Apparatus and method for forming a front tooth on an inner race of a wheel hub

Abstract

A device (30) comprising a plurality of first pressing elements (12) and a plurality of second pressing elements (13) symmetrically arranged in a crown around a symmetry axis (B) so that first ends (14) of the first pressing elements are in contact with second ends (15) of the second pressing elements; the first pressing elements and the second pressing elements are respectively slidably supported by a first plate (16) and a second plate (18) coupled and joined to each other and respectively passed through the first plate and the second plate in respective second slots (21) and first slots (19) angularly spaced apart; the first pressing elements are provided with hammer heads (23) wider than said second slots in a circumferential direction and in contact with each other without play in the circumferential direction, the second pressing elements are provided with engraving heads (20) wider than the first slots in a circumferential direction and in contact with each other without play in the circumferential direction.

Description

TECHNICAL FIELD

[0001] The present invention relates to an innovative apparatus for forming a front toothing on an inner ring of a wheel hub by plastic deformation and to a method associated therewith.

[0002] In particular, the present invention is applicable to a wheel hub whose inner ring comprises a spindle provided with a first raceway for a first row of rolling elements and an added ring provided with a second raceway for a second row of rolling elements, wherein the added ring is axially locked on the spindle by means of an upset collar defined by an end segment of the spindle which has been plastically deformed. BACKGROUND

[0003] In the wheel hubs of the above type, said front toothing has the function of coupling the inner ring of the wheel hub head to head to a corresponding front toothing of an outer ring of a constant-velocity joint to ensure the transmission of the torque from the constant-velocity joint to the inner ring of the wheel hub which carries via a flanged end a wheel of a vehicle. This type of coupling is described in US-A-4893960 which also teaches how to make the front toothing on the inner ring of the wheel hub.

[0004] According to this document, the front toothing is obtained, at the same time as the upset collar, by means of a tool comprising a truncated cone element which makes the collar by upset forging and by means of a frontally toothed tubular element which is axially slidingly mounted on the outside of the truncated cone element which, in the deformation phase, impresses the desired toothing on the collar.

[0005] The forming method as described above requires the use of relatively complex tools and, above all, it is not possible to obtain teeth with a highly constant tooth profile.

[0006] EP2551034B1 does not completely solve the problem, in which the toothing is formed by means of a plurality of sliding knives configured in crown on a support, angularly spaced to allow its mounting.

[0007] Therefore, the teeth are not always properly (correctly) formed, in particular as regards the shape of the tips or crests (peaks / tooth tips).

[0008] As a result, first of all, it is not always possible to provide increasingly high torques to be transmitted, and secondly, during assembly between the hub and the constant joint, there can be incorrect teeth / tooth mounting, which means that the teeth of the two assemblies do not intermesh correctly during coupling. In use, when the teeth end up snapped into the correct position due to the torque applied, the central nut or screw used to lock the two assemblies together immediately loses the clamping force applied during assembly, and a small frontal play can also be created between the two coupling toothings of the hub and the constant joint, which does not reduce the transmission of the torque, but causes noise on the axle due to the fact that the teeth jump out of the correct engagement position each time a higher torque is transmitted.

[0009] Finally, in vehicles subjected to these conditions, the teeth can gradually be ground down, leading to complete loss of traction in 2WD (two-wheel drive) vehicles, or partial loss of traction in 4WD (four-wheel drive, not always engaged) vehicles.

[0010] In both cases, if the driver does not notice the loss of power on the axle, this problem can gradually destroy the gearbox in the long term, as the vehicle CPU will not detect the anomaly quickly enough when the axle without traction still sends apparently reasonable ABS signals. SUMMARY

[0011] The aim of the present application is therefore to provide a device and an associated method for forming a front toothing on the inner ring of a hub by plastic deformation, which provides an alternative to the devices and methods of the prior art, and in particular is able to combine the advantages of the two known forming systems described above without being affected by their drawbacks, thus providing greater precision in the dimensions of the teeth and a highly constant size and geometry in the profile of the teeth, in particular the crests.

