Method for Manufacturing a Synchronizer Ring and Synchronizer Ring for Synchronized Manual Transmissions

Abstract

A synchronizer ring (10) for synchronized manual transmissions is manufactured by forming or reshaping a flat material of metal, wherein a conical friction surface (20) is produced, into which axial grooves (24) are incorporated by chipless machining, wherein a tool is axially shifted relative to the friction surface (20) to produce the final friction surface (20). At least the friction surface (20) is vibration-ground and subsequently hardened.

Claims

1. A method for manufacturing a synchronizer ring for synchronized manual transmissions, characterized by the following steps: a) producing a conical friction surface; b) incorporating axial grooves having edges and a depth into the friction surface by chipless machining wherein a tool is axially shifted relative to the friction surface to produce a final friction surface; c) vibratory grinding of at least the friction surface; and d) subsequent hardening of at least the friction surface.

2. The method according to claim 1, wherein hardening in achieved by nitriding.

3. The method according to claim 1, wherein producing a conical friction surface is achieved by reshaping a flat material of metal

4. The method according to claim 1, wherein at least one groove extends only axially when viewed in the axial direction.

5. The method according to claim 4, wherein all grooves only extend axially as when viewed in the axial direction.

6. The method according to claim 1, wherein the friction surface is produced by deep-drawing wherein the grooves are incorporated into the friction surface by using a correspondingly profiled deep-drawing tool for deep-drawing.

7. The method according to claim 1, wherein the grooves each include two side walls which extend obliquely to each other as as seen in radial section.

8. The method according to claim 1, wherein during vibratory grinding the edges of the grooves are rounded.

9. The method according to claim 8, wherein after vibratory grinding the edges have an edge radius in the range from 0.01 mm to 0.20 mm.

10. The method according to claim 9, wherein after vibratory grinding the edges have an edge radius in the range from 0.02 mm to 0.10 mm, as seen in radial section.

11. The method according to claim 1, wherein an oblong axial depression is incorporated into the friction surface between two adjacent grooves, whose depth is smaller than the depth of the grooves.

12. The method according to claim 11, wherein an oblong axial depression is incorporated into the friction surface between all adjacent grooves.

13. The method according to claim 11, wherein the depth of the depressions amounts to maximally 20% of the depth of the grooves.

14. The method according to claim 11, wherein the depressions have a substantially trapezoidal cross-section as seen in radial section.

15. The method according to claim 11, wherein the depressions are produced directly when incorporating the grooves into the friction surface.

16. The method according to claim 15, wherein the depressions are produced directly when incorporating the grooves into the friction surface by upsetting the wall portion forming the friction surface.

17. A synchronizer ring for synchronized manual transmissions, which includes at least one conical friction surface with axially extending grooves incorporated by chipless forming and is hardened at least in the region of the friction surface, wherein the grooves have edges that are rounded by vibratory grinding before hardening the friction surface.

18. The synchronizer ring according to claim 17, wherein the friction surface includes an oblong axial depression between two adjacent grooves each, whose depth amounts to maximally 20% of the depth of the grooves.

19. The synchronizer ring according to claim 18, wherein the friction surface includes an oblong axial between all adjacent grooves

20. The synchronizer ring according to claim 17, wherein the synchronizer ring is a blocker ring with radially protruding blocking teeth.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 shows a perspective view of a synchronizer ring according to the invention;

[0036] FIG. 2 shows a sectional view of the synchronizer ring of FIG. 1;

[0037] FIG. 3 shows a greatly enlarged section of the friction surface of the synchronizer ring of FIGS. 1 and 2 in a radial sectional view;

[0038] FIG. 4 shows a view of a flat material of metal, out of which the synchronizer ring according to the invention is formed; and

[0039] FIGS. 5 and 6 show succeeding steps during forming of the flat material for producing the synchronizer ring according to the invention, with reference to which the method according to the invention will be explained.

DETAILED DESCRIPTION

[0040] FIG. 1 shows a synchronizer ring 10 in the form of a blocker ring or blocking synchronizer ring. The same includes a ring body 12 from which several blocking teeth 16 protrude at an axial end 14. The blocking teeth 16 are part of a collar pointing radially to the outside.

[0041] This collar can be provided with so-called index cams 18, which as tabs originally protruding radially to the outside are axially bent by about 90. These index cams 18 are located between adjacent groups of blocking teeth 16.

