Method for producing a cone of a tripod star

Abstract

Method for manufacturing a pin (11, 12, 13), in particular a tripod star (10) of a tripod joint, wherein the pin (11, 12, 13) has an extension axis (A) and a non-rotationally symmetric, in particular elliptical, cross-section with respect to the extension axis (A), characterized in that the pin (11, 12, 13) is produced by means of a bell tool (30), wherein the bell tool (30) has a hood (31) that rotates, in particular under feed, wherein the hood (31) defines a substantially cylindrical receptacle (32) for the pin (11, 12, 13), and wherein at least one cutting and / or grinding element (33) is arranged in the receptacle (32), and characterized by the following steps: - Positioning the bell tool (30) along the extension axis (A), in particular centrally to an end face of the pin (11a), - Tilting the bell tool (30) by an adjustment angle (α) with respect to the extension axis of the pin (A), - Machining the tenon (11, 12, 13) using the bell tool (30).

Description

[0001] The invention relates to a method for manufacturing a pin, in particular a tripod star of a tripod joint, according to the preamble of claim 1 and a corresponding tripod star according to claim 7.

[0002] Such a method and such a tripod star are known, for example, from DE 10 2007 057 538 A1.

[0003] Tripod joints, which incorporate tripod stars, are known as constant velocity joints (CV joints) and serve to transmit the angular velocity and torque from one shaft to a second shaft mounted at an angle to it. Tripod joints are most commonly used in automotive engineering and are typically employed as inner CV joints for the drive shafts of front-wheel-drive vehicles. They exhibit good sliding properties and allow angular deflections of over 10° relative to the steering axis of the wheels. Furthermore, tripod joints compensate for changes in the length of the drive shaft during wheel suspension travel of over 10 mm, particularly in contrast to other universal joints, such as cardan joints.

[0004] The tripod joints feature an outer joint element, referred to as a tulip, with several, usually three, axially extending, elongated tracks on its inner circumference. An inner joint element with several, usually three, radial pins can slide within these tracks. The radial pins are typically mounted in rotating rollers that slidably engage with the elongated tracks of the outer joint element. Several needle rollers are arranged within the rollers to allow them to roll on the pins. The inner joint element is connected to the drive shaft, and the outer joint element to the transmission output, or vice versa, in a rotationally fixed manner. The pins are designed to set the required angle between the drive shaft and the steering axis.During torque transmission in the tripod joint, very high surface pressures (Hertzian contact pressure) occur between the journals and the needle rollers. To distribute the pressure evenly between the needle rollers and the journals during rolling, the journals are designed with a non-rotationally symmetrical, usually elliptical, cross-section. Conventionally, round journals are ground to produce journals with an elliptical cross-section. In this process, a grinding wheel and the journal rotate relative to each other. To achieve non-circular journal profiles, the distance between the axes of rotation of the journal and the grinding wheel must be varied. This infeed movement must be controlled during machining depending on the rotational angular position of the journal, which has proven to be complicated and time-consuming.The grinding process must also be carried out with a coolant (wet machining) to dissipate the heat and grinding chips generated, as the tripod joints are typically made of a heat-treated case-hardened steel (e.g., 16MnCr5, case-hardened and tempered). Insufficient cooling can lead to material transformation (loss of hardness), which can severely impair the wear resistance and thus the service life of the tripod joint. An oil or oil-water mixture (emulsion) is used as the coolant, which can be environmentally hazardous. This necessitates enhanced groundwater protection in the machine's vicinity (oil containment basin and floor sealing). Furthermore, the cooling of the coolant is costly and expensive in large-scale production.The associated disposal of the resulting sludge (grinding wheel residue + chips + coolant) is also very expensive. Furthermore, the use of swivel chucks is a disadvantage for grinding tripod joints in high-volume production. These bucket-sized clamping devices must rotate during the grinding process and are therefore screwed onto a drive spindle. The swivel chucks contain a mechanism that clamps the tripod joint and can index it by 120°. The use of clamping devices is therefore expensive, maintenance-intensive, and, unfortunately, increases the weight of the grinding machine, as the machine must then meet higher demands in terms of rigidity and motor power.

