DE102005027053A1 - Design calculation for blanks for sintered metal gears, e.g. for cars and other machines, uses input data determined from a specified final form and calculates local overmeasures correlating with expected surface compaction - Google Patents

Abstract

A method of calculation for designing a blank for a gear made of sintered material (I), in which the input data are determined from a specified final form, one or more loading parameters for the gearing are determined depending on at least one usage condition for the final form, a local overmeasure is calculated for the blank which correlates with an expected surface compaction of the blank, and sub-surface loading on (I) also enters into the calculation. Independent claims are included for (1) a computer program; (2) a machine for calculating and/or carrying out surface compaction.

Description

The The invention relates to a calculation method for designing a Preform of a toothing made of sintered material.

sintered Gear elements such as produced by powder metallurgy gears are used in a wide range. Sintered materials exhibit generally a lower density compared to conventional Forged materials such as steel on. Therefore, one is surface compaction a sintered workpiece desirable. However, in practice, it causes problems to obtain suitable gears, as a geometry of a sintered gear with surface compression essentially over Try and error attempts are determined.

task The present invention is an improvement of a manufacturing process for a toothed element having a sintered material to allow. Furthermore it is Object of the invention, an interpretation of gears made of sintered material to simplify.

These Task is performed by a calculation method with the characteristics of Claim 1, by a computer program product with the features of claim 7 and with a machine having the features of the claim 8 solved. Advantageous embodiments and further developments are in the respective dependent claims specified. The specified features in the description can be general as well as being specifically linked to other features to trainings. Especially are the examples given with their respective characteristics not restrictive interpreted. The features specified there can also be used with others Features from other examples or from the general description connected become.

According to one Thought of the invention, which is independent as well as associated with is applicable to the further features of the disclosure, is a calculation method for designing a preform of a toothing made of sintered material proposed, with data entered into the calculation method, the be determined from a given final shape of the gearing, dependent on of at least one use condition of the final shape one or more Load parameters of the gearing are determined, a local Excess of the Preform is calculated, with an expected compression of the pre form on the surface correlated, with a load of the sintered material below the Surface in the calculation is received.

Preferably will add to the calculation a penetration of the tool in the workpiece to be produced in the Calculation is based, in particular, the behavior of the sintered material during penetration and after penetration Can be found. For example, the calculation method provides that an elastic deformation of the sintering material to be compacted considered becomes. Also, the calculation method may provide that an elastic-plastic Deformation of the surface is taken into account to be compacted sintered material. Preferably For example, a depth of maximum stress below the surface goes when using the workpiece as a force-transmitting Gear in the calculation method. The calculation method may continue to shrink the sintered material during sintering in to let the calculation go. Also empirically determined data also included in the calculation.

at a development of the method for producing an at least partially surface-hardened metal Gear element, which has a compacted sintered material, is a preform of the toothed element with a locally-selective Sizing based to a final measure of Gear element manufactured and by means of at least one rolling tool rolled to final gauge, wherein the toothed element at least in the region of at least one Flank and / or one foot a tooth of the toothed element to produce a compacted Surface layer on a surface locally varies is compressed.

One Gear element is, for example, a gear, a rack, a cam, a P-type rotor, a ring gear, a sprocket or the like. The compacted sintered material is used in particular by methods of Powder metallurgy produced. For example, a metal powder sintered under pressure in conjunction with a heat treatment. Of Further, for example, metal powder in conjunction with plastic injection-molded and in particular under a pressure preferably with a heat treatment sintered. For one Shaping a sintered workpiece In particular, a sintered mold is used which is at least nearly the final dimension of the having to be produced toothing element. Preferred is as Preform uses the directly resulting from the sintering process workpiece. In another variant, however, at least one other Surface processing step be followed. The preform has an allowance, which as a difference to a final measure aufzufas sen is, wherein the difference is preferably defined pointwise perpendicular to the surface is.

As a rolling tool, for example, a roller is used, which is provided with a toothing, which is engageable with the toothing of the toothing element. Such a rolling tool is in particular rolled under pressure on a surface of the toothed element. In particular, two or more such rolling tools are preferably used simultaneously. For example, a gear to be produced can be arranged centrally between two rolling tools. By delivery of both rolling tools then a surface compression of the sintered material of the toothing can be effected. In general, such a manufacturing process is evident, for example, from Takeya et al, "Surface Rolling of Sintered Gears", SAE 1982 World Congress, Technical Paper 820234. Also available DE 33 250 37 , out U.S. 4,059,879 , out EP 0 552 272 A1 , out EP 1 268 102 A1 , out US 5,729,822 , out US 5,711,187 , out US 5,884,527 , out US 5,754,937 , out US 6,193,927 , out EP 0 600 421 A1 , out GB 2,250,227 For example, different production methods, sintering materials, tools, the course of compaction, and devices for sintered gears, which can also be used adapted to the invention, emerge. Reference is made to the above publications in accordance with the scope of this disclosure.

For example can also be a first rolling tool under a first pressure substantially to Coarse contour rolls and then a second rolling tool under a second pressure to achieve be used specifically adjusted surface compaction.

The locally-selective allowance is in particular dimensioned such that the toothed element is compacted locally at least in the region of at least one flank and / or one foot of a tooth of the toothed element in a peripheral layer on a surface. Preferably, a full density is achieved within the compacted edge layer, the full density preferably being understood based on a density of a comparable powder-forged tooth. For example, a preform made of a sintered material in a core has a density of at least 6.8 d / cm ³ , preferably at least 7.1 g / cm ^3, and more preferably at least 7.3 g / cm ³ . In the compacted edge layer, the preform has, for example, a density of at least 7.7 g / cm ³ , preferably of at least 7.8 g / cm ³ , which corresponds to the density of a powder-forged preform of the same material. In this case, a load-bearing strength characteristic is achieved particularly advantageously. Furthermore, a highly durable sintered toothing is preferably provided with a local Lich variable and stress-appropriate density profile. The density profile can have a greater degree of density over a larger area, in particular in the areas subject to higher stress, in comparison to areas of lesser load which are directly adjacent to one another. By means of a determination of an optimized dimension, a toothing produced in this way can also be manufactured economically in a few work steps.

According to one Design is the respectively differently densified edge layer over a different allowance along a flank and / or tooth bottom of the preform mitprodut. For example is provided that a depth of the compacted boundary layer, respectively perpendicular to the surface considered, a maximum at about the place of maximum stress has the density. This can be, for example, halfway up the tooth and steadily decrease to zero at each tooth tip and tooth root. In particular to avoid pittings, for example, it is provided that in a range between 20% and 30%, especially between 23% and 25% below the pitch circle a particularly high compression is set in the sintered material. It can but also other courses be provided. In particular, in a design of a compression curve a force curve on a tooth flank of the toothing element in its intended use considered. For example, the teeth of a gear in a Transmission occurring forces used and the resulting comparison voltage curves below the surface used. This procedure is also with other gears possible.

Especially It is advantageous if an allowance on a first flank of the Zahn's chosen differently is considered on a second flank of the tooth. This is especially a power transmission direction in an intended use of a Gear element considered. For example, in the case of a gearwheel in a gearbox, that dependent from a direction of rotation in the direction of rotation other forces occur on the tooth flanks as contrary to the direction of rotation. Furthermore, a different Compression compensated due to a direction of rotation of a rolling tool become. Preferably, the oversizes are selected so that after a compression process identical compression curve along the first and the second Tooth flank results.

For example, to avoid stress cracks in a tooth root or tooth root area, a locally compressed surface layer is also sought in these areas. It is particularly useful if an asymmetric allowance is selected in a tooth base. Beispielswei For example, a left tooth root area has a different compaction depth than a right tooth root. In particular, between two teeth in each case a preferably continuous variation of a depth of a boundary layer can be provided by a corresponding variation of the oversize.

Preferably In the design of a gearing, a different, in particular asymmetric measurement not only with respect to a flank, but preferably with respect two opposite each other Flanks provided. additionally a different measure in the tooth root is provided, preferably is asymmetric. Also can Tooth flanks and tooth feet of a Each toothing be asymmetrical. As a measure is not here only the available Position of additional Material to understand. Rather, this also includes an undersize. among them is to be understood that less sintered material provided in a Beeich than with respect to a final contour after a processing step should be provided. The ascertained undersize for example, sure that when displacing sintered material no undesirable Surveys arise. The undersize is therefore one through especially displacement of Sustained material to be filled Area of a preform with a toothing dar.

