Method for hardening a component

Abstract

A method for hardening a component (10) in which the component (10) is hardened at least locally in a hardening area (12) by means of an energy beam depending on process parameters, wherein at least one process parameter of the method is variably set in the hardening area (12) during operation depending on a previously determined load parameter of the component (10), characterized in that areas (18, 20, 22, 24) are provided locally in the hardening area (12) which have a higher hardness level than other areas of the hardening area (12), wherein a speed at which the energy beam is guided over the hardening area is set as a process parameter, wherein a curve (44) indicates the speed profile, and a cooling of the component (10) by means of a cooling medium is set as a further process parameter.where, analogous to the velocity profile (44), a variable supply rate of the cooling medium is set in the hardening area (12) and an additional heating of the component (10) by means of another energy source is set as a process parameter.

Description

[0001] The invention relates to a method for hardening a component of the type specified in the preamble of claim 1 and a component of the type specified in the preamble of claim 10.

[0002] DE 37 33 147 A1 discloses a method for laser heat treatment, such as laser hardening, laser annealing, laser recrystallization of components in the solid state, wherein the surface temperature along a processing area of ​​the components is determined using at least one radiation pyrometer which isolates only the thermal radiation of a specific wavelength or a specific wavelength range, and the power of a laser is controlled online so quickly using a PID controller that the temperature of the surface in the processing area is kept constant within a specified temperature interval.

[0003] Maintaining a constant temperature means that the hardness properties of components treated by such a process can only be adjusted to a limited extent. The same applies to well-known hardening processes such as induction hardening and flame hardening, which allow only very limited local adjustment of component properties.

[0004] The Fig. Figure 4 shows a component in the form of a cam. 10 according to the state of the art, which is achieved by induction hardening in a hardness range 12 is hardened, with the hardness range 12 in circumferential direction according to a directional arrow 16 across the entire cam 10 extends across.

[0005] Based on the Fig. Section 4 highlights the disadvantages of induction hardening. For example, in one area... 18 A high case hardening depth, also known as hardening depth, results from high heat build-up during induction hardening. In one area 20This results in a hardening depth that varies circumferentially over a certain area, which is also disadvantageous. Induction hardening according to the state of the art has a particularly detrimental effect on a [missing information - likely a specific type of hardening process]. 14 of the cam 10 on, via which of the cams 10 It can be connected to a camshaft on the internal combustion engine in a rotationally fixed manner.

[0006] Is the recording 14 after the cam was manufactured 10 and which, before induction hardening, is essentially circular, induction hardening leads to distortion due to high heat input, resulting in an undesirable, non-round, almost oval shape of the workpiece. 14 leads.

[0007] It is therefore an object of the present invention to provide a method for hardening a component and such a component by which improved mechanical properties of the component can be achieved.

[0008] This problem is solved by a method for hardening a component with the features of claim 1 and by a component with the features of claim 10. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the dependent claims.

[0009] An inventive method for hardening a component, in which the component is hardened at least locally in a hardening range depending on process parameters by means of an energy beam, in particular a laser beam, an electron beam or the like, is characterized in that at least one process parameter of the method is variably adjusted in the hardening range during operation depending on a previously determined load parameter of the component. This allows the hardening range and the hardness properties of the component to be adapted to the at least one previously determined load parameter, resulting in improved mechanical properties of the component.For example, local areas can be provided within the hardening area which, as a result of a greater hardening depth and / or a higher hardness level, are more resilient than other local areas of the hardening area in which the hardening depth and / or the hardness level is lower than in the aforementioned areas.

[0010] This can be useful, for example, if the pre-determined load parameter makes it clear that the component needs to be harder in some areas of the hardness range, while in other areas a lower hardness level but better elastic deformability is advantageous. The same applies to areas of the component that, for functional reasons, need to be hardened more deeply, or to those that, for functional reasons, require only a shallower hardening depth but must simultaneously exhibit reduced component distortion.

[0011] In contrast to keeping the process parameter constant, for example the feed rate at a controlled, constant temperature of the component's surface in the hardening area, the hardness level and / or hardening depth in the hardening area can be controlled or regulated locally, resulting in the component exhibiting different hardness properties across the hardening area.