[0005] WO 01 / 47 663 A1 discloses a method and a device for grinding, in particular, joint stars with at least two joint pins, in which at least two joint pins are ground simultaneously in the same clamping of the joint star with grinding wheels guided around the joint pins.

[0006] In the method described in WO 2013 / 149 271 A1 for machining a functional part that extends in a longitudinal direction and has a cylindrical surface surrounding a longitudinal central axis of the functional part and an end face that bounds the functional part at a free end in the axial direction, a punch movable in the longitudinal direction of the functional part is pressed against the end face of the functional part, while the functional part is initially located, at least over a partial section of its longitudinal extension adjoining its free end, in a cavity of a tool, which is bounded in the radial direction with respect to the longitudinal central axis by a wall surface surrounding the cylindrical surface and at least partially in contact with the cylindrical surface, and subsequently the tool is withdrawn from the functional part via a withdrawal path over the free end of the functional part.while the punch remains pressed against the end face of the functional part, at least for part of the tool's withdrawal path. As the tool withdraws from the functional part, a flow of material from the functional part is caused.

[0007] DE 197 12 985 A1 discloses a method for machining tenons on workpieces such as tripods, spiders, etc. The workpieces are manufactured by extrusion. The finished tenons have annular grooves. The grooves are formed by cold forming and finished by rolling. The surface of the tenons can be calibrated by rolling. Cutting the groove and calibrating the tenon surface can be performed simultaneously in a single operation.

[0008] Therefore, the object of the present invention is to overcome at least one disadvantage known from the prior art, at least in part. In particular, the object of the present invention is to provide a method for manufacturing an elliptical pin, especially a tripod star of a tripod joint, which can be realized more simply, with fewer steps, more efficiently, and in a shorter time than conventional methods. Furthermore, the object of the present invention is to provide a corresponding tripod star that can be manufactured quickly and easily, especially using the method according to the invention.

[0009] The foregoing problem is solved by a method having the features according to the characterizing part of claim 1 and by a tripod star having the features of claim 7. Further advantages, features, and details of the invention will become apparent from the dependent claims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the tripod star according to the invention, and vice versa, so that the disclosure regarding the individual aspects of the invention always refers, or can refer, to each other.

[0010] The invention provides a method for producing a pin, in particular a tripod star of a tripod joint, using a bell-shaped tool, wherein the pin has an axis of extension and a non-rotationally symmetrical, in particular elliptical, cross-section with respect to the axis of extension, wherein the bell-shaped tool has a hood that rotates, in particular under feed, wherein the hood defines a substantially cylindrical receptacle for the pin, and wherein at least one cutting and / or grinding element is arranged in the receptacle, comprising the following steps: - Positioning the bell tool along the axis of extension, in particular centered on an end face of the pin, - Tilting the bell tool by an adjustment angle with respect to the extension axis of the pin, - Machining the tenon using the bell tool.

[0011] The term "bell tool" can be understood as a tool that can machine pins and pipe fittings on non-rotationally symmetrical workpieces using only a single bell-shaped tool. This machining can advantageously be carried out in large series production. The inventive concept lies in machining a tripod star using such a bell tool to produce a specific, non-rotationally symmetrical shape for the pin of the tripod star. According to the invention, the bell tool has a hood for machining the pin, which defines a substantially cylindrical receptacle for the pin and which can be lowered onto the pin to enclose it from all sides.The hood can rotate around the pin with or without feed, whereby the outer diameter of the pin can be milled in one direction of rotation with transverse feed of the cutting and / or grinding element, and ground in another direction of rotation without transverse feed. The hood can have several arms, for example, two or three, with a milling element attached to one arm and a grinding element to another, or similar configurations. The tripod star can be made of metal, e.g., steel.