[0012] Therefore, the present invention provides an innovative apparatus and associated method for forming a front tooth portion on an inner ring of a wheel hub by plastic deformation, wherein the inner ring has an annular collar at one end; the apparatus includes a plate support and a base, the plate support having an axis of symmetry, the base being configured to support the wheel hub coaxial with the axis of symmetry of the plate support, the plate support being axially movable relative to the base such that it engages with the annular collar in use; wherein the apparatus further includes: a plurality of blade-shaped first pressing elements and second pressing elements, arranged symmetrically in a crown shape around the axis of symmetry, such that a first end of each first pressing element facing the base engages with a second end of a corresponding second pressing element facing away from the base in frontal contact; a first plate, supported on the shaft The first pressing element passes upward; a second plate is connected to the first plate on the front and axially coupled to the first plate, the second plate supporting the second pressing element passing axially, the second plate being disposed on one side of the base, and the first plate and the second plate being supported by the plate support member; the second pressing element is slidably received in a corresponding axial first slot, the first slot being obtained radially in a crown shape by the second plate, the second pressing elements being circumferentially spaced from each other, and each having an engraving head on the side opposite the second end and facing the base, the engraving head being wider in the circumferential direction than the first slot, the engraving head being configured such that the engraving heads of the second pressing elements contact each other circumferentially without play and engage in a sliding manner. Attached Figure Description

[0013] Other features and advantages of the invention will become clear from the following description of a non-limiting exemplary embodiment of the invention provided with reference to the accompanying drawings, in which:

[0014] Figure 1 A schematic frontal radial cross-sectional view of a device manufactured according to the present invention is shown, which is capable of manufacturing front teeth on the inner ring of a wheel hub by plastic deformation;

[0015] Figure 2 Schematally shown at an enlarged scale Figure 1 Details of the main components of the equipment;

[0016] Figure 3 To illustrate this more clearly, a radial cross-sectional view of a portion of a wheel hub equipped with a front tooth is schematically shown at a further enlarged scale. This front tooth can be achieved by means of... Figure 1 The equipment was obtained;

[0017] Figure 4 and Figure 5 The diagrams are shown schematically at a further magnified scale. Figure 1A three-quarter perspective side view of the first pressing element (or first blade) and the second pressing element (or second blade) of the device;

[0018] Figure 6 and Figure 7 The diagrams are shown schematically at a further magnified scale. Figure 5 A series of second pressing elements (or second blades) and Figure 4 A partial frontal cross-sectional view of a series of first pressing elements (or first blades);

[0019] Figure 8 schematically shown Figure 5 and Figure 6 A three-dimensional view showing details of one of the pressing elements (or blades);

[0020] Figure 9 The longitudinal (axial) profile of the tooth portion, shown in radial section, is schematically illustrated at an enlarged scale, which can be visualized by means of... Figure 1 The acquisition of equipment; and

[0021] Figure 10 The theoretical geometry of the tooth profile is schematically shown, which can be achieved by means of... Figure 1 The equipment was obtained. Detailed Implementation

[0022] Reference Figure 3 Reference numeral 1 in the attached figure indicates the entire wheel hub. The wheel hub itself is known, and for simplicity, only a portion of the wheel hub is shown. The wheel hub includes an outer ring 2 and an inner ring 3. The outer ring 2 is used to connect to the vehicle's suspension pillar (not shown) in a known manner during use. Two rows of rolling elements 4 are arranged between the outer ring 2 and the inner ring 3. Figure 3 The image shows only one column of scrolling elements.

[0023] The inner ring 3 can be operatively associated with a constant-velocity joint (known, but not shown for simplicity) by means of front toothing 5 obtained on its first end 6, and is provided with a flange (known, but not shown for simplicity) for attaching the vehicle's wheel at the end opposite to the first end 6.