[0012] It is also conceivable to utilize this flexibility to selectively and advantageously influence component variations, such as dimensional accuracy, residual stress distribution, or microstructure. Since the aforementioned process parameters can generally be easily modified via software settings, hardness profiles for similar or even different components or batches can be readily stored and recalled as needed. This results in greater flexibility compared to systems that require mechanical modifications for such changes.

[0013] This demand-driven adjustment of the component's hardness properties, tailored to the load parameters, enables the production of delicate, surface-hardened components with locally high resistance, for example, to abrasion and rolling stress. This is particularly advantageous in connection with shafts, especially cams and camshafts, or also with crankshafts, balance shafts, transmission shafts, or engine shafts. This, in turn, allows for smaller and lighter designs, which can significantly contribute to reducing the fuel consumption and CO2 emissions of an internal combustion engine with such machined shafts.

[0014] The described method of locally determining the hardening depth and / or hardness level, depending on at least one load parameter, by variably adjusting at least one process parameter in addition to temperature control, also offers the advantage of facilitating functional integration through local optimization of the component's properties, which is associated with a reduction in the number of parts and thus with a reduction in costs.

[0015] The load parameter of the component is determined, for example, by computer-aided simulation and / or by a test and / or by a calculation and / or the like, which makes it possible to determine the hardness properties of the component, which vary in the hardness range, particularly quickly and cost-effectively.

[0016] In an advantageous embodiment of the invention, an additional process parameter is set: the speed at which the energy jet is guided over the hardening area, i.e., over the surface of the component. This speed is referred to as the feed rate and influences both the setting of the hardening level and the hardening depth.

[0017] Furthermore, it can be advantageously provided that, as an additional process parameter, cooling or heating of the component or its surface is set using a liquid or gaseous medium, which also makes it possible to adjust the hardness properties of the component in the hardness range.

[0018] Furthermore, it can be advantageously provided that, as an additional process parameter, the component or its surface is heated by means of an additional heat source, such as inductive or radiant heating, thereby enabling the hardness properties of the component to be varied within the hardness range. In this way, a tempering effect can be achieved by utilizing reduced cooling, which has a beneficial effect on toughness, fatigue strength, or crack susceptibility.

[0019] It is also possible to set the energy level of the energy beam as an additional process parameter. It should be noted here that the energy beam can be designed, for example, as a laser beam or an electron beam.

[0020] Thus, the hardening depth, also known as case hardening depth, and / or the hardness level can be optimally adjusted to the requirements using a laser beam or an electron beam. The hardening depth and / or hardness level can be set as high as necessary to produce a robust component, but simultaneously as low as possible to reduce costs, minimize thermal stress, and / or the component's susceptibility to cracking. Minimizing the component's thermal stress is advantageous because it minimizes distortion, oxidation, and tempering effects on adjacent areas.

[0021] The customized settings also enable optimal utilization of the energy beam, resulting in reduced costs and shorter cycle times. To achieve short cycle times, the highest possible feed rate should be aimed for, while the variation in hardness properties within the hardening range can be adjusted by other process parameters. It should be noted here that not only one process parameter, but several process parameters can be variably adjusted within the hardening range using the inventive method.

[0022] The ability to control the hardness properties makes it possible, if necessary, to deliberately create distortions or release residual stresses that counteract distortion elsewhere and thus allow a limited degree of straightening of the component. The distortion of the bore in the cam serves as an example.

[0023] This eliminates time-consuming and costly rework. This reduces the costs for the inventive method as well as for a component produced by the inventive method. The rework includes, for example, straightening, measurements, and / or machining, all of which may be eliminated by the inventive method – depending on the component.

[0024] Tempering zones refer to zones with altered hardness and reduced compressive or even tensile stress in order to counteract or avoid the aforementioned distortions of the component.

[0025] The invention also includes a component which is hardened, at least locally, in a hardness zone by means of an energy beam, in particular a laser beam, an electron beam, or the like, depending on process parameters, wherein the hardness zone of the component is variably adjusted during operation by at least one process parameter of the hardening process depending on a previously determined load parameter of the component. Advantageous embodiments of the method according to the invention are to be regarded as advantageous embodiments of the component according to the invention, and vice versa.Thus, the component according to the invention is a component which, in its hardness range, has hardness properties adjusted to at least one load parameter and therefore exhibits this robustness in areas where high robustness is required, while in order to save time and costs, in less heavily stressed areas, which for example also require higher elasticity, the component can be less hard, i.e., with a smaller hardening depth and / or with a lower hardness level.