[0042] The synchronizer ring 10 is a so-called single-cone synchronizer ring with a conical friction surface 20 on the inside of the ring body 12. Such synchronizer ring 10 is used for a so-called internal synchronization.

[0043] Alternatively or in addition, the radially outer shell surface 22 also can be designed conical and form a friction surface, whereby an intermediate ring for a so-called double-cone system is obtained.

[0044] The conical friction surface 20 is provided with numerous axial grooves 24 succeeding each other very closely on its circumference, whose width substantially is equal to the distance between two adjacent grooves 24. In FIGS. 1 and 2, the distances between two adjacent grooves 24 are shown larger than is the case in the preferred embodiment, in order to preserve clarity.

[0045] The grooves 24 exclusively extend in purely axial direction with a view in axial direction, i.e. there is no extension in circumferential direction. The grooves of course also extend in radial direction.

[0046] According to the preferred embodiment, the conical friction surface 20 consists of the material of which the entire synchronizer ring 10 is made and is designed without a friction layer applied thereto. This means that the friction surface 20 is formed by the flat material of which the entire synchronizer ring 10 is made. In operation, the grooves 24 prevent welding to a counter-cone ring and represent a receiving space for oil.

[0047] As can be taken from FIG. 3, each of the grooves 24 has two side walls 26, which as seen in radial section extend obliquely to each other, i.e. at an acute angle. In addition, at least the edges 30 of the grooves 24 arranged at the friction surface 20 are rounded by vibratory grinding, wherein as seen in radial section the edges have an edge radius in the range from 0.01 mm to 0.2 mm, in particular in the range from 0.02 mm to 0.1 mm.

[0048] Between two adjacent grooves 24 (preferably between all grooves) an oblong axial depression 32 is incorporated into the friction surface 20, whose depth is distinctly smaller than the depth of the grooves 24, in particular amounts to maximally 20% of the depth of the grooves 24. As seen in radial section, these axial depressions 32 have a substantially trapezoidal cross-section, which likewise has rounded edges 34, and are arranged approximately centrally in the wall portions 36 forming the friction surface 20, which lie on a cone surface.

[0049] The manufacture of the synchronizer ring 10 will be explained below with reference to FIGS. 4 to 6. The synchronizer ring 10 is manufactured from a flat material of metal, which is shown in FIG. 4 and is treated on the outside and on the inside, e.g. by punching. As after punching no machining aftertreatment preferably takes place, the blocking teeth 16 also are formed already in the flat material of metal. Optionally, index cams 18 can of course also be punched out. As flat material, in particular 16MnCr5 or C30 to C35 steel is used, wherein the steel preferably is nitridable.

[0050] The synchronizer ring 10 subsequently is plastically formed to its final geometry shown in FIG. 1, preferably by deep-drawing and without machining treatment.

[0051] The first deep-drawing step is schematically shown in FIG. 5, in which a deep-drawing tool with a drawing punch 38, a hold-down clamp 40 and a drawing die 42 is used. There is furthermore provided a receptacle 44 which can also be part of the drawing die 42.

[0052] After several forming operations, a tool 46 in the form of a particular drawing punch finally is used (see FIG. 6), which has a conical end with ribs and grooves 48. By axially shifting the tool 46 relative to the almost finished synchronizer ring 10, the grooves 24 are formed into the friction surface 20 without cutting. The grooves 24 can of course also be produced in several forming steps.

[0053] Between two grooves 24 an oblong axial depression 32 (see FIG. 3) is incorporated into the friction surface 20. The depressions 32 are produced directly when incorporating the grooves 24 into the friction surface 20, in particular by upsetting the wall portion 36 forming the friction surface 20.

[0054] Both the grooves 24 and the axial depressions 32 hence are made during deep-drawing itself or directly subsequent thereto.

[0055] After the synchronizer ring 10 has received its final shape, at least the friction surface 20, but preferably the entire synchronizer ring 10, is vibration-ground. In the process, the edges 30 of the grooves 24 as well as the edges 34 of the axial depressions 32 are rounded.

[0056] Subsequently, the synchronizer ring 10 is hardened by nitriding at least in the region of the blocking teeth 16 and the friction surface 20.

[0057] A machining aftertreatment after producing the grooves 24 and after hardening incidentally is not effected.