JP6101350B2 - Method for manufacturing at least one component and open-loop control and / or closed-loop control device - Google Patents

Description

  The invention relates to a method for manufacturing at least one component and to an open-loop control and / or a closed-loop control device as described in the preamble of the independent claim.

  Patent Document 1 describes a carbonitriding method. In this carbonitriding method, diffusion penetration of nitrogen is performed during the entire process, or preferably when elemental nitrogen is used as a donor gas. It takes place only in the last process step. Nitrogen donors include molecular nitrogen, ammonia and other nitrogen-containing compounds, among others. Carbon donors are not specifically described.

  Patent Document 2 describes a low-pressure carbonitriding method. In this low-pressure carbonitriding method, a steel portion is first carburized and then nitrided with a nitrogen donor gas. Acetylene, propane and ethylene are described as carbon donors. As the nitrogen donor, a donor gas containing ammonia is cited. There are no other statements about nitrogen donors.

  Patent Document 3 describes a method for carburizing a steel part. In this method, a gas that generates nitrogen is supplied both during the heating stage and during the diffusion stage. Nitrogen donors include ammonia and laughter, and carbon donors include acetylene, propane and ethylene.

  Patent Document 2 and Patent Document 3 describe a low-pressure carbonitriding method in a pulse mode. In this case, a nitrogen compound such as ammonia or laughter gas is used as a nitrogen donor gas, and this nitrogen compound is subjected to carburizing treatment. Nitrogen is fed into the processing chamber to infiltrate into the component surface during the intervening feeding phase and / or during heating of the charge and / or during the subsequent carbon diffusion phase.

  Continuous carbon and nitrogen permeation cannot be ensured by alternating carbon and nitrogen feed stages constrained by the process. Therefore, the process time is extended. This is because, between the carbon supply stage and the nitrogen supply stage, the diffusion stage must be considered in order to accelerate the penetration of carbon or nitrogen in the next supply stage.

  Patent Document 4 describes a method for carbonitriding a metal component, in which case an amine compound such as methylamine, dimethylamine, and the like is used to simultaneously penetrate carbon and nitrogen into the component surface. Dibutylamine is used as a carbon donor and a nitrogen donor. In this method, the amine is fed into the process chamber at a high temperature (T = 1100 ° C. to 1200 ° C.) to produce an atmosphere of increased carbon and nitrogen. This process is performed under atmospheric pressure.

  In such a carbonitriding method, a high processing temperature and atmospheric pressure of 1100 ° C. to 1200 ° C. are problematic. At such high temperatures, the reaction rate of the amine compound in the gas phase and on the surface of the component is such that complex structures having an inner surface, such as pores or closely packed component charges, High enough to be carbonitrided unevenly. Furthermore, a process pressure of 1 bar makes the diffusion of donor gas significantly difficult in structures located in and / or inside the charge, for example in blind holes. From the standpoint of equipment technology, such a temperature range, combined with high process pressure, can be assessed as requiring very much maintenance. In addition, at such temperatures, inexpensive metal materials are prone to coarsening, which adversely affects the fatigue resistance of the components, and therefore, more expensive materials need to be used and / or finer. It is necessary to carry out an additional heat treatment step to granulate.

  A further important aspect is that all of the above low pressure carbonitriding processes are not provided with closed loop control means for controlling carbon and nitrogen permeation. However, the ratio of carbon and nitrogen that has penetrated into the surface layer is critical to the resulting material and component properties.

German Patent Publication No. 19909694 German Patent No. 10118494 German Patent Publication No. 10322255 Soviet Union Patent No. 1680798

  In contrast, the method according to the invention for producing at least one component, and the open-loop control and / or closed-loop control device according to the invention, having the features of the independent claims, in at least one processing stage, A gas for generating carbon and a gas for generating nitrogen are simultaneously supplied into the processing chamber and adjusted in the processing chamber based on a predetermined ratio of the carbon concentration and the nitrogen concentration to be penetrated into the surface layer of at least one component. It has the advantage that a target value for the temperature and / or pressure to be calculated is calculated and this target value is adjusted in the processing chamber for a predetermined time. In this manner, continuous carbon and nitrogen penetration can be ensured. Carbon and nitrogen are supplied at the same time, and thus without performing a process gas exchange or diffusion stage between alternating carbon and nitrogen supply stages. This reduces process time. In addition, low pressure carbonitriding allows for uniform carburizing and nitriding even in densely packed charges or complex component structures such as pore structures. By controlling the temperature and / or pressure in a closed loop, it is possible to adjust the predetermined ratio of carbon concentration and nitrogen concentration permeated into the surface layer, thereby affecting the resulting material and component properties. Can affect.

  By means of the dependent claims, preferred embodiments and improvements of the methods described in the independent claims are possible.

  Particularly preferably, the same gas is supplied into the processing chamber as the gas generating carbon and the gas generating nitrogen. This greatly simplifies the method. This is because only one kind of gas needs to be supplied into the processing chamber.

