EP0970765B1 - Method for forming a workpiece by flow-turning - Google Patents

Description

The invention relates to a method for forming a workpiece by spinning rollers, in particular for producing internal teeth on the workpiece that has a cup-shaped preform axially clamped against a tool chuck and by means of at least a rolling element is pressed onto the tool chuck and the preform rotates relative to the rolling element.

With the non-cutting production of internal gears by Different processes are used for spinning rollers. So is a manufacturing process in DE 196 36 567 A1 (cf. FIG. 4) described, which are referred to as synchronous paths can. A preform is centered radially and through clamped an axial pressure against the tool chuck. The feed movement the pressure rollers are carried out from the tailstock side off so that the set to the outside diameter of the workpiece Press rollers reduce the outer diameter of the preform and the material in the profile on the circumference of the tool chuck press and roll out in the axial direction.

Furthermore, in DE 196 36 567 A1 (see FIG. 5) one Production of an internal toothing described by radial rolling. The preform is centered radially and on the Axially clamped on the bottom side, so that in the case of a radial infeed the press rolls the displaced material into the profile of the tool chuck penetrates radially and axially.

In a further process variant (see DE 196 36 567 A1, Fig. 6) the preform is centered radially and on both sides axially clamped so that the radial pressure of the spinning rollers the displaced material in the profile of the tool chuck penetrates and fills it.

Finally, in the case of synchronous stretching with an axial stop (see DE 196 36 567 A1, Fig. 7) the preform radially centered and axially clamped on the bottom side of the preform. In In the axial direction there is a stop on the tool chuck which the material flows during the pressure rolling and from which it stops as soon as the Outside diameter of the workpiece set pressure rollers of the tailstock side against the preform and the material displace. With this method, the material can only be radial Penetrate direction in the profile of the tool chuck and it can be against the frictional resistance of the flat surface of the Thicken the stop in diameter.

The problem of radial bulges occurs in all of these methods due to the mutual spacing of the spinning rollers, due to the geometric dimensions of the spinning rollers with their bearings results. The result is an alternating load in the profiles of the tool chuck during the forming process.

Furthermore, all processes have in common that at the beginning of the Reshaping the radial resistance of the material from the annular Transition zone between floor and wall of the preform must be overcome. The wall is also supported the preform on the tooth tips of the tool chuck. This has the consequence that changing forming forces due to the different Resistance during the forming of the preform different consolidations within the shaped profiles in the workpiece. Because constant forming forces a Requirement for constant tolerance spreads on the profile of the workpiece is with a fluctuating tolerance to count. This is a procedural, serious disadvantage in the manufacture of precisely dimensioned Workpieces according to the procedures listed.

The invention is therefore based on the object of specifying a method in which, in order to achieve a high-quality workpiece, the deformation resistance of the preform is virtually constant in the region of the inner profile during the pressure rolling.

This object is achieved according to the invention in the method mentioned at the outset by the characteristics of the Claim 1 solved.

Preferred variants of the method according to the invention are in specified in the subclaims.

A reliable profiling of the inside of the preform is made achieved according to the invention in that an internal toothing on molded into the cylinder wall area with an axial length which is less than the length of the cylinder wall area, and that the molded internal teeth in a defined Distance to the ground is formed. In the invention Spinning rolls from the open side of the preform can be material be moved towards the floor. It is according to the invention a space between the desired internal teeth and provided the floor in which the axially displaced material can be absorbed without an undesirable compression. The at least one rolling element overflows the cylinder wall of the Preform not all the way to the bottom, but stops in a defined one axial distance in front of the floor area. With a continuous axial formation of the outer profile on the tool chuck For example, sufficient free space can be provided become. Alternatively, a special annular groove can also be used on the tool chuck adjacent to the bottom of the clamped Preform can be arranged. This ensures that a required axial length of the internal toothing reliably on the Work piece can be rolled.

Furthermore, it is preferred according to the invention that in one Corner area between the floor and the cylinder wall area one Transition contour formed with a wall thickness reinforcement becomes. In the corner area between the substantially radial extending bottom and the substantially axial Cylinder wall area has the highest bending stress if the molded workpiece, for example, as a gear transmission part is used. Because on the inside of the corner area no defined design of the internal toothing achieved is a reliable high strength by a specially designed transition contour with a wall thickness reinforcement compared to the deformed cylinder wall area. The transition area preferably has a conical contour which tapers from the bottom to the cylinder wall area.

If according to a preferred embodiment, the preform is formed by a large number of rolling elements, which are ring-like arranged around the preform and in a cage each are rotatably mounted, the preform can be geometrically maximum number of pressure rollers, rollers or balls on the circumference supported during their rotation and reshaped at the same time become. The reshaping rolling elements circle the preform like a planet, when you touch and reshape them.

In the known pressure rolling, the separate storage and Control of the axes due to the axial misalignment of the rollers getting a roller to start the molding process, making it the tool is inevitably deflected until more axially offset rollers are used. As a consequence, that by this mutual deflection of the forming tool not even load and self-centering is possible. In contrast, this variant of the invention Process the force symmetrically via an outer ring of a bearing evenly transferred to all rollers. All rollers intervene in the forming process at the same time. It can the internal tool will center itself and will evenly loaded.

