DE10142805A1 - One-piece joint body - Google Patents

Abstract

Method for producing a metallic component, in particular a joint inner part of a shaft joint having ball tracks, powder being filled into a filling space, the filling space being delimited by a die, at least one shaping mandrel and a filling mandrel arranged opposite it, a central mandrel, at least one lower and one Upper stamp, wherein the powder is pressed into the green space by pressing the upper and / or lower stamp into a green body, ejected and sintered.

Description

The invention relates to a metallic sintered part, in particular an inner joint part of a shaft joint, with in one Angle to the pressing direction arranged ball tracks and / or a curvature of the ball tracks, together with the method and device for its implementation.

Universal joints consisting of an inner joint part and a Joint outer part are known. They are mainly used for Torque transmission between shafts in operation are subject to major relocations. Even the inclusion of axial displacements are possible.

An example of the transmission of torque via angled shafts is the constant velocity universal joint. Constant velocity universal joints belong to the genus of Pin joints, the most common design of which is the universal joint. At the The universal joint is the joint fork of the two shafts with one Spigot connected. Simple universal joints leave in significant small angle changes. Axial and radial Shifts of the waves are not possible.

The constant velocity joint avoids these disadvantages. In contrast become universal joints with constant velocity universal joints become uniform at a uniform angular velocity Speeds generated on the output side. The same goes for for the torques.

The PTO shaft consists of two joints and one Intermediate shaft. The intermediate shaft is to compensate for Length changes mostly carried out as a telescopic shaft. The condition for a uniform transmission is that the two articulated forks lie in one plane and, if the deflection angle is on two joint forks are always the same size, at least in the Operation most common location. This can be done by Z- or W arrangement can be achieved. In motor vehicles mostly the former common. This causes irregularities only in the intermediate shaft. To be large in a small space Compensate for angular movements, for example when Front wheel drive of motor vehicles, double joints are used. This correspond in principle to the cardan shaft, but instead of Intermediate shaft only a short intermediate piece - shaft or sleeve - Available, which is guided so that the deflection angle of both Joints are always the same. The longitudinal displaceability is in Input or output shaft provided. Enable next to it Constant velocity joints are a uniform, non-positive Transmission of the torque or the angular velocity mostly About balls, which are guided in ball tracks so that they always lie in the mirror plane of the joint. For larger ones Centering is necessary for constant velocity joints. The Constant velocity joints allow for large deflection angles uniform transmission. Constant velocity joints are called Fixed joint or sliding joint, the fixed joint being the Drive axis fixed in the axial direction and that Sliding joint compensates for by longitudinal displacement Axis length changes enabled.

Universal joints of this type are with an outer joint part and an inner joint part connected to the shafts. The Inner joint part is guided over balls in the outer joint part. The Balls move in a ball cage in ball tracks, which on the outer surface of the inner joint part and on the Inner surface of the outer joint part are formed. The Geometry of the universal joints requires that the recesses for the ball tracks are machined.

This type of manufacturing usually requires one costly and high-precision machining. adversely is that the inner joint part in a variety of Steps and in different processing machines must be manufactured. So far, the inner joint part was open conventional way from a forging blank, because the undercuts or shapes, for example the Ball tracks, not to be produced in any pressing process were and therefore not pressed from metal powder and sintered to the final shape. This required usually additional procedural steps to the To achieve the shape of the undercuts.

The object of the invention is a method and To provide device with which in simple and a metallic sintered or forged part, in particular an inner joint part of a shaft joint can be manufactured.

The invention solves this problem with the Device and property claims specified features.

According to the invention, a method for Production of a metallic sintered part or forged part, in particular of a joint inner part having ball tracks of a shaft joint, powder being filled into a filling space the filling space is limited by a die, at least one mandrel and one arranged opposite this Cornucopia, a central mandrel, at least one lower and one Upper stamp, the powder in the filling space by the pressure between the upper and lower stamp to form a green compact pressed, ejected and sintered. In the filling room metallic sinter powder introduced. The mandrel is up retracted to the mandrel and by moving the The part geometry becomes tools relative to each other fixed and then the powder is applied a pressure on the upper and / or lower stamp to one Green compacted. The green compact is pressed after the retraction of the upper punch and the mandrels from the Pressing device ejected and sintered. To achieve a higher density, it is useful if the sintered part is reformed hot or cold after sintering. to Achieve low tolerances and / or partial Compression is a calibration process after sintering and / or Forging possible. For example, it is advantageous Roll the ball tracks of the inner joint part cold or alternatively to roll after sinter forging.