[0024] In the non-limiting example shown, the inner ring 3 includes a spindle 7 defining the first end 6 and a small ring 8 pressing against the first end 6, the small ring 8 facing the constant velocity joint in use; the inner ring 3, the spindle 7 and the small ring 8 are coaxial with each other and have a common axis of symmetry A that coincides with the overall axis of symmetry of the entire hub 1.

[0025] The inner ring 3 is provided with an upset collar, which is obtained by orbital forming of the end 6 through plastic deformation in a known manner. In the non-limiting embodiment shown, the smaller ring 8 is axially locked to the shaft 7 by means of the upset collar, which protrudes axially relative to the smaller ring 8.

[0026] The upsetting collar carries a front tooth 5, which is formed on the front end face of the upsetting collar that is configured to be generally perpendicular to the axis of symmetry A, and includes a plurality of teeth 11.

[0027] Also refer to Figure 1 , Figure 2 as well as Figures 4 to 7 The front tooth 5 is formed by means of a device 30 for track forming by plastic deformation. Figure 1 The device 30 is similar to a known device for track forming of an upsetting collar on the inner ring 3 of a hub 1.

[0028] Equipment 30 includes: a generally rigid plate support 22 ( Figure 1 and Figure 2 ), having an axis A ( ) that is connected to hub 1 during use Figure 1 The symmetrical axis B coincides with the axis of symmetry of the plate support 22; and the base (or base) 31 is used to support the hub 1, which is coaxial with the axis of symmetry B of the plate support 22.

[0029] The plate support 22 and the base 31 are axially movable relative to each other, parallel to axis B (and therefore also parallel to axis A) (e.g., one is fixed and the other moves, or vice versa), so that the plate support 22 can cooperate with the upsetting collar, which is an annular collar 10, in use in frontally.

[0030] In use, the hub 1 is inserted between the plate support 22 and the base 31, angularly and axially joined to the base 31, wherein the front tooth 5 has not yet been formed, but the annular collar 10 has been formed, for example by means of track forming using known equipment.

[0031] Once the semi-finished product consisting of a hub 1 without the front tooth portion 5 but having an upset collar is in position on the base 31, the plate support 22 and the base 31 are moved toward each other in a known manner (e.g., the plate support 22 moves toward the base 31 while the base 31 remains fixed, or vice versa) so that the plate support 22 is close to the annular collar 10 and the front tooth portion 5 is formed as will be seen below.

[0032] According to one aspect of the invention, in addition to the plate support 22 and the base 31, the device 30 also includes a plurality of first pressing elements 12 and an equal number of second pressing elements 13.

[0033] Pressing elements 12 and 13 are blade-shaped and are arranged symmetrically about the axis of symmetry B of the plate support 22 in a crown shape, oriented radially, and configured head-to-head as a first pressing element on a second pressing element, the first pressing element and the second pressing element being two coaxial, axially overlapping crowns carried by the plate support 22 (as will be seen below).

[0034] Specifically, the first end 14 of each first pressing element 12 facing the base 31 and the second end 15 of the corresponding second pressing element 13 opposite to the base 31 are in frontal contact. Figure 2 ).

[0035] The device 30 also includes: a first plate 16, which supports a first pressing element 12 that passes through and slides axially in the axial direction; and a second plate 18, which is connected to the first plate 16 on the front side of the base 31 and is axially bound to the first plate 16.

[0036] The second plate 18 is supported by the second pressing element 13, which passes through and slides axially in the axial direction, is disposed on one side of the base 31, and is supported by the plate support 22 together with the first plate 16 in any suitable manner.

[0037] According to a first important aspect of the invention, the second pressing elements 13 are slidably received, substantially without play, in corresponding first slits 19 (which are first axial slits) (obtained radially in a crown shape by the second plate 18), spaced apart from each other in the circumferential direction, and each is provided with an engraving head 20 on the side opposite to the second end 15 and facing the base 31. The engraving head 20 is wider in the circumferential direction than the first slit 19. The engraving head 20 is configured such that the engraving heads 20 of the second pressing elements 13 engage with each other in the circumferential direction with substantially no circumferential play, and thus are in direct and slidable contact with each other. In the remaining portion of the axial extension of the second pressing elements 13, the pressing elements 13 are not in circumferential contact with each other and are "sheathed" in the first slit 19.