  In a preferred form, as the gas, an amine compound, preferably an aliphatic monoamine, is selected as the primary compound, secondary compound and also as the tertiary compound, or an aliphatic diamine or these two A mixture consisting of is selected.

  In this case, as the gas for generating carbon and nitrogen, a gas for generating carbon and nitrogen having a ratio of carbon to nitrogen smaller than 3 or the same as 3 is selected. In this manner, the desired ratio in carbon and nitrogen profiles is adjusted and carbon formation in the furnace apparatus is reduced.

  When various gases for generating carbon and nitrogen are used in the processing chamber, the volume of the carbon generating gas supplied to the processing chamber, particularly the volumetric flow rate, and the nitrogen generating gas supplied to the processing chamber The same advantages are obtained even if the volumetric flow rate is selected such that the ratio of carbon to nitrogen generated in the processing chamber is less than 3.

  If the pressure and / or temperature in the processing chamber is measured and updated to the calculated target value as an actual value, it is suitable for closed-loop control. As a result, the predetermined ratio of the carbon concentration and the nitrogen concentration permeated into the surface layer of at least one constituent part can be controlled in a closed loop particularly easily and reliably.

  The actual value for temperature is updated to the target value for temperature via the control of the heating device in the process chamber, when the actual value for temperature is smaller than the target value for temperature Closed loop control is also particularly simple and easy to configure, by reducing the temperature of the heating device when the temperature of the heating device is raised and the actual value for the temperature is greater than the target value for the temperature The

  In addition, the actual value for pressure is updated to the target value for pressure via adjustment of the amount of gas derived from the processing chamber, in particular the volumetric flow. By reducing the amount of gas derived when it is less than the target value for, and by increasing the amount of gas derived when the actual value for pressure is greater than the target value for pressure Closed loop control is simple and easy to configure.

  It is preferable if the target value for the temperature in the processing chamber is changed at least once. This makes it possible to adjust various ratios of carbon concentration and nitrogen concentration penetrated in various depth regions in the surface layer.

  Another advantage is obtained if a temperature stabilization step is provided following at least one heating step or at least one cooling step in the process chamber. In this way, the target value for temperature can be adjusted as accurately as possible for all components within a single charge.

  It is preferable if the target value for the pressure in the processing chamber is changed at least once. This makes it possible to adjust various ratios of carbon concentration and nitrogen concentration penetrated in various depth regions in the surface layer.

  Another advantage is obtained if the target pressure in the process chamber is equal to or less than 100 mbar, preferably 2 to 30 mbar. In this way, the corresponding gas diffusion process in a single charge or in the inner structure, for example in the bag hole, is significantly reduced.

  More preferably, the target value for temperature is in the range of 650 ° C. to 1050 ° C., preferably in the range of 650 ° C. to 960 ° C. In this way, a uniform carbonitriding of closely packed component charges or a uniform carbonitriding of complex structures with an inner surface, for example a pore structure, is ensured.

  In continuous process runs, inconvenient and uncontrollable precipitates such as carbides, nitrides and carbonitrides form in the surface of at least one component based on temperature and the generated carbon and nitrogen penetration profiles Can be done. It is therefore particularly advantageous if the process according to the invention is provided with a plurality of processing stages, each of which is separated from one another by one diffusion stage. In this manner, the formation of undesired precipitates such as carbides, nitrides and carbonitrides in the surface of at least one component is avoided, and the desired or predetermined carbon penetration profile and nitrogen are avoided. The penetration profile is adjusted within the surface of at least one component.

  Such a carbon permeation profile and a nitrogen permeation profile are such that a predetermined ratio of carbon concentration and nitrogen concentration to be infiltrated into the surface layer of at least one component is a predetermined carbon permeation in the surface layer of at least one component. It is particularly easy to manufacture by selecting separately in at least two processing steps based on the profile and the nitrogen penetration profile.

1 is a schematic view of an apparatus for low pressure carbonitriding of at least one component. FIG. 4 is a diagram showing the effect of temperature on the ratio of carbon and nitrogen adjusted in the surface layer of the constituent parts. FIG. 3 is a schematic view of a process guide for low pressure carbonitriding with closed loop controlled temperature. FIG. 4 is a schematic diagram showing a processed component surface structure obtained by the process guide shown in FIG. 3. FIG. 2 is a block control circuit diagram of an open loop control and / or closed loop control device used for process guide.

  Embodiments of the invention are illustrated in the drawings and are described in detail below.