Components produced by sinter metallurgy have the advantage on that the entire body of the inner joint part high-strength structure that has excellent material properties and has surface quality.

In an advantageous embodiment of the invention, that for the filling process the mandrel in a filling position in the die retracts, the central mandrel into a filling position the die retracts and the lower stamp in one Filling position is held, the pressing mandrel moves during the pressing process assigned mandrel into the die, the mandrel pushes the mandrel down in the die while doing so due to the geometry of the mandrel, the ball tracks in the powder be shaped, and at the same time the upper stamp in the Retracts die up to an upper die pressing position and that Powder compacted to form a green compact with ball tracks through the Geometry of the die and the lower die are formed retracts to a bottom postmark and that too Powder compacted during the ejection process of the upper punches and Extend the mandrel out of the die and the central mandrel out of the Green compact is withdrawn. The outer contour of the The inner part of the joint, the ball hub, is partially covered by the die itself and partly by moving in the die in the pressing direction Shaped mandrels. Depending on the geometry of the Inner joint part are at least two upper mandrels and two lower mandrels, preferably three mandrels that are in Press direction are slidably mounted in the die provided.

In a particularly advantageous embodiment of the invention provided that the side facing the mandrel of the Mandrel in the filling position flush with the top of the Completes the matrix and the top of the middle spine in the Pressing position of the mandrel rests on the top of the mandrel and pushes it back while at the same time pressing pressure the upper punch is applied, which enters the die and then the upper punch and the mandrel from the Extend the die and the pressed green body out of the Die is ejected through the lower punch.

In an expedient embodiment of the invention, that the powder becomes a green body by pressure and heat is pressed.

In a particularly expedient embodiment of the invention provided that the die and at least one stamp is heated.

In an expedient embodiment of the invention, that the shape of the ball tracks is shaped by the mandrels becomes.

In a further expedient embodiment of the invention provided that the shape of the ball tracks through the mandrels and the die is molded.

In an advantageous embodiment of the invention, that the surface of the ball tracks after sintering is compressed. The compaction of the surface to achieve a Higher strength can be achieved, for example, by rolling take place, it being advantageous if only partial areas of the Ball track surface to be compressed. It is useful if at least the running surface of the balls of the ball track surface is compressed.

In a particularly advantageous embodiment of the invention provided that the surface of the ball tracks after the Sintering is compacted by means of at least one ball Exerts pressure perpendicular to the ball track surface.

In a further advantageous embodiment of the invention provided that the ball at least once at least once Part of the ball track compressed. It is useful if the ball, which is preferably made of hard metal, at least once, preferably several times over the one to be compressed Surface rolls so that the surface gradually densifies and is deformed.

In an advantageous embodiment of the invention, that the finished sintered part is then forged, the sintered part with ball tracks in the die on a Middle mandrel is inserted, a forging tool for shaping the outer contour presses the sintered part, and then this is expelled.

In a further advantageous embodiment of the invention provided that the finished sintered part after sintering or forging is calibrated, the sintered part with Ball tracks are inserted into the die on a central mandrel, a calibration tool for shaping the outer contour Sintered part presses, and this is then ejected.

Another solution to the problem is given by a Device for the production of metallic sintered parts, in particular an inner joint part of a shaft joint, with Ball tracks, with a pressing device, with at least one Mandrel and at least one opposite the mandrel assigned mandrel, a lower and an upper stamp and a Central mandrel that form the filling space and radial of one Are enclosed. Such a press device is characterized by a simple workflow. The Pressing process is inexpensive and, above all, time-saving Comparison to the well-known machining production. It will this enables a large number of pieces to be produced in a short time To produce inner joint parts. The die, the filling and Shaping mandrels encloses the radial on the mandrels acting pressure from.

In an advantageous embodiment of the invention, that three mandrels and three associated with them Mandrels are provided in recesses in the die be performed. The in the recesses of the die arranged filling and forming mandrels and the die itself form the Outer contour of the inner joint part that due to its geometric design with conventional pressing devices not can be produced.

The task is still solved by a metallic Sintered part, in particular inner joint part of a shaft joint, with ball tracks arranged on the outer circumference, the Sintered part is formed in one piece. Because of It is strength and durability of the inner joint part advantageous to form this in one piece and not from for example, two that are easy to manufacture in terms of press technology Components.