[0038] Obviously, to achieve a similar construction, on one side of the base 31, the engraving head 20 protrudes axially from the second plate 18 and extends to the outside of the first slot 19. Figure 2 ).

[0039] According to another important aspect of the invention, and in conjunction with the above, the first pressing element 12 is slidably received in a corresponding second slot 21 (which is a second axial slot). Figure 2 (Obtained radially in a crown shape via the first plate 16) are spaced apart circumferentially and each has a hammerhead 23 on the side opposite to the first end 14. The hammerhead 23 is wider circumferentially than the second slot 21. The hammerheads 23 are configured such that the hammerheads 23 of the first pressing element 12 circumferentially engage with each other with substantially no circumferential play, thus directly contacting each other and slidingly. In the remaining portion of the axial extension of the first pressing element 12, the pressing elements 12 do not circumferentially contact each other and are "sheathed" in the second slot 21.

[0040] Obviously, to achieve a similar construction, on the side opposite to the base 31 and the ends 14 and 15, the hammerhead 23 protrudes axially from the first plate 16 and extends to the outside of the second slot 21. Figure 2 ).

[0041] The device 30 also includes a known pressure head 24 that rotates in an orbital motion.

[0042] The hammerhead 23 is configured to cooperate with the pressure head 24 in use to push the first pressing element 12 against the second pressing element 13 one at a time using sequential axial movement. Accordingly, each second pressing element 13 is selectively pushed toward the base 31 using a corresponding sequential axial movement, and each second pressing element 13 abuts against the annular collar 10 in use to engrave the desired front teeth 5 on the annular collar 10 through controlled plastic deformation.

[0043] According to another aspect of the invention, the second end 15 of the second pressing element 13 is provided with a corresponding radial notch 25 on its radially outer side. Figure 5 The radial notch 25 extends a predetermined length T in the axial direction, defining a first shoulder face 26 and a second shoulder face 27 on each second pressing element 13. Figure 5 The first shoulder surface 26 and the second shoulder surface 27 are opposite to each other and face each other.

[0044] To connect the pressing element 13 to the second plate 18 so that the element 13 will not "fall" off the second plate 18 due to gravity when it is not pressed against the annular collar 10, the device 30 also includes a plurality of end-stoke elements 28. Figure 2Multiple stroke termination elements 28 are configured to engage the radial notches 25 and cooperate with the first shoulder surface 26 and the second shoulder surface 27 of each radial notch 25 to limit the axial movement of each second pressing element 13 to the predetermined length T.

[0045] Specifically, device 30 includes a third board 29 ( Figure 1 and Figure 2 The third plate 29 is arranged radially outside the second plate 18.

[0046] The first annular end 34 of the third plate 29 is mounted adjacent to the first plate 16 and is axially overhanging relative to the second plate 18 to form an annular seat 35 between the first plate 16 and the second plate 18. Figure 2 The annular seat 35 is configured corresponding to the second end 15 of the second pressing element 13.

[0047] These second ends 15 are configured to protrude at least partially in the axial direction relative to the first slot 19 on one side of the first plate 16.

[0048] The third plate 29 is axially tightly packed between the first plate 16 and the second plate 18, forming an annular seat 35 together with the second plate 18 through its L-shaped radial end 34.

[0049] The annular seat 35 accommodates at least one pair of half rings (or multiple ring segments), the at least one pair of half rings being configured to extend radially outward from the second plate 18 toward the second pressing element 13 to engage a corresponding radial notch 25 having an axial extension, thus serving as the stroke termination element in the axial sliding movement of the second pressing element 13 from and toward the base 31.

