DE102016005833A1 - Shaft, in particular crankshaft, and method for producing such a shaft - Google Patents

Abstract

The invention relates to a method for producing a shaft, in particular a crankshaft, and a shaft, in particular a crankshaft, which at least partially in at least one radius and / or in at least one groove has a different chemical composition than a main body of the shaft, wherein the radius and / or the groove is at least partially cured martensitic and / or bainitic or are.

Description

The invention relates to a shaft, in particular a crankshaft, according to the preamble of patent claim 1 and a method for producing such a shaft according to the preamble of patent claim 4.

Such, for example, designed as a crankshaft shaft and a method for producing such a shaft are for example already in the DE 2 226 530 A1 known. The shaft has at least partially in at least one radius and / or in at least one groove on a different chemical composition than a main body of the shaft. In the method, the shaft is thus at least partially formed in at least one radius and / or in at least one groove with a different chemical composition than a main body of the shaft and at least locally in the region of the radius and / or the groove opposite at least one to the radius or the groove subsequent subregion of the shaft is hardened at least by the action of heat,

Object of the present invention is to develop a shaft and a method of the type mentioned in such a way that the shaft can be cured particularly advantageous.

This object is achieved by a shaft with the features of claim 1 and by a method having the features of claim 4. Advantageous embodiments with expedient developments of the invention are specified in the remaining claims.

In order to further develop a shaft of the type specified in the preamble of patent claim 1 such that the shaft formed, for example, as a crankshaft for a reciprocating engine can be hardened particularly advantageously, it is provided according to the invention that the radius and / or the groove are at least partially martensitic and / or bainitic is cured or are. As a result, the shaft in the usually highly loaded region of the radius or the groove has a particularly advantageous hardness and thus stability, wherein a predominant part of the shaft of a cost-effective material from which at least the main body is formed, can be produced.

Alternatively or additionally, it can be provided that the radius and / or the groove is at least partially mechanically consolidated or are. In other words, it is alternatively or additionally provided that the shaft or the base body is at least partially mechanically consolidated in the region of the radius or the groove. In this way, a particularly high strength of the shaft in the region of the radius or the groove can be realized.

It has been found to be particularly advantageous if the main body of the shaft is formed of steel, wherein the radius and / or the groove at least partially a higher by at least 0.1 percent by weight carbon content, in particular by at least 0.15 weight percent higher carbon content, as the main body has. In other words, the carbon content in the region of the radius or the groove is at least 0.1 weight percent, in particular at least 0.15 weight percent, higher than the carbon content of the base body, so that in the region of the radius or the groove of a particularly high hardness can be realized.

To further develop a method specified in the preamble of claim 4 such that the example formed as a crankshaft for a reciprocating engine shaft can be cured particularly advantageous, a first step is provided according to the invention, in which an at least carbon-containing material targeted partially to the area of Radius or the groove is applied. The inventive method further comprises a second step preferably subsequent to the first step, in which the material applied to the region is heated by means of at least one laser, whereby the region is hardened while alloying the material into the region. In other words, in the second step, the material, while the material is applied to the area, is applied with at least one laser or a laser beam and thereby heated. As a result, the material is alloyed in the region of the radius or the groove, whereby the shaft is partially or locally, that is hardened in the region of the radius or the groove. A hardening of the adjoining the region of the radius or the groove portion of the shaft is omitted, however, so that the shaft, in particular the body can be made of a cost base material.

The base material can be partially carburized by the material and thereby hardened, so that not the entire base material must be cured. Overall, so the wave can be made in a particularly cost-effective manner, the base material may be, for example, a low-cost, low-carbon material. Due to the partial or local carburizing and hardening of the base material can high Compressive residual stresses can be realized, whereby the load capacity of the shaft can be significantly increased compared to conventional waves. In particular, it is possible to partially carburize the base material by means of the method according to the invention and thereby to harden, in particular in highly stressed areas such as areas of radii and / or grooves, so that the shaft can be produced as a very durable and robust component in a cost effective manner. By means of the method according to the invention, the residual compressive stresses in the region of the radius or the fillet can be significantly increased in comparison to conventional hardening methods, wherein the shaft as a whole can be produced particularly inexpensively.

The material is applied, for example as a powder, wire, tape or platelets, in particular adhesive platelets, to the area, so that the material which constitutes a carbonaceous substance, can be particularly targeted and partially applied to the shaft or to the base material. Under the targeted partial application of the material is only a local application of the material to understand, so that not the entire shaft or the entire base material is provided with the material, but the at least carbon-containing material is only in the range of at least one radius or a groove on the Applied wave, so that at least one subsequent to the radius or the groove portion of the shaft is not provided with the material. Thus, not the entire shaft is carburized or hardened, but there is only partial or local carburization and thus hardening of the shaft, so that the shaft only in the radius or the groove or only in areas of radii or grooves, and not in itself hardened subsections is hardened. In particular, it can be provided that respective material having at least carbon is applied in respective regions of respective radii or fillets, so that the shaft is carburized and hardened relative to respective further portions of the shaft adjoining the radii or fillets. This makes it possible to carburize targeted highly stressed areas of the shaft and thus to harden, with a carburizing and hardening of other, less loaded portions of the shaft can be omitted.

