DE102007023087A1 - Manufacturing cam for built-up cam shaft used in vehicle engine, employs steel of specified carbon content, hot or cold deformation, tempering and hardening operations - Google Patents

Abstract

The steel, which is capable of being hardened, has a carbon content in the range 0.3-0.8 wt%. It is Cf53 or C56E2. The heat treatment includes brief inductive tempering and inductive case hardening. Following inductive hardening, the blank cam is tempered. The cam is manufactured by cold deformation, especially cold forging or extrusion. Before deformation, the blank is heated to 200-500[deg] C. Hot forging or hot pressing is optionally employed, followed by controlled cooling. Before and/or after heat treatment, the blank cam is machined by cutting or grinding. Heat treatment and machining take place with the blank cams held together as a clamped pack.

Description

The The invention relates to a method for producing a cam a curable Steel material for a built camshaft in an internal combustion engine of a motor vehicle.

In Internal combustion engines for Motor vehicles are often used so-called built camshafts. Such a built camshaft consists of one (hollow or solid) Carrier wave, on the several attachments (cam discs, thrust washer, drive wheel, momentum wheels ...) are. Built camshafts have the advantage that the materials the individual components very precisely the functional requirements of this Components can be adjusted so that opposite a conventional one one-piece Camshaft both weight and material and / or manufacturing costs can be saved. Furthermore, lets the design of the individual components greater freedom of design for one Manufacturing cost-optimal design of the production process chain and their individual sections.

The production of individual cams is usually carried out in a three-stage process, in which initially a cam blank is forged or thermoformed from a suitable steel material, then machined and finally annealed and / or cured in a heat treatment. Such methods are for example from DE 197 16 554 C1 , of the DE 100 48 234 A1 and the DE 101 13 952 A1 known. To cope with the high loads during operation of the camshaft, these cams are often made of the bearing material 100Cr6 and then hardened and tempered. However, this process is associated with high costs, since the material 100Cr6 for improving the structure and the machinability after forging must be heat treated (eg GKZ-annealed). After machining, the material is then given an increased resistance to wear (resistance to abrasion, rolling resistance) for later use in the engine by means of hardening (eg, heat soaking with subsequent quenching in the salt or oil bath) and subsequent tempering. In addition, the cam must be blasted and washed several times during the manufacturing process. The process chain described is complex and prone to edge decarburization, cracking and distortion in terms of component quality. These quality risks can only be countered by a complex process management of the individual processes and additionally by a cost-intensive 100-test with increased scrap quantities.

Of the Invention is based on the object, a process for the preparation from cams for to specify a built camshaft, which - at a consistently high Load capacity of the cams - one cost-effective Production possible and the cam production makes it more robust against quality-reducing process disturbances.

The The object is achieved by the Characteristics of claim 1 solved.

After that becomes a curable material as cam material Steel material with a carbon content between 0.3 wt .-% and 0.8% by weight, preferably Cf53 or C56E2, if appropriate with one opposite the DIN 17212 or DIN EN ISO 683-17 restricted or modified chemical Composition, improved formability, machinability and / or hardenability to reach. Furthermore, it is also possible, case hardenable or carbonitrizable steels to use.

in the Difference to the previously used cam material 100Cr6 (with approx 1 wt .-% C and 1.5 wt .-% Cr), which formed by hot forming (forging) Must have, these cam materials have the advantage of being are cold formable. Cold forming causes thermally induced damage the cam surface (Edge carburizing etc.) avoided. From this and through the cold forming connected higher Dimensional accuracy follows a reduction of the grinding allowance up to 30% compared usual 100Cr6 cam. Similar Benefits can even with warm forging (at temperatures up to 400 ° C or 500 ° C, depending on the concrete material composition). Even hot forging (at approx. 1100 ° C) offers with these materials (e.g., Df53 or C56E2) over the previously used material 100Cr6 with skillful coordination of the entire process chain significant starting points for quality improvement and cost reduction.

Opposite cam from the conventional cam material 100Cr6 Cf53 and C56E2 cams continue to be characterized by a higher metallurgical robustness, e.g. a lower sensitivity to hypersensitivity. For example, a 100Cr6 cam must be started immediately after curing become; In contrast, allows Cf53 a much less stringent litigation.

Farther the material price is in the comparable initial state of Cf53 or C56E2 well below that of 100Cr6, resulting in further savings can be achieved.