[0050] The engraving head 20 of the second pressing element 13 is provided with a corresponding wedge-shaped cutter 36 that extends axially toward the base 31. Figure 5 and Figure 8 The wedge cutter 36 presents a profile in the circumferential direction that is complementary to the profile of the front tooth portion 5 to be obtained, and is configured such that each wedge cutter 36 forms the side profile 113 of each of the two adjacent teeth 11 of the front tooth portion 5 to be obtained on the inner ring 3 when it is pushed against the annular collar 10. Figure 10 ).

[0051] There is a groove 112 between each pair of teeth 11 defined by the side surface 113 of the adjacent teeth 11, and each tooth 11 has a tip or peak ( / crest / tooth tip) 114.

[0052] The wedge 36 is configured to obtain a circular peak 114 and a groove 112, the peak 114 having a radius of curvature R1, and the groove 112 being circular and having a radius of curvature R2, which is different from R1 and preferably smaller than R1.

[0053] With the aid of the present invention, an almost perfect circular peak is obtained, especially since each of the engraving teeth in the prior art is subdivided into a pair of separate and independent pressing elements (such as pressing elements 12 and 13) arranged sequentially in the axial direction, so that there can be continuous guided deformation between the corresponding faces 37 on the opposite sides of the wedge blade 36. This continuity is not available in the prior art because the engraving teeth or blades must be spaced apart in the circumferential direction for installation reasons.

[0054] The presence of head 23 (also configured to be in close circumferential contact and substantially without clearance) allows for a virtually continuous annular working surface for the pressure head 24 rotating in a track motion, in particular preventing any lateral thrust on the pressing elements 12, 13 due to the action of the pressure head 24.

[0055] According to one aspect of the invention, the wedge cutter 36 is further configured to obtain teeth 11, wherein R2 is preferably between 0.5 mm and 0.8 mm, and wherein the theoretical height H1 of the teeth 11 is ( Figure 10 The ratio between the actual height of the tooth (which does not slide through the plastic deformation of the annular collar 10, causing the actual height of the tooth to reach the value H) and the radius R1 of the peak 114 is always less than 5 (i.e., H1 / R1<5), wherein R1 is preferably greater than or equal to 1 mm.

[0056] Finally, since the teeth 11 are wedge-shaped, their height is reduced, and the distance L between the bottoms of two consecutive teeth 11 also decreases in the direction of radial movement toward axis A.

[0057] Therefore, the wedge blade 36 is configured such that, for any radial distance from axis A, a ratio H1 / L of less than 0.866 is preferably obtained.

[0058] Reference Figure 9 The profile of the peak 114 of tooth 11 is such that there is no corner point between the two points P1 and P2, and the curvature between the two points P1 and P2 is always greater than 1 mm.

[0059] From the above description, the advantages of the present invention are clear.

[0060] It is also clear that the present invention relates to a method for forming a front tooth 5 on the inner ring 3 of a hub 1 by plastic deformation, the method comprising the following steps:

[0061] An upsetting annular collar 10 is formed (in a known manner, preferably by track forming) at one end of the inner ring 3 of the hub 1;

[0062] The annular collar 10 is plastically deformed by pressing multiple pressing elements axially and sequentially onto it to create a front tooth 5 on the front side of the annular collar 10; this includes the following steps:

[0063] i) Provide a first pressing element 12 and a second pressing element 13, the first pressing element 12 being slidably supported in the axial direction by a first plate 16, the second pressing element 13 being slidably supported in the axial direction by a second plate 18, the second plate 18 being connected to the first plate 16 on the front, the corresponding first end 14 of the first pressing element 12 contacting and engaging head-to-head with the second end 15 of the second pressing element 13, the second end 15 being disposed on the side opposite to the annular collar 10;

[0064] ii) An engraving head 20 is obtained on each second pressing element 13, the engraving head 20 having a corresponding wedge-shaped knife 36 on the side opposite to the second end 15, the wedge-shaped knife 36 having a circumferential profile that is complementary to the profile of the front tooth 5 to be obtained.

