DE102013017132A1 - Hardening portion of component, comprises placing component at distance from first electrode, connecting capacitor to first and second electrodes, charging capacitor with electric voltage, and applying shock wave to portion - Google Patents

Abstract

The method comprises placing a component at a distance from a first electrode (14), providing a capacitor (20) and connecting the capacitor to the first electrode via a first connection (22) and a second electrode via a second connection, partially and electrically insulating the first and second electrodes by an insulator (16), charging the capacitor with an electric voltage such that an electrical breakdown between the electrodes is prevented, and applying shock wave to a portion of the component for hardening the portion of the component between the electrodes. The method comprises placing a component at a distance from a first electrode (14), providing a capacitor (20) and connecting the capacitor to the first electrode via a first connection (22) and a second electrode via a second connection, partially and electrically insulating the first and second electrodes by an insulator (16), charging the capacitor with an electric voltage such that an electrical breakdown between the electrodes is prevented, and applying shock wave to a portion of the component for hardening the portion of the component between the electrodes or partially vaporizing and ionizing the component or an electrode surface by an energy beam. The shock wave causes the electrical discharge between the electrodes. The electrodes are provided close to the component. The insulator circumferentially surrounds the electrode, and includes a gas, a liquid, a solid body or vacuum. A portion of one of the electrodes, the portion of the component and/or the insulator are applied with the energy beam such that a material of the portions is vaporized and charge carriers are provided for a high-voltage breakdown.

Description

The invention relates to a method for solidifying at least a portion of a component.

Methods for consolidating at least one subarea of a component are already well known from the general state of the art. By solidifying the portion, the strength of the component in the portion can be increased from a condition without solidification. As solidification process, for example, rollers or hammers are known. However, these solidification methods have only a low depth effect. In addition, massive tools are required to perform this solidification process, with the portion to be consolidated accessible to these massive tools. In addition, when solidifying the portion usually heavy loads on the component act as the component must be kept, for example, in a counter-holder. Usually, the component has to be subsequently adjusted or machined or reshaped to measure, in order to compensate for the deformations or distortions that have occurred.

Another method for solidifying at least a portion of a component is, for example, shot peening. However, the shot peening also has a low depth effect. In addition, it comes to abrasion of the blasting agent, whereby the component can be contaminated. In addition, conventional systems for shot peening are wear-intensive. Another disadvantage is that the surface of the portion can be damaged by the shot peening.

Another possibility for solidifying at least one subregion of a component is the so-called laser peening. By means of the Laserpeenings a high depth effect can be realized. In addition, a thermal influence on the component can be avoided or at least kept low. A laser peening method and an apparatus for performing such a laser peening method are, for example, the US 5,741,559 A to be known as known. As part of the laser peening process, at least one laser beam is used to solidify the subregion. A coating for absorbing energy provided by the laser beam is applied to the subregion to be consolidated. The laser beam or a laser for providing the laser beam is operated pulsed. The coating is acted upon by laser beam pulses and leads to a sudden evaporation of the coating, whereby pressure waves or shock waves are generated. These propagate from the surface into the material, similar to sound waves. Due to these shock waves, the sub-area is also solidified in depth.

The disadvantage of laser peening processes, however, is that costly special lasers with extremely high pulse peak power are required to perform the laser peening processes. Standard components such as optics, cabs, etc. are hardly usable here. The component must also be provided in advance with a coating, which may need to be removed after peening again. Thus, such laser peening process can be very expensive to perform.

Finally, from the general state of the art, thermal methods for increasing the strength of the component are also known. These thermal methods may be, for example, hardening or tempering. However, this leads to an undesirably high heat load on the component, which can result in a distortion of the component. Furthermore, a high expenditure on equipment and energy is required for these thermal processes. Furthermore, these thermal methods are poorly applicable locally limited, which can make it difficult, for example, a subsequent cutting. The effect in depth is limited, since a minimum quenching speed must be achieved for the hardening effect.

The US 2012/0114007 A1 discloses a method for generating a laser-guided electrical discharge under water. At a first time, a laser pulse is fired past a first electrode, the laser pulse being fired in the direction of a desired electrical discharge. The electrode is connected to an external energy source.