Furthermore it is possible, different pressure angles on a tooth of a toothing provided. Thus, the pressure angle of a flank of the tooth by at least 15% of the pressure angle of the other flank of the tooth differ.

In one embodiment, it is provided that at least 20 .mu.m below a surface of a first flank of the tooth is generated by 2% to at least 15% higher density than on a second flank of the tooth at the same height. Preferably, a density is achieved on the first flank of the tooth, which corresponds at least approximately to the density which is achieved for a powder-forged toothed element, whereas the second flank has a lower density. For example, at a density in a range between 7.2 g / cm ³ and 7.7 g / cm ³ is set an edge, while in the corresponding region of the second flank has a density between 7.5 g / cm ³ and 7.82 g / cm ^{3 is} set. In particular, in turn, for example, rotational direction-dependent different loads of the two tooth flanks are taken into account. Preferably, a requirement-based elasticity and hardness profile is achieved. More preferably, this reduces a noise development, for example in a transmission.

Farther is provided that a local allowance on a first flank of Tooth is at least 10% larger, as an oversize on one second flank of the tooth at the same height. In a first variant is achieved, for example, that due to different Pressurization during compression depending on the direction of rotation identical compression curve on the first and second tooth flank is achieved. In a further variant, for example, a different compression process on the first and the second Tooth flank achieved. Here you can especially different maximum densities, their depths like but also their location targeted with respect to the height of the gearing become.

It is particularly expedient if an amount of a maximum local allowance is at least 15 μm, preferably at least 100 μm and particularly preferably at least 400 μm. If the density of the preform in a range between 7.2 g / cm ³ and 7.5 g / cm ³ , preferably a maximum allowance between 20 and 150 microns is provided. If the density of the preform between 6.7 g / cm ³ and 7.2 g / cm ³ , preferably a maximum allowance between 50 microns and 500 microns is used. An oversize may also be negative locally, taking into account, for example, a lateral redistribution of material. A lateral redistribution can be done by flowing material as a result of a rolling process. In particular, an at least locally negative oversize can be provided, which lies locally below the final dimension. The negative allowance is preferably at most 100 μm. According to one embodiment, the negative measurement is at most less than 50 μm and in particular less than 20 μm. In particular, the maximum negative allowance is in a range between 100 μm and 20 μm.

Preferably a compression is achieved, at least in one area of a Tooth flank of the toothing reaches a depth between 1 mm and 1.5 mm. The compression in the tooth root can however, be lower. According to one Design is the maximum depth of compaction of a tooth flank by at least a factor of 6 greater than a maximum depth of compaction in an area of the associated tooth root. This allows the teeth on the one hand sufficient strength has, on the other hand, but also a certain deformability reserves. One Tooth breakage is avoided.

In one embodiment of the method, it is provided that the preform and the rolling tool are rolled on each other until a final shaping movement between the toothed element produced thereby and the rolling tool is generated. This is used for example for the production of intermeshing gears. Preferably, a distance between rolling tool and preform is verrin during the rolling process with the rolling tool siege. Accordingly, in particular a rolling pressure is adjusted or adjusted. In addition to the possibility of force control and a path control can be realized on the machine. In addition, it is possible to provide a combination of force and path control in the manufacture of the teeth. In this case, in one section of the production, a pure travel control can take place and in another section of the production a pure force control. These can also alternate several times.

In a further embodiment is provided that by means of rolling movement between the preform and the rolling tool a cycloid-shaped and / or involute Gearing arises.

Next Gear elements in the sense of gears can also other teeth elements getting produced. For example, it is provided that as a toothed element a cam is made. In particular, a cam can be produced be, as for example, for the mechanical actuation of a Adjustment device, for example for adjusting a valve or the like is used. Preferably is characterized by a locally varied Compaction of a boundary layer on a flank of a cam improved strength process with less susceptibility to wear provided.

A Further improvement of surface hardening can be particularly so be achieved that the process of producing an at least partially surface-compressed metal Verzahnungselementes a thermal and / or chemical Surface hardening process includes.

In a first variant is used as a thermal and / or chemical curing process for example, a case hardening used. Preference is given here in addition to an increase in hardness, a reduction of tension achieved. In a further variant, for example, a carbonitriding process used. Furthermore, a nitration or Nitrocaborierprozess and a boriding process can be used. In particular, at these processes in conjunction with a heat treatment also a Reduction of a tension achieved. By hiring the prevailing Pressure can also influence the hardening be taken. For example, a vacuum can be set, especially when a case hardening made becomes. There is also the possibility of a induction make.

The hardening is according to a Design only partially executed, for example, only in Area of the toothing made.

In a preferred variant, it is provided that a method for Production of an at least partially surface-hardened metal toothed element, which comprises a compacted sintered material, the steps "cold or warm Pressing, sintering, dimensional and surface compacting rolls and case hardening. "For example takes place first a cold pressing of a metal powder in a mold, which at least approximately the final dimension of the having to be produced toothing element. In a second step For example, the sintering process takes place with or without heat Pressure. Preferably thereafter, the dimensional and surface compression takes place by means of rollers. As already mentioned above, dimensional and surface compacting rolls take place preferably simultaneously by means of at least two rolling tools. After that can finally the hardening, in particular case hardening done, which is a further hardening the surface allows.

• – gemischte Pulver (admixed powders): Zum Beispiel Eisenpulver wird mit anderen vorzugsweise elementaren Pulvern gemischt. Zum Beispiel: Ancorsteel 1000+1,5–3,5 w/o Cu+0,6–1,1 w/o Graphit+0,5–1,2 w/o Schmiermittel Ancorsteel 1000B+1,5–2,2 w/o Ni+0.4–0,9 w/o Graphit+0,6–1,1 w/o Schmiermittel
• – teilweise legierte Pulver (partially alloyed, diffusion alloyed powders): Ein Pulver bei dem der oder die Legierungsbestandteile metallurgisch mit elementarem Pulver oder vorlegiertem Pulver verbunden sind. Zum Beispiel: Distaloy AB, Distaloy 4600A, Distaloy AE, Distaloy 4800A
• – vorlegierte Pulver (pre-alloyed powders): Pulver aus zwei oder mehr Elementen, die während der Pulverherstellung legiert werden, wobei die Pulverpartikel gleichverteilt werden. Zum Beispiel: Ancorsteel 4600V, Ancorsteel 2000, Ancorsteel 86, Ancorsteel 150HP
• – Hybridlegierung (hybrid alloy): vorlegierte oder partiell legierte Pulver mit elementaren oder eisenlegierten Zugaben, die vermischt werden, um die gewünschte Materialzusammenstellung zu erhalten. Zum Beispiel: Ancorsteel 85P+1,5–2,5 w/o Ni + 0,4–0,8 w/o Graphit+0,55–1,1 w/o Schmierzusatz Distaloy AE+1,5–2,5 w/o Ni+0,4–0,8 w/o Graphit+0,55–0,95 Schmierzusatz Ancorsteel 85HP+1,1–1,6 w/o FeMn+0,35–0,65 w/o Graphit+0,6–0,95 Schmierzusatz

Further possible method steps or procedures as well as more details on workpieces are given below by way of example. However, the process steps are also executable with other materials and achieved density values. The usable sintered materials are generally usable within the scope of the invention as follows, examples of materials which can be used being specified:

• - Mixed powders (admixed powders): For example, iron powder is mixed with other preferably elemental powders. For example: Ancorsteel 1000 + 1.5-3.5 w / o Cu + 0.6-1.1 w / o graphite + 0.5-1.2 w / o lubricant Ancorsteel 1000B + 1.5-2, 2 w / o Ni + 0.4-0.9 w / o graphite + 0.6-1.1 w / o lubricant
• Partially alloyed, diffusion alloyed powders: A powder in which the alloying element (s) are metallurgically bonded to elemental powder or prealloyed powder. For example: Distaloy AB, Distaloy 4600A, Distaloy AE, Distaloy 4800A
• Pre-alloyed powders: powders of two or more elements which are alloyed during powder production, whereby the powder particles are uniformly distributed. For example: Ancorsteel 4600V, Ancorsteel 2000, Ancorsteel 86, Ancorsteel 150HP
• Hybrid alloy: pre-alloyed or partially alloyed powders with elemental or iron-alloyed admixtures which are mixed to obtain the desired composition of materials. For example: Ancorsteel 85P + 1.5-2.5 w / o Ni + 0.4-0.8 w / o graphite + 0.55-1.1 w / o Lubricating additive Distaloy AE + 1.5-2, 5 w / o Ni + 0.4-0.8 w / o graphite + 0.55-0.95 lubricant additive Ancorsteel 85HP + 1.1-1.6 w / o FeMn + 0.35-0.65 w / o Graphite + 0,6-0,95 Lubricant

1. The workpiece has a core density between 6.5 and 7.5 g / cm ³ . The surface density is more than 7.5 g / cm ³ . A maximum density is generated to a depth of 0.1 mm.

raw materials for the Preform are sintered metallic powders, in particular pre-alloyed materials, partially alloyed materials or hybrid alloys.