[0065] iii) The pressure head 24, moving along the track, presses down on the corresponding hammer head 23 of the first pressing element 12, pushing the first pressing element 12 against the second pressing element 13, thus selectively and sequentially pushing each wedge 36 against the annular collar 10, wherein each wedge 36 is configured to form the side profile 113 of two adjacent teeth 11 of the desired front tooth portion 5 when pushed against the annular collar 10; and

[0066] v) During stage iii), the first pressing element 12 and the second pressing element 13 are guided such that the first pressing element 12 is angularly spaced apart while the hammerheads 23 of the first pressing element 12 always remain in circumferential contact with each other with substantially no play, and the second pressing element 13 is angularly spaced apart while the engraving heads 20 of the second pressing element 13 always remain in circumferential contact with each other with substantially no play.

[0067] Furthermore, in the method according to the invention, during the imprinting stage where the wedge blade 36 abuts against the annular collar 10, the hub 1 is axially and radially locked against the base 31, which is configured to face the second plate 18, relative to its own axis of symmetry A; furthermore, the second pressing element 13 is held attached to the second plate 18 by means of an axial travel termination element 28, which engages with a corresponding radial indentation 25, which corresponds to the radially obtained outer side of the second end 15. Thus, all the objectives of the invention are achieved.

Claims

1. An apparatus (30) for forming a front tooth (5) on the inner ring (3) of a wheel hub (1) by plastic deformation, wherein, The inner ring is provided with an annular collar (10) at one end (6); the device includes a plate support (22) and a base (31), the plate support (22) having an axis of symmetry (B), the base (31) being configured to support the hub coaxial with the axis of symmetry (B) of the plate support, the plate support being axially movable relative to the base (31) such that it engages with the annular collar on the front side during use; characterized in that the device further includes: Multiple leaf-shaped first pressing elements (12) and second pressing elements (13) are arranged symmetrically in a crown shape around the axis of symmetry (B), such that the first end (14) of each first pressing element (12) facing the base and the second end (15) of the corresponding second pressing element (13) facing away from the base are engaged in frontal contact. The first plate (16) supports the first pressing element (12) that passes through it axially; The second plate (18) is connected to the first plate on the front and is axially coupled to the first plate. The second plate supports the second pressing element (13) that passes through it axially. The second plate (18) is disposed on one side of the base. The first plate (16) and the second plate (18) are supported by the plate support (22). The second pressing element (13) is slidably received in a corresponding axial first slot (19), the first slot (19) being obtained radially in a crown shape by the second plate (18), the second pressing elements (13) being circumferentially spaced apart from each other, and each having an engraving head (20) on the side opposite to the second end and facing the base, the engraving head (20) being wider in the circumferential direction than the first slot (19), the engraving head (20) being configured such that the engraving heads of the second pressing elements contact each other without play in the circumferential direction and engage in a sliding manner.

2. The device according to claim 1, characterized in that, The first pressing element (12) is slidably received in a corresponding axial second slot (21), which is obtained radially in a crown shape by the first plate (16). The first pressing elements (12) are spaced apart from each other in the circumferential direction and are provided with hammers (23) on the side opposite to the first end (14). The hammers (23) are wider in the circumferential direction than the second slot (21). The hammers (23) are configured such that the hammers of the first pressing elements contact each other in the circumferential direction without play and engage in a sliding manner.

3. The device according to claim 2, characterized in that, The device also includes a pressure head (24) that rotates in a track motion, the hammer head (23) being configured to cooperate with the pressure head (24) in use to push the first pressing element (12) against the second pressing element (13) one at a time by sequential axial motion, and accordingly, selectively and by corresponding sequential axial motion push each second pressing element (13) toward the base (31), and push each second pressing element (13) against the annular collar (10) in use to carve the front teeth (5) on the annular collar.

4. The device according to any one of claims 1 to 3, characterized in that, The second end (15) of the second pressing element (13) is provided with a corresponding radial notch (25) on the radially outer side, the radial notch (25) extending a predetermined length (T) in the axial direction, defining a first shoulder surface (26) and a second shoulder surface (27) on each second pressing element, the first shoulder surface (26) and the second shoulder surface (27) being opposite to each other and facing each other.