In an expedient embodiment of the invention, that the ball tracks are arranged at an angle to the press axis are and / or are curved to the press axis. The Inner joint part is with undercuts, recesses and profiles designed, preferably with the joint body axis, d. H. also to the pressing direction, axially on the outer surface aligned, radially curved ball tracks, the ball tracks with a web base and web sides are designed and that Inner joint part has a geometry that enables the Press the inner joint part axially and out of the pressing device or forging device.

In a further expedient embodiment of the invention provided that the ball tracks are round.

In an advantageous embodiment of the invention, that the ball tracks are approximately elliptical. This configuration is particularly advantageous because the balls only lie on the ball track at two points and Rolling only one contact line on the ball track results. This area is set out as above advantageously compressed and possibly heat and / or surface-treated.

In an expedient embodiment of the invention, that the ball tracks are polygonal. This too Design of the ball track offers something like that elliptical ball track the advantage that the balls only a small Have contact surface on the ball track and thus the Rolling resistance drops and especially Hertzian pressure can be optimized.

In an advantageous embodiment of the invention, that the ball tracks in some areas, especially in the area the ball tread have a higher density.

In a further advantageous embodiment of the invention provided that the ball tracks in partial areas, are heat-treated, in particular in the area of the ball tread. On Such a component has the advantage that the ball tracks maintain high strength. The component can at least in Area of the ball tracks, for example, are heat treated through induction hardening and case hardening.

In a particularly advantageous embodiment of the invention provided that the ball tracks in partial areas, are surface-treated, in particular in the area of the ball tread. For example, the surface can be Plasma nitriding, nitrocarburizing, phosphating and rolling in cold and warm condition to be treated Optimizing the properties of the ball tread.

In the drawings, the invention is based on a Embodiment of a constant velocity universal joint shown. It demonstrate:

Fig. 1 A constant velocity universal joint,

Fig. 2 is a perspective view of a pressing tool for a ball hub,

Fig. 3 shows the molding die cut with retracted thorns

Fig. 4, the pressing tool in the filling position,

Fig. 5, the pressing tool in the pressing position,

Fig. 6, the pressing tool in the ejection position,

Fig. 7 is a ball hub in plan view

Fig. 8 is a ball hub according to section AA in Fig. 7

Fig. 9 is a ball track with ball in cross section

In Fig. 1, a constant velocity universal joint 1 is shown. It has an outer joint part 2 and an inner joint part 3 . The outer joint part 2 is connected to a shaft 4 , and the inner joint part 3 is connected to a shaft 5 . The shaft 4 and the shaft 5 form a drive-output system. The inner joint part 3 is in the outer joint part. 2 added. Balls 6 are arranged in ball tracks 7 between the outer joint part 2 and the inner joint part 3 such that the balls 6 are guided against each other in the ball tracks 7 when the shafts 4 , 5 are bent. The balls inevitably run in the mirror plane. In the form shown, the bending angle is 0 ° and the ball lies in a plane perpendicular to the straight line formed by the axes of the shafts 4 and 5 . The arrangement has a cover ring 8 which holds the ball in the ball tracks. When the drive shaft is rotated, the output shaft is transmitted at a constant speed and torque even with appropriate deflection within the possible limits. The shaft joint 1 is sealed to the outside with a flexible seal 18 .

The ball tracks 7 can be arranged parallel or at an angle to the press axis (ball hub axis 20 ). It is also possible that the ball tracks 7 are curved to the press axis (ball hub axis 20 ). Radially curved ball tracks 7 are thus possible, the ball tracks 7 being designed with a track base 12 and track sides 13 .

Fig. 2 is a perspective view showing a pressing device 21 for a ball hub 3 (the inner joint part), the pressing device 21 three mandrels 22.1, 22.2, 22.3 and having these opposite filling mandrels associated 23.1, 23.2, 23.3. A lower punch 24 , an upper punch 25 and a central mandrel 26 are also provided. The punches 24 , 25 and mandrels 22 , 23 , 26 are radially enclosed by a die 27 . The die 27 , which surrounds the filling and shaping mandrels 23 , 22 intercepts the radial pressure acting radially on the shaping mandrels 22 .