With a prealloyed material is cold-pressed, sintered in a temperature range between 1100 ° C and 1150 ° C, a surface compression, a case hardening and a subsequent grinding made to achieve a final shape of a workpiece with teeth.

With a partially alloyed metallic sintered material becomes a hot pressing at a press temperature in a range between 50 ° C and 80 ° C, high temperature sintering in a range preferably between 1250 ° C and 1280 ° C, surface compacting, a subsequent one Vacuum carburizing and honing, around a final shape of a workpiece to achieve with toothing.

With A sintered material comprising a hybrid alloy becomes a hot pressing executed in which preferably the powder and the tool are heated. Preferably these are heated in a range between 120 ° C and 150 °. Then took place a sintering step, for example as high-temperature sintering surface compaction and subsequently Induction hardening. An aftertreatment can be omitted, for example.

2. The preform is powder forged. This preform is at least partially surface-compacted in the region of the tooth flanks and / or the tooth root. A core density of the workpiece is between 5.7 g / cm ³ and 7.7 g / cm ³ . A surface density in the range of more than 7.8 g / cm ³ , wherein preferably in this area all remaining pores are closed at the surface. However, a maximum density up to a depth of 1.5 mm can also be generated.

One Manufacturing process can proceed as follows: choice of powder material, Cold pressing of the powder material, sintering preferably with a Temperature around 1120 ° C, connect Forging, preferably at a temperature around 1000 ° C, eventually removing an oxidation layer, surface compacting in particular by rolling, surface hardening, in particular Case hardening, and possibly subsequent partial grinding on a final contour. The procedure can be completely or partially in a production line.

A Another embodiment provides that when surface hardening a Vacuum case hardening is performed, to which a honing step for connect partial areas of the teeth.

3. In particular, for the production of rotors and oil pump wheels, a preform made of an aluminum-containing material in the region of the tooth flanks and / or the tooth roots is surface-compacted. In surface compacting, in particular a final shape of the toothing is achieved. The core density of the workpiece is preferably between 2.6 g / cm ³ and 2.8 g / cm ³ .

The Sintered material is hot-pressed, for example, for example at a temperature between 40 ° C and 65 ° C, subsequently dewaxed, for example at a temperature of more than 400 ° C, in particular then sintered in a temperature range between 420 ° C and 440 ° C, for example in a temperature range above 550 °, in particular in a temperature range between 600 ° C and 630 ° C, then homogenized and cooled, For example, to a temperature between 480 ° C and 535 ° C, followed by a surface compacting in particular by rolling. Subsequently, a curing can take place, for example in a temperature range between 120 ° C and 185 ° C for a period between 6 h and 24 h.

4. The preform is preferably compressed along the tooth flank and the tooth root, in particular two rolling tools are used, in the middle of which the preform is rotatably arranged. Depending on the material, a core density of the workpiece is preferably between 7.2 g / cm ³ and 7.5 g / cm ³ ; depending on the material, a surface density, at least in sections, is greater than 7.8 g / cm ³ . A maximum density is present in particular to a depth of 1 mm, possibly even beyond.

From the manufacturing steps are proposed according to an embodiment, Pre-alloyed material cold pressed, then closed sintering, in particular in a temperature range between 1100C ° and 1150 ° C, to perform a surface compression, a hardening perform and the surface partially possibly to grind.

A Another embodiment provides a partially alloyed sintered material to be hot pressed, especially in a temperature range between 50 ° C and 90 ° C, a high temperature sintering perform, especially in a temperature range between 1240 ° C and 1290 ° C, a surface compression perform, to perform a vacuum case hardening and possibly afterwards to be honed.

A another embodiment provides for hot pressing a hybrid alloy, wherein the powder and the pressing tool preferably in a temperature range between 120 ° C and 160 ° C warmed up are. After a sintering step, a surface compression takes place, to which a hardening, preferably an induction hardening followed.

5th It is also possible the pre-sintering a surface compacting succeeds and then in turn a resintering as a process step in the manufacture of a workpiece provided with teeth. The pre-sintering can, for example be carried out in a temperature range between 650 ° C to 950 ° C. Post-sintering For example, at a for the material usual Sintering temperature, for example, between 1050 ° C and 1180 ° C. Also exists the possibility high-temperature sintering, for example in the range between 1250 ° C and 1280 ° C. hereafter may optionally be a hardening and / or post-processing, for example, honing or even a grinding.

The previous pressing can be done cold, warm or hot, in the latter, preferably the pressing tool and the powder are heated. For example, the hot pressing takes place in one Temperature range between 120 ° C and 160 ° C.

6th A further development provides that a subsequent sintering step is followed by a sintering hardening. Optionally, this may be followed by grinding or honing.

7th Another manufacturing method provides the preform at a To compress the temperature above 150 ° C, in particular over 500 ° C. For example The preform can be fed directly from a sintering furnace into a machine surface compaction guided become. In this case, the preform may have a temperature, for example above 600 ° C lies, especially over 800 ° C is. Preferably be heated or the tools for surface compression, for Example, to a temperature of about 150 ° C. According to another embodiment is the tool for surface compaction cooled, preferably by running inside the tool cooling.

8th. Another manufacturing method provides that a surface compaction done while the preform is at least partially heated. In particular heating to a temperature that compresses the surface simplified. Preferably, this is an induction heating used. Subsequently a rapid cooling takes place, to create a martensitic structure. This way you can For example, a molding process with a surface compression be combined.

A Further embodiment of the invention provides that a surface compression Executable with a variety of methods. An embodiment sees in particular, that in a first area the surface compression is performed with a different method than in a second, another Area. As a method can doing a beam hardening, shot peening, a compression by means of a ball, by means of a roller or by means of another rotatable body, by tooth-shaped designed tools, in particular rolling tools and the like be used. These methods are also individually separated mutually suitable to allow a necessary surface compaction.

For example the tooth base is cooked not or only slightly compacted with a tool, with that too the tooth flank is compressed. There is the possibility of the surface in one To compact section so far that only the pores are closed at the surface are. Subsequently can the tooth base with another tool or Oberflächenverdichtungsverfahren be processed. In particular, about it a different surface compaction along the tooth flank compared to the tooth root. For example So different surface qualities, for example with regard to roughness, to adjust. Also, the maximum surface depth may vary due to the different techniques. It is also possible that the entire workpiece with the gearing a surface compression gets such as surface blasting. In this way, in particular aluminum-containing sintered materials or other oxide-forming sintered materials, since with the surface compaction additionally Also, a removal of an oxide layer can be made possible.

The The invention further relates to a preform for a method of preparation an at least partially surface-hardened metal Gear element, which has a compacted sintered material, wherein a first and a second edge of a tooth from each other different asymmetric dimensions exhibit. Furthermore, it is also envisaged that a first and a second foot area a tooth divergent, especially asymmetric allowances exhibit.

Furthermore, the invention relates to a toothed element with a metallic sintered material, wherein the toothed element at least in the region of at least one flank of a tooth of the Gear element has a locally varied compression. This is preferably a suitable for many applications elasticity of the powder metallurgical material in conjunction with a surface hardening possible. Particularly preferred, for example, in transmission gears, a noise reduction in the power transmission allows and at the same time provided a good wear resistance.

In a first variant is provided that the toothed element a gerverzahntes gear is.

Especially for one improved power transmission as well as for noise reduction between gears is provided in a further variant, that the toothed element an oblique toothed gear is. Furthermore, in another variant also be provided a bevel gear. According to the continue above Description, it is appropriate if opposite each other Flanks of teeth a Verzahnungselementes have an asymmetric compression.

Of Furthermore, it is useful if There is an asymmetric compaction in a foot area. This compression is in particular at a use according to the application occurring forces customized. To avoid voltage cracks is in particular provided that the depth of the locally densified boundary layer only so high is that still sufficient elasticity or rigidity of the tooth becomes. Particularly preferred is the depth of the compacted boundary layer in the foot area less than on a tooth flank.