The laser pulse has a propagation path and a power greater than a critical power level. The laser pulse generates on its way through the water by evaporation and ionization a channel in which there are many free charge carriers. The laser ionized channel has a higher conductivity than the surrounding water, so that the discharge takes place abruptly along the channel and the direction can be specified with the laser beam.

As part of the method, the external power source is used to generate an electric drive field, wherein by means of the electric drive field, an electrical discharge is effected at a second time following the first time. The electrical discharge passes through the water along the path of the laser-ionized channel.

In addition, laser peening methods are the US 4,937,421 , of the US Pat. No. 6,049,058 and the US 2003/0029522 A1 to be known as known.

The object of the present invention is to provide a method for solidifying at least one subregion of a component which can be carried out cost-effectively and in which undesired impairments such as, for example, thermal and mechanical stresses and undesirable microstructural transformations of the component can be avoided.

This object is achieved by a method having the features of patent claim 1. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the remaining claims.

Such a method for solidifying at least one partial region of a component by means of at least one pressure wave using at least one energy beam comprises a first step, in which the component is arranged at a distance from at least one electrode. In a second step of the method, at least one capacitor is provided. Further, the capacitor is electrically connected on the one hand to the first electrode and on the other hand to a second electrode or to the component as an electrode. This means that the electrodes are connected or coupled capacitively to one another via the capacitor.

In a third step of the method, the first electrode is electrically insulated from the second electrode at least partially by means of at least one insulator or insulating means. In a fourth step of the method, the capacitor is charged with an electrical voltage, in particular with an electrical high voltage, in such a way that an electrical breakdown between the electrodes is omitted. In a fifth step of the method, the pressure wave acting on the partial area of the component is solidified of the subregion is effected by at least partially vaporising and / or ionizing the insulator arranged between the electrodes by means of the energy beam, resulting in at least one electrical discharge between the electrodes which effects the pressure wave. The decisive factor is the generation of charge carriers for the rollover. This can also be done by evaporating or ablating the component, a layer on the component or the electrode surface.

The energy used to evaporate the insulator is much lower than in classical laser peening. Also, a local evaporation of the electrode or the component requires comparatively small amounts of energy, the z. B. already be achieved by popular, very inexpensive labeling lasers. Most of the energy for the pressure wave comes from the electrical discharge, comparable to the pressure wave in a lightning strike. The insulator can be formed as a gas, solid or liquid. In the case of a liquid, the surrounding liquid around the vapor bubble additionally impedes the lateral propagation of the pressure wave.

By means of the method according to the invention, the advantages of the laser peening method can be realized. However, the mentioned disadvantages of the laser peening method can be avoided since the method can be carried out with simple and inexpensive components. Electrical energy for the pressure wave is more cost-effective, since no conversion from electrical to laser energy. Efficiency Laser today approx. Max. 40% electrical-optical.

By means of the method according to the invention, for example, the structural strength of the entire component or locally in critical component areas can be increased without or with only a slight influence of heat. As a result, the component can be made slimmer, that is to say with a smaller wall thickness, at least in the solidified subregion in relation to a non-solidified state, or endures higher loads for the same wall thickness, especially under dynamic load. Furthermore, it may be possible to dispense with the use of costly materials under certain circumstances. At the same time, a particularly high durability or robustness of the component can be realized above all against dynamic loads or even ensured at all.

An example of a component which can be solidified by means of the method at least in a partial area is a crankshaft for a reciprocating internal combustion engine. Such a crankshaft has bearings with radii. At these radii, the crankshaft can be solidified by means of the method according to the invention. Without this consolidation cracks could occur during operation due to notch effects and stress concentrations.

The inventive method has a high depth effect. This means that the sub-area can be particularly deep, that is solidified to a very large depth. In addition, a heat load on the component can be avoided or at least kept low. In addition, the method is locally applicable. This means that the component can be solidified there and only where solidification is required. The energy for carrying out the method can be generated particularly inexpensively. About that In addition, the network load can be kept low because the charging time for charging the capacitor can be made much larger than the discharge time of the capacitor, which is discharged through the electrodes in the electrical discharge.