[0026] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0027] The drawings show in:

[0028] Fig. 1 a schematic longitudinal sectional view of an embodiment of the component according to the invention in the form of a cam for a camshaft, which is hardened by means of an embodiment of the method according to the invention;

[0029] Fig. 2 a further schematic longitudinal sectional view of an alternative embodiment of the cam according to Fig. 1;

[0030] Fig. 3A another schematic longitudinal section view of the cam according to Fig. 2;

[0031] Fig. 3B a velocity profile of a laser beam for hardening the cam according to Fig. 3A across the circumference of the cam according to the preceding figures; and

[0032] Fig. 4 A schematic longitudinal section view of a cam for a camshaft, which is hardened by induction hardening in accordance with the state of the art.

[0033] The Fig. Figure 1 shows a component in the form of a cam. 10 , which uses an energy beam in the form of a laser beam in a hardening area 12 is hardened. The following applies equally to one or more cams. 10a cam piece that is axially movable on a support shaft. The hardness range 12 extends over the entire circumference of the cam 10 .

[0034] The cam 10 is hardened by means of a process in which process parameters of the process depend on a previously determined load parameter of the cam. 10 during its operation, variable in the hardness range 12 be hired.

[0035] During the operation of the cam 10 is this via a corresponding recording 14 It is connected to a camshaft of an internal combustion engine in a rotationally fixed manner and actuates a corresponding gas exchange valve of the same.

[0036] Again Fig. As can be seen from point 1, the hardness range is 12 about the circumference of the cam 10The cam's hardness properties are variable. This means that the cam's hardness characteristics, i.e., its case hardening depth (also known as case indentation depth) and hardness level, are variable, i.e., not constant, across the cam's circumference. 10 are formed. The hardening depth is determined in the circumferential direction according to a directional arrow. 16 of the cam 10 adapted to the load.

[0037] The aforementioned, pre-determined load parameter is a measure of the load on the cam. 10 during its operation and, for example, within the framework of a simulation or the like.

[0038] Depending on the load parameter, whereby a plurality of load parameters may be provided, which are determined in advance, areas are 18 , 20 , 22 and 24 about the circumference of the cam 10determined which exhibit different loads and therefore must have different hardness properties in order to produce a particularly robust cam. 10 to produce something that, on the other hand, has low costs. This compromise is feasible in such a way that the areas 18 , 20 , 22 and 24 a sufficiently high, but only as low as possible, hardness and hardening depth to precisely fit the cam. 10 to be able to manufacture it in a particularly robust way on the one hand, but also cost-effectively on the other.

[0039] The area 18 This marks the tip of the cam. 10 , in which area 18 a high surface hardness, i.e. a high level of hardness on the surface, and a medium case hardening depth, i.e. a medium case hardening depth, are necessary.

[0040] The area 20 marks the flanks of the cam 10, where high surface hardness and a high case hardening depth are required. In the area 20 , i.e., the bore, it is particularly important to avoid any distortion of the cam. 10 to avoid this in order to achieve a trouble-free fit on the camshaft or when forming the cam contour on a sliding piece on a carrier shaft.

[0041] The area 24 identifies the area of ​​the cam's base circle 10 , in which typically only a low to medium surface hardness and a low case hardening depth are required.

[0042] Based on the Fig. 2. The aforementioned method for representing the hardness range will be used. 12 of the cam 10 clarifies. In the area 18 is the described formation of the hardness area 12 for example, this can be achieved by increasing the speed at which the laser beam is used to harden the cam. 10and thus to the formation of the hardness zone 12 over the surface of the cam 10 is guided. In this process, the feed rate of the laser beam is varied as a process parameter within the hardening range. 12 set.

[0043] In the areas 20 and 24 If the bore is distorted, the contour of the bore can be influenced by deliberately increasing the hardening depth or by adjusting the cooling.

[0044] Directional arrows 26 , 28 and 30 This indicates a targeted, local cooling of the cam. 10 During the execution of the process, more intensive cooling increases the hardness level and the case hardening depth. This cooling thus represents a further process parameter, which depends on the previously determined load parameter of the cam. 10 variable in the hardness range 12 is being discontinued.

[0045] Monitoring the surface temperature of the cam 10 During the execution of the process, temperature control within the process is permitted, thus keeping the temperature constant, which reduces fluctuations in the hardening depth and prevents melting of the surface.