  FIG. 1 shows a schematic view of an apparatus 1 for low-pressure carbonitriding of one or more component parts 2. FIG. 1 shows, for example, five components 2. These components 2 are arranged on the mounting portion 3 in the processing chamber 4. The component 2 is heated by a heating device 5 shown at the bottom of the drawing. A carbon and nitrogen donor gas 8 can be supplied by an intake 6 equipped with an associated flow control valve 7. The temperature sensor 9 and the pressure sensor 10 are arranged in the upper region of the processing chamber 4 in the drawing. An open loop control and / or closed loop control device 11 disposed thereon receives signals sent from the temperature sensor 9 and the pressure sensor 10. The take-out port 12 of the processing chamber 4 leads to the inlet of the pump 13, and this pump 13 may be configured as a vacuum pump, for example. A throttle valve 14 for adjusting the pressure is disposed upstream of the pump 13.

  During operation of the apparatus 1, carbon and nitrogen donor gas 8 are simultaneously supplied into the processing chamber 4 by the flow control valve 7 at various process stages. The open-loop control and / or closed-loop control device 11 monitors the process or individual process steps, and controls the open-loop control or the closed-loop control, in particular by means of the temperature sensor 9 and the pressure sensor 10. In particular, the temperature detected by the temperature sensor 9 and hereinafter also referred to as a processing temperature is important. The processing temperature is obtained in the atmosphere of the processing chamber 4 as will be further described below with reference to FIGS. The pump 13 acts like a valve at the outlet 12 in cooperation with the throttle valve 14. In order to adjust the required processing pressure in the processing chamber 4 and to partially evacuate the processing chamber 4 or to exhaust or replace the gas present in the processing chamber 4, the opening angle of the throttle valve 14 is set to open loop. The control and / or the closed-loop control device 11 provides a closed-loop control based on the process, in particular on the basis of a pressure detected by the pressure sensor 10, hereinafter also referred to as process pressure. The heating device 5 is closed-loop controlled by the open-loop control and / or the closed-loop control device 11, in particular based on the processing temperature detected by the temperature sensor 9. The flow control valve 7 is controlled by the open loop control and / or the closed loop control device 11 in order to perform the closed loop control of the flow rate of the process gas based on the process.

  The carbon donor gas, also referred to as carbon generating gas, and the nitrogen donor gas, also referred to as nitrogen generating gas, may be different from each other. In this case, different gases are supplied to the processing chamber 4 at a desired mixing ratio in a mixing chamber (not shown) upstream of the flow control valve 7 or by individual flow control valves. In this case, a known gas may be selected. Examples of the carbon donor gas include acetylene, propane, and ethylene. Examples of the nitrogen donor gas include ammonia and laughing gas. The process gas composition for the processing chamber 4 is adjusted via the gas amounts of the gas generating carbon and the gas generating nitrogen.

  For the carbon donor gas and the nitrogen donor gas, the same gas, for example an amine compound, preferably an aliphatic monoamine, is selected as the primary compound, as the secondary compound or as the tertiary compound, Alternatively, it has been found to be particularly suitable if an aliphatic diamine or a mixture of these two is selected. This significantly reduces the process guide. In this case, no mixing chamber upstream of the flow control valve 7 or an additional flow control valve is required.

  Instead of being based on temperature and pressure, as described above, closed loop control or open loop control may optionally be based on temperature alone or pressure alone, so that one of the two sensors It is only necessary. In temperature closed loop control, only a temperature sensor is required, and in pressure closed loop control, only a pressure sensor is required.

FIG. 2 shows the surface of component 2 after carbonitriding for 20 minutes at a controlled processing pressure of 10 mbar with dimethylamine (C ₂ H ₆ NH) as the donor gas, with a spacing of 50 μm from the component surface Figure 6 shows the effect of processing temperature on the supplied carbon and nitrogen in the region. In this case, FIG. 2 shows the influence of the experimentally calculated treatment temperature on the ratio of the carbon concentration and the nitrogen concentration adjusted to the surface region of component 2 for two temperatures of 800 ° C. and 850 ° C. An example is given. Two temperatures have been selected to account for the change in the ratio of carbon and nitrogen permeated. At 800 ° C, the amount of permeated nitrogen is higher, whereas more carbon permeates at the same process time and temperature of 850 ° C. Generally, when the treatment temperature is increased, the ratio of the amount of carbon penetrated and the amount of nitrogen is shifted to a further increased amount of carbon penetration. By knowing the effect of temperature on the ratio of the amount of carbon penetrated and the amount of nitrogen, closed-loop control temperature management can be performed. This closed-loop control type temperature management is performed by a constant closed-loop controlled temperature and / or processing temperature decrease or / or a processing temperature depending on a predetermined ratio between the carbon concentration and the nitrogen concentration to be infiltrated into the surface layer of the component 2. Need a rise.

  Furthermore, it has been experimentally proven that by increasing the processing pressure, the ratio of carbon to nitrogen can be changed so that the carbon predominates.