The starting material for the production of the cam is rod material, from which in a first process step a slit is cut, from which a cam blank is formed. This transformation is preferably carried out by cold forming, in particular by means of cold extrusion. In order to facilitate the forming process, the rod material or the cam disk may optionally be heated to a temperature of up to 400 ° C.-500 ° C. prior to forming (depending on the material), so that the deformation takes place as warm forging. Such a temperature increase naturally increases the deformability. The temperature is chosen in such a way that the forming takes place without microstructure impairment and no scaling occurs. For example, when forming by hot forging, Cf53 or C56E2 offer the possibility of substituting the usual subsequent isothermal heat treatment process with a cost-effective controlled cooling process from forging heat compared to the previously used 100Cr6.

• – ein möglichst geringes Aufmaß auf der Lauffläche des Nockens zu erreichen und damit den in einem späteren Prozessschritt erforderlichen Schleifaufwand zu minimieren, und
• – ggf. spanende Bearbeitungsschritte wie das Drehen/Schleifen der Stirnflächen oder der Bohrung zu reduzieren bzw. zu vermeiden.

Subsequent to cold, warm or hot forming, the cam blank may be subjected to a cold and / or hot calibration process to achieve a highly accurate cam shape. Depending on the achievable accuracy of forming this may be necessary to

• - To achieve the lowest possible oversize on the tread of the cam and thus to minimize the required in a later process step grinding effort, and
• - If necessary, to reduce or avoid machining operations such as turning / grinding of the end faces or the bore.

Around the oversize too reduce the cam blank can subsequently or alternatively machined become. In this way is already in the soft state of the cam that later (i.e., after curing and the joining the cam on the shaft) to be abraded to a minimum; this saves on the later Contour grinding (i.e., finishing the camshaft) Cycle time and thus machine capacity and investment costs. A machining preprocessing (e.g., milling) The cam blanks after forming also offers the advantage that thereby the variety of variants of the semifinished product and / or the tools be reduced. The machining of the cam blanks takes place preferably in a package clamping on a common mandrel. Several cam blanks are on a common mandrel taken and the outer contour all around except for a remaining grinding allowance (about 0.4 mm) removed by machining. Alternatively, the machining can also be carried out in single clamping.

It may also be advantageous, the cam blanks before and / or Deburr and / or clean after machining. In particular, you can the cam blanks shot blasted or sandblasted become.

Then be the cold or half warm or hot formed and possibly calibrated and / or machined cam blanks of a heat treatment for the purpose of hardening subjected to the cam track. Preferably, the cam blanks induction hardened surface hardened.

alternative can the cam blanks also first Inductively short-tempered and then inductively surface hardened be, preferably then with a suitable multi-frequency technique. Alternatively, with the induction technology, a through hardening of the Cams take place.

At the inductive surface hardening the cam disk is locally austenitized, quenched and then tempered. The parameters of this hardening process are chosen that the edge hardening depth the cam in the ready-to-install state on the cam track at least 0.3 mm. It must the joining tolerances as well as the allowance for grinding the joined Camshaft taken into account so while the surface hardening a correspondingly deeper hardening the cam blanks is required.

By the residual stress distribution in the cam between in the case of inductive surface hardening produced hard layer in the area of the cam track and the unchanged soft core results in the possibility an elevated one Wälzbeständigkeit / wear resistance. Such an intrinsic stress characteristic of surface hardened cams is much more advantageous in terms of operating stress as the one through hardened cam.

The Starting the cam blanks can be started by inductive short-term starting, by conventional oven firing (typically about 2 hours at about 180 ° C) or by tempering from the residual heat of the previous process step. Optionally, tempering may be performed at e.g. Cf53 and C56E2 cams completely omitted.