Preferably, the laser beam used as the energy beam is a laser beam provided by a laser. For this a standard laser and standard components can be used. In addition, low-cost protection devices such as KE welding (capacitor discharge welding) or laser welding can be used. Except for the electrodes wear parts are not provided in the process. In this case, the electrodes can be simple and inexpensive copper parts or the like. In addition, the use of blasting agents is not required and not provided.

Furthermore, by means of the method according to the invention it is also possible to solidify subregions which would not be accessible to conventional solidification methods such as, for example, rolls or the like. In the method, only an accessibility for the electrode and the laser beam must be provided, with optionally a beam guidance can be carried out in the electrode. Thus, under certain circumstances, bores and inner walls of components can be solidified by means of the method according to the invention. Due to the particularly high depth effect compared to conventional methods, the inventive method also has a very high lightweight and integration potential.

By means of the method according to the invention, for example, at least partial areas of highly stressed components of motors can be handled. The component with the portion to be solidified is formed for example as a bearing or connecting rod. The component may be, for example, a shaft or a pinion of a transmission or a hub or a bearing of an axle of a motor vehicle. The method can also be applied to components for aircraft construction, for turbines, engines, compressors, etc. In particular, in internal combustion engines, which are executed according to the so-called downsizing concept, the demand for local solidification of components is steadily increasing.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

The drawing shows in:

1a Each a schematic view of a component having at least a portion which is solidified by means of at least one pressure wave using at least one energy beam in a corresponding method, wherein 1a Show different steps of the method according to a first embodiment;

2 a schematic side view of an electrode, which is used in the context of the method;

3a Each is a schematic side view of an embodiment of an electrode for performing the method;

4 a schematic view of the component for illustrating a second embodiment of the method;

5 a schematic view of two components for illustrating a third embodiment of the method; and

6 a further schematic view of the component for illustrating a fourth embodiment of the method.

In the figures, the same or functionally identical elements are provided with the same reference numerals.

1a 1 serve to illustrate a first embodiment of a method for solidifying at least one partial area 10 a component 12 , The component 12 is also referred to as a workpiece.

In one out 1a recognizable, first step of the procedure becomes the component 12 at a distance a to an electrode 14 arranged. Furthermore, the component 12 from the electrode 14 by means of an insulator 16 electrically isolated. In one based on 1a -E, the first embodiment of the method is referred to as the insulator 16 a fluid, for example a gas or a liquid used. For example, air can be used as the gas. Alternatively, it may be at the insulator 16 to act a vacuum.

How out 1a recognizable, become the component 12 and the electrode 14 at least partially in a container 18 arranged, in which also the insulator 16 is arranged. At the container 18 it is, for example, a chamber or a basin. The container 18 is filled or evacuated with the insulator in the form of a liquid or a gas or a gas mixture.

In a third step of the method, at least one capacitor 20 provided with a capacitance C and on the one hand with the component 12 and on the other hand with the electrode 14 electrically connected. It can be seen that the electrode 14 as the first electrode and the component 12 be used as a second electrode, wherein the component 12 is arranged at a distance a to the first electrode. The capacitor 20 has a first connection 22 on, over which the capacitor 20 with the component 12 (second electrode) is connected. Further, the capacitor has 20 a second connection 24 on, over which the capacitor 20 with the electrode 14 (first electrode) is connected.

Thus, the component 12 and the electrode 14 over the capacitor 20 capacitively connected.

Out 1a is also a charging circuit 26 for the capacitor 20 recognizable. By means of the charging circuit 26 becomes the capacitor 20 in a fourth step of the method with an electrical voltage U charged such that an electrical breakdown between the component 12 and the electrode 14 omitted. In other words, the capacitor 20 Charged with high voltage via a charger. The distance a and the voltage U are to be chosen so that just no electrical breakdown or electrical breakdown between the component 12 and the electrode 14 he follows.

In one out 1b A recognizable fifth step of the method is, for example, an energy beam in the form of a laser beam 28 between the electrode 14 and the component 12 focused. The laser beam 28 is provided by a laser, not shown in the figures, which is operated pulsed. This will cause the laser beam 28 provided in the form of one or more laser pulses or laser beam pulses. In other words, one or more laser pulses are ignited and emitted by the laser.