  FIG. 3 shows an experimental time course of processing temperature and processing pressure, also called process gas pressure, during low-pressure carbonitriding. For illustration purposes, a process guide for low-pressure carbonitriding with a closed-loop controlled temperature, for example used in the apparatus 1 shown in FIG. 1, is schematically shown. The abscissa of the diagram shows the process duration t, the left ordinate shows the temperature T, and the right ordinate shows the pressure p of the atmosphere in the processing chamber 4. Low pressure carbonitriding has a heating stage A, two temperature stabilization stages B1, B2, two carbonitriding stages C1, C2, two diffusion stages D1, D2, a temperature switching stage E and a cooling stage F. The interruption of the abscissa indicates that each of the illustrated process steps may not have the indicated duration and may differ from the display of FIG.

  FIG. 3 shows that during the heating phase A, the temperature is raised by the heating device 5 continuously to a processing temperature of about 950 ° C. with a substantially constant heating rate. For this purpose, the heating device 5 is correspondingly controlled by the open-loop control and / or the closed-loop control device 11 to adjust the heating rate ΔT / Δt.

  In the temperature stabilization stage B1 following the heating stage A, the processing temperature is compared with a first target value which is a temperature of 950 ° C. by the open loop control and / or the closed loop control device 11 with the temperature measured by the temperature sensor 9. Then, by controlling the heating device 5 accordingly, the temperature is adjusted to a first target value which is a temperature of about 950 ° C. During the heating stage A and the first temperature stabilization stage B, no gas that generates carbon or nitrogen is supplied to the processing chamber 4.

  In a first processing stage, also referred to as a first carbonitriding stage C1, following the first temperature stabilization stage B1, the processing temperature is further adjusted to its first target value. Further, a gas that generates carbon and nitrogen, for example, methylamine, also called carbon and nitrogen donor gas, is supplied to the processing chamber 4 via the flow control valve 7. In this case, the processing pressure, also referred to as process pressure or donor gas pressure or donor gas partial pressure, is the first measured by the open loop control and / or closed loop control device 11 with the pressure measured by the pressure sensor 10 being a pressure of 15 mbar. Compared with the target value, the opening of the throttle valve 14 is controlled accordingly, so that the first target value, which is a pressure of about 15 mbar, is constantly adjusted.

  In order to maintain a first predetermined ratio of the amount of carbon and nitrogen permeated into the surface region of component 2, a first target value for the processing temperature and a first target value for the processing pressure Is calculated by the open-loop control and / or the closed-loop control device 11 according to the experimentally calculated relationship described above, using a correspondingly stored characteristic map. Depending on the selected first treatment duration Δt1 of the first carbonitriding stage C1, the amount or penetration depth of carbon and nitrogen supplied into the component part 2 is determined according to a first predetermined ratio. In this connection, a first process duration characteristic map is stored in the open loop control and / or closed loop controller 11, the first process duration characteristic map being a selected target value of the process temperature, and The selected target value for the processing pressure, and the processing duration for the material composition of the component 2 and the amount of carbon and / or nitrogen that has penetrated into the component 2 or the carbon and nitrogen into the surface layer. Describe the relationship between penetration depth, calculated experimentally or by calculation. In this case, all components 2 processed in the processing chamber should have the same material composition, thereby obtaining the desired result with respect to the carbon and nitrogen concentrations to be supplied.

  In the illustrated embodiment, a first diffusion stage D1 is additionally performed following the first carbonitriding stage C1, in which the open-loop control and / or the closed-loop control device 11 performs the first diffusion stage D1. By controlling the throttle valve 14 and the flow control valve 7 accordingly, the process chamber 4 is evacuated via the pump 13 when the flow control valve 7 is closed, or cleaned with an inert gas, such as nitrogen or argon, Next, this inert gas is supplied to the processing chamber 4 through the flow control valve 7 instead of the carbon and nitrogen donor gas, and is exhausted again by the pump 13.

  Then, in order to adjust the carbon to nitrogen ratio, which is confined in the surface of component 2, the heating device 5 is controlled accordingly to bring the treatment temperature to a second target value of about 850 ° C. A temperature switching stage E for switching is performed.

  In the second temperature stabilization stage B2 following the temperature switching stage E, the processing temperature is a second target value that is 850 ° C., the temperature measured by the temperature sensor 9 by the open loop control and / or the closed loop control device 11. In comparison with, the heating device 5 is correspondingly adjusted to a second target value which is a temperature of about 850 ° C. During the temperature switching stage E and the second temperature stabilization stage B2, no gas that generates carbon or nitrogen is supplied to the processing chamber 4.

  In a second processing stage, also referred to as a second carbonitriding stage C2, following the second temperature stabilization stage B2, the processing temperature is further adjusted to its second target value. In addition, a gas that generates carbon and nitrogen, for example, methylamine, is supplied to the processing chamber 4 via the flow control valve 7. In this case, the processing pressure is determined by comparing the pressure measured by the pressure sensor 10 with the second target value, which is a pressure of 10 mbar, by the open-loop control and / or the closed-loop control device 11 and the flow control valve 7 correspondingly. By controlling, the pressure is adjusted to a second target value which is a pressure of about 10 mbar.