[0012] The inventive concept also lies in the fact that by simply adjusting the angle between the axis of extension of the bell-shaped tool, which is simultaneously the machining axis of the bell-shaped tool, and the axis of extension of the tenon, an elliptical cross-section of the tenon can be produced instead of the original round cross-section of the tenon. According to the invention, by tilting the bell-shaped tool by 0° to 20°, in particular by 1° to 5°, preferably by 4°, two opposite sides of the tenon can be subjected more intensely to the cutting and / or grinding medium inside the housing of the bell-shaped tool than the other opposite sides of the tenon. This results in these sides being machined more intensively than the other sides, and the diameter of the tenon between these sides becomes smaller than the diameter between the other sides of the tenon.This results in an elliptical cross-section of the tenon, with a minor semi-axis between the more heavily stressed sides and a major semi-axis between two less heavily stressed sides. This simple approach not only significantly simplifies tenon machining but also advantageously improves and refines it. By varying the setting angle, an elliptical cross-section with different dimensions / semi-axes can be produced. In particular, the more heavily stressed sides can be machined with varying cross-feeds simply by adjusting the setting angle. This allows for the degree of grinding on these sides and the degree of protrusion of the minor semi-axis of the ellipse in the tenon's cross-section.Consequently, this allows for the production of different sizes and geometries of the pin using a single tool. The pins and tripod stars produced in this way can then be adapted as needed for different vehicle models that require varying pin and tripod star dimensions.

[0013] Furthermore, the use of the bell-shaped tool offers several other advantages compared to known methods for producing a tenon, especially compared to the conventional grinding of the tenon, such as - Using simpler tools, which results in lower tooling costs, - simultaneous machining of both sides of the tenon, - faster processing of the tenon, - more environmentally friendly processing, - Lower energy, cost, and maintenance requirements, especially compared to wet grinding. Unlike wet grinding, the inventive method allows for purely dry machining of the journal, eliminating the need for subsequent washing and polishing of the parts. The inventive method thus makes it possible to dispense with the cooling lubricant, thereby eliminating the need for complex cooling and disposal of lubricant residue. The wear resistance and service life of the tripod chuck can also be improved, particularly compared to improper cooling with the cooling lubricant, which can lead to a loss of hardness in the journal material. Furthermore, the invention eliminates the need for the large, motor-driven swivel chuck that must rotate during grinding. This also results in savings in effort, time, and energy.Advantageously, the method according to the invention can include at least one further step, such as:. - Supporting the tripod star (star base body) on a clamping device.

[0014] According to the invention, the tripod star can be mounted on a clamping device, which can also be referred to as a workpiece holder, to enable machining of the pin by the bell-shaped tool. The tripod star can be mounted on the clamping device through a central opening, which is provided in the inner joint element of the tripod joint for receiving a drive shaft or a transmission output shaft. In each machining cycle, the clamping device can automatically rotate or reposition one pin after another, which are formed on the outer side of the inner joint element of the tripod joint (on the tripod star), such that one pin after another is brought towards the bell-shaped tool and machined by it.As mentioned above, the clamping device can be simpler and designed to absorb lower forces than a clamping device used in other known manufacturing processes, in order to reduce both material and the costs and effort required for a suitable clamping device to absorb higher forces. After clamping the tripod star onto the clamping device, machining of the respective pin can begin.

[0015] According to an advantage of the invention, the method can comprise at least one of the following steps, such as: - Setting the bell tool to rotation, in particular to rotation under feed, preferably on spindles, in clockwise rotation, - Cutting, in particular roughing, an outer diameter of the journal, preferably with transverse feed, planar.

[0016] The machining of the tenon from the outside through the hood of the bell-shaped tool can be described as spindle machining. Advantageously, spindle machining can be performed as a rotation with feed, first downwards and then upwards. By simultaneously rotating and lowering or lifting the hood, the tenon can be machined not only from all sides at once, but also uniformly from top to bottom and vice versa. When spindle machining in clockwise direction, the tenon can be machined, for example, with a cross feed, i.e., with the cutting element moving forward on the tenon, which is necessary for shaping the tenon by chip removal.The bell-shaped tool's housing, which defines a substantially cylindrical receptacle for the journal and in which at least one cutting and / or grinding element can be arranged, can be pressed against the journal in clockwise rotation such that the cutting element can remove the excess material from the journal in the form of chips. When the journal is positioned below the clockwise-rotating housing by the clamping device, the bell-shaped tool can be lowered centrally to the end face of the journal to be milled flat by the clockwise-rotating housing / spindle with a cross feed. This milling or cutting with a cross feed can be referred to as roughing.

[0017] Furthermore, the procedure may include at least one of the following steps: - Stopping the bell-ringing mechanism, - Resetting the bell tool.

[0018] After the spindle has rotated clockwise, the bell tool can stop and reset the rotating hood.

