Method for Producing at least One Component and Open-Loop and/or Closed-Loop Control Device

Abstract

The disclosure relates to a method for producing at least one, in particular metal, component, preferably a cylinder head, a nozzle body for a high-pressure injection pump, a component of a diesel injection engine, or a throttle disk, by means of low-pressure carbonitriding in at least one treatment chamber, which preferably can be evacuated, and an open-loop and/or closed-loop control device, which enables the setting of a specified ratio between a carbon concentration and a nitrogen concentration in a surface layer of the at least one component. In at least one treatment phase, a carbon-providing gas and a nitrogen-providing gas are simultaneously introduced into the treatment chamber. Based on a specified ratio between a carbon concentration and a nitrogen concentration to be absorbed by the at least one component in a surface layer of the component, a target value for the temperature and/or the pressure to be set in the treatment chamber is determined and is set in the treatment chamber for a specified time.

Description

[0001]The present invention relates to a method for producing at least one component and to an open-loop and / or closed-loop control device of the generic type of the independent claims.PRIOR ART[0002]The document DE 199 09 694 A1 describes a carbonitriding process in which the inward diffusion of the nitrogen takes place during the entire process or, if elemental nitrogen is used as the donor gas, preferably only in the last process phase. Molecular nitrogen, ammonia and other nitrogen-containing compounds are mentioned in particular as nitrogen donors. Carbon donors are not specified.[0003]The document DE 101 18 494 C2 describes a low-pressure carbonitriding process in which steel parts are first carburized and subsequently nitrogenized with a nitrogen-donor gas. Acetylene, propane and ethylene are specified as carbon donors. A donor gas that contains ammonia is mentioned as the nitrogen donor. Nothing further is specified about the nitrogen donor.[0004]The document DE 103 22 255 A...

AI Technical Summary

Benefits of technology

[0019]The closed-loop control is made correspondingly simple and convenient if the actual value for the pressure is corrected to the target value for the pressure by setting an amount of gas, in particular volumetric flow, discharged from the treatment chamber, the discharged amount of gas being lowered if the actual value for the pressure is less than the target value for the pressure and the discharged amount of gas being increased if the actual value for the pressure is greater than the target value for the pressure.

[0020]It is also advantageous if the target value for the temperature in the treatment chamber is changed at least once. This makes it possible to set different ratios between the carbon concentration and the nitrogen concentration used in different zones of depth of the outer layer.

[0021]A further advantage is obtained if a temperature-equalizing phase is arranged downstream of at least one heating-up phase or at least one cooling-down phase in the treatment chamber. In this way, the target value for the temperature can be adjusted as exactly as possible for all of the components within a charge.

[0022]It is advantageous that the target value for the pressure in the treatment chamber is changed at least once. This makes it possible to set different ratios between the carbon concentration and the nitrogen concentration used in different zones of depth of the outer layer.

[0023]A further advantage is that the target pressure in the treatment chamber is less than or equal to 100 mbar, preferably between two and 30 mbar. In this way, diffusion processes of the corresponding gas within a charge or within interior geometries, such as for example blind-hole bores, become considerably easier.

[0024]It is also advantageous that the target value for the temperature lies in a range from 650° C. to 1050° C., preferably in a range from 650° C. to 960° C. In this way, homogeneous carbonitriding of closely packed component charges or complex geometries with interior surfaces, such as for example with bore geometries, can be ensured.

Problems solved by technology

Due to the alternating carbon and nitrogen offering phases, caused as a result of the process, it is not possible to ensure a continuous uptake of carbon and nitrogen.

In the case of this carbonitriding process, the high treatment temperatures of 1100 to 1200° C. and the atmospheric pressure are problematic.

In addition, the process gas pressure of 1 bar makes the diffusion of the donor gases within the charge and / or within interior geometries, such as for example blind-hole bores, considerably more difficult.

Furthermore, at these temperatures, low-cost metallic materials have a tendency to form coarse grains, which can have adverse effects on the durability of the component, as a result of which more expensive materials have to be used and / or an additional heat treatment step has to be carried out to make the grains fine.

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