  To obtain a second predetermined ratio of carbon to nitrogen for component 2 in the surface region, a second target value for process temperature and a second target value for process pressure are In the open-loop control and / or the closed-loop control device 11, it is calculated using the corresponding characteristic map stored on the basis of the experimentally calculated relationship. Depending on the selected second treatment duration Δt2 of the second carbonitriding stage C2, the amount or depth of carbon and nitrogen that has penetrated into the component 2 is determined according to a second predetermined ratio. In this connection, a second process duration characteristic map stored in the open-loop control and / or closed-loop controller 11 is used, which is selected for the process temperature. The amount of carbon and / or nitrogen additionally supplied in component 2 calculated experimentally or by calculation based on the target value and the processing pressure and the selected target value for the material composition of component 2 Describe the penetration depth of carbon and nitrogen into the surface layer, which can be realized on the premise of the relationship between the amount and the treatment duration, or the penetration depth obtained in the first carbonitriding stage C1. When the process pressure and process temperature of the second carbonitriding stage are selected according to the first carbonitriding stage, the first process duration characteristic map is used instead of the second process duration characteristic map. May be used.

  In the illustrated embodiment, the process chamber is placed in the component 2 by means of a second target value for the process temperature in the second carbonitriding stage C2, which is reduced compared to the first carbonitriding stage C1. The permeated nitrogen ratio is adjusted to a higher temperature and the carbon ratio permeated into the component 2 is adjusted to a lower temperature.

  In the embodiment shown, the process pressure in the second carbonitriding stage C2 is lower compared to the first carbonitriding stage C1, so that it penetrates into the component 2 as well as due to the reduced process temperature. The ratio of the carbon content to the nitrogen content is changed so that the nitrogen content becomes dominant.

  The second carbonitriding stage C2 may optionally follow directly the temperature switching stage E without the second temperature stabilization stage B2.

  The amount of carbon and nitrogen permeated in the first carbonitriding stage C1 is further away from the surface of the component 2 than the position of carbon and nitrogen permeated in the second carbonitriding stage C2. Large, located in the second region 110 of the surface layer 125, the amount of carbon and nitrogen penetrated during the second carbonitriding stage C2, as shown in FIG. Is located in the first region 105 of the surface layer 125, which is adjacent to the region 110 and is closed on the other side by the surface 100 of each component 2.

  This produces a corresponding permeation profile of carbon and nitrogen concentrations that have penetrated into the surface layer 125 of the component 2. In this embodiment, the second processing duration Δt2 is selected to be shorter than the first processing duration Δt1. Therefore, the second region 110 in the surface layer 125 of the component 2 is configured to be thicker than the first region 105. In this case, the first region 105 has a first thickness d1 that is smaller than the second thickness d2 of the second region 110. Then, on the side opposite to the first region 105, the second region 110 is followed by the core 115 of each component, and carbon or nitrogen is not permeated into the core 115 by the processing. In this case, the transition between the two regions 105, 110 is described in a dramatic manner in the ideal form in FIG. 4, but in practice the corresponding carbon and nitrogen concentrations between adjacent regions The transition of the ratio is adjusted to a smooth shape.

  Subsequently, another diffusion stage D2 is performed, in which the process chamber 4 is evacuated or cleaned with an inert gas, for example nitrogen or argon. A cooling stage F is then performed.

  Many methods for carbonitriding in this manner are possible, and the present invention provides two temperature stabilization stages B1, B2, two carbonitriding stages C1, C2, two diffusion stages D1, D2, It is clear that the temperature switching stage E and the cooling stage F are not limited to the above sequence and number.

  Depending on the desired material and component properties, such as wear and heat resistance, and the iron material used for component 2, the maximum surface concentration of carbon and nitrogen is maintained at a total of 1.5 weight percent. Should be. In a desirable format, the surface carbon concentration is 0.5 to 0.8 weight percent when the surface nitrogen concentration is 0.2 to 0.7 weight percent.

  Individual carbonitriding to avoid undesired precipitation of carbides, nitrides and carbonitrides and / or to produce a predetermined carbon and nitrogen penetration profile in the surface of component 2 as described above In addition, one or more diffusion steps may be inserted between the steps. In this case, the predetermined carbon permeation profile and nitrogen permeation profile are determined by the ratio of the carbon concentration and the nitrogen concentration to be permeated into the surface layer of the component part, and from the surface of the component part within the surface layer of the component part Decide whether to keep the distance. A corresponding carbonitriding step is then performed as described above for each of these regions of the surface layer having individually given ratios of carbon concentration and nitrogen concentration.