When Special form of the toothed element can be provided that the Gear element is a cam. The above statements are to apply accordingly, for example flanks kick the cam instead of the flanks of teeth.

For a material a Verzahnungselementes can various compositions are provided. In a first Variant is an iron material as the main component of the sintered material and at least one alloying constituent selected from the group consisting of carbon, Molybdenum, Selected from nickel, copper, manganese, chromium and vanadium. An iron alloy For example, Fe is -1.0 Cr -0.3 V +0.2 relative to a reference 15CrNiMo6. Another iron alloy For example, Fe is -1.5 Mo + 0.2C based on 20MnCr5. Furthermore, for example, as ferrous alloy Fe -3.5 Mo based on 16MnCr5 provided. Likewise, for example, the Alloy C 0.2% Cr 0.5% Mn 0.5% Mo 0.5%, with the remainder iron and Contamination is used. In addition, more can Be provided compositions.

Preferably, for a reduction of a weight of a toothed element is provided that aluminum or magnesium is selected as the main component of the sintered material. According to one aspect of the invention, it is provided that a surface-compressed toothing made of sintered material has at least 80% aluminum and at least copper and magnesium as further sintering materials. A first embodiment provides that additionally silicon is used as sintered material. For example, silicon may range from about 0.45% to about 0.8%, preferably between 0.6% and 0.75%. However, silicon may also be present in a higher range, for example between 13% and 17%, in particular between 14.5% and 15.5%. If the silicon content is higher, the copper content of the sintered material is reduced. For example, a first mixture may comprise copper at 4% to 5%, silicon at 0.45% to about 0.8%, magnesium at about 0.35% to 0.7%, and the balance at least primarily aluminum. In addition, a pressing aid is preferably added. This can have a proportion between 0.8 and 1.8%. For example, a wax, in particular amide wax used for this purpose. For example, a second blend may comprise copper at 2.2% to 3%, silicon at 13% to about 17%, magnesium at about 0.4% to 0.9%, and the balance at least primarily aluminum. Also, a pressing aid can be used as exemplified above. After a surface compaction, at least one region of the toothing has a density of, for example, more than 2.5 g / cm ^3, preferably up to the maximum density. Preferably, such a manufactured workpiece with a toothing has a tensile strength of at least 240 N / mm ² and a hardness of at least 90HB. If the silicon is higher, the density may in particular also be more than 2.6 g / cm ³ .

A second embodiment provides that in addition at least zinc is used as the sintering material in addition to copper and magnesium as additives and aluminum. Preferably, copper has a content in a range between 1.2% and 2.1%, in particular between 1.5% and 1.65%, magnesium between 1.9% and 3.1%, preferably between 2.45% and 2.65%, zinc between 4.7% and 6.1%, in particular between 2.3% and 5.55%. The rest is at least mainly aluminum. In addition, a pressing aid as described above can also be used here. A workpiece made from this mixture with a toothing preferably has at least one area of the toothing after the surface compaction in which a density of at least 2.58 g / cm ³ extends to the maximum density. Preferably, a workpiece produced in this way with a toothing has a tensile strength of at least 280 N / mm ² and a hardness of at least 120HB.

Especially is appropriate it, if a toothed element with another functional component, in particular a shaft or another gear, sintered is. In particular, this is a compliance with a precise working distance between several gear elements, for example in one Transmission, relieved.

In A further embodiment provides that the toothed element Part of a pump is. For example, it is a involute gear, which with another involute Gear is engaged.

Of Furthermore, the invention relates to a device for manufacturing an at least partially surface-compressed Gear element in particular for carrying out a method described above Method with a adapted to a different measure Tool control. The device comprises in particular at least a rolling tool, which preferably with the aid of the adapted tool control preferably under a customized pressure and / or controlled path can act on the preform in an adapted engagement. Especially The device comprises a rolling tool with a toothed surface, which engageable with the toothing of the toothing element and it can be rolled over.

Further The invention relates to a device for producing a at least partially surface-hardened toothing element one at least in a surface area a sintered material preform, wherein the device a tool comprising a compensation of different allowances at a first and a second edge of a rolling motion having to be compacted tooth of the preform. The rolling tool can doing one for the shape necessary contour, for example, an involute Gearing, only on one flank or on both flanks of a tooth exhibit. In another variant, however, it is also provided that on each of a first and a second edge of a tooth the teeth of the rolling tool each differing from each other allowances available. This can, for example, a different be involute interlocking.

Further The invention relates to a method for designing an oversize for Achieving a surface compaction a sintered metal toothed element in a rolling process, where the allowance is iterative is determined. In a first step, for example, a Geometry and in particular a torque and / or a pressure distribution specified. In a further step, for example, a design defined a rolling tool. Furthermore, a preform with determined a locally defined allowance. For example, a selection can be made using data libraries. Such a data library contains, for example, based on various Parameter determined experimental density courses. Furthermore, a Simulation of the compression or rolling process done. To For example, the kinematics of the rolling process in conjunction with a simulation of elastic and plastic properties of the preform and possibly the rolling tool simulated. For the simulation the elastic or plastic properties of the preform is For example, related to continuum mechanics models with a discrete solution by means of, for example, finite element or finite volume methods resorted.

In A preferred embodiment provides that a geometry a hobbing tool iteratively, taking into account of the oversize is determined. For example, an allowance of involute toothing of the hob tool be determined. Accordingly, an allowance for other than an involute Gearing be determined.

In A particularly preferred embodiment provides that in a first step at least in an area of a flank of a tooth locally varied, at least pointwise definable Excess of a Preform of the toothed element based on at least one design specification is automatically generated, in a second step, a geometry a rolling tool is automatically generated in a third Step a rolling process and a local course of a compression generated thereby at least an edge layer of the toothed element is simulated and in a fourth step, an automatic evaluation of the generated History of the compression is compared with a specification as well optionally, the method from the first step using at least one variation is repeated for optimization until a Abort criterion fulfilled is. The variation takes place, for example, with the help of a Optimization method. An abort criterion is for example one Tolerance between desired Density gradient and density gradient achieved in the simulation. Furthermore If an abort criterion also exceeds a predefinable Number of iterations.

It is particularly useful if the Design specification from the group material density, geometry, torque and pressure distribution is selected. The torque is to be understood here as the torque occurring in the intended use of a toothed element.

Especially to avoid material cracks, it is expedient if simulated a material tension at least in the area of compression and in particular for evaluation. It is preferred thereby avoiding that a surface is sufficiently hardened, However, due to voltages is brittle and stress cracks inclines.

Of Furthermore, it is advantageous if for variation in a database library stored data can be used. In particular, it can process on for optimization and data analysis, for example by means of neural Networks are used become. Furthermore, features stored in the database are displayed for example, for optimization by means of a genetic algorithm used.

In In a further embodiment, at least one of the steps can be achieved by a default will be replaced. Preferably, a rolling tool geometry fixed. This takes into account, for example, the fact worn that a rolling tool much more expensive to modify is, for example, as a preform. Another embodiment provides a reverse approach. Preferably, starting from a final shape, a preform or the rolling tool for producing the Endform as well as the press tool for the production of the preform calculated.

Finally is The invention relates to a computer program product with program code means, which are stored on a computer readable medium, at least perform any of the procedures described above when the program is up running a computer becomes. For example, a computer readable medium is a magnetic, a magneto-optical or optical storage medium. Furthermore For example, a memory chip is used. In addition, a computer readable medium also by means of a remote memory, for example be realized by means of a computer network.

The Computer program, for example, deposited in a machine for surface compaction be. Also, a calculation may be separate from the machine for surface compaction respectively. The machine has however over a control, in particular a path and / or force-controlled control, in which the coordinates and movements can be entered to the Compacting preform.

According to one Another aspect of the invention provides a die mold. with which a preform made of sintered material can be pressed, the subsequently surface-compacted to a final shape. These Press tool shape is calculated iteratively. Preferably is doing also assumed data from a final contour of the workpiece with its teeth.

Also can be a rolling test bench be provided, the possibility offers, test rolls for a variety of surface compaction to be able to make. About that can In particular, data are also determined which are evaluated in the calculation methods can enter. For example, you can therefor suitable characteristics are formed from a plurality of measurements. This can be for example Start values for the iterative calculation of preform, tool or pressing tool respectively. Also, the rolling test bench an automated measurement of surface-compacted workpieces, the have a toothing possess.

in the Following are further thoughts proposed with the previous ones proposed aspects combined but also be carried out independently.