The shaping mandrels 22 and the filling mandrels 23 assigned to them are guided in recesses 28.1 , 28.2 in the die 27 . The filling and shaping mandrels 23 , 22 arranged in the recesses 28.1 , 28.2 of the die 27 and the die 27 itself form the outer contour of the inner joint part 3 , which due to its geometric design cannot be produced with conventional pressing devices.

FIG. 3 shows a perspective view of the pressing device 21 , the shaping mandrels 22 being inserted into the die 27 . During the pressing process, the mandrels 22 move into the die 27 , the mandrels 22 pushing the mandrels 23 down in the die 27 , the ball tracks 7 of the ball hub 3 being formed in powder by means of the geometry of the mandrel 22 .

Fig. 4 shows the pressing tool 21 in the filling position. It is provided that for the filling process the filling mandrel 23 moves into a filling position in the die 27 , the central mandrel 26 moves into a filling position in the die and the lower punch 24 is held in a filling position. In the filling position, metallic sintered powder 29 is filled into the filling space 28 , the filling space 28 being delimited by the die 27 , the three shaping mandrels 22.1 , 22.2 , 22.3 and the filling mandrels 23.1 , 23.2 , 23.3 arranged opposite them, the central mandrel 26 and the Lower and upper stamps 24 , 25 . In the filling position, the side of the filling mandrel 23 facing the shaping mandrel 22 is at the same height as the upper side 30 of the die 27 and the upper side 31 of the central mandrel 26 .

The filling and shaping mandrels 23 , 22 arranged in the recesses 28 of the die 27 and the die 27 itself form the outer contour of the inner joint part 3 that, due to its geometrical design, cannot be produced with conventional pressing devices.

Fig. 5 shows the pressing tool 21 in the pressing position. The mandrels 22 are retracted as far as the mandrels 23 , the mandrels 22 pushing the mandrels 23 down in the die 27 and the ball tracks 7 of the ball hub 3 being formed in powder by the geometry of the mandrels 22 . At the same time, the upper punch 25 is moved into the die 27 up to an upper punch pressing position, so that the powder is compacted into the green compact, the ball tracks 7 also being shaped by the geometry of the die 27 . The lower punch 24 moves up to a lower punch end position, whereby the powder is also compacted. The die 27 , which surrounds the filling and shaping mandrels 23 , 22 intercepts the radial pressure acting radially on the shaping mandrels 22 . By moving the tools relative to one another during the pressing process, the part geometry of the ball hub 3 is fixed.

It is advantageous if the sintered powder is pressed into a green compact using heat. For example, the die 27 and at least one punch 24 , 25 can be heated during the pressing.

Fig. 6 shows the pressing tool 21 in the ejection position. During the ejection process, the upper punch 25 and the shaping mandrels 22 are moved out of the die 27 . The central mandrel 26 is withdrawn from the green compact 3 . The fully pressed green compact 3 is ejected from the die through the lower punch 24 . The green compact 3 is then sintered.

It is advantageous if the finished pressed green compact 3 is post-shaped hot or cold to achieve a higher density after sintering. A calibration process after sintering and / or forging is possible to achieve small tolerances and / or partial compression. For example, it is advantageous to roll the ball tracks 7 of the inner joint part 3 cold or alternatively to roll them after sinter forging. It is advantageous if only partial areas of the ball track surface are compacted, wherein at least the running surface 16 of the balls 32 of the ball track surface should be compacted.

The ball track surface can be compacted, for example, by compressing the surface of the ball tracks 7 after sintering by means of a ball which exerts pressure perpendicular to the ball track surface, the ball compressing at least one portion of the ball track 7 at least once. However, it is advantageous if the ball, which is preferably made of hard metal, rolls several times over the surface to be compressed, so that the surface is gradually compressed and deformed.

It is advantageous if the finished sintered part 3 is subsequently forged, the sintered part 3 with ball tracks 7 being inserted into the die 27 on a central mandrel 26 , a forging tool for shaping the outer contour pressing the sintered part 3 , and this being subsequently ejected.

After sintering or forging, it is also advantageous if the sintered part 3 is calibrated. Tools can be used for the forging and calibration, which have approximately the same design as the pressing tool 21 described above.

In particular, it is also possible to forge a regular blank into a ball hub 3 using the above-mentioned forging tool.

