Metal deforming – By use of tool acting during relative rotation between tool... – During rotation of work
Reexamination Certificate
2001-02-08
2002-12-17
Tolan, Ed (Department: 3725)
Metal deforming
By use of tool acting during relative rotation between tool...
During rotation of work
C072S082000, C072S084000, C072S086000, C072S107000, C072S120000, C029S893320
Reexamination Certificate
active
06494072
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of manufacturing the clutch gear toothing on gearwheels in change speed gears (FIG.
1
).
Gearwheels having such a clutch gear toothing are employed, for instance, in gear sets for manual shifting. As a rule, they are supported for rotation on the gear shad The transmission of torque from and to the gear shaft is possible only upon axial movement of a shifting sleeve and its engagement in the clutch gear toothing. By means of the undercut on the external toothing the shifting sleeve is prevented from being disengaged when the vehicle is running.
The clutch gear toothings on these gearwheels should generally present a specific geometry for easy engagement of the shifting sleeve as well as an external toothing with axial undercut for reliable torque transmission from and to the shifting sleeve.
PRIOR ART
Several methods are common in engineering for the manufacture of toothing systems having such a geometry. In these methods it is required that, on the one hand, the geometry will be formed on the gear wheel face for permitting easy engagement and that, on the other hand, the axial undercut will be produced to ensure the transmission of torque. It is common in particular to achieve such geometries by a forming operation by cutting, for instance by gear shaping.
A cutting tool such as a pinion-type cutter performs an oscillating motion at a slight angle relative to the longitudinal axis of the gearwheel as well as a feeding motion in a radial direction to the first one. At the same time, the gearwheel and the tool perform a rotating movement so that the required involute shape with undercut will be created when the two bodies move on rolling contact with chip removal.
Another method consists in producing a separate sheet metal disk carrying such a toothing, and in welding this sheet metal disk to the base body of the gearwheel. In such a case the toothing is normally applied by fine pressing.
It is known from the German Patent DE 4335505 C1 to manufacture spur toothings by a rolling operation wherein toothed shaping rolls are axially moved with respect to the rotating work piece, while the shaping rolls are synchronised with the work piece by means of a so-called attachment carrying an external toothing. even though this method is suitable to produce external toothings having tooth traces extending in parallel with the work piece axis it is not appropriate to generate the tooth shape here described.
Another known approach permitting the integral manufacture of the gearwheel in its entirety consists in a calibration of the teeth in a press tool wherein individual toothed quadrants are impressed into the work piece by radial and/or axial movements. Such quadrant tools are not only very complex and highly expensive but have also short service lives. Apart therefrom, it is very difficult with these tools to produce the tooth forming tolerances which are mostly very narrow.
The German Patent DE 22 54 460 discloses a method of and a device for manufacturing clutch gearwheels with engagement securing means. In that method a rolling wheel with a clutch gearwheel is caused to perform a rolling operation, whilst the axes of the rolling wheel and of the clutch gearwheel are aligned in parallel. The shape of the rolling wheel, inclusive of the undercut corresponds to the shape of the toothing to be generated on the gearwheel.
The German Patent DE 198 09 039 A1 equally discloses a method of applying undercuts on individual tooth flanks in an internal toothing on sliding sleeves, In that method the metal material is shaped by way of plastic deformation by rolling on the rear side and/or by pressing so that sub-areas with pull-out preventing function and sub-areas without pull-out preventing faction are pre-shaped on the individual tooth flank to be undercut, and subsequently, when the undercut is generated, some plastified material is urged out of the sections of the sub-areas having a locking function ands pressed into sub-areas without locking function which are configured as recesses of the re-entrant areas.
BRIEF DESCRIPTION OF THE INVENTION
Starting out from the facts that linear press tools are unsuitable for generating the undercut and that quadrant tools are expensive and not precise, the present invention is based on the problem of proposing an economic method and a device permitting the manufacture of high-quality external toothings by non-cutting manufacture, which toothings are suitable to ensure the engagement and disengagement of gear wheels in change speed gears due to a specific lateral entry geometry and an axial undercut,
This problem is solved by a method using the features defined in claim
1
or
3
or by a device presenting the features defined in claims
11
or
12
. Expedient embodiments are characterised by the remaining claims.
The device comprises a spindle supported for rotation, on which the work piece is clamped by means of a chuck. This spindle is caused to rotate together with the chuck and the work piece.
Shaping tools in the form of rolls with external toothing, toothed racks adapted for linear movement, or hollow internally geared wheels are caused to engage on the work piece and to perform a motion with rolling contact on the work piece. The subsequent movement of these tools towards the work piece at least in a radial direction and possibly also in an axial direction initiates the shaping of a work piece with movement in rolling contact. The axial feed motion or the combined axial/radial feed motion becomes necessary when the axes of rotation of the work piece and of the tool extend in parallel with each other for generating the undercut With this arrangement the rotating movement may be performed by driving the spindle or by driving the shaping tool. What is important is the feed of the shaping tool concurrently with the movement of the tooth profile with rolling contact.
In the present description the term “axial” is to be understood to denote that direction which extends in parallel with the axis of tool rotation along the axis of work piece rotation. In correspondence therewith, a merely radial direction is meant to denote a direction extending radially with respect to the axis of tool rotation. A combined radial and axial direction is correspondingly involved when the tool is moved along a direction towards the axis of work piece rotation that is defined by a purely radial and a purely axial direction.
The present invention is based on the idea of achieving a tooth formation with undercut on a gearwheel by a shaping technique wherein the application of a quadrant tool is avoided. Quadrant tools are inexpedient specifically insofar as a pressing operation with segments is, as a rule, linked up with high tolerances. On the other hand, the undercut renders it impossible to employ common linear presses. At the same time, a specific geometry is to be created on the face of the gearwheel, that permits easy engagement of the shifting sleeve. Such a geometry, that permits an easy engagement, is, for instance, a roof-shaped design of the face or a bow-shaped curvature.
Due to the application of the shaping tool on a feed means in such a way that a combined radial and anal feed motion of the tool will be performed relative to the work piece while the work piece is exposed to a rotating movement at the same time, it is possible to produce a toothing with axially undercut tooth flanks in an axially undercut section of an integral gearwheel. Apart from the rotating movement that is performed by both the work piece and the shaping tool about its respective axis, with these axes extending either in parallel with each other or at an angle a relative to each other, that is wider than 0°, it is essential that the tool feed motion takes place at least in a radial direction. An axial feed motion in addition to the radial movement may be omitted when the axes of rotation of the tool and of the work piece do not extend in parallel with each other. It is moreover possible that the tool performs an additional mo
PSW Press-und Schiedewerk GmbH
Sughrue & Mion, PLLC
Tolan Ed
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