  The desired carbon and nitrogen concentration distribution in the surface of component 2 can be determined by closed loop controlled temperature management and / or closed loop control of donor gas pressure during low pressure carbonitriding, and the duration and time of the carbonitriding stage. It is adjusted by selecting it appropriately. For this purpose, in the carbonitriding stage in which the process chamber 4 is supplied with a carbon donor gas and a nitrogen donor gas, the process temperature of the components is preferably within a maximum deviation of +/− 15 ° C., preferably +/− 8 ° C. Closed loop control within the maximum deviation of.

  Furthermore, the advantage of the method according to the invention is that the process is carried out at a pressure as low as 2 mbar to 30 mbar, preferably less than or equal to 100 mbar, and thus a pore structure for receiving carbon and nitrogen The accessibility is increased. For this purpose, the process gas pressures of the carbon and nitrogen donor gases are preferably closed-loop controlled within a deviation of +/− 8 mbar, more preferably within a deviation of +/− 3 mbar. Uniformity of a dense component charge due to a low temperature less than or equal to 1050 ° C., preferably less than or equal to 960 ° C. and greater than or equal to 650 ° C. Carbonitriding, or uniform carbonitriding of components having complex structures such as pore structures can be performed.

  The characteristic map described above has been developed from a simulation model that calculates the diffusion of nitrogen and carbon depending on time, temperature, pressure and material composition.

  FIG. 5 shows an open loop control and / or a closed loop with components provided for the control of the flow control valve 7, the opening of the throttle valve 14 and the control of the heating device 5 for adjusting the carbonitriding stage. The block control circuit diagram of the control apparatus 11 is shown. In this case, during the carbonitriding stage, the opening degree of the throttle valve 14 when the vacuum pump 13 is operated is adjusted by the open loop control and / or the closed loop control device 11, so that the processing pressure in the processing chamber 4 is adjusted each time. Is adjusted to the target value. The processing pressure is adjusted at the gas outlet from the processing chamber 4 upstream of the pump 13 by adjusting the opening of the throttle valve 14 accordingly. When the actual value of the processing pressure measured by the pressure sensor 10 exceeds a predetermined target value for the processing pressure, the throttle valve 14 is controlled accordingly from the open-loop control and / or closed-loop control device 11 side. By means of which the pump 13 can withdraw a larger volume flow from the process chamber 4 and the actual value for the process pressure is reduced. When the actual value of the processing pressure measured by the pressure sensor 10 falls below a predetermined target value for the processing pressure, the throttle valve 14 is correspondingly controlled from the open-loop control and / or closed-loop control device 11 side. Is further closed, thereby reducing the volumetric flow that the pump 13 draws from the process chamber 4 and increasing the actual value for the process pressure in the process chamber 4.

  Other components of the open loop control and / or closed loop control device 11, such as those required to adjust the heating stage A or the diffusion stages D1, D2, are not shown for the sake of clarity of the drawing. Can be configured in a manner known to those skilled in the art.

  The user can input a plurality of parameters for processing the component 2 as desired in the processing chamber 4 to the input unit 200 of the open loop control and / or the closed loop control device 11. Therefore, the user can set the ratio or ratios between the carbon concentration and the nitrogen concentration to be permeated into the surface layer 125 of the component 2 by corresponding inputs. The first ratio set in such a format is shown in FIG. 5 as the first ratio data record 205, where n is greater than or equal to 1 in the n set ratios. The n set ratios are shown as n ratio data records 215. If n = 1, this provides only one ratio data record for a given ratio corresponding to the first ratio data record 205. If more than one ratio is set, a corresponding number of ratio data records are provided. All of the set ratio data records are indicated at 220. In this case, one assigned carbonitriding stage must be adjusted for each ratio data record in order to execute a predetermined ratio in the surface layer 125. When only one ratio data record is set, a correspondingly set ratio is given to only one region of the surface layer 125. In a plurality of ratio data records, one carbonitriding is performed for each ratio data record. The time sequence of stage entry or number setting is adjusted. In this case, for each ratio data record, and thus for each carbonitriding stage, a region having a corresponding ratio of carbon concentration and nitrogen concentration in the surface layer 125 is formed, wherein a plurality of regions are It is formed towards the surface 100 of each component 2 in accordance with the time sequence of inputs of the assigned predetermined ratio and thus in numbering sequence. In this case, the first ratio data record maintains the maximum distance to the surface 100 of each component 2 to adjust the carbon concentration and nitrogen concentration, and the last used data record is the carbon concentration closest to the surface. And adjust the nitrogen concentration. An example with two such regions and thus two ratios set in this way is described with reference to FIG. In this case, the second area 110 having the thickness d2 is adjusted to the surface layer of the component part 2 by the first ratio data record, and the first area 105 having the thickness d1 is adjusted by the second ratio data record. Is done.