According to a further aspect of the invention, which can be used independently as well as linked to the further features of the disclosure, a method for producing a toothing of compacted sintered material is provided, wherein a precompressed tooth preform at least in a range by means of iteratively determined data by at least 0.05 mm is compacted on its surface to its final shape, and a quality of the final shape at least in a range of at least f _Hα = 4, F _α = 7 and F _fα = 7 is achieved. Here, f _{Hα are} the deviation with respect to the toothing, F _{α is} the total deviation and f _{fα is} the profile shape deviation of the flanks. The specified values correspond to the DIN classes with respect to the deviation.

According to a further development, it is provided that an iteration takes into account parameters which relate to a material behavior in a surface compression of the tooth form. An embodiment provides that an iteration for determining a preform of input data emanates, which are taken from a specification of the final shape. Preferably, at least one rolling tool is used, which has the same quality as the final shape created later. Through the iterative determination and thus extremely accurate processing in the surface compaction is possible, the quality of the Tool can be transferred to the preform. In particular, the extremely accurate surface compaction makes it possible for the toothing to have this quality of the final shape after the surface compacting without any further material-removing post-processing step. For example, a workpiece with the gearing is made to have a core density of at least 7.4 g / cm ³ with a surface density that is at most in a region of a tooth flank, with the maximum surface density extending at least 0.02 μm in depth in the region ,

According to a further aspect of the invention, which can be used independently as well as combined with the further features of the disclosure, a method for producing a toothing of compacted sintered material, wherein a pre-compacted tooth preform is compacted to its final shape at least in one area by means of iteratively determined data, and a roughness in the area opposite the preform is improved by at least 400%, with a surface hardness of at least 130 HB being set. Preferably, a core density of the final shape is set which has at least a density of 7.3 g / cm ³ and imprinted with a surface hardness having a convex course from the surface toward a center of the final shape.

The toothing of precompressed material has, in a first surface-compacted area, a roughness which is at least 400% smaller than a roughness in a second area which is less or not surface-compacted. The roughness R _z is, for example, less than 1 μm in the first region. A further embodiment provides that a surface hardness of at least 700 HV [0.3] is present at the surface of the final shape, while at a depth of 0.4 mm from the surface at least a hardness of 500 HV [0.3] is present , Another embodiment has a surface hardness of at least 700 HV [0.3] on the surface of a tooth flank and in a tooth root, wherein a hardness of at least 500 HV [0.3] at a depth of 0.6 mm from the surface in the Tooth base and a hardness of at least 500 HV [0.3] is present at a depth of 0.8 mm from the surface on the tooth flank. The production of surface compaction makes it possible to set exact compaction as well as hardening according to desired specifications.

According to one another idea of the invention, which is independent as well as associated with is applicable to the further features of the disclosure, is a Calculation method for designing a tool for surface compaction a preform of a toothing of particular compacted sintered material proposed for the creation of a predetermined tooth geometry, wherein determined data from the given tooth geometry to be produced for the calculation of machine tool kinematics under consideration from associated machine parts of a workpiece which the tool to be produced is formed, and at least one Werkzeugformgebers, their coupled system coordinates and their Move towards each other, enter iteratively. This is now the Possibility, instead of over repeated tests, measurement results and adjustments of the workpiece former after all a final form to find this by means of an iterative calculation. This is much more time-saving and allows the consideration of different Influencing parameters. In particular, a simulation of the design is also allows, so that, for example, a mode of action of the tool to be produced can be checked for a designed preform in the simulation.

According to one Design go into the calculation method contact conditions between the workpiece to be produced and the tool former between a tip and a foot of toothing. Preferably this also goes in the area of a foot of the gearing a maximum Tension on the surface included in the calculation. Furthermore, there is the possibility that in the region of a flank of the toothing a maximum voltage below the surface included in the calculation. This process is particular for sintered materials suitable, but also for steel workpieces or workpieces other materials.

According to one another idea of the invention, which is independent as well as associated with is applicable to the further features of the disclosure, is a Press mold with a press geometry for producing a Preform of a toothing made of sintered material proposed, wherein the press geometry on a surface compression of the toothing has adapted course with at least one survey, at least generated in the region of the toothing of the preform a depression, the with sintering material during surface compacting refillable is.

Preferably, the survey on a front side of the preform causes a depression in the region of a head of a tooth of the toothing. For example, by iterative calculation, the height of the elevation or depth of the depression as well as other dimensions thereof can be determined. A further embodiment provides, instead of a one-sided survey, that a bilateral elevation is provided in order to effect a depression on both end faces of the tooth. The survey is according to a development in an area of Ge ometry, which causes a depression on a tooth head of the preform, wherein the protrusion has a dimension such that the formed recess at least partially reduces growth of the tooth tip due to the machining of the preform into the final shape by surface compacting. In this way, for example, a preform with at least one depression on an end face of a toothing to compensate for a material Aufwurfes in a surface compression of a tread of the toothing calculate and in particular finished. Also can be in this way a preform with at least one depression on a tooth head of a toothing for at least reducing a growth of the tooth head in the amount in a surface compaction at least calculate the flanks of the teeth and in particular finished. The calculation method for determining a geometry of a preform or of a compression molding tool preferably provides that the geometry is determined based on data of a final shape of the preform and at least one depression or elevation is calculated which at least partially effects a compensation of a material displacement during surface compression.

According to one another idea of the invention, which is independent as well as associated with is applicable to the further features of the disclosure, is a Process for surface compaction a toothing proposed, wherein a number of repeating Compression movement of a molding tool for surface compacting a surface is calculated iteratively at the preform. Preferably, a roll over iteratively calculated until a predetermined surface density is reached. A further development provides that a feed of the molding tool iteratively calculated. According to one Design takes place less than 20 times a roll over the preform to achieve the predetermined geometry of a final shape of the surface compacting. Preferably, less than 10 times the rolling over. In particular, will rolling over less than 6 times the preform performed, to a given geometry of a final shape of the surface compacting is reached. It should be noted that with the achievement no termination of surface compaction takes place. Rather, it will be repeated several times, especially less than 25 times, preferably less than 15 times, further that Tool on the surface traveled. As a result, an accuracy of the surface shape is ensured.

According to one another idea of the invention, which is independent as well as associated with is applicable to the further features of the disclosure, is a Proposed method in which a reversing rolling on a Gearing made of sintered material is used to form the preform Final shape of a surface compacting to condense. Preferably, before a reversal of direction, a short unloading the preform is performed by the mold. It turned out that by reversing, that means by reversing the movement a uniformed compaction can be created. About that In addition, manufacturing problems were further minimized, by reducing the pressure of the tool on the workpiece before the movement reversal begins. The tool can remain in contact with the workpiece. It can also be detached from the surface for a short time.

According to one another idea of the invention, which is independent as well as associated with can be used in the further features of the disclosure, is a surface compaction a workpiece with proposed at least one toothing of sintered material, wherein a first surface of the workpiece is densified with a different method than a second surface of the Workpiece. Preferably, a first toothing of the workpiece has a has other compression than a second toothing of the workpiece. A Further, provides that an internal toothing of the workpiece a other surface compaction learns as an external toothing of the workpiece. Also it is possible, that an external toothing by means of a rolling process peened is while a second area a hole that is surface-compacted with another method is. Preferably receives a hole in the workpiece after a surface compacting one hardened surface and afterwards brought to a final shape. This allows the use of the hole for one Wave or an axis. An improvement in accuracy is thereby achievable that after curing the gearing a surface compression he follows.

According to one another idea of the invention, which is independent as well as associated with can be used in the further features of the disclosure, is a Shaft with at least a first and a second toothing, wherein the first toothing made of sintered material and rolled is surface-compressed. The following are features regarding indicated the shaft or the teeth. Here can for further Embodiments in particular also the further disclosure with regard to gearing, materials, manufacturing steps, etc. are used.

According to one embodiment, the shaft has a second toothing, which is produced by a different method than the first toothing. This allows a variety of combinations, which provides different material solutions for each case of stress. The second toothing forms According to a further embodiment with the first toothing a workpiece. For example, both teeth may have been produced together in a press machine. Preferably, the first and second teeth have been calculated iteratively and prepared accordingly. According to one embodiment, the production can take place successively, but also simultaneously according to another embodiment. In particular, this also applies to further processing steps such as a surface compaction.