5. The device according to claim 4, characterized in that, The device also includes a plurality of stroke termination elements (28) configured to engage the radial notches (25) and mate with a first shoulder face and a second shoulder face of each radial notch to limit the axial movement of each second pressing element (13) to the predetermined length.

6. The device according to any one of claims 1 to 3, characterized in that, The device includes a third plate (29) which is radially disposed outside the second plate; a first annular end (34) of the third plate is mounted adjacent to the first plate (16) and is axially overhanging relative to the second plate (18) such that an annular seat (35) is formed between the first plate and the second plate, the annular seat (35) being disposed corresponding to the second end (15) of the second pressing element (13), the second end (15) being at least partially axially overhanging relative to the first slot (19) on one side of the first plate (16).

7. The device according to claim 6, characterized in that, The third plate (29) is axially tightly packed between the first plate (16) and the second plate (18); the annular seat (35) accommodates at least one pair of semi-rings, which are configured to extend radially outward from the second plate and toward the second pressing element (13) to engage a corresponding radial notch (25) with an axial extension of the second pressing element, and serve as a stroke termination element in the axial sliding movement of the second pressing element to and from the base.

8. The device according to any one of claims 1 to 3, characterized in that, The engraving head (20) of the second pressing element is provided with corresponding wedge cutters (36), each of the wedge cutters (36) extending axially toward the base, the wedge cutters (36) presenting a profile in the circumferential direction complementary to the profile of the front tooth portion (5) to be obtained, and being configured such that each wedge cutter (36) forms the side profile (113) of two adjacent teeth (11) of the front tooth portion (5) to be obtained on the inner ring when it is pushed against the annular collar.

9. A method for forming a front tooth (5) on the inner ring of a hub (1) by plastic deformation, comprising the following steps: An upsetting annular collar (10) is formed on one end of the inner ring (3) of the hub; The annular collar (10) is plastically deformed by pressing multiple pressing elements axially and sequentially onto it to achieve the front tooth portion (5) on the front side of the annular collar (10); characterized in that the method includes the following steps: i) Provide a first pressing element (12) and a second pressing element (13), the first pressing element (12) being axially slidably supported by a first plate (16), the second pressing element (13) being axially slidably supported by a second plate (18), the second plate (18) being connected to the first plate on the front, a corresponding first end (14) of the first pressing element contacting and engaging head-to-head with a second end (15) of the second pressing element, the second end (15) being disposed on the side opposite to the annular collar; ii) A carving head (20) is obtained on each second pressing element (13), the carving head (20) having a corresponding wedge (36) on the side opposite to the second end, the wedge (36) presenting a contour in the circumferential direction that is complementary to the contour of the front tooth (5) to be obtained; iii) The corresponding hammer (23) of the first pressing element (12) is pressed by means of the pressing head (24) moving along the track, so as to push the first pressing element against the second pressing element (13), thus selectively and sequentially pushing each wedge (36) against the annular collar; iv) Each wedge cutter (36) is configured to form the side profile (113) of two adjacent teeth (11) of the front tooth portion (5) to be obtained when it is pushed against the annular collar; v) During stage iii), the first pressing element (12) and the second pressing element (13) are guided such that the first pressing element is angularly spaced apart while the hammers (23) of the first pressing element remain in circumferential contact with each other with substantially no play, and the second pressing element is angularly spaced apart while the engraving heads (20) of the second pressing element remain in circumferential contact with each other with substantially no play.

10. The method according to claim 9, characterized in that, During the imprinting stage of pressing the wedge blade (36) against the annular collar (10), the hub (1) is axially and radially locked on the base (31) relative to its own axis of symmetry (A), the base (31) being configured to face the second plate (18); and the second pressing element (13) is held attached to the second plate (18) by means of an axial travel termination element (28) that engages with a corresponding radial notch (25) of the second pressing element, the radial notch (25) corresponding to the second end being radially obtained on the outside of the second pressing element.

Images