Fig. 7 shows a ball hub 3 in a plan view. The ball hub 3 is formed in one piece, whereby the strength and the service life of the ball hub 3 is high. The ball tracks 7 are arranged at an angle to the press axis (ball hub axis 20 ). The ball hub 3 each has paired ball tracks 7 . The ball tracks 7 are aligned axially into the image plane and have a radial curvature 14 . In each of the ball tracks 7 assigned to one another in pairs, the curvature 14 is opposed, ie the ball tracks 7 run towards one another in an axial direction. The ball hub axis 20 runs perpendicular to the image plane through the center of the ball hub 3 .

FIG. 8 shows a ball hub 3 according to the section AA in FIG. 7.

Fig. 9 shows a ball track 7 with a ball 32 in section. The ball 32 has a round geometry. The ball track 7 has a geometry that is approximately elliptical. The ball 32 runs on the running surface 16 , 16 'and has two contact points 17 , 17 ' on the ball track 7 at every moment. Each point of contact 17 , 17 'lies on another side of the path 13 , 13 '. The points of contact 17 , 17 'are separated from one another at an angle 2 δ from the center of the sphere. This configuration is particularly advantageous since the balls 32 rest only on the ball track 7 at two points and, when rolling, there is only one contact line on the ball track 7 . The fact that the balls 32 have only a small contact surface on the ball track 7 reduces the rolling resistance. The curvature of the ball 32 and the ball track 7 are optimized so that the Hertzian pressure is minimized. This area is advantageously compacted and, if necessary, heat and / or surface treated. Possible processes would include induction hardening, case hardening, shot peening, plasma nitriding, nitrocarburizing, phosphating and rolling in cold and warm condition.

Claims (23)

