the production of structural components made of sheet metal forming processes are used, in which a forming tool consisting of an upper tool and a lower tool, also known as die and bit, are moved together with a sheet metal plate therein and thus form or form the resulting sheet metal component.

The forming tools themselves are driven by actuator drives, for example pneumatically, hydraulically or electromechanically. On the sheet metal plate forming forces are transferred by the upper tool and / or the lower tool, which take over the molding work. During the forming process and also in the formed sheet metal part, ironing or thickening occurs. As a result of the material displacements or the material flow which occurs during the forming process, areas are formed in the sheet metal component in which more material is arranged, that is to say areas which have a higher material thickness. Other areas in turn experience a material removal or are drawn or stretched and thus have ironing on. In the field of ironing, the sheet metal component has a, in relation to the other contours, only small material thickness.

For tool makers who create appropriate forming tools or matrices and / or Patritzen a dyed component is inserted to produce a desired and uniform drawing nip. The component's color transfers to the tool at high contact pressure points. At the places where no contact takes place, there is no coloring of the tool. By machining the die or die thus machining takes place a manual adjustment to the desired target geometry or an optimized geometry of the tool. The steels used for producing a tool, also called tool steels, however, have a particularly high hardness, so that a subsequent processing is possible only with great effort.

Furthermore, the resulting drawing gaps or tool geometries can be increased by machining, but they can not be downsized. A thickening of the tool steel is therefore not possible with conventional production methods.

Furthermore, the process of hot forming has increasingly prevailed for the production of ultra-high-strength structural components in car bodywork. In hot forming, sheet metal blanks are first heated in a heating device or in the tool itself to a temperature equal to or higher than the austenitizing temperature of the material used and subsequently reshaped. During or shortly after the forming then a cooling, the so-called press-hardening, takes place, wherein a cooling-down speed is selected so that a grain hardening or a matensite formation is produced in the material.

As a result, a component is created which has at least some areas of high strength.

Decisive for the uniform hardening of the component is the contact between the forming tool or between the press-hardening tool and the component itself. Good shape retention ensures optimal heat transfer over the entire surface, so that the component can be cooled evenly and quickly.

The object of the present invention is therefore to improve the production of a forming tool, in particular a die and die, with an optimized drawing gap in comparison with the production method known from the prior art.

The aforementioned object is achieved with a method according to the invention for producing a forming tool, in particular a hot forming tool having the features of patent claim 1.

Advantageous embodiments of the present invention are part of the dependent claims.

• – Rechnergestützte Konstruktion eines herzustellenden Blechbauteils und einer dazu korrespondierenden Werkezuggeometrie,
• – Berechnung der entstehenden Kontaktdrücke zwischen Werkzeuggeometrie und herzustellendem Bauteil,
• – Optimierung der Kontaktflächen, so dass im Wesentlichen überall zwischen Werkzeuggeometrie und Blechbauteil ein gleichmäßiger Kontaktdruck entsteht,
• – Herstellen des Umformwerkzeuges mit optimierter Werkzeuggeometrie, insbesondere durch spanabhebende Bearbeitung.

The method according to the invention for producing a forming tool, in particular a hot forming tool, is characterized by the following method steps:

• Computer-aided construction of a sheet-metal component to be produced and of a corresponding tool-train geometry,
• - calculation of the resulting contact pressures between the tool geometry and the component to be manufactured,
• - Optimization of the contact surfaces, so that a uniform contact pressure arises substantially everywhere between tool geometry and sheet metal component,
• - Manufacture of the forming tool with optimized tool geometry, in particular by machining.

The computer-aided construction of a sheet-metal component to be produced is to be understood as meaning that the sheet-metal component is produced in a design program (CAX, Computer Aided X, in particular CAD, Computer Aided Design or CAM, Computer Aided Manufacturing). For the constructed sheet metal component, a corresponding tool geometry is calculated. The tool geometry itself can also be calculated and created, for example, in a design program or in another parameter program.

With the virtually created geometries of the sheet metal component and the tool geometry, the contact pressure between the component to be produced and the tool is now calculated in a calculation method step. The calculation can be created, for example, as a vector parameter, as a gradient or as a flow parameter calculation. The results from this result serve as a starting point for a subsequent optimization in a further process step.

Here, the parameters of the tool geometry are changed so that a substantially uniform contact pressure in the desired order of magnitude. This is to be understood that due to the planned component or the planned manufacturing sequence is previously determined in what accuracy a uniform contact pressure prevail. Due to production inaccuracies and production fluctuations and wear during the use of a tool according to the invention, for example, a 70, 80, 90 or even 95% accuracy of a uniform contact pressure produced anywhere between tool geometry and sheet metal component is sufficient.