[0019] In addition to or instead of the steps described above, the method according to the invention may include at least one of the following steps: - Setting the bell tool to rotation, in particular to rotation under feed, preferably on spindles, in counterclockwise rotation, - Fine grinding, especially finishing, of the outer diameter of the pin.

[0020] When the spindle rotates counterclockwise, the journal can be machined, for example, without cross feed or with only a small cross feed. The hood of the bell-shaped tool, in which at least one cutting and / or grinding element can be arranged, can be pressed against the journal in counterclockwise rotation in such a way that the cutting and / or grinding element can perform a fine grinding operation. If the journal is positioned below the counterclockwise rotating hood by the clamping device, the bell-shaped tool can be lowered centrally to the end face of the journal to be finely ground by the counterclockwise rotating hood / spindle. This fine grinding can be described as finishing.

[0021] The bell tool can then stop and retract the rotating hood.

[0022] Consequently, the bell tool can actuate the tenon in clockwise and / or counterclockwise rotation, whereby the tenon can be machined by roughing and / or finishing.

[0023] Advantageously, the process can include at least one further step after machining the first tenon: - Moving another pin on the clamping device.

[0024] The clamping device can rotate the tripod star in such a way that another pin can be faced towards the bell-shaped tool to be machined according to the inventive method. Thus, the pins of the tripod star can be machined one after the other.

[0025] According to the inventive method, it is also conceivable that other non-rotationally symmetric shapes than the ellipse can be produced by the bell tool, which allow a developed alignment between the inner and outer joint element of the tripod joint.

[0026] Furthermore, the problem according to the invention is solved by a tripod star with at least one pin, wherein the pin has an axis of extension and a non-rotationally symmetric, in particular elliptical, cross-section with respect to the axis of extension, and wherein the pin can be manufactured by means of a method which has been described above.

[0027] Advantageously, the pin can have an elliptical cross-section about its axis of extension. This allows for better retention of the inner joint element within the outer joint element of the tripod joint, with the flattened sides of the pin on the minor semi-axis of the ellipse serving to improve torque transmission between the pin and the needle rollers, which are provided for the rotatable mounting of the inner joint element within the outer joint element.

[0028] According to the invention, the pin can have two opposing circular segments in its cross-section relative to its axis of extension. These segments can be easily tilted and axially displaceable within the elongated tracks of the outer joint element of the tripod joint. Furthermore, the pin can have two opposing flat sides in its cross-section relative to its axis of extension. Various pin shapes are conceivable that enable uniform torque transmission between the pin and the needle rollers.

[0029] Further measures improving the invention are described in more detail below with reference to the figures and the preferred embodiments of the invention. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination. It should be noted that the figures are for descriptive purposes only and are not intended to limit the invention in any way.

[0030] They show: Fig. 1 a schematic representation of a tripod star, Fig. 2 a schematic representation of the tripod star with an elliptical cross-section of the cones, Fig. 3 a perspective view of a tripod star produced according to a method according to the invention using a bell tool, Fig. 4 an embodiment of the tripod stern which can be produced according to the inventive method, and Fig. 5 another embodiment of the tripod star, which can be produced according to the inventive method.

[0031] In the different figures, identical parts are always marked with the same reference symbols, which is why they are usually only described once.

[0032] In the Fig. Figure 1 schematically shows a tripod star 10 of a tripod joint, which is used in motor vehicles to transmit the engine's drive force to the vehicle wheels at an angle. The tripod star 10 of the Fig. 1 can be manufactured using a known method by grinding. However, this conventional method has several disadvantages. It is a wet machining process, which requires the use of cooling lubricant, which is environmentally hazardous and expensive. Furthermore, grinding tripod stars in mass production requires the use of large swivel chucks that must be driven, as the chucks must rotate along with the workpiece, which is also complex and costly.