Furthermore, it can be provided that the radius or the groove is arranged in the region of at least one bearing, via which the shaft can be mounted, for example, on a housing. The targeted partial carburizing and hardening of the shaft, for example, the diameter of the bearing can be made very small, so that material and processing time can be saved. In addition, the wear of tools for machining the bearing can be kept low. Likewise, the energy consumption for producing the shaft can be kept low, so that the shaft can be made particularly time-consuming and inexpensive. Furthermore, this can reduce the weight of the shaft, so that a particularly low moment of inertia of the shaft can be realized. As a result, a particularly high performance of a shaft-comprising machine such as an internal combustion engine can be realized, so that the internal combustion engine can be operated with low fuel consumption and high speeds.

It has proven to be particularly advantageous if the region is heated in time after the alloying in of the material by means of a heat source, in particular by means of a laser, and is thereby newly hardened and / or tempered. As a result, a particularly uniform diffusion of the carbon in the region of the radius or the groove can be established.

Alternatively or additionally, it is also possible to work with the heat treatments mentioned with the aid of a laser with other heat sources, for example with the aid of an electron beam.

Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing; 1 shows a schematic perspective view of a crankshaft for a motor vehicle, wherein the shaft is locally carburized and hardened by at least partially depositing at least carbon-bearing material on at least a portion of a radius or a groove a laser is alloyed in the area.

The single FIGURE shows a detail in a schematic perspective view of a shaft, which is presently designed as a crankshaft for a reciprocating engine. The reciprocating engine is designed in particular as a reciprocating internal combustion engine and is used, for example, in a motor vehicle, which can be driven by means of the reciprocating internal combustion engine. The reciprocating internal combustion engine is also referred to as an internal combustion engine.

In its finished state, the internal combustion engine comprises a crankcase in which the crankshaft is rotatably mounted about an axis of rotation relative to the crankcase. For this purpose, the crankshaft comprises a plurality of shaft journals, which are arranged one behind the other or in succession in the axial direction of the crankshaft. Of these shaft journal is in the Fig. A with 10 identified shaft journal recognizable. At least on one side joins the shaft journal 10 a crank arm 12 the crankshaft. To the crank arm 12 closes in the axial direction in the Fig. A detail recognizable crank pin 14 the crankshaft, wherein on the crank pin 14 a connecting rod of the internal combustion engine can be rotatably mounted.

The shaft journal 10 forms a bearing over which the crankshaft is rotatably mounted in the finished state of the engine to the crankcase. The bearing is also referred to as bearing or main bearing. From the Fig. It can be seen that the shaft journal 10 The outer peripheral side is cylindrical or has the shape of an at least substantially straight circular cylinder, so that the shaft journal 10 and thus the bearing have a predeterminable diameter, in particular outer diameter.

In the following, the shaft itself and a method of manufacturing the shaft will be described. The shaft has at least partially in at least one radius and / or in at least one groove on a different chemical composition than a main body of the shaft. In order to be able to harden the shaft in a particularly advantageous manner, the radius and / or the fillet is at least partially hardened martensitic and / or bainitic. Alternatively or additionally, the radius and / or the groove are at least partially mechanically consolidated.

In the process, the crankshaft becomes local in area 16 the at least one radius or the at least one groove opposite to at least one adjoining the radius or the groove portion of the crankshaft hardened at least by the action of heat. In other words, in the field 16 a radius or a groove of the crankshaft is arranged. To the radius or the groove, that is to the area 16 close in the axial direction of the crankshaft on both sides more sections 18 the crankshaft, with the crankshaft in the range 16 but not in the area 16 subsequent subareas 18 carburized and thereby hardened. As a result, the crankshaft is not completely or completely, but only locally and thus partially hardened, so that the crankshaft can be made particularly cost-effective as a robust and resilient component.

In this case, the crankshaft, in particular its base body, made of a low-cost and low-carbon base material in particular, wherein the base material is locally or partially carburized and thereby cured. The previous and following remarks regarding the carburizing and the resulting local hardening of the crankshaft or the base material in the area 16 can be readily transferred to other, not shown in the Fig. areas of the crankshaft, in which, for example, at least one radius or at least one groove is arranged. The range of such a radius or such a groove is usually a highly loaded area of the crankshaft, in which high loads, in particular high voltages, can occur. By the local carburizing and hardening of the crankshaft in these areas, that is in the present example in the area 16 , the heavily loaded areas can be upgraded, so that the crankshaft can withstand high loads without damage and at the same time can be manufactured from a particularly cost-effective base material. In this example, the range is 16 a transition region over which the shaft journal 10 in the crank arm 12 passes.