A Continuing provides that the second gearing a hardened surface without surface compaction having. For some load cases is the density obtained by sintering or the material used inherent strength sufficient. This applies, for example for pump applications.

Farther It has proved to be advantageous if at least the first toothing at least on a tooth in each case different edge slopes same height of the tooth. This is beneficial in applications where which a main direction of rotation and in particular only one direction of rotation the wave is predetermined. The different flank slopes can thereby wear and noise reducing be interpreted.

A Another embodiment provides that the second toothing forged is. You can also peened be. This gearing can, for example, a larger power transmission record as the first gearing.

Preferably is the second toothing of a different material than the first Toothing is. For example, the second toothing is made of steel. The However, second gearing can also be made of another sintered material exist as the first gearing. In addition, the wave can also be made of sintered material. For example, it can be the same material as the first gearing. Also, the wave can at least are formed together with the first gearing, i. made of powder material be pressed, preferably in a common mold.

One exemplary process for the preparation of the above-described Wave can also provide that at least the first gearing a surface compaction receives and a bore for receiving the shaft surface-compacted, hardened and then honed is connected before the shaft and the first gearing become. Therefor is preferably carried out starting from a final shape of the shaft with the first gearing an iterative calculation of a preform of the first Toothing.

preferred Applications for such a wave arise in automotive engineering as well in gearbox construction as well as household appliances.

According to one another idea of the invention, which is independent as well as associated with can be used in the further features of the disclosure, is a Preform used for producing a toothing of sintered material, wherein the preform has a negative allowance. Preferably the negative oversize at least is arranged on a flank of a tooth of the toothing. In particular, can the negative allowance asymmetrical run along the flank.

A Continuing training provides that on each flank of a tooth a negative one Measure is. For example, a tooth on the same Height first negative oversize a first flank and a second negative measure on one second edge, wherein the first and the second edge to each other run asymmetrically.

Preferably is the negative oversize between a head portion of the tooth and an overlay on a flank of the tooth Tooth arranged. additionally or alternatively, the negative allowance in a corner region of the tooth root be arranged. Furthermore, there is the possibility that an edge slope the flanks of a tooth are different.

Next an external toothing or other Verzahnungsart is a surface compression even in a Toothing executed, which is an internal toothing. The preform eventually becomes one surface-densified Gear.

A Further development provides a method for producing a toothing from a sintered material, wherein a preform at least one associated with iterative calculation assigned negative allowance is that in a surface compression of the Gearing is at least partially filled by displacement of the sintered material. Preferably, a stock material adjacent to the negative allowance is formed displaced into the negative oversize. The preform can be surface-compacted in the desired final shape, wherein optionally a curing and / or a surface finish he follows. This can be done before or after surface compacting. When Fine machining is a honing as well as a grinding into consideration.

The design of the negative amount preferably takes place via an iterative calculation, in which a simulation of the surface compression on the preform determines whether the adjacent allowance of its shape is designed such that d is the negative allowance for the desired final contour can be smoothed. For this purpose, a machine for calculating and / or performing a surface compaction of a toothing is provided, wherein a calculated kinematics is einar, by means of the surface densification a negative allowance on a flank of the toothing can be smoothed to a desired final contour.

According to one another idea of the invention, which is independent as well as associated with is applicable to the further features of the disclosure, is a Process for producing a surface compaction on a toothing proposed, wherein at least two preforms simultaneously a surface compaction obtained in a device.

According to one Embodiment, the preforms on parallel shafts arranged and simultaneously engage with at least one Tool for surface compaction.

According to one second embodiment, at least two preforms on a common shaft arranged and engaged in common with at least a tool for surface compaction brought.

Of Further, an apparatus for producing a surface compaction proposed on a toothing, wherein at least two preforms for surface compaction Durable in the device and simultaneously editable.

For example is provided that provides a movement of at least one shaft is in which both preforms engage with a tool for surface compaction reach. A further development provides that at least three waves for at least two preforms and at least one tool arranged parallel to each other and form a triangle, with at least one of the waves on the two other waves is zubewegbar. A further embodiment provides that at least two preforms on a common shaft are attachable, wherein the tool has a greater length than an added Length at least both preforms. Preferably the preforms with their faces lie together. Another embodiment provides that between the preforms a distance is arranged, wherein the tool along the Wave over both outer faces of the preforms protrudes.

According to one another idea of the invention, which is independent as well as associated with is applicable to the further features of the disclosure, is a Component with a surface-compressed toothing proposed from sintered material, wherein the component via a Cross-section considered, a gradient with respect to sintered materials used having.

Preferably the component has a gradient that has a jump function. The sintered materials are at least in this area with a transition boundary Mistake. According to one Design is this transitional boundary along the entire surface present between the first and second sintered material. Another Embodiment provides that in a range no fixed limit but a gradual transition is present. In particular, it can be provided that the component is different Having sintered materials which extend into each other, without a pronounced Have mixing zone with increasing or decreasing gradient.

A first development of the component includes that the sintered material the toothing has a lower core density than the sintered material of a following the gearing Area of the component. A second development of the component sees suggest that the sintered material of the gearing a higher core density has as the sintered material adjoining the toothing area of the component.

A Another embodiment has a component which has a first toothing with a first sintered material and a second toothing with a second sintered material.

Preferably has a toothing different flank angles at one Tooth at the same height on.

For example may be a first sintered material in an outer region of the component be arranged and form the teeth, and a second sintered material is arranged in an inner region of the component and forms a hole.

Of Another method for producing a surface-compressed Gearing proposed on a component, wherein a first sintered material is embedded in a mold before a second sintered material add out will, then a pressing and sintering takes place and by means of a surface compression the gearing compacts only one of the two sintered materials, while the other sinter material undergoes no change.

A Continuation provides that a second surface compaction accomplished is concerned, which concerns only the not yet surface-compressed sintered material. It is preferably provided that the first sintered material at least a surface the tooth flanks forms and the second material is a relining the toothing forms.

One Another proposed method for producing a surface-compressed Gearing on a component provides a first sintered material into a mold before adding a second sintered material, subsequently to carry out a pressing and sintering and by means of a surface compression the toothing to compact the first and the second sintered material.

For the implementation of It has proved to be advantageous that a movement sequence for surface compaction under consideration a material behavior of at least one of the two sintered materials iteratively determined.

A Continuing education for both procedures provides that between the form, in particular a die, and a sintered material to be filled Relative rotation acts, allowing the sintered material in dependence from a speed of relative rotation in an outer area the form accumulates.

For the rest, can also be provided that the first and at least the second sintered material at least one Overlapping period be added to the mold.

Furthermore, on the US 5,903,815 directed. From this, various sintering materials, conditions for sintering materials, shapes, principles regarding the processing of two or more sintered materials, applications and process steps are apparent. In this regard, in the context of the disclosure reference is made to the content of this document, which belongs to the disclosure of this invention.

According to a further aspect of the invention, it is proposed that, in particular in the case of a forged toothed wheel, sprocket or ring gear, the manufacturing process also provides grinding or honing of the compacted tooth flanks and / or tooth roots in addition to the surface compacting step of the toothing. Preferably, the forging achieves a density of at least 7.6 g / cm ³ as the core density. The surface compacting can therefore cause a full compression and / or a precision of the shape of the toothing. A further development provides that an oversize for this step in a range of 4 μm to 8 μm material is above the final dimension for a material-removing machining step after surface compacting. If pressing, sintering and hardening, in particular case hardening, are carried out instead of forging, honing is preferably 30 .mu.m to 50 .mu.m and grinding is 50 .mu.m to 0.3 mm, preferably 0.1 mm to 0.2 mm Surface compacting provided. The iterative calculation makes it possible to determine the areas and dimensions beforehand and to be able to implement them later in the procedure. For a bore in the gearwheel, sprocket or ring gear, surface densification is also preferably provided, followed by hardening followed by preferably honing. The bore may also have an oversize between 30 μm and 50 μm after surface compacting.

One Another advantage has been found when lubricating the surface compacting he follows. In addition to the use of emulsions in particular also with oils be lubricated. This is preferred in hot rolling, for Example at temperatures above 220 ° C. In addition, will proposed to carry out the hot rolling at a temperature between 500 ° C and 600 ° C, wherein preferably used oil cooling on the one hand to smear, on the other hand, the tool to cool.

in the The invention will be described in detail below by way of example with reference to FIGS Drawing explained. However, these illustrated embodiments are not limitative of the scope and re To lay out details of the invention. Rather, they are from the Figures resulting features not on each individual Embodiments limited. Rather, these features with each other, in the drawing and / or in the description including the description of the figures specified features in each case to further developments not shown combined.