• – So kann eine vorgeschaltete induktive Kurzzeitvergütung notwendig sein, z.B. falls eine definierte Kernfestigkeit benötigt wird, die sich von derjenigen des Ausgangsmaterials unterscheidet.
• – Die Vorvergütung vor der induktiven Randschichthärtung kann auch im Härteofen mit anschließendem Abschrecken im Öl- oder Salzbad erfolgen.
• – Anstelle der induktiven Randschichthärtung können die Nockenrohlinge auch durch Austenitisierung in einem Härteofen unter definierter Atmosphäre und anschließendem Abschrecken im Salz- oder Ölbad gehärtet bzw. vergütet werden.
• – Weiterhin kann auf die Randschichthärtung verzichtet werden, so dass die Wärmebehandlung der Nockenrohlinge nur eine induktive Kurzzeitvergütung und ein anschließendes Anlassen umfasst.
• – Gegebenenfalls kann der Anlassschritt entfallen, so dass die Wärmebehandlung der Nockenrohlinge nur eine induktive Härtung umfasst, im Bedarfsfall ist ein induktiver oder konventioneller Vergütungsschritt (im Härteofen mit anschließendem Abschrecken im Öl- oder Salzbad) vorgeschaltet.
• – Weiterhin können bei geeigneter Werkstoffauswahl die Nockenrohlinge einsatzgehärtet oder carbonitriert und anschließend im Ofen angelassen werden.

As an alternative to the above-described heat treatment of the cam blanks in the form of inductive surface hardening and subsequent tempering, variations of this heat treatment process are also possible:

• - Thus, an upstream inductive Kurzzeitvergütung may be necessary, for example, if a defined core strength is required, which differs from that of the starting material.
• - The pre-coating before inductive surface hardening can also be done in the curing oven followed by quenching in an oil or salt bath.
• - Instead of inductive surface hardening the cam blanks can also Austeniti Hardened or tempered in a curing oven under a defined atmosphere and subsequent quenching in a salt or oil bath.
• - Furthermore, can be dispensed with the surface hardening, so that the heat treatment of the cam blanks includes only an inductive Kurzzeitvergütung and a subsequent tempering.
• - If necessary, the annealing step can be omitted, so that the heat treatment of the cam blanks includes only an inductive hardening, if necessary, an inductive or conventional annealing step upstream (in the hardening furnace followed by quenching in oil or salt bath).
• - Furthermore, the cam blanks can be case hardened or carbonitrided and then tempered in the oven with a suitable material selection.

Out cost reasons includes the heat treatment process only those process steps that are necessary to reach the cams requirements (hardness, permanently sustainable surface pressure etc.) are necessary.

The inductive hardening can be done in single clamping. Conveniently, the cam blanks however, heat treated in package clamping; This has the advantage that while the clamping of the previous taken over machining can be.

To the heat treatment can the hardened Cam blank are machined. Optionally, this can assumed the package internal tension of the cam blanks from the previous heat treatment process be and cost-effective in a package outside voltage for the Bore processing to be implemented. As in the further process steps until joining the cam on the shaft no longer thermally induced distortions take place, in particular a final contour accurate, cost-effective internal machining the then still soft cam hole done. This can be a accuracy increase of the single cam can be achieved, the higher accuracy of joining the camshaft blanks has the consequence and thus allows a reduction in the grinding allowance.

• – der Werkstoff kaltumformbar und somit der Nocken endkonturnah darstellbar ist; zusätzlich ist kein Schleifaufmaß zur Beseitigung thermisch bedingter Oberflächenschädigungen vorzuhalten;
• – der Werkstoff induktiv randschichthärtbar ist, wodurch gegenüber durchgehärteten Nocken der Verzug bei der Wärmebehandlung reduziert wird. Dies kann als Basis einer kostengünstigen Konturbearbeitung (Zerspanung mehrerer gleichgerichteter Nocken auf einem Spanndort o.ä.) vor dem Härten dienen. Gegebenenfalls kann auch die Bohrung vor dem induktiven Randschichthärten bearbeitet werden.

In sum, the use according to the invention of a hardenable steel material having a carbon content of between 0.3 and 0.8% by weight thus permits a considerable reduction in the grinding allowance of the cam

• - The material cold forming and thus the cam is near net shape representable; In addition, no grinding allowance is to be provided for the removal of thermally induced surface damage;
• - The material is inductively surface hardening, which is reduced compared to through hardened cam, the delay in the heat treatment. This can serve as the basis for a cost-effective contour machining (machining of several straightened cams on a Spanndort or similar) before curing. Optionally, the bore can be edited before inductive surface hardening.

Provided it for cleaning the cam surface, for setting defined Roughness conditions and / or is necessary for the defined introduction of residual compressive stresses, becomes the cam after the heat treatment shot blasted or sandblasted. Unless it is used to make fit ratios between the inner bore of the cam and outer diameter of the shaft required is, the cams are finished inside. For example, if the cams be added to the shaft by hydroforming, so it is advantageous to radiate the inner holes of the cams. On the other hand, the cams should open with the help of thermal joining be fastened to the shaft, so the inner holes should be machined become.