The preform is expediently in an axial relative movement moved by the ring-shaped rolling element arrangement and thereby pressed onto the spinning or tool chuck by the rolling elements. Alternatively, those stored in the cage can be used Rolling elements are fed radially.

If preferably the preform by tapered rollers is formed, which is inclined to the axis of rotation of the preform Roll arrangement in a conical outer ring, so can improved centering when inserting the preform into the rolling element arrangement be achieved. Furthermore is by a axial displacement and positioning of the rolling elements with the Cage radial positioning and adjustment of the rolling elements possible.

The preform is expediently between two axially movable Drive spindles of a pressure rolling machine clamped, whereby the tool chuck on one of the drive spindles and on the other Drive spindle a centering device are provided, that the preform is first on the drive spindle with the centering device arranged and kept centered and that the drive spindles for clamping the preform on the tool chuck be moved axially against each other. Then she can movement unit formed from the two drive spindles and the preform are used to generate the feed movement, which enables quick clamping and forming.

It is preferred that a centering pin is used as the centering device is used, on which the preform with a Hub opening is fitted with a precise fit. The centering pin and the hub opening can be a clearance fit or a form a slight interference fit, thereby ensuring that the preform is first fixed to one drive spindle. The opposite is used to clamp the preform onto the tool chuck Drive spindle axially retracted into the pot, the preform in its bottom area between the two drive spindles is clamped. The two moved against each other Drive spindles form a composite, which preferably then with the workpiece through an axially fixed Forming device driven with the at least one rolling element becomes.

The preform is in any case with the open side Forming tool moved d. H. the open side of the preform is the large diameter of those formed by the rolling elements conical receiving opening facing.

Due to the large number of rollers, the distance between the rollers is different reduced to a minimum. This will cause the radial bulge of the preform and thus the alternating stress on the Profiles of the tool chuck reduced to a minimum and one uniform material hardening is achieved.

Fig. 1:

in einer Schnittansicht eine Teildarstellung einer Drückwalzmaschine mit einer Vorrichtung zum Ausführen des erfindungsgemäßen Verfahrens in einer Ladestellung;

Fig. 2:

in einer Schnittansicht quer zu einer Maschinenrotationsachse die Vorrichtung der Fig. 1;

Fig. 3:

in einer Schnittansicht die Vorrichtung der Fig. 1 mit einer an einem Werkzeug eingespannten Vorform;

Fig. 4:

in einer Ansicht gemäß Fig. 3 die Vorrichtung in einer Betriebsstellung beim Umformen der Vorform;

Fig. 5:

in einer Schnittansicht eine Vorform, an der eine Innenverzahnung nach dem erfindungsgemäßen Verfahren hergestellt werden soll; und

Fig. 6:

in einer Schnittansicht ein Werkstück mit einer Innenverzahnung, die durch Umformung der in Fig. 5 dargestellten Vorform hergestellt worden ist.

The invention is explained in more detail below using an exemplary embodiment with reference to drawings. It shows:

Fig. 1:

in a sectional view, a partial representation of a press-rolling machine with a device for carrying out the method according to the invention in a loading position;

Fig. 2:

in a sectional view transverse to a machine axis of rotation, the device of FIG. 1;

Fig. 3:

in a sectional view the device of Figure 1 with a preform clamped to a tool.

Fig. 4:

3 the device in an operating position when the preform is being formed;

Fig. 5:

in a sectional view a preform on which an internal toothing is to be produced by the method according to the invention; and

Fig. 6:

in a sectional view a workpiece with an internal toothing, which has been produced by reshaping the preform shown in FIG. 5.

A device 10 or a forming tool for performing the method according to the invention (see in particular FIGS. 1 to 3) has a plurality of rollers 11 as rolling elements or spinning rollers in an annular arrangement (in the illustrated embodiment 14 rollers, see Fig. 2), which are in recesses, the in an annular support body or cage 13 of the device 10 are formed, recorded and guided axially and radially are. A fixed outer race or outer ring 14 is inserted in a housing 15 of the device 10 and forms an outer, hardened raceway 16 for the rollers 11, during an inner race through a preform 18 to be formed is formed. The annular support body 13 is via a ball bearing 19 radially and rotatably in the housing 15 of the device 10 stored. An axial bearing 20, for example a needle bearing, supports the supporting body 13 axially via a spring device, z. B. in the form of several coil springs 21, on one with the housing 15 z. B. connected by screw housing end part 22 from.