[0033] As in the Fig. As can be seen in Figure 1, the tripod star 10 represents an inner joint element 10 of the tripod joint, which has three radial pins 11, 12, 13 designed to slide in three corresponding tracks on the inner circumference of an outer joint element of the tripod joint. For the sake of simplicity, the outer joint element of the tripod joint, which is also called a tulip, is shown in the Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. 5 not shown. Also not shown are three rollers in which the radial pins can usually be movably, mostly rotatingly, received, the rollers being axially displaceable in the elongated tracks of the outer joint element. The inner joint element 10 (the tripod star 10) can be non-rotatably connected to the drive shaft and the outer joint element to the transmission output shaft, or vice versa, in order to transmit a rotating movement of the drive shaft at an angle uniformly to the transmission output shaft. The pins 11, 12, 13 are designed to enable uniform force transmission as the pins 11, 12, 13 roll in rollers that are inserted into the corresponding tracks on the inner circumference of the outer joint element. For this purpose, the pins 11, 12, 13 are designed with a non-rotationally symmetrical, usually elliptical, cross-section, as shown in the Fig. 2 can be seen.

[0034] An elliptical shape of cones 11, 12, 13, which is in the Fig. As illustrated in Figure 2, this is important for several factors, such as the stability of the connection between the inner and outer joint elements of the tripod joint and the service life of the tripod joint.

[0035] In the Fig. Figure 3 schematically illustrates the concept of the invention, namely, to use a bell-shaped tool 30 to produce an elliptical pin 11, 12, 13 of the tripod star 10. In the Fig. Figure 3 shows that according to the inventive method, the pins 11, 12, 13 can be machined successively by the bell tool 30 by means of a clamping device 20, in order to be machined by the bell tool 30.

[0036] The method according to the invention may comprise the following steps, such as: - Positioning the bell tool 30 along an axis of extension of the pin A, centered on an end face of the pin 11a, - Tilting of the bell tool 30 by an adjustment angle α with respect to the extension axis of the pin A, - Machining of the tenon 11, 12, 13 using the bell tool 30.

[0037] The bell-shaped tool 30 is particularly suitable for machining tenons 11, 12, 13 on non-rotationally symmetrical workpieces, such as the tripod star 10, in large series production using only a single bell-shaped tool 30. The idea of ​​the invention lies according to the Fig. 3 in that the tripod star 10 can be machined using such a bell-shaped tool 30 to produce a specific shape for the pins 11, 12, 13 of the tripod star 10, usually an ellipse. For this purpose, the bell-shaped tool 30 has a hood 31 which defines a substantially cylindrical receptacle 32 for the pin 11, 12, 13, in which the pin 11, 12, 13 can be machined using a cutting and / or grinding element 33, for example, a cutting plate 33. The hood 31 is designed to rotate. The pin 11, 12, 13 can be machined using the rotating hood 31 or using a hood 31 that is moved only with feed along the axis of extension A, depending on which shape of the pin 11, 12, 13 is required. The possible shapes of cones 11, 12, 13 are then described based on the Fig. 4 and Fig. 5 described in more detail.

[0038] The cutting plate 33 of the bell-shaped tool 30 rotates on a circular path. According to the invention, the axes of rotation A, B of the bell-shaped tool 30 and of the pin 11, 12, 13 are inclined to each other by preferably 4° (α). This results in a smaller pin diameter (b = D*cos α) in the cross-section of the pin 11, 12, 13 on the plane formed by the two axes of rotation A, B. The pin profile thus becomes elliptical. The major semi-axis a corresponds to the original diameter of the pin D.

[0039] The hood 31 of the bell tool 30 can thus rotate around the pin 11, 12, 13 and simultaneously be lowered onto the pin 11, 12, 13. However, it is also conceivable that the hood 31 can act on the pin 11, 12, 13 only by lowering and raising it. When the hood 31 rotates, the outer diameter of the pin D can be milled in one direction of rotation with transverse feed and ground in another direction of rotation with no or only a small transverse feed of the cutting and / or grinding element. To achieve this, the hood 31 is designed with several arms, for example, two, whereby a milling element 33 can be attached to the inside of one arm and a grinding element 33 to another arm.