To conclude the cams in terms of appropriate test accuracy Geometry, material properties and crack-free tested.

Of the Cam produced in this way is then to Representation of a camshaft mounted on a hollow or solid shaft. Should the cams are mounted on a hollow shaft, this is done joining step preferably using the hydroforming of the hollow shaft. Alternatively or additionally but the cam can also by other joining methods, for example attached to the shaft by thermal or mechanical joining techniques become.

In Sum can through the use of the method according to the process chain for the production of cams and assembled camshafts considerably shorter and made easier. The resources needed for production can be clear be reduced while at the same time the process chain is qualitatively safer or more robust can be designed as with the currently used cams 100Cr6.

Of the Cam may have the classic blank shape, be nearly annular or have multiple surveys. Furthermore, this is suitable Process for the production of pump cams.

Further advantageous embodiments and modifications of the invention will become apparent from the remaining dependent claims and from the following Gend based on the drawing in principle illustrated embodiments.

there demonstrate:

1 a perspective view of a built camshaft ( 1a ) and a cam ( 1b );

2 a schematic representation of the process steps of a method for producing a cam of 100Cr6 (prior art);

3 a schematic representation of the process steps of a method according to the invention for producing a cam of Cf53;

4 a schematic representation of the process steps of an alternative inventive method for producing a cam of Cf53;

1a shows a built camshaft 1 with cams 2 , using a joining process (eg hydroforming, thermal joining) along with other attachments (thrust washer, drive wheel, impulses ...) on a shaft 3 are attached. 1b shows a detailed view of a cam 2 ,

Conventionally, the cams 2 made from the bearing material 100Cr6; 2 shows a typical procedure 100 for the production of cam discs made of 100Cr6 according to the prior art: starting from a cam piece made of 100Cr6, a cam blank is first produced by hot forming, in particular by forging (step 102 ), which essentially already has the in 1b has shown shape. Subsequently, the cam is blasted for surface cleaning and descaled (step 104 ). To improve the structure or to achieve better machinability, the cam blank is subsequently isothermally annealed (step 106 ). Subsequently, the cam blank is machined in the soft state (step 108 ). To increase wear resistance, the cam blank is then hardened and tempered (step 110 ). Should the cam 2 later by hydroforming (hydroforming) with the shaft 3 be joined, so will the cam 2 blasted in the area of the inner holes (step 112 ). Finally, a quality assurance of the cam 2 performed (step 114 ). For the production of the camshaft is the cam 2 finally with hydroforming (hydroforming) on the shaft 3 joined (step 116 ). Finally, a fine machining (grinding) of the camshaft 1 to give the cam the required shape (step 118 ).

The in 2 The process sequence shown has the disadvantage that due to thermal damage to the cam blank during hot forming 102 (Edge carburizing, cracking, ...), the isothermal heat treatment 106 and due to thermal distortion during oven curing 110 on the cam blank a large (grinding) allowance must be kept in the steps 108 and 118 is removed consuming.

According to an advantageous embodiment of the invention, the cam is made of the cold-formable material Cf53; 3 shows a procedure 200 for manufacturing cf53 cams using hot forming:
From a bar stock made of Cf53 in the shelled or unpeeled state, a slug is first cut to length after heating the rod, from which a cam blank is produced by a hot forming step, in particular by forging or by hot extrusion at about 1100 ° C (step 202 ), which is essentially already in 1b has shown shape. The cam blank is advantageously cooled directly after the hot forming in a targeted manner to a suitable structure as a basis for subsequent steps ie for a spin out and, if necessary, facing (step 206 ), a contour processing in the soft state (step 208 ) and inductive hardening (step 210 ).

The cam blank is surface cleaned (blasted) and descaled (step 204 ). Depending on the accuracy required by the joining process, the bore machining (step 206 ) either before or after the inductive surface hardening (step 210 ) respectively. Before the cam is hardened (step 210 ), as an option for further optimization of the overall process chain, the outer contour is machined in the unhardened state on the single cam or in package tension (step 208 ).

Subsequently, the raceway of the cam is inductively hardened and tempered (step 210 ). Should be made of the cam blank cam 2 later by hydroforming (hydroforming) on the shaft 3 be joined, so will the cam 2 blasted in the area of the inner holes (step 212 ). Finally, there is a quality assurance of the cam 2 in a suitable test severity (process step 214 ). For the production of the camshaft is the cam 2 eg with hydroforming (hydroforming) on the shaft 3 joined (step 216 ); then the cams are brought by grinding on the final contour (step 218 ).