After optimizing the contact surfaces between the tool geometry and the sheet metal component, the parameter data obtained are in turn fed to a design program with which a corresponding tool geometry is produced by machining. For example, the data can then be fed to a CNC milling machine, which in turn manufactures the die and / or die from a tool steel by machining production measures.

In a further embodiment variant of the present invention, the method is carried out by means of the calculated gap dimensions between the sheet metal component to be produced and the tool surface. At the points where there are gaps at least in some areas, an approach from the tool surface to the sheet metal component surface takes place through various iterative optimization steps. The data determined therefrom are in turn parameterized in such a way that they can be transferred in a subsequent production step, for example to a CNC milling machine.

An elaborate pre- or post-processing during the manufacture of the mold itself is eliminated by the manufacturing method according to the invention. The possibility that a tool is lost in its manufacture, for example, by unwanted excessive wear in certain areas is thus avoided. The achievable accuracy, in particular in the case of three-dimensional, complex-shaped sheet metal component geometries to be produced, is superior to the manual post-processing method hitherto known from the prior art through the computer-aided simulation.

In a further particularly advantageous embodiment variant of the present invention, the contact pressures in a drawing gap between an upper tool and a lower tool of the forming tool are calculated and optimized. According to the invention, the contact pressures in the drawing gap created between the upper tool and the lower tool are thereby calculated and optimized in relation to the component to be produced.

In particular, the tool surfaces are calculated, constructed and optimized here in the drawing gap. The manufactured tool surfaces of the lower tool and upper tool thus experience an optimal adaptation to the sheet metal component to be produced, due to an optimized contact pressure.

Particularly preferably, the tool geometry is formed by tool inner surfaces, wherein the tool inner surfaces are optimized by a simulation of the resulting during the forming process ironing and thickening of the sheet metal component to be produced. In this case, it is particularly advantageous that the virtually existing tool inner surface or tool inner contour of the die and male die or upper die and lower die is simulated by the simulation, and thus multiple iterative optimization calculations can be made, which serve to improve the adaptation of the tool inner surfaces on the sheet metal component to be produced , The simulation program can be, for example, a multi-body simulation in which the up and down movement and the resulting contact pressures are simulated.

Particularly preferably, the simulation is carried out as a mechanically-thermally coupled simulation. This makes it possible on the one hand to couple the movement parameters during the forming process and the resulting ironing and thickening with the thermal aspects of hot forming and press hardening. Under the thermal aspects or thermal simulations is to be understood in the context of the invention, the press hardening process itself. The Presshärtvorgang is inventively formed as a heat transfer between the component to be manufactured and the tool geometries or tool inner surfaces itself.

With the method according to the invention during the simulation at low contact pressure, the drawing gap existing between the upper tool and the lower tool is particularly preferably at least partially displaced towards the sheet metal component and displaced away from the sheet metal component at a high contact pressure. In this way, it is possible to virtually lift or remove the tool and thus to provide an optimum tool manufactured for the particular forming method used.

The optimization is carried out particularly preferably iteratively, so that the accuracy in terms of computer performance and taking into account unknown process parameters can be performed well compromised. The iterative implementation possibility also allows to proceed with unknown boundary parameters. At the same time, a predetermined accuracy requirement avoids an infinite optimization process to achieve a nearly one hundred percent solution.

Preferably, then, the optimized by the simulation tool inner surface is transferred to a computer-aided design program and milled there parameterized tool made of tool steel. Within the scope of the invention, initially a plastic model for checking the computer-aided and optimized tool geometry can also be manufactured. The actual tool itself or the die or die is then milled from tool steel. With the parameterized data, for example, a CNC milling machine can be fed, which then in turn generates the tool or the tool geometry to be produced.

Particularly preferably, the drawing gap of the forming tool for the closed tool can be optimized with the procedure according to the invention for the production of a forming tool. In the case of the investment of the tool inner surface of the produced sheet metal component after completion of the forming process thus optimal heat transfer for the subsequent hardening process is made possible by quenching.

In a further preferred Auführungsvariante the drawing gap for the occurring during the forming process contact pressures can be optimized. Especially with complex components to be produced, it is necessary here not to optimize the drawing gap for the adapted final contour of the component, but for the forming itself. Furthermore, an optimal drawing gap or an optimal tool inner surface can be calculated, simulated, optimized, parametised, constructed and manufactured particularly preferably already during the forming process to be produced heat transfers for example partially cured components or especially by the forming process stressed component sections.