1. A method for producing a metallic sintered part, in particular an inner joint part ( 3 ) of a shaft joint ( 1 ) with ball tracks ( 7 ), powder being filled into a filling space ( 28 ), the filling space ( 28 ) being delimited by a die ( 27 ) , at least one shaping mandrel ( 22 ) and a filling mandrel ( 23 ) arranged opposite it, a central mandrel ( 26 ), at least one lower and one upper punch ( 24 , 25 ), the powder in the filling space ( 28 ) being pressed by the upper - And / or lower stamp ( 24 , 25 ) is pressed to a green body, ejected and sintered. 2. The method according to claim 1, characterized in that for the filling process the mandrel ( 23 ) moves into a filling position in the die ( 27 ) and the lower punch ( 24 ) is held in a filling position, during the pressing process the mandrel ( 23 ) moves an assigned mandrel ( 22 ) into the die 27 , the mandrel 22 pushing the mandrel ( 23 ) down in the die ( 27 ) and thereby the ball tracks ( 7 ) being formed in the powder by the geometry of the mandrel ( 22 ), and at the same time the upper punch ( 25 ) moves into the die ( 27 ) up to an upper punch pressing position and the powder is compacted to form a green compact, ball tracks ( 7 ) being formed by the geometry of the die ( 27 ), and the lower punch ( 24 ) up to a lower punch end position retracts and also compresses the powder, during the ejection process the upper punch ( 25 ) and shaped mandrel ( 22 ) extend from the die ( 27 ) and the central mandrel ( 26 ) is withdrawn from the green compact ( 3 ) will. 3. The method according to claim 1 or 2, characterized in that the mandrel ( 22 ) facing side of the mandrel ( 23 ) in the filling position flush with the top ( 30 ) of the die ( 27 ) and the top ( 31 ) of the central mandrel ( 26 ), in the pressing position the shaping mandrel ( 22 ) rests on the top ( 33 ) of the filling mandrel ( 23 ) and pushes it back, while at the same time pressing pressure is applied to the upper punch ( 25 ) and then the upper punch ( 25 ) and the shaping mandrel ( 22 ) extend out of the die ( 27 ) and the completely pressed green compact ( 3 ) is ejected from the die ( 27 ) through the lower punch ( 24 ). 4. The method according to any one of claims 1 to 3, characterized characterized in that the powder by pressure and heat to a Green compact is pressed. 5. The method according to claim 1 or 4, characterized in that the die and at least one punch ( 24 , 25 ) is heated during the pressing. 6. The method according to any one of claims 1 to 5, characterized in that the shape of the ball tracks ( 7 ) is formed by the mandrels ( 22 ). 7. The method according to claim 1 or 6, characterized in that the shape of the ball tracks ( 7 ) through the mandrels ( 22 ) and the die ( 27 ) is formed. 8. The method according to any one of claims 1 to 7, characterized in that the surface of the ball tracks ( 7 ) is compressed after sintering. 9. The method according to any one of claims 1 to 8, characterized in that the surface of the ball tracks ( 7 ) is compressed after sintering by means of at least one ball ( 32 ) which exerts pressure perpendicular to the ball track surface, the compression in the cold or warm state can be done. 10. The method according to any one of claims 1 to 9, characterized in that the ball ( 32 ) compresses at least once at least a portion of the ball track ( 7 ). 11. The method according to any one of claims 1 to 10, characterized in that the finished sintered part ( 3 ) is then forged, the sintered part ( 3 ) with ball tracks ( 7 ) in the die ( 27 ) placed on a central mandrel ( 26 ) is, a forging tool of the same type for shaping the outer contour presses the sintered part ( 3 ), and this is then ejected. 12. The method according to any one of claims 1 to 11, characterized in that the finished sintered part ( 3 ) is calibrated after sintering or forging, the sintered part ( 3 ) with ball tracks ( 7 ) in the die ( 27 ) on a central mandrel ( 26 ) is inserted, a calibration tool of the same design for shaping the outer contour presses the sintered part ( 3 ), and this is then ejected. 13. Process for producing a metallic. Component, in particular a ball tracks (7) having the inner joint part (3) of the universal joint (1), wherein a blank is inserted into the die (27) to a central spine (26), a forging tool of the same type for shaping the outer contour presses the blank, and this is then ejected. 14. Device for producing metallic components, in particular sintered and metallurgically manufactured and / or forged components, in particular an inner joint part of a shaft joint ( 1 ), with ball tracks ( 7 ), according to the method according to claims 1 to 13, characterized by a pressing device ( 21 ) , with at least one shaping mandrel ( 22 ) and at least one filling mandrel ( 23 ) assigned to the shaping mandrel ( 22 ), a lower and an upper punch ( 24 , 25 ) and a central mandrel ( 26 ) which form the filling space ( 28 ) and radially are enclosed by a die ( 27 ). 15. The device according to one of claims 1 to 14, characterized in that three shaping mandrels ( 22 ) and three facing mandrels ( 23 ) are provided, which are guided in recesses ( 28 ) in the die ( 27 ). 16. Metallic component, in particular sintered metallurgically produced and / or forged component, in particular inner joint part ( 3 ) of a shaft joint ( 1 ), with ball tracks ( 7 ) arranged on the outer circumference, produced by the method according to method claims 1 to 13 , characterized in that the sintered part is formed in one piece. 17. Metallic component, in particular sintered-metallurgically manufactured and / or forged component, in particular inner joint part ( 3 ) of a shaft joint ( 1 ), according to one of claims 1 to 16, characterized in that the ball tracks ( 7 ) at an angle to the press axis ( 20 ) are arranged and / or are curved to the press axis ( 20 ). 18. Metallic component, in particular sintered metallurgy manufactured and / or forged component, in particular Inner joint part of a shaft joint, according to one of the claims 1 to 17, characterized in that the ball tracks are round are trained. 19. Metallic component, in particular sintered-metallurgically manufactured and / or forged component, in particular inner joint part ( 3 ) of a shaft joint ( 1 ), according to one of claims 1 to 18, characterized in that the ball tracks ( 7 ) are approximately elliptical. 20. Metallic component, in particular sintered-metallurgically manufactured and / or forged component, in particular inner joint part ( 3 ) of a shaft joint ( 1 ), according to one of claims 1 to 19, characterized in that the ball tracks ( 7 ) are polygonal. 21. Metallic component, in particular sintered metallurgically manufactured and / or forged component, in particular inner joint part ( 3 ) of a shaft joint ( 1 ), according to one of claims 1 to 20, characterized in that the ball tracks ( 7 ) in partial areas, in particular in the area of the ball tread ( 16 , 16 ') have a higher density. 22. Metallic component, in particular sinter-metallurgically manufactured and / or forged component, in particular inner joint part ( 3 ) of a shaft joint ( 1 ), according to one of claims 1 to 21, characterized in that the ball tracks ( 7 ) in partial areas, in particular in the area of the ball contact surface ( 16 , 16 ') are heat treated. 23. Metallic component, in particular sintered and metallurgically manufactured and / or forged component, in particular inner joint part ( 3 ) of a shaft joint ( 1 ), according to one of claims 1 to 22, characterized in that the ball tracks ( 7 ) in partial areas, in particular in the area of the ball contact surface ( 16 , 16 ') are surface treated.