It demonstrate:

1 a rolling arrangement,

2 a first tooth,

3 a second tooth,

4 a third tooth,

5 to 7 various measurement progressions of different tooth elements,

8th a first process scheme,

9 a second process scheme,

10 an oversize course of a toothed element of a rolling tool,

11 a schematic view of a calculated depression on a front side,

12 a schematic view of calculated extreme cases of tools,

13 a schematic view of an approach in the iterative calculation and links in a simulation,

14 , a view of density gradients as a function of different initial densities of the preforms used,

15 an overview of the detected errors that occur at different surface densification steps and characterize the material behavior,

16 a hardness curve in HV on a flank of a toothing in different surface compacting steps,

17 a hardness curve in HV in a foot region of a toothing in different surface compacting steps,

18 a schematic view of various calculated Aufmaßverläufen for different densities,

19 a schematic representation of parameters that can be included in the iterative calculation.

1 shows an exemplary Wälzanordnung in a schematic view. A first rolling tool 101 with a first toothing 102 is about a first axis 103 in a direction of rotation 104 rotatably mounted. The first gearing 102 is located with a second toothing 105 a preform 106 engaged. The preform 106 is about a second axis 107 rotatably mounted. Accordingly, a second rotation direction results 108 , Furthermore, there is the second gearing 105 with a third toothing 109 a second rolling tool 110 engaged. This second rolling tool 110 is about a third axis 111 in a third direction of rotation 112 rotatably mounted. For example, the first axis 103 or the second axis 107 Be hard axles, while the other two axes can perform a feed movement. For example, the third axis 111 in a direction of displacement 113 along a connecting line 114 the first 103 , The second 107 and the third axis 111 displaceable. For example, a Maßwalzvorgang be made. In particular, tooth flanks are only slightly compacted and, in particular, the tooth roots are not compacted. This results in a surface compaction in a desired area. On the other hand, in the case of a surface compaction, the tooth base can also be surface-compacted only or additionally. For example, during a rolling process there is a progressive shift in the direction of the displacement direction 113 instead of. In particular, by means of the first and the second rolling tool 101 . 110 also an area of the tooth feet of the preform 106 compacted. For adjusting the first and / or the second rolling tool 110 and for impressing a pressure necessary for a rolling operation, an adjusting device, not shown, is preferably provided with a gear. In particular, very high pressures can be applied.

2 shows a first tooth 201 an associated toothed element, not shown. This toothed element is a toothed wheel. A geometry of the toothed element or of the first tooth 201 is thereby by a first foot circle 202 , a first foot circuit 203 , a first pitch circle 204 and a first head circle 205 characterized. At a first flank 206 indicates the first tooth 201 before a rolling process, a first measurement course 207 on. After a completed rolling process results in a first Endmaßverlauf 208 , wherein correspondingly a first compacted edge layer 209 results. Schematically represented by a first compression boundary line 210 limited. This line limits the area of the first tooth 201 within which the full density is reached. The full density is preferably based on a density of a comparable powder-forged tooth.

3 shows a second tooth 301 a toothed element, not shown. This toothed element is also a gear wheel. Second tooth 301 and gear are through a second head circle 302 , a second pitch circle 303 , a second foot circuit 304 and a second root circle 305 characterized. To achieve one on a second flank 306 and a third flank 307 identical compression curve is a second oversize course 308 and a third oversize course 309 intended. After a rolling process results on the second flank 306 a second final dimension course 310 and on the third flank 307 a third final dimension course 311 , Furthermore, a second compression limit line results 312 and a third compression boundary 313 , Because of the rolling motion in a rotational direction different forces on the second flank 306 and the third flank 307 are the second oversize course 308 and the third oversize course 309 differently designed. The different effect of forces on the tooth flanks is illustrated 306 . 307 in a rolling process by the illustrated Gleitgeschwindigkeitsrichtungen. At the second flank 306 result in a first 314 and a second sliding speed direction 315 , These are based on the second pitch circle 303 in Rich tion of the second tip circle 302 or in the direction of the second root circle 305 directed. At the third flank 307 whereas a third sliding speed direction results 316 and a fourth sliding speed direction 317 , which are directed against each other.

4 shows a third tooth 401 a toothed element, not shown. This toothed element is also a gear wheel. Gear and third tooth 401 are in turn by a third head circle 402 , a head circle 403 , a third pitch circle 404 , a third foot circuit 405 as well as by a third foot circle 406 characterized. In the third tooth shown 401 it is a toothing with a head return, preferably in the form of a head rounding. However, other geometries in this area are possible. It is in a tooth tip area 401.1 between the third tip circle 402 and the head cycle 403 a tooth profile withdrawn. As a result, the tooth does not engage in involute counter-toothing in this area. In this case, an active tooth area lies only in the area between the head cycle 403 and the foot circuit 405 or between the head cycle 403 and the third foot circle 406 , A fourth ascending course 407 results after a rolling process in a fourth compression boundary line 408 , Furthermore, on the fourth flank 409 a fourth final measurement course 410 achieved.

5 shows a Aufmaßverlauf between two adjacent teeth of a toothed element, not shown. This toothed element is again a toothed wheel. Gear and teeth are through a fourth root circle 502 , a fourth Nutzfußkreis 503 the preform, a fifth Nutzfußkreis 504 the preform after a grinding process, a fourth tip circle 505 after a milling process and a fifth tip circle 506 characterized after a finishing process. After a rolling process results in a fifth Endmaßverlauf 507 , On the abscissa a lateral dimension in millimeters is plotted. On the ordinate axis, the correspondingly perpendicular lateral dimension is also plotted in millimeters. The teeth run completely in the plane of the drawing.

6 shows a compilation of further measurement progressions. On the abscissa the nomierte ground length along a flank line of a toothing element is Darge presents. In each case, this curved line relates to a progression from a tooth tip of a first tooth to a tooth tip of an adjacent tooth. The absolute arc length of the corresponding flank line in millimeters is correspondingly shown on the upper abscissa axis. The left ordinate axis indicates an allowance in millimeters. The right ordinate axis describes the corresponding radius of the associated toothing. Shown are a sixth oversize course 601 , a seventh oversize course 602 and an eighth oversize course 603 , Furthermore, there is an associated radius 604 represented the corresponding toothing. The sixth oversize course 601 and the eighth oversize course 603 are symmetrical to a tooth root symmetry line 605 executed. The seventh oversize course 607 is, however, designed asymmetrically. Near the tooth symmetry baseline 605 , ie in the tooth base area, the allowances each have a local minimum. This promotes a reduction of a risk of stress cracking.

7 shows a further oversize course. Shown is a ninth oversize course, that of a left tooth head 702 to a right tooth head 703 runs asymmetrically. As already in 6 shown here is an allowance in the area of a tooth base 704 less than in the fifth 705 and the sixth flank 706 , This serves in particular to avoid stress cracks.

8th shows a first process scheme. Starting from a target 801 , which includes the geometry, a torque of a gear to be transmitted and a pressure distribution, is provided with a first geometry generation module 802 generates a geometry of a rolling tool. In addition, both based on the target 801 as well as based on the geometry of the rolling tool a geometry of a preform in a second geometry generation module 803 generated. In a first simulation module 804 a rolling process is simulated. In this case, both a kinematics of the rolling process and the compression process, which is caused during rolling, simulated. In particular, a redistribution of material, such as in 3 outlined, considered. The simulation of a plastic deformation takes place here for example by means of a finite element method. This can be coupled with a CAD program. Optionally, a second simulation module 805 be taken into account for simulating a stress. Both the goal and the goal go into this module 801 as well as the geometry of the preform. On the other hand, the second simulation module allows 805 Furthermore, a correction of the determined geometry of the preform. In particular, the first geometry generation module 802 , the second geometry generation module 803 , the first simulation module 804 and optionally the second simulation module 805 be executed repeatedly in an optimization loop.

9 shows a second process scheme. In a first step 901 becomes a ninth oversize course 902 a tooth profile 903 generated. Subsequently, in a second step 904 a second tooth profile 905 a third rolling tool 906 generated. After that, in a third step 907 simulates a rolling process. In this case, the rolling process of the first tooth profile 903 on the second tooth profile of the rolling tool 905 and simulated the resulting compaction. Subsequently, the first, second and third step 901 . 904 . 907 in a variation 908 if necessary repeated.