Further advantages, features and characteristics of the present invention are part of the following description. Advantageous embodiments are shown in the schematic figures. Show it:

1 a known from the prior art forming tool for producing a sheet metal component,

2 Forming tool during optimization according to the manufacturing method of the invention and

3 a forming tool produced by the manufacturing method according to the invention.

In the figures, the same reference numerals are used for the same or similar components, even if a repeated description is omitted for reasons of simplicity.

1 shows a known from the prior art forming tool 1 , The forming tool 1 consists of an upper tool 2 and a lower tool 3 , being between the upper tool 2 and the lower tool 3 a drawing gap 4 is trained. The drawing gap 4 is formed by a tool inner surface 5 of the upper tool 2 and a tool inner surface 5 of the lower tool 3 , In the drawing gap 4 itself is a formed from a metal sheet metal part 6 , The sheet metal component 6 itself is in 1 shown in regions on the tool inner surface 5 but there are also air gaps 7 trained, in which no contact between sheet metal component 6 and tool inner surface 5 given is.

The inventive method calculates in 2 already shown before production of the tool in a virtually generated tool inner surface 5 the potential contact pressures 8th , These are optimized so that the air gaps 7 or not shown in detail thickenings or ironing be optimized so that a full-scale investment of tool inner surface 5 and sheet metal component 6 given is.

In 3 A pre-calculated, simulated and constructed tool inner surface is shown 5 shown. The tool inner surface 5 from upper tool 2 and also the tool inner surface 5 from lower tool 3 lie in each case over the entire surface of the sheet metal component to be produced 6 at. In particular, in a hot forming process, not shown here, this has a particularly advantageous effect on the production accuracy of the sheet metal component to be produced 6 and the cured properties caused by cooling processes.

LIST OF REFERENCE NUMBERS

1

forming tool

2

upper tool

3

lower tool

4

drawing gap

5

Cavity surface

6

sheet metal component

7

air gaps

8th

contact pressures

Claims (11)

Method for producing a forming tool ( 1 ), in particular a hot forming train, characterized by the following method steps: - Computer-aided construction of a sheet-metal component to be produced ( 6 ) and a corresponding tool geometry, - calculation of the resulting contact pressures ( 8th ) between the tool geometry and the sheet metal component to be produced ( 6 ), - optimization of the contact surfaces, so that essentially everywhere between tool geometry and sheet metal component ( 6 ) a uniform contact pressure ( 8th ), - manufacture of the forming tool ( 1 ) with optimized tool geometry, in particular by machining. Method for producing a forming tool ( 1 ), in particular a hot forming train, characterized by the following method steps: - Computer-aided construction of a sheet-metal component to be produced ( 6 ) and a corresponding corresponding tool geometry, - at least partially calculation of the between the tool geometry and the sheet metal component to be produced ( 6 ) geometrical deviations, - optimization of the geometric deviations, so that substantially everywhere between tool geometry and sheet metal component ( 6 ) a uniform plant arises, - manufacture of the forming tool ( 1 ) with optimized tool geometry, in particular by machining. Method according to claim 2, characterized in that the contact pressures ( 8th ) in a drawing nip ( 4 ) between an upper tool ( 2 ) and a lower tool ( 3 ) of the forming tool ( 1 ) can be calculated and optimized. Method according to claim 3, characterized in that in the drawing gap ( 4 ) the tool surfaces are designed and optimized. Method according to one of claims 1 to 4, characterized in that the tool geometry through tool inner surfaces ( 5 ) is formed, wherein the Werkzeugzeuginneflächen ( 5 ) by a simulation of the ironing and thickening during the forming process on the sheet metal component to be produced ( 6 ). Method according to one of claims 1 to 5, characterized in that the simulation is carried out as mechanically thermally coupled simulation. Method according to one of claims 3 to 6, characterized in that during the simulation at low contact pressure ( 8th ) between the upper tool ( 2 ) and the lower tool ( 3 ) existing draw gap ( 4 ) in sections to the sheet metal component ( 6 ) and at high contact pressure ( 8th ) of the sheet metal component ( 6 ) is moved away. Method according to one of claims 1 to 7, characterized in that the optimization is carried out iteratively. Method according to one of claims 1 to 8, characterized in that the optimized by the simulation tool inner surface ( 5 ) is transferred to a computer-aided design program and the specified tool geometry is machined from tool steel. Method according to one of claims 1 to 9, characterized in that the drawing gap ( 4 ) is optimized when the tool is closed. Method according to one of claims 3 to 10, characterized in that the drawing gap ( 4 ) for the contact pressures occurring during the forming process ( 8th ) is optimized.

Images