  For each given ratio, the desired amount or penetration depth, in other words the thickness of the assigned region, must also be selectable. Correspondingly, in FIG. 5, the first predetermined thickness data record is indicated by reference numeral 225, and the n predetermined thickness data records are indicated by reference numeral 235. The entire thickness data record is indicated at 240. In accordance with the time input sequence, for each necessary carbonitriding step, a corresponding ratio data record is supplied as an input value to the temperature-pressure characteristic map 250, and the associated thickness data record is input to the process duration characteristic map 255. Supplied as an input value. In this case, the temperature-pressure characteristic map is experimentally calculated and set at the input part thereof, because of the ratio of the carbon concentration and the nitrogen concentration to be infiltrated into the surface layer 125 of the component part 2. The processing temperature target value ST and the target processing pressure target value SD are provided at the output section. FIG. 2 shows the results of such an experimental evaluation, for example for process temperature and process pressure. A target value ST for the processing temperature and a target value SD for the processing pressure are similarly supplied to the processing duration characteristic map 255 as input values. Further, the target value ST for the processing temperature is supplied to the first comparator 265 as an input value. Furthermore, the target value SD for the processing pressure is supplied to the second comparator 260 as an input value.

  In addition, in the input unit 200, a material composition consisting of the proposed quantities that characterize the material composition of the component 2 is selected, for example, case-hardened steel 20MnCr5. In this case, a material composition data record 245 is generated, and this material composition data record 245 is also supplied to the processing duration characteristic map 255 as an input value. In this case, the processing duration characteristic map 255 is also calculated experimentally and is a component of the material composition selected with the predetermined target value ST for the processing temperature and the predetermined target value SD for the processing pressure. In the surface layer 125 of each component 2, how long it takes to form a region of a predetermined thickness having carbon and nitrogen permeated according to a predetermined ratio of carbon concentration and nitrogen concentration Select whether or not. A corresponding opening signal is transmitted to the flow control valve 7 at the output of the processing duration characteristic map 255, so that the flow control valve 7 is connected to the associated carbonitriding stage. Open during the calculated processing duration. Outside the calculated processing duration, the flow control valve 7 is closed or known to the person skilled in the art only during the diffusion stage which is possibly provided for cleaning with an inert gas such as nitrogen or argon. Freed in form.

  As other input values, the actual value IT for the processing temperature calculated by the temperature sensor 9 is supplied to the first comparator 265. In order to minimize the adjustment difference and update the processing temperature actual value IT to the processing temperature target value ST, the first comparator 265 compares the processing temperature target value ST with the processing temperature actual value IT, A control signal is supplied to the heating device 5 based on the difference between the target value ST of the processing temperature and the actual value IT of the processing temperature.

  As another input value, the actual value ID for the processing pressure calculated by the pressure sensor 10 is supplied to the second comparator 260. In order to minimize the adjustment difference and update the processing pressure actual value ID to the processing pressure target value SD, the second comparator 260 compares the processing pressure target value SD with the processing pressure actual value ID; A control signal is provided to the throttle valve 14 based on the difference between the target value SD of the processing pressure and the actual value ID of the processing pressure.

  In such a format, the predetermined ratio of the carbon concentration and the nitrogen concentration in the surface layer 125 of each component part 2 within the desired thickness in the corresponding region is calculated for the calculated processing duration. Adjusted. In setting a plurality of such ratios, ratio data records 205,..., 215 and thickness data records 225 are assigned by a plurality of carbonitriding stages that are assigned and additionally separated from each other by respective diffusion stages. ..., 235, the predetermined nitrogen and carbon penetration profiles in the surface layer 125 are adjusted.

DESCRIPTION OF SYMBOLS 1 Apparatus for low-pressure carbonitriding 2 Component part 3 Mounting part 4 Processing chamber 5 Heating apparatus 6 Intake port 7 Flow control valve 8 Carbon and nitrogen donor gas 9 Temperature sensor 10 Pressure sensor 11 Open loop control and / or closed loop control apparatus 12 Outlet 13 Pump 14 Throttle valve 100 Surface 105 First region 110 Second region 115 Core 125 Surface layer 200 Input unit 205 First ratio data record 215 n ratio data record 220 All ratio data record 225 First Predetermined thickness data record 235 n predetermined thickness data records 240 total thickness data record 245 material composition data record 250 temperature pressure characteristic map 255 process duration characteristic map 260 second comparator 265 first comparison A Stage B1, B2 Temperature stabilization stage C1, C2 Carbonitriding stage d1 First thickness d2 Second thickness D1, D2 Diffusion stage E Temperature switching stage F Cooling stage SD Target value of processing pressure ST Target value of processing temperature T temperature t process duration Δt1 first treatment duration Δt2 second treatment duration p pressure of atmosphere

Claims (22)