• – Geringerer Materialpreis von Cf53 gegenüber 100Cr6;
• – Auf Grund der wegfallenden isothermen Glühung nach dem Schmieden reduziert sich die thermische Vorschädigung an der Nockenoberfläche; es muss daher ein geringeres Schleifaufmaß vorgehalten werden.
• – Auf Grund der wegfallenden isothermen Glühung nach dem Schmieden verringern sich Anlageninvest und Betriebskosten.
• – Eine vor dem Induktionshärten durchführbare Konturbearbeitung am weichen Nocken bringt folgende Zusatzeffekte mit sich: 1. Verbesserung der Härtequalität, da das Härten auf homogenem Kerngefüge erfolgt; 2. Einsatz von kostengünstigem/ungeschältem Ausgangsmaterial ohne Qualitätseinbußen möglich; 3. Erhöhung der Genauigkeiten im Fügeprozess; daraus folgt wiederum eine Verringerung des Schleifaufmaßes in der Fertigbearbeitung; 4. Verringerte Investitionsbedarfe in der Fertigbearbeitung der Nockenwellen, da je nach Fertigteiltolerierungen maximal ein Finish-Schleifen mit geringem Restaufmaß verbleibt.

Compared with the process flow 100 for the production of cams made of 100Cr6 (see 2 ) offers the process flow 200 for making cams from Cf53 using a hot forming process (see 3 ) the following advantages:

• - Lower material price of Cf53 compared to 100Cr6;
• - Due to the omitted isothermal annealing after forging, the thermal damage to the cam surface is reduced; Therefore, a lower grinding allowance must be provided.
• - Due to the omitted isothermal annealing after forging reduce Anlageninvest and operating costs.
• - A contouring operation on the soft cam, which can be carried out before induction hardening, has the following additional effects: 1. Improvement of the hardness quality, since hardening takes place on a homogeneous core structure; 2. Use of inexpensive / ungeschältem starting material without loss of quality possible; 3. increasing the accuracy in the joining process; this in turn results in a reduction of the grinding allowance in finishing; 4. Reduced investment requirements in the finishing of the camshafts, as depending on finished part tolerances a maximum of a finishing grinding remains with low residual allowance.

• – Kalibrieren von Außenkontur, Nockenbreite und Bohrung im kalten bzw. halbwarmen Zustand (Schritt 304),
• – Ausspindeln und Plandrehen (Schritt 306), sowie
• – Konturbearbeitung (Schritt 308).

A particularly advantageous embodiment of the invention is in 4 shown. Again, the cam is made of the cold-formable material Cf53, the shaping takes place in this process sequence 300 However, with the help of a cold forming process, in particular by means of cold extrusion. Here, too, a slug is first cut to length from a bar stock made of Cf53 in the peeled or unpeeled state, from which cold cuts (step 302 ) is formed a cam blank, which substantially already in 1b has shown shape. In order to increase the formability, the slug can be heated up to 500 ° C before cold working, which is far below the structural transformation temperature of Cf53, but provides improved deformability. The cold forming (or hot forging) allows a near-net shape production of the cam blank, since the cam is not subject to strong thermal influences and no adverse structural changes occur. Depending on the accuracy requirements of the subsequent joining process, the following process steps may optionally be carried out before the cam is hardened:

• - Calibration of outer contour, cam width and bore in cold or semi-warm state (step 304 )
• - Unscrewing and facing (step 306 ), such as
• - Contouring (step 308 ).

Subsequently, the cam is inductively hardened and tempered (step 310 ). Optionally, the hole can also be machined only after hardening.

After blasting (step 312 ) there is a quality assurance (step 314 ) in a suitable test severity. For the production of the camshaft is the cam 2 by hydroforming (hydroforming) on the shaft 3 joined (step 316 ); then the cams are brought by grinding on the final contour (step 318 ).