Fig. 1 shows the arrangement of the device 10 for rolling Internal toothing in a schematically shown spinning roll machine. The cup-shaped preform 18 is on a centering pin 30, which has a fit with a hub opening 29 the preform 18 forms on a first, right drive spindle 31, which serves as a pressing element, coaxial to its axis of rotation 32 recorded and held. This is the preform 18 with its bottom 33 against the front 34 of the drive spindle 31 created so that the open end 35 of the preform 18 a coaxially arranged, second, left drive spindle 36 points on which a tool chuck 37 with a tooth profile 38 is set. The inner diameter of the preform 18 corresponds approximately the outer diameter of the tool chuck 37. The left drive spindle 36 is axially against the right drive spindle 31 driven until the tool chuck 37 in the Preform 18 is retracted and the bottom 33 of the preform 18 against clamps the right drive spindle 31 (see FIG. 3). By rotating the left drive spindle 36 and / or the right drive spindle 31, the preform 18 in Rotation offset. The combination of left and right drive spindle 36 and 31 and preform 18 clamped between them then in a feed movement in the axial direction through the Device 10 driven (see FIG. 4), the free end 40th of the cylinder wall region 39 at the open end 35 of the preform 18 in the larger diameter of that set by the tapered Rolling elements 11 formed ring immersed and against the rolling elements 11 is pressed. This is done during the axial feed movement the cylinder wall area 39 from the open end 35 of the preform 18 reduced in diameter (see FIG. 4), see above that by rolling the recesses on the tooth profile 38th of the tool chuck 37 by material of the cylinder wall area 39 can be filled and the inner profile or the internal toothing 41 (see Fig. 6) is produced. The length of the feed motion or the feed path 42 is reached when the internal toothing 41 or the inner profile formed from the preform 18 Workpiece 43 has been formed in the desired length 44 is, with a defined distance 46 or free space to the floor 33 is complied with. Next is between the floor 33 and the molded internal toothing 41 on the cylinder wall area 39 a transition contour 47 with a wall thickness reinforcement is formed, through which a targeted stiffening of the highly loaded Corner area of the workpiece 43 is guaranteed.

In this embodiment, the device 10 or Forming tool on a radially adjustable cross support 45 Press rolling machine attached so that the housing 15 rests and the Rotate rolling elements 11 with their cage 13 about the axis of rotation 32. The pressure rolling machine can also be constructed in such a way that the cross support 45 is axially movable and the axial feed movement of the forming tool 10 with axially stationary drive spindles 31, 36 executes.

At the end of the feed motion, i.e. H. after reshaping the preform 18 and the production of the inner profile or the internal toothing 41 becomes an ejector 46, which is in the left drive spindle 36 is arranged, applied with an axial pressure force (Force action to the right in Fig. 4). During the axial Return movement of the two drive spindles 31, 36 will Finished workpiece 43 moved out of the forming tool 10 and from the left drive spindle 36 or the tool chuck 37 pushed off as soon as the left drive spindle 36 their Has reached the starting position and the right drive spindle 31 themselves away from the left drive spindles 36 into their starting position moved further back. The workpiece 43 is by a scraper 47 pushed by the right drive spindle 31. On new process cycle for producing the next workpiece can start.

Claims (8)

1. Method for forming a workpiece (43) by flow-forming, especially for forming internal teeth (41) on the workpiece (43), in which a cup-shaped blank (18) is axially fixed against a tool chuck (37) and is fixed on both sides and pressed by means of at least one rolling body (11) onto the tool chuck (37) and the blank (18) is rotated relative to the rolling body (11), wherein the at least one rolling body (11), at the start of forming, is pressed against a cylinder wall area (39) of the blank (18) and is guided in an axial relative movement over the cylinder wall area (39) in forming contact,
   characterized in that
   the rolling body (11) is guided from the open end of the blank (18) to the base (33) of the blank (18) in forming contact.
2. Method according to claim 1,
   characterized in that
   internal teeth (41) are formed on the cylinder wall area (39) with an axial length (44) smaller than the length of the cylinder wall area (39) and that the shaped in internal teeth (41) are formed at a clearly defined distance (46) from the base (33).
3. Method according to claim 1 or 2,
   characterized in that
   in a corner area between the base (33) and the cylinder wall area (39) is formed a transition contour (47) with a wall thickness increase.
4. Method according to one of claims 1 to 3,
   characterized in that
   the blank (18) is formed by a plurality of rolling bodies (11), which are arranged in ring-like manner round the blank (18) and are in each case mounted in rotary manner in a cage (13).
5. Method according to claim 4,
   characterized in that
   the blank (18) is moved in an axial relative movement through the ring-like arrangement of the rolling bodies (11) and is pressed by the latter onto the tool chuck (37).
6. Method according to one of claims 1 to 5,
   characterized in that
   the blank (18) is formed by conical rolling bodies (11), which roll in a conical outer race (14) inclined to the rotation axis (32) of the blank (18).
7. Method according to one of claims 1 to 6,
   characterized in that

   the blank (18) is fixed between two axially movable drive spindles (31, 36) of a flow-forming machine and on one of the drive spindles (36) is provided the tool chuck (37) and on the other drive spindle (31) a centring device,

   the blank (18) is initially positioned and kept centred with the centring device on the drive spindle (36) and

   for fixing the blank (18) on the tool chuck (37) the drive spindles (31, 36) are moved axially against one another.
8. Method according to claim 7,
   characterized in that
   the centring device is constituted by a centring pin (30), on which the blank (18) is mounted in accurately fitting manner with a hub opening (29).

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