In a method for producing at least one component (2) in at least one processing chamber (4) by low pressure carbonitriding,
Providing a plurality of processing stages, each of which is separated from one another by one diffusion stage;
In at least one processing stage, a gas for generating carbon and a gas (8) for generating nitrogen are simultaneously supplied into the processing chamber (4) so as to penetrate into the surface layer of at least one of the component parts (2). A target value for the temperature and / or pressure to be adjusted in the processing chamber is calculated based on a predetermined ratio between the carbon concentration and the nitrogen concentration, and the target value is adjusted in the processing chamber for a predetermined time. A method for manufacturing at least one component.   The method according to claim 1, wherein the same gas is supplied into the processing chamber as a gas for generating carbon and a gas for generating nitrogen.   As the gas, an amine compound is selected as a primary compound, a secondary compound and also as a tertiary compound, or an aliphatic diamine or a mixture of these two is selected. Item 3. The method according to Item 2.   As the gas, an aliphatic monoamine is selected as a primary compound, a secondary compound and also as a tertiary compound, or an aliphatic diamine or a mixture of these two is selected, The method according to claim 2 or 3.   The gas for generating carbon and nitrogen is selected such that carbon / nitrogen, which is a ratio of carbon to nitrogen, is less than or equal to 3, as a ratio of carbon to nitrogen. 5. The method according to any one of items 1 to 4.   Carbon and nitrogen generated in the processing chamber are expressed in terms of the volume flow of the gas generating carbon supplied to the processing chamber and the volume flow of the gas generating nitrogen supplied to the processing chamber. The method according to claim 1, wherein the ratio is selected to be smaller than 3.   The method according to any one of claims 1 to 6, characterized in that the pressure and / or temperature in the processing chamber (4) is measured and updated to the calculated target value as an actual value. .   The actual value for temperature is updated to the target value for temperature via control of the heating device (5) in the processing chamber (4), where the actual value for temperature is When the temperature of the heating device (5) is smaller than the target value for temperature, the heating device (5) is increased when the actual value for temperature is larger than the target value for temperature. The method according to claim 1, wherein the temperature of 5) is lowered.   The actual value for pressure is updated to a target value for pressure via adjustment of the amount of volumetric flow of gas derived from the process chamber (4), wherein the pressure for pressure Derived when the actual value is less than the target value for pressure, reducing the amount of gas derived, and when the actual value for pressure is greater than the target value for pressure The method according to claim 1, wherein the amount of gas is increased.   10. A method according to any one of the preceding claims, characterized in that the target value for the temperature in the processing chamber (4) is changed at least once.   11. The temperature stabilization stage according to claim 1, further comprising a temperature stabilization stage subsequent to at least one heating stage or at least one cooling stage in the processing chamber (4). Method.   12. Method according to any one of the preceding claims, characterized in that the target value for pressure in the processing chamber (4) is changed at least once.   13. A method according to any one of the preceding claims, characterized in that the target pressure in the processing chamber (4) is equal to or less than 100 mbar.   14. The method according to any one of claims 1 to 13, characterized in that the target pressure in the processing chamber (4) is 2 to 30 mbar.   15. A method according to any one of the preceding claims, characterized in that the target value for temperature is in the range of 650 <0> C to 1050 <0> C.   The method according to any one of claims 1 to 15, characterized in that the target value for temperature is in the range of 650C to 960C. A predetermined ratio of carbon concentration and nitrogen concentration to be permeated into the surface layer of at least one of the component parts (2) is determined according to a predetermined carbon permeation profile and nitrogen permeation in the surface layer of the at least one component part (2). 17. A method according to any one of the preceding claims, characterized in that selection is made separately in at least two processing steps based on the profile. 18. At least one component (2) is a cylinder head, a nozzle body of a high-pressure injection pump, a component of a diesel injection engine, or a valve disk, according to any one of claims 1 to 17 The method described. At least one of the processing chamber (4) The method according to any one of claims 1 18, characterized in that the evacuatable processing chamber. In an apparatus for performing open-loop control and / or closed-loop control for producing at least one component (2) in at least one processing chamber (4) by low-pressure carbonitriding,
A control means is provided for executing a plurality of processing stages separated from each other in one diffusion stage,
In at least one processing step, a gas generating carbon and a gas generating nitrogen (8) supplied simultaneously into the processing chamber (4) are permeated into the surface layer of at least one component (2). Means (250) are provided for calculating a target value for the temperature and / or pressure of the processing chamber (4) based on a predetermined ratio between the carbon concentration and the nitrogen concentration to be obtained, and at least 1 Means for closed-loop control, wherein target values for temperature and / or pressure to be adjusted in the processing chamber (4) in one processing stage are adjusted in the processing chamber (4) for a predetermined time (255, 260, 265) characterized in that an apparatus for performing open-loop control and / or closed-loop control for producing at least one component is provided. 21. Open loop control and / or according to claim 20 , characterized in that at least one said component (2) is a cylinder head, a nozzle body of a high-pressure injection pump, a component of a diesel injection engine, or a valve disc. Or a device that performs closed-loop control. Device for performing open-loop control and / or closed-loop control according to claim 20 or 21 , characterized in that at least one of the process chambers (4) is an exhaustable process chamber.

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