[0040] The method according to the invention is characterized in that an elliptical cross-section of the pin 11, 12, 13 can be produced in a simple manner by adjusting the angle α between an extension axis B of the bell tool 30, which is simultaneously the machining axis B of the bell tool 30, and the extension axis of the pin A, instead of the original round cross-section. The bell tool 30 can be easily tilted relative to the extension axis of the pin A by 0° to 20°, in particular 1° to 5°, preferably 4°, in order to set a suitable angle between the drive shaft and the steering axle. This results in two opposite sides of the pin 11c being subjected more strongly to the cutting or grinding medium 33 in the receptacle 32 of the bell tool 30 than the other two opposite sides of the pin 11b.These sides 11c are thus machined more intensively and become flatter than the other, still circular segments of the pin 11b. Consequently, the diameter of the pin D=2b between these flat sides 11c becomes narrower than the diameter D=2a between the circular segments of the pin 11b. Thus, according to the invention, an elliptical shape in the cross-section of the pin 11, 12, 13 can be achieved with a small semi-axis b between the flattened sides 11c and a large semi-axis a between the circular segments of the pin 11b. This simple step allows the machining of the pin 11, 12, 13 to be carried out easily, quickly, and precisely. Furthermore, it is a particular advantage of the invention that an elliptical cross-section with different semi-axes a, b can be produced by selectively varying the setting angle α.At a larger angle α, the more heavily stressed sides 11c can be ground down and / or cut away more, so that the minor semi-axis b of the ellipse in the cross-section of the pin 11, 12, 13 can be more pronounced. Advantageously, this results in a further benefit: using one and the same bell-shaped tool 30, not only different geometries but also different sizes of pins 11, 12, 13 can be produced. The pins 11, 12, 13 and tripod stars 10 thus provided can therefore be used in different vehicle models with different size and angle specifications. By using the bell tool 30, even more advantages can be achieved, such as the use of simpler, cheaper tools, such as a clamping device 20 for absorbing lower forces than the clamping device for grinding the pins 11, 12, 13, faster machining of the pins 11, 12, 13, lower energy consumption, etc.In particular, in contrast to wet grinding, the method according to the invention can enable purely dry machining of the pins 11, 12, 13, which does not require subsequent washing of the pins 11, 12, 13.

[0041] As in the Fig. As can be seen in Figure 3, the tripod star 10 can be mounted on the clamping device 20 (also called tool holder) to enable machining of the journals 11, 12, 13 under transverse feed. The tripod star 10 can be mounted on the clamping device 20 through a central opening 14, which is primarily provided in the inner joint element 10 of the tripod joint for receiving a drive shaft or a steering axle. The clamping device 20 can then rotate the tripod star 10 to move one journal 11, 12, 13 after the other, which are formed on the outside of the tripod star 10, towards the bell tool 30 in each machining cycle.

[0042] According to the invention, the rotation of the hood 31 with feed along the axis of extension of the pin A can be referred to as spindle operation. By simultaneously rotating and feeding the hood 31, each pin 11, 12, 13 can be machined from all sides simultaneously and uniformly. During spindle operation in clockwise rotation, the respective pin 11, 12, 13 can be milled, for example, with a cross feed using a cutting element 33. The hood 31 of the bell-shaped tool 30 can be adjusted in clockwise rotation such that the cutting element 33 can act on the pin 11, 12, 13. When the pin 11, 12, 13 is positioned below the hood 31 by the clamping device 20, the hood 31 can be lowered centrally to the end face of the pin 11a in order to be milled flat by the clockwise rotating hood / spindle with a cross feed. Milling or cutting with cross feed can also be referred to as roughing.

[0043] After the spindle has rotated clockwise, the bell tool 30 can stop and reset the rotating hood 31.

[0044] Subsequently or alternatively, the hood 31 can be set on spindles rotating counterclockwise, allowing the journal 11, 12, 13 to be machined, for example, without cross feed or with only a small cross feed. The hood 31 of the bell-shaped tool 30, in which at least one cutting and / or grinding element 33 is arranged, can be adjusted such that the hood 31, with the grinding element 33, is in contact with the journal 11, 12, 13. When the journal 11, 12, 13 is positioned below the hood 31 by the clamping device 20, the bell-shaped tool 30 can be lowered centrally to the end face of the journal 11a in order to fine-grind the outer diameter D of the journal by the counterclockwise rotating hood / spindle. This fine grinding can also be referred to as finishing.

[0045] The bell tool 30 can then stop and reset the hood 31.

[0046] Consequently, the bell tool 30 can actuate the pin 11, 12, 13 clockwise with a cutting element 33 and / or counterclockwise with an abrasive element 33, whereby the pin 11, 12, 13 can be roughened and / or ground. This advantageously allows the elliptical shape of the pin 11, 12, 13 to be produced, which is described in the Fig. 4 is shown.