Order now the area 16 harden in a particularly advantageous manner, the method comprises a first step, in which a material having at least carbon 20 targeted partially on the area 16 the radius or the groove is applied. The method further comprises a second step subsequent to the first step, in which the at least carbonaceous material 20 is heated by means of at least one laser or by means of at least one laser beam, whereby the material 20 in the area 16 and thus alloyed into the base material. As an alternative to a laser, another heat source, for example an electron beam, can also be used. This will be the area 16 , but not the subarea 18 specifically hardened. Through this partial or local and targeted carburizing and thus hardening of the crankshaft, the crankshaft can be configured as required with particularly advantageous mechanical properties, so that a particularly high mechanical load capacity of the shaft can be realized. Through targeted carburizing it is possible, despite the use of the base material, which may have only a relatively low carbon content in the area 16 to realize a sufficient carbon content, since the carbonaceous material 20 in the area 16 is alloyed. This is it for example, possible in the field 16 to produce a metal alloy specifically, the composition of which depends on the composition of the subregions 18 or the base material. In particular, it is conceivable that the material 20 in itself a metal alloy which is in the range 16 and thus alloyed into the base material.

In particular, it is possible that the material 20 in powder form, that is, as a powder or as a wire or tape or platelets, in particular adhesive platelets, on the area 16 is applied. For example, the material becomes 20 on the area 16 glued or by means of an adhesive to the area 16 fixed, especially before alloying. By this fixing of the material 20 before alloying can the area 16 particularly targeted and needs-based with the material 20 be provided. In particular, it is possible that the material 20 Molybdenum and / or manganese and / or cobalt with or without each 30 percent mixing proportion and the remainder iron and / or graphite.

For applying the material 20 on the area 16 Different application methods can be used. For example, the material becomes 20 by magnetization or by magnetic force at the area 16 or held on the base material. In particular, a magnetizing without adhesion promoter or with a primer layer is conceivable, under whose mediation the material 20 in that area 16 is fixed before alloying. Further, graphitization such as coating a piston skirt with thin film screen printing may be used. Furthermore, it is conceivable to use metal guidance and thorough mixing with an exothermic feeder cap and eddy current mixer.

Before alloying the material 20 in the area 16 especially before applying the material 20 on the area 16 , pretreatment with plasma cleaning and surface tension reduction to, for example, 42 millinewtons per meter can be performed. Alternatively or additionally, an inductive preheating of the region representing a local radius region 16 possible in order to avoid hardening cracks or to keep the susceptibility to hardening low.

In principle, it may be advantageous after alloying the area 16 with the help of a heat source, in particular with the help of a laser, to heat once again while the area 16 austenitize first to produce a finer hardness structure there after quenching in a kind of Umhärtevorgang.

Additionally or alternatively, it may also be advantageous, after alloying the area 16 with the help of a heat source, in particular with the help of a laser, to heat again. This process step serves to start or relax the structure.

It has also proven to be particularly advantageous if the range 16 after alloying the material 20 is mechanically strengthened. For mechanical post consolidation, for example, burnishing is used, whereby the area 16 is post-solidified after alloying.

By heating the material 20 this is melted and locally alloyed into the base material, thereby creating a particularly advantageous structure, in particular hardness structure of the base material. This local carburization and thus hardening will cause residual compressive stresses in the area 16 significantly increased compared to conventional hardening processes. In other words, it comes by the method for increasing the compressive residual stresses in the structure and thus to increase the hardness, so that the crankshaft can be partially designed with particularly advantageous mechanical properties.

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

• DE 2226530 A1 [0002]

Claims (9)

Shaft, in particular crankshaft, which at least partially in at least one radius and / or in at least one groove has a different chemical composition than a main body of the shaft, characterized in that the radius and / or the groove is at least partially hardened martensitic and / or bainitic or are. Shaft according to claim 1, characterized in that the radius and / or the groove is at least partially mechanically consolidated or are. Shaft according to claim 1 or 2, characterized in that the main body of the shaft is formed of steel, wherein the radius and / or the groove at least partially a by at least 0.1 percent by weight higher carbon content, in particular by at least 0.15 weight percent higher carbon content , as the main body of the shaft has. A method for producing a shaft, in particular a crankshaft, in which the shaft is formed at least in sections in at least one radius and / or in at least one groove with a different chemical composition than a main body of the shaft and at least locally in the area ( 16 ) of the radius and / or the groove opposite at least one adjoining the radius or the groove portion ( 18 ) of the shaft is cured at least by the action of heat, characterized by the steps: - targeted partial application of an at least carbon-containing material ( 20 ) on the area ( 16 ) of the radius or the groove; and - heating the material ( 16 ) by means of at least one laser, whereby the area ( 16 ) while alloying the material ( 20 ) in the area ( 16 ) is hardened. Method according to claim 4, characterized in that the material ( 20 ) as powder, wire, tape or platelets on the area ( 16 ) is applied. Method according to claim 4 or 5, characterized in that the area ( 16 ) after alloying the material ( 20 ) is heated by means of a heat source, in particular by means of a laser, and thereby hardened again and / or tempered. Method according to one of claims 4 to 6, characterized in that the area ( 16 ) after alloying the material ( 20 ) mechanically strengthened, in particular, is rolled. Method according to one of claims 4 to 7, characterized in that the material ( 20 ) is carbonaceous and also has iron and / or chromium and / or molybdenum and / or manganese and / or cobalt. Method according to one of claims 4 to 8, characterized in that the material ( 20 ) prior to alloying by magnetic force at the region ( 16 ) is fixed.

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