Method and apparatus for producing sheet metal components

Abstract

A method and apparatus for making sheet metal components includes heating a sheet of hardenable steel to its austenitizing temperature and hot forming the same in a hot forming tool to define a formed workpiece. The formed workpiece is held in the hot forming tool for a first holding time. The formed workpiece is then removed from the hot forming tool and immediately placed in a cooled, form holding tool and is held therein in a closed condition for a second holding time. The form holding tool may be constructed from a material that has greater heat conductivity than that of the hot forming tool.

Description

CLAIM OF PRIORITY[0001]Applicants hereby claim the priority benefits under the provisions of 35 U.S.C. §119, basing said claim of priority on German Patent Application Serial No. 10 2009 021 395.3, filed May 14, 2009. In accordance with the provisions of 35 U.S.C. §119 and Rule 55(b), a certified copy of the above-listed German patent application will be filed before grant of a patent.BACKGROUND OF THE INVENTION[0002]The present invention relates to a method and apparatus for producing sheet metal components.[0003]Form-hardening and press-hardening of sheet metal components are established in the automobile industry. However, the associated component manufacturing costs are relatively high, so there are efforts to reduce cycle times for the production process. One reason for the current long cycle times is that a certain holding time in the forming tool is required during form-hardening in order to extract or remove the heat from the formed workpiece that is to be hardened. Because ...

AI Technical Summary

Benefits of technology

[0011]This procedure has the advantage that the forming tool, which is in high demand, does not need to be closed for 15 to 20 seconds. Rather, after a relatively brief holding period it can be re-opened, so that it is available again for forming another sheet metal component after a brief period of time. The cycle time for producing sheet metal components is thereby cut, and in the best case can be halved, by using two tools. These two tools are specifically a first tool that is configured for forming, and a second tool that is configured for cooling and, where necessary, sizing as well. This feature of the present invention is clarified by the following example.

[0022]Another distinct advantage of the present inventive apparatus is that there may be fewer cooling bores and / or grooves in the form-holding tool than in the forming tool. Fundamentally, both the forming tool and the form-holding tool are liquid-cooled in order to be able to remove the greatest quantity of heat in a short period of time. Because of the fact that the form-holding tool itself has no role in the forming of the steel sheet, it is possible to choose larger cooling cross-sections and simpler cooling geometries, such as shaft cooling for instance, wherein a series of grooves are provided in the surface of the form-holding tool. Cold water flows through the grooves. The same is true concerning the arrangement of the cooling bores. It is possible to provide only a few central cooling bores, so that the machining of the form-holding tool is significantly less complex than that of the first or forming tool.

Problems solved by technology

However, the associated component manufacturing costs are relatively high, so there are efforts to reduce cycle times for the production process.

This leads to relatively long holding times of 15 to 20 seconds during which the forming tool is closed and not available for producing other sheet metal components.

However, the components are still warm and will warp, leading to increased rejections because of defects.

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