The laser beam 28 For example, from the outside, if necessary, by at least one opening in the container 18 to a desired site of action in the container 18 be directed. In such an opening, through which the laser beam 28 from the outside to the inside of the container 18 is guided, it may be, for example, an anti-reflective window or the like. Alternatively, the laser beam 28 for example via the electrode 14 be made available 2 is recognizable. 2 shows the electrode 14 , in which at least one light guide in the form of a glass fiber 32 extends. In the electrode 14 is also at least one lens 34 provided, by means of which emerging from the light guide light beams can be bundled. The laser beam 28 can then, for example, a protective glass 36 from the electrode 14 emerge and be led to the site of action.

How out 1c is recognizable, by means of the laser beam 28 the insulator 16 that means the component 12 from the electrode 14 electrically insulating medium between the electrode 14 and the subarea 10 vaporized and ionized abruptly. This will increase the dielectric strength between the electrode 14 and the component 12 , that is abruptly lowered between the electrodes, because free charge carriers are generated and the temperature in one of the evaporation of the insulator 16 resulting vapor bubble 30 is very high. This will be an off 1d detectable ignition between the component 12 and the electrode 14 that is the capacitor 20 discharges abruptly across the electrode 14 and the component 12 ,

Optionally, at least a portion of the electrode 14 and / or at least a portion of the component 12 with the laser beam 28 be acted upon, so that material of the respective portion is evaporated. In other words, the laser beam can 28 optionally also on the electrode 14 or the component 12 be directed to vaporize material there. This can be done especially when, as the insulator 16 Vacuum is used. By this evaporation of material of the electrode 14 or the component 12 If necessary, the ionization can be facilitated, so that a higher number of free charge carriers can be generated. By evaporation and ionization of the insulator 16 At least one electrical discharge between the component 12 and the electrode 14 causes what is in 1d through a flash 38 is illustrated. During the electrical discharge, the laser beam can 28 additionally provide energy or be shut off. The electric discharge creates an out 1d recognizable pressure wave in the form of an acoustic shock wave 40 , which are also in the component 12 moved and there in the subarea 10 leads to a solidification effect.

3a Figure d show different embodiments of the electrode 14 to the shock wave 40 specifically lead and in addition an energy release mainly into the component 12 to cause or the pressure wave at the electrode 14 to reflect or to focus. How out 3a -D can be seen, this can be done on the electrode 14 different electrical insulation elements 42 be arranged. In addition, at least one of the sub-area 10 facing end face 44 the electrode 14 and / or one of the subarea 10 facing end face 46 of the insulation element 42 concave or partial area 10 be arched trained.

Out 1e it can be seen that after discharge the capacitor 20 over the charging circuit 26 is recharged. In addition, the electrode becomes 14 and / or the laser beam 28 along a component contour to be solidified, that is, along the partial area 10 emotional. For this purpose, the laser beam 28 and / or the electrode 14 relative to the container 18 be moved while the component 12 relative to the container 18 is not moved. Alternatively or additionally, the component 12 relative to the container 18 and relative to the electrode 14 and / or to the laser beam 28 to be moved.

If necessary, it may be useful to use the electrode 14 as a negative form of the part to be consolidated 10 of the component 12 form and only the laser beam 28 for example, to move over a scanner. For a rotationally symmetrical component, for example a in 1e indicated by a hatching bearing seat, the electrode could 14 for example, be formed linear and the component 12 turns while the laser beam 28 along a gap between the component 12 and the electrode 14 scanned back and forth.

Based on 4 a second embodiment of the method is illustrated. In the second embodiment, as the insulator 16 at least one solid used. This solid is, for example, a coating of the component 12 , in particular a paint. The solid may also be a film, an insert or the like. As an insulator 16 common plastics such as polypropylene and polyethylene terephthalate (PET) can be used, which have a high dielectric strength. The solid can affect the component 12 Applied, between the component 12 and the electrode 14 guided and / or clamped or formed as a continuous feed, for example as a strip material.

5 shows a third embodiment of the method. In the third embodiment, as the electrode 14 a second component 48 used. Thus, in the third embodiment, it is possible to have at least two components 12 . 48 in respective subareas 10 . 50 consolidate at the same time.