10 shows an oversize course of a toothed element of a rolling tool. Shown is a tenth oversize course 1001 a fifth tooth 1002 a rolling tool, not shown. On a seventh flank 1003 and an eighth edge 1004 of the fifth tooth 1002 a different oversize is provided. At the seventh flank 1003 is a material allowance provided by a first arrow 1005 is indicated. On the other hand is on the eighth edge 1004 a tooth return provided by the second arrow 1006 is indicated. The allowance in this example is based on a regular profile of involute toothing. Due to the asymmetrical configurations of the two tooth flanks 1003 . 1004 In particular, an unbalanced material load of a gear element to be compacted is taken into account. Also, with respect to the final shape of the workpiece a symmetrical profile of both flanks of a tooth can be achieved by means of this rolling tool, for which compensations in the range of preferably less than 0.1 microns are made.

11 shows a schematic view of a calculated depression on an end face of a toothing. The depression serves to at least minimize, if not even compensate, growth of the sintering material displacement achieved by the surface compaction and concomitant growth of the tooth in height and / or width. The shape of the depression depends on the allowance and on the dimensions of the tooth. The shape can be optimized iteratively using the calculation method. A simulation allows an estimation of the actual behavior of the preform later on.

12 Figure 11 is a schematic view of calculated extreme cases of surface compaction tools that are calculable. The starting point of the calculation is the left-hand end geometry of the toothing. By taking into account rolling conditions, measuring parameters and other influencing factors, it is possible to determine iteratively the tool shapes that are shown in the middle and to the right of it.

13 a schematic view of an approach in the iterative calculation and links in a simulation. Based on the given end data of the workpiece and its toothing, the machine kinematics can be modeled. This is assumed, for example, by the associated machine axes. By means of the kinematics and functional links, an optimization of the tool to be designed can then be carried out by means of the available degrees of freedom. This will be on again 12 directed. The examples presented there have corresponding disadvantages, for example too weak foot region in the middle representation or too pointed head design in the right representation. Additional influencing parameters, such as strength considerations and / or stress curves in the material, can then be used to execute an iteration towards a contour of the tool that is suitable for the respective requirement profile. For the tool for producing the preform, for example, the determined final geometry with the calculated measurements is taken as a starting point.

14 shows a view of density gradients as a function of different initial densities of the preforms used. If the density of the preform in its core as well as in the course changed outward, there are influences on the surface densification course. This goes from the right picture of the 14 out. By changing the respective preform, the density profile after a surface compression can also be strongly influenced. Therefore, the output core density as well as the shape of the preform are important parameters in the iteration and computation.

15 gives an exemplary overview of the detected errors that occur at different surface densification steps and characterize the material behavior. The error is specified in error classes according to DIN 3972 or DIN 3970. An important point in determining a suitable surface compaction by rolling is the profile change of the rolling tool. By using the above calculation method for the preform and the rolling tool, it is possible to modify the rolling tool based on the obtained results. This will be in 15 was presented at a preform having a core density of 7.3 g / cm ^3, which was in engagement with an unmodified set of rolling tools and surface densified.

Depending on a feed movement of the rolling tool, the geometry of the gear changes. The goal is to achieve the desired final contour, as it is prescribed. From the picture of the 15 There are different states for different feed movements. As an example, the profile angle error is shown on the left, the full profile shape error in the middle and the shape error on the right. These were measured on the gear produced in each case. For example, a tooth thickness reduction of 0.27 mm leads to a profile angle deviation corresponding to class 7 according to DIN. In order to achieve a necessary final form of tooth thickness reduction, however, a feed of 0.4 mm is necessary. However, this leads to an increase in the respective error. This means that the finished final contour in the other values comes to lie outside of the required quality grades. Therefore, a change in the geometry of the tool is necessary. Taking into account the found values as input values, a new tool can then be determined, again perform the tests and iteratively determine an optimized geometry for the tool in this way. The calculation makes it possible to determine a final contour for the tool with, for example, two or even one iteration.

16 shows a hardness curve in HV on a flank of a toothing applied over the distance from the surface on the x-axis in [mm]. In the case of various surface compacting steps, the profile profile of the hardness can be influenced by suitable dimensioning as well as by feed movement. For example, the course may be at least partially convex or concave. As indicated, the preform designated AVA7-1 has a larger oversize than the preform designated AVA4-2. Both have an opposite course of hardness: while in the first part until reaching 550 HVAVA7-1 has a more convex shape, AVA4-2 has a more concave course. After falling below 550HV this changes.

17 a hardness curve in HV in a foot region of a toothing at different Oberflächenverdichtungsschritten. Due to the smaller oversize there compared to the flank allowance and due to the geometry results in a different hardness profile. The hardness initially drops steeper, but then goes over almost in a straight course with only a slight inclination.

18 shows a schematic view of various calculated Aufmaßverläufen for different densities based on a final tooth thickness. The diameter is plotted on the y-axis. The oversize is indicated on the x-axis. D_a or d_a indicates the head circle diameter or the tip circle diameter, 0 is a Vorga be a measure, for example, by a value at the pitch circle, d_b is the base circle diameter. A indicates the range of preferred values for the pitch circle area. B indicates a critical area, since material failure during rolling can already occur there.

19 shows a schematic representation of parameters that can be included in the iterative calculation. In particular, these locations may be the maximum load. As shown in the left photo, pitting damage may occur on the flank. Therefore, a comparison voltage curve is preferably used in which the following applies: A maximum voltage occurs below the surface, in particular in the region of a negative slip, therefore preferably below the specified pitch circle diameter d_w1. The right photo indicates a tooth fracture due to excessive bending load. It follows for the calculation model that a location of the maximum Zahnfußbeanspruchung is determined and taken into account. This can be determined, for example, via the 30 ° tangent according to DIN or via the Lewis parabola according to AGMA. For the comparison voltage, it is preferably assumed that a maximum stress occurs on the surface.

20 shows a schematic view of another way, such as simultaneously at least two preforms can be compacted. In addition to the movement of the tool, a movement of the preforms in the direction of the tool can be carried out according to an embodiment. In addition, it is possible to arrange two or more preforms on a preform axis.

The invention can be used, for example, in camshaft toothed wheels, in planetary gears, in sun gears, in drive gears, in differential gears, in gear wheels, clutch gears, pump gears, spur gears, helical gears, electric motors, internal combustion engines, in epicyclic gears, in external gears. or internal gears, for straight or helical or external helical gear units, for bevel gear units with straight, helical or curved teeth, for helical gear units or worm gears, as well as for helical and helical hub connections. Another embodiment provides that a gear made of sintered metal. The other may be made of plastic or another material, for example. Furthermore, there is the possibility that at least one of the two gear wheels has a coating which in particular has a noise minimizing effect. Preferably, a Kegelschraubradpaar can be created to thereby form a Hypoidgetriebe. In particular, the workpieces me gearing in automotive technology, in the engine technology, in transmission technology, with adjusting devices, in power transmitting devices, in toys, in precision mechanical devices, in household appliances, especially mobile home appliances, and other applicable.

Claims (8)

Calculation method for the design of a preform a toothing made of sintered material, with data in the calculation method enter, which determined from a predetermined final shape of the gearing be, depending of at least one use condition of the final shape one or more Load parameters of the gearing are determined, a local Excess of the Preform is calculated with an expected densification of the preform on the surface correlated, with a load of the sintered material below the Surface in the calculation is received. Calculation method according to claim 1, characterized in that that penetration of the tool into the workpiece to be produced in the calculation is taken as a basis. Calculation method according to claim 1 or 2, characterized characterized in that an elastic deformation of the to be compacted Considered sintered material becomes. Calculation method according to claim 1, 2 or 3, characterized characterized in that an elastic-plastic deformation of the is taken into account compacting sintered material. Calculation method according to one of the preceding Claims, characterized in that a depth of a maximum load below the surface enters the calculation process. Calculation method according to one of the preceding Claims, characterized in that a shrinkage of the sintered material during Sintering is included in the calculation. Computer program product with program code means, which are stored on a computer readable medium to a method according to at least one of the claims 1 to 6, if the program is running on a computer. Machine for calculating and / or executing a Surface compaction, wherein a method according to any one of claims 1 to 6 is deposited for calculating the production of a gearing with a surface compression.