• – Zunächst fällt unmittelbar auf, dass der Prozessablauf 300 bei Entfall der optionalen Schritte 304, 306 und 308 weniger Einzelschritte umfasst als der Prozessablauf 100 und somit prinzipiell einfacher ist als das herkömmliche Nockenherstellungsverfahren 100.
• – Da der Nockenrohling im Prozessablauf 300 kalt/halbwarm geformt wird (Schritt 302) und während der induktiven Wärmebehandlung nur in einem Randschichtbereich gehärtet wird (Schritt 310), sind die thermischen Schädigungen und Verzüge des Nockenrohlings sehr viel geringer als beim Prozessablauf 100. Das hat zur Folge, dass die Nocken mit einer wesentlich höheren dimensionalen Genauigkeit hergestellt werden können. Daher kann das Schleifaufmaß stark verringert werden, was eine erheblich einfachere und kostengünstigere spanende Endbearbeitung der Nockenwelle (Schritt 318) zur Folge hat.
• – Da der Werkstoff Cf53 unempfindlicher ist als 100Cr6, insbesondere eine geringere Rissempfindlichkeit hat, und da die thermischen Belastungen des Nockenrohlings während der Herstellung im Prozessablauf 300 wesentlich geringer sind als im Prozessablauf 100, ist der im Schritt 314 zu leistende Messumfang erheblich geringer und somit kostengünstiger als beim herkömmlichen Verfahren (Schritt 114). Weiterhin führt dies zu einem geringeren Ausschuss.
• – Weiterhin ist der Materialpreis von Cf53 geringer als der von 100Cr6.

Compared with the process flow 100 for the production of cams made of 100Cr6 (see 2 ) provides the process flow 300 for making cams from Cf53 using a cold / semi-hot forming process (see 4 ) the following advantages:

• - First, it immediately stands out that the process flow 300 if the optional steps are omitted 304 . 306 and 308 includes fewer individual steps than the process flow 100 and thus in principle easier than the conventional cam production method 100 ,
• - Since the cam blank in the process flow 300 cold / semi-warm is formed (step 302 ) and hardened during the inductive heat treatment only in an edge layer area (step 310 ), the thermal damage and distortion of the cam blank are much lower than during the process 100 , As a result, the cams can be manufactured with a much higher dimensional accuracy. Therefore, the grinding allowance can be greatly reduced, resulting in a considerably simpler and less costly machining of the camshaft (step 318 ).
• - Since the material Cf53 is less sensitive than 100Cr6, in particular has a lower crack sensitivity, and because the thermal stresses of the cam blank during production in the process flow 300 are significantly lower than in the process 100 , that's in step 314 to be paid considerably less and thus cheaper than the conventional method (step 114 ). Furthermore, this leads to a lower reject rate.
• - Furthermore, the material price of Cf53 is lower than that of 100Cr6.

Induction hardening (steps 210 . 310 ) and the machining of the cams (steps 206 and 208 respectively. 306 and 308 ) take place advantageously in a package clamping, in which a plurality of cams are connected to each other by means of a clamping device, for example using a mandrel or an outer clamping device, and are cured or processed together in this state.

In addition to the in 3 and 4 shown process flows 200 . 300 Combinations of these processes are also possible.

Claims (12)

A method for producing a cam of a hardenable steel material for a camshaft in an internal combustion engine of a motor vehicle, comprising the following process steps: - forming a semi-finished product to produce a cam blank; - Heat treatment of the cam blank. characterized in that the hardenable steel material has a carbon content between 0.3 wt .-% and 0.8 wt .-%. Method according to claim 1, characterized in that that the hardenable Steel material is Cf53 or C56E2. Method according to one of claims 1 or 2, characterized that the heat treatment the process steps tempering and hardening includes. Method according to claim 3, characterized that the tempering by inductive short-term tempering he follows. Method according to claim 3 or 4, characterized that hardening done by an inductive surface hardening. Method according to one of claims 3 to 5, characterized that the cam blank is tempered after induction hardening. Method according to one of claims 1 to 6, characterized that the production of the cam blank by cold forming, in particular cold extrusion, he follows. Method according to claim 7, characterized in that that the semi-finished product before forming to a temperature between 200 ° C and 500 ° C is heated. Method according to one of claims 1 to 6, characterized that the production of the cam blank by hot forming, in particular Forging or hot extrusion, takes place, wherein the cam blank after the hot forming of the deformation heat controlled cooled becomes. Method according to one of claims 1 to 9, characterized that before and / or after the heat treatment a machining of the cam blanks takes place. Method according to claim 10, characterized in that that the heat treatment and the machining in a package setup of several Cam blanks on a common mandrel done. Use of a by a method according to a the claims 1 to 11 manufactured cam in one using hydroforming built camshaft.