In the first embodiment, the second embodiment and the third embodiment, the component becomes 12 as an electrode, that is as a counter electrode to the electrode 14 used. In one based on 6 Illustrated fifth embodiment, the component 12 not used as an electrode. In the fourth embodiment, the electrode becomes 14 and as a counter electrode to the electrode 14 a second electrode 52 used. The electrical discharge is thus not between the electrode 14 and the component 12 but between the electrodes 14 . 52 , where the pressure wave on the sub-area 10 of the component 12 acts. Characterized in that in the fourth embodiment of the electrical flashover between the electrodes 14 . 52 and not between one of the electrodes 14 . 52 and the component 12 takes place, a possibly caused by the discharge influencing the surface of the component 12 be avoided.

In contrast to the laser peening method is based on 1a - 6 illustrate methods for generating the shockwave 40 required energy at least almost exclusively provided by the electrical discharge and not about the laser beam 28 , This allows the pulse peak power and the total energy of the laser beam 28 be kept low, there by means of the laser beam 28 only the insulator 16 or the component is vaporized or ionized. Is considered the insulator 16 used a fluid, as provided for example in the first embodiment, the subregion 10 be processed at least almost as often as the insulator 16 can flow. So it may be possible to increase the depth of consolidation by means of several shock waves. In contrast, the surface is increasingly eroded during laser peening. As a laser for providing the laser beam 28 Standard equipment such as welding lasers or surface finishing lasers can be used. As a result, the method can be carried out inexpensively. A coating of the part to be consolidated 10 to ensure sufficient absorption is not required but can be used as an electrical insulator if required 16 be used. The wavelength of the laser can be adjusted as needed for absorption in the insulator 16 be selected and not after that of the component 12 , Thus, even highly reflective, poorly or non-uniformly absorbing workpiece surfaces can be machined.

The insulator 16 can be optimized by absorption-enhancing additives such as particles and / or additives with improved ionizability to the particular application. By the at least one electrode 14 Optionally, energy can be applied to the component 12 be reflected back, which would otherwise be lost in free irradiation into the environment. This could increase the solidification effect.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5741559 A [0004]
• US 2012/0114007 A1 [0007]
• US 4937421 [0010]
• US 6049058 [0010]
• US 2003/0029522 A1 [0010]

Claims (8)

Method for consolidating at least one partial area ( 10 ) of a component ( 12 ) by means of at least one pressure wave ( 40 ) using at least one energy beam ( 28 ), with the steps: - arranging the component ( 10 ) at a distance from at least one first electrode ( 14 ), - providing at least one capacitor ( 20 ) and connecting the capacitor ( 20 ) on the one hand with the first electrode ( 14 ) and on the other hand with a second electrode ( 52 ), - at least partially electrically insulating the first electrode ( 14 ) from the second electrode ( 52 ) by means of at least one isolator ( 16 ), - Charging the capacitor ( 20 ) with an electrical voltage (U) such that an electrical breakdown between the electrodes ( 14 . 52 ), - effecting on the subregion of the component ( 12 ) acting pressure wave ( 40 ) for solidifying the subregion ( 10 ) by the between the electrodes ( 14 . 52 ) insulator ( 16 ) or the component or the electrode surface at least partially by means of the energy beam ( 28 ) is evaporated and ionized, from which at least one of the pressure wave ( 40 ) causing electrical discharge between the electrodes ( 14 . 52 ) results. Method according to claim 1, characterized in that the component ( 10 ) as one of the electrodes ( 14 . 52 ) is used. Method according to claim 1 or 2, characterized in that the two electrodes ( 14 . 52 ) close to the component ( 12 ) be used. Method according to one of the preceding claims, characterized in that the insulator ( 16 ) the electrodes ( 14 . 52 ) surrounds allumfangsseitig. Method according to one of the preceding claims, characterized in that as insulator ( 16 ) a fluid, in particular a gas or a liquid, is used. Method according to one of claims 1 to 4, characterized in that as insulator ( 16 ) a solid is used. Method according to one of claims 1 to 4, characterized in that as insulator ( 16 ) a vacuum is used. Method according to one of the preceding claims, characterized in that at least a portion of one of the electrodes ( 14 . 52 ) and / or at least a portion of the component ( 10 ) and / or the insulator ( 16 ) with the energy beam ( 28 ) is applied, wherein material of the respective portion is evaporated and charge carriers are provided for a high-voltage flashover.

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