[0047] However, it is conceivable, either simultaneously or alternatively, that the bell tool 30 can machine the pin 11, 12, 13 solely by lowering and raising the hood 31 or additionally by rotating the hood 11, for example to machine flat sides 11c according to the Fig. 5 to realize.

[0048] The flat sides of the pin 11c advantageously provide better support for the inner joint element 10 in the outer joint element of the tripod star 10, while the circular segments of the pin 11b on the major semi-axis a of the ellipse can engage in the elongated tracks of the outer joint element of the tripod star 10. The flat sides of the pin 11c also serve to even out the pressure between the pins 11, 12, 13 and the needle rollers in the rollers (not shown) of the tripod joint.

[0049] The preceding description of Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. Section 5 describes the present invention exclusively by way of examples. Of course, individual features of the embodiments can be freely combined with one another, provided it is technically feasible, without departing from the scope of the invention. Reference symbol list 10 Tripod star, inner joint element 11, 12, 13 cones 11a End face of the pin 11b circular segments of the cone 11c flat sides of the tenon 11d Foot of the cone 14 central opening in the inner joint element of the tripod joint 20 clamping devices 30 bell tools 31 Hood 32 cylindrical recordings 33 Cutting and / or grinding tools a major semi-axis b minor axis A Extension axis of the pin B Machining axis of the bell tool D Diameter of the pin α Angle between A and B

Claims

[1] Method for manufacturing a pin (11, 12, 13), in particular a tripod star (10) of a tripod joint, wherein the pin (11, 12, 13) has an extension axis (A) and a non-rotationally symmetric, in particular elliptical, cross-section with respect to the extension axis (A), characterized by , that the tenon (11, 12, 13) is produced using a bell tool (30), wherein the bell tool (30) has a hood (31) that rotates, in particular under feed, wherein the hood (31) defines a substantially cylindrical receptacle (32) for the pin (11, 12, 13), and wherein at least one cutting and / or grinding element (33) is arranged in the receptacle (32), and characterized by the following steps: - Positioning the bell tool (30) along the extension axis (A), in particular centrally to an end face of the pin (11a), - Tilting the bell tool (30) by an adjustment angle (α) with respect to the extension axis of the pin (A), - Machining the tenon (11, 12, 13) using the bell tool (30). [2] Method according to claim 1, characterized by that the procedure includes at least one further step: - Supporting the tripod star (10) on a clamping device (20). [3] Method according to claim 1 or 2, characterized by that the procedure includes at least one of the following steps: - Setting the bell tool (30) to rotation, in particular to rotation under feed, preferably on spindles, in clockwise rotation, - Cutting, in particular roughing, of an outer diameter of the journal (D), preferably under transverse feed, planar. [4] Method according to claim 2 or 3, characterized by that the procedure includes at least one of the following steps: - Setting the bell tool (30) to rotation, in particular to rotation under feed, preferably on spindles, in counterclockwise rotation, - Fine grinding, in particular finishing, of an outer diameter of the pin (D). [5] Method according to any one of claims 2 to 4, characterized by that the procedure includes at least one of the following steps: - Stopping the bell tool (30), - Resetting the bell tool (30). [6] Method according to any one of claims 2 to 5, characterized by that the procedure includes at least one further step: - Moving another pin (11, 12, 13) on the clamping device (20). [7] Tripod star (10) with at least one pin (11, 12, 13), wherein the pin (11, 12, 13) has an extension axis (A) and a non-rotationally symmetric, in particular elliptical, cross-section with respect to the extension axis (A), and wherein the pin (11, 12, 13) can be manufactured by a method according to one of the preceding claims. [8] Tripod star (10) according to claim 7, characterized by , that the pin (11, 12, 13) has an elliptical cross-section with respect to the axis of extension (A). [9] Tripod star (10) according to claim 7 or 8, characterized by , that the cone (11, 12, 13) has two opposing circular segments (11b) in its cross-section with respect to the axis of extension (A). [10] Tripod ester (10) according to any one of claims 7 to 9, characterized by , that the pin (11, 12, 13) has two opposite flat sides (11c) in its cross-section with respect to the axis of extension (A).

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