[0046] The Fig. 3A and Fig. Figure 3B, taken together, illustrates the described variation in the circumferential feed of the laser beam according to the direction arrow. 16 of the cam 10 for variable adjustment of the hardness range 12 , whereby according to the Fig. 3A of the cams 10 is divided into four areas A, B, C and D, which in turn are on the abscissa 32 a diagram 34 are applied, on whose ordinate 36 The feed rate, also known as feed rate, is plotted on the second ordinate. 38 of the diagram 34The power of the laser beam is plotted, with a dotted line pattern. 40 This indicates the maximum power of the laser beam, i.e., 100% of its capacity. The direction of rotation can also be reversed.

[0047] It is particularly advantageous to select the laser beam source at a maximum power level that ensures sufficient power, including a control reserve, for all ranges at the chosen feed rate. The higher the feed rate that can be selected, the shorter the cycle time and the more efficiently the beam source is utilized; that is, the closer the curves approximate. 40 and 42 This allows the costs for the procedure as well as for the cam to be calculated. 10 Keep low.

[0048] A regulation is only necessary insofar as it prevents overheating of the cam's surface. 10to avoid, but still achieve a sufficiently high conversion temperature, whereby this regulation is achieved through a process 42 The diagram shows the performance curve during the cam hardening process. 10 reflects.

[0049] A course 44 indicates the feed rate during the cam hardening process. 10 starting from area A to area D, where area D is referred to in the diagram 34 shown course 40 mirror symmetric with respect to an axis 46 connects. Further axes 48 and 50 serve to divide the diagram 34 in the aforementioned areas A, B, C and D.

[0050] Again Fig. As can be seen in 3B, a variation in the feed rate occurs during the process, which corresponds to the course 44obeyed, for the required development of the cam's hardness properties in accordance with the previously determined load parameter. 10 in the hardness range 12 carried out, whereby the case hardening depth and / or the surface hardness (hardness level) within the hardness range 12 can be adjusted, or is adjusted, by varying the exemplary process parameter feed rate within the hardening range. 12 is being discontinued.

[0051] The same applies, for example, to the aforementioned cooling of the cam. 10 in the procedure, whereby analogous to the course 44 a corresponding flow or supply rate of cooling medium, which is, for example, oil or water or the like, variably within the hardness range during the process 12 is being discontinued.

[0052] The adjustment of the hardness properties is variable within the hardness range. 12This allows for the creation of a robust yet cost-effective component in the form of the cam. 10 , which has load-adapted hardness properties. QUOTES INCLUDED IN THE DESCRIPTION

[0053] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0054] DE 3733147 A1

[0002]

Claims

[1] Method for hardening a component ( 10 ), in which the component ( 10 ) by means of an energy beam, in particular a laser beam, an electron beam or the like, at least locally in a hardness area ( 12 ) is hardened depending on process parameters, characterized by , that at least one process parameter of the procedure depends on a previously determined load parameter of the component ( 10 ) variable in operation within the hardness range ( 12 ) is set up. [2] Method according to claim 1, characterized in that a speed at which the energy jet is guided over the hardening area is set as a process parameter. [3] Method according to one of claims 1 or 2, characterized in that the process parameter is cooling of the component ( 10 ) is adjusted using a cooling medium. [4] Method according to one of claims 1 or 2, characterized in that an additional heating of the component is used as a process parameter ( 10 ) is set using another energy source. [5] Method according to one of the preceding claims, characterized in that an energy level of the energy beam is set as a process parameter. [6] Method according to one of the preceding claims, characterized in that the load parameter of the component is determined by a computer-aided simulation and / or by a test and / or by a calculation. [7] Method according to one of the preceding claims, characterized in that in the hardness area ( 12 Variable hardness values ​​can be generated. [8] Method according to one of the preceding claims, characterized in that in the hardness range ( 12 Variable hardening depths can be produced. [9] Method according to one of the preceding claims, characterized in that in the hardness range ( 12 ) Starting zones are created. [10] Component ( 10 ), which, by means of an energy beam, in particular a laser beam, an electron beam or the like, at least locally in a hardness area ( 12 ) is hardened depending on process parameters, characterized in that the hardness range ( 12 ) of the component ( 10 ) by at least one process parameter of the hardening process depending on a previously determined load parameter of the component ( 10 ) is variably set during operation.

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