EP1915225B1 - Method for producing internal and external toothings on thin-walled, cylindrical hollow parts - Google Patents

Description

The present invention relates to a method according to the preamble of claim 1, a device for its implementation, and its use, see for example the GB-A-1 324 090 ,

The production of an axial profiling of a thin-walled, cylindrical hollow part can be done for example by means of cold rolling. For example, procedures are off US 5,355,706 in which profile rollers are radially brought as tools on a circular path on the workpiece in striking engagement and produce by axial feed of the workpiece relative to the profile rollers, the desired profiling using a toothed mandrel tool inside and outside. However, due to the circular path of the profile rollers when engaging in the workpiece arcuate longitudinal contours are generated, which depending on the size of the web diameter have a larger or smaller radius, but are always present. A disadvantage of this cold forming process by means of profile rollers is that the teeth on a cylindrical workpiece with shoulder can not be executed close to this shoulder zoom. Due to the circular path of the profile rollers remains between the end of the profiling and the shoulder a certain section on the workpiece, which can not be edited. The object of the present invention was to find a method and an apparatus which a accurate profiling of thin-walled, cylindrical hollow bodies with a defined profile geometry, even close to a shoulder area zoom.

This object is achieved by the method having the features of claim 1. Further embodiments emerge from the features of the further claims 2 to 9.

In particular, in the claimed method a cold-forming profiling of cylindrical, thin-walled hollow parts is carried out, with substantially parallel to the longitudinal axis of the hollow part extending profiles, wherein radially to the longitudinal axis of the hollow part on the hollow part from the outside at least one profiling tool is suddenly hammered acting, wherein the profiling tool is brought in each case in an essentially vertical direction oscillating on the surface of the hollow part to act. Furthermore, the profiling tool is displaced axially relative to the hollow part at a constant radial infeed depth until the desired profile length has been reached. Thus, in one operation, the profile can be completely generated in its entire length, wherein the entire forming work is divided into a plurality of individual steps. As a result, the forming forces of each individual step can be kept relatively small. This leads to a high accuracy of the profile produced, both as an inner or outer profile, as well as an excellent Profilausformung. In particular, with the method can be relatively small profile radii are generated, which significantly increases the load-bearing flank share compared to identical profile dimensions. Furthermore, the profiling tool can be positioned close to a possible shoulder of the hollow part thanks to substantially vertical oscillating movement with respect to the surface of the hollow part, thus profiling up to close to this shoulder. This means that the profiling tool performs virtually no movement in the axial direction and thus also does not require any free movement space in the axial direction in the machining area of the hollow part.

For example, the profiling tool is delivered radially to the longitudinal axis of the hollow part up to a predefined feed depth for axial displacement. Because the resp. the profiling tools are arranged radially before the actual machining operation in a remote position from the hollow part, the hollow part can be arranged with sufficient free space in the processing device resp. be connected with a workpiece holder.

For example, a change of direction of the axial displacement between profiling tool and hollow part is performed at least once, in particular after reaching the desired profile length back to the original relative starting position between profiling tool and hollow part. This allows very high demands on the accuracy and surface quality of the profiling can be met. It is even conceivable a multiple axially parallel back and forth move the hollow part with respect to the profiling tool to achieve the desired surface quality.

For example, respectively after completion of the axial relative displacement resp. Move the profiling tool radially out of the profile of the hollow part. Thus, the finished molded hollow part can be easily removed from the processing device and insert a new blank. With the claimed method, for example, a defined profiling, such as a toothing with a defined pitch, can be generated.

According to the claim, the oscillating stroke movement of the profiling tools is chosen to be greater than the maximum radial insertion depth of the profiling tools into the hollow part. In this case, the hollow part, for example, intermittently, synchronized with the oscillating stroke movement rotates about its axis, for example, in each case by the pitch of the profiling to be generated. For example, the profiling tool may be operated at over 1000 beats per minute, for example at over 1500 beats per minute. This allows very high production rates to be achieved, which is of great advantage, especially for mass production in the automotive industry.

According to the claim, the hollow part is placed on a profiled mandrel for machining, which is displaceable relative to the profiling tool along the longitudinal axis. This will be the outdoor as well as the Inner profile of the hollow body made according to the specifications of the shape quickly and very accurate.

For example, the profiling of the mandrel ranges from its free end to a radially outwardly projecting shoulder and it is placed a hollow part, which is pot-shaped and also a shoulder resp. has an edge. Such hollow parts are used for example in gearbox application, as for the transmission of rotation and torque in automatic transmissions. Frequently, the profiles must be executed as exact internal and external teeth to close to the outwardly projecting edge of the hollow part resp. be made.

For example, the profiling tool for the first process section in the region of the shoulder of the mandrel resp. brought radially to the action in the region of the edge of the hollow part and in the second process section, the mandrel is axially displaced away from the profiling tool. In this case, either the profiling tool or the hollow part can be moved in the machine to produce the axial relative movement between the hollow part and profiling tool. This movement is carried out, for example, in such a length until the profiling tool no longer comes to act on the hollow part. This movement is referred to as a pulling movement, since the profiling tool moves practically after the piercing process to the base of the profile pulling relative to the hollow part and thus the entire length of the profiling is generated.

For example, the profiling tool is first in the region of the free end of the hollow part resp. the mandrel radially delivered and then the mandrel resp. the hollow part axially with respect to the profiling tool to the shoulder resp. moved to the edge, for example, until the profiling tool close to the shoulder of the mandrel resp. the edge of the hollow part is in action. Again, of course, the relative movement between Profilierungswerkzeug and hollow part in the machine can be accomplished by axial displacement of the hollow part. This movement is referred to as an abutting movement, since the profiling tool primarily shapes and completes the profile against the edge of the hollow part. In this case, for example, the tool can be delivered outside the free end to the predefined feed depth and only then brought to the hollow part to act. For example, in each case at least two profiling tools arranged radially opposite one another are used which, for example, are driven synchronized with one another with respect to their radial infeed and their oscillatory movement. This ensures optimal force distribution and introduction. For example, the profiling tool is delivered radially in relation to the workpiece continuously or in discrete, adjustable steps until the final profile depth of the hollow part is reached.

Further, the object is achieved by a device having the features of claim 10.

Further embodiments of the device result from the features of further claims 11 to 18.

According to the claim, the device for carrying out the claimed method at least one operatively connected to an eccentric tool holder for a profiling tool, a relative to the tool holder along its longitudinal axis slidably formed mandrel resp. Workpiece holder for a hollow part, a drive for rotating the mandrel resp. Workpiece holder about its longitudinal axis, and at least one profiling tool designed as a stamp. In this case, the stamp on a work profile that corresponds to the profile shape to be generated on the outside of the hollow part, wherein the working profile axis resp. Work surface is aligned at an acute angle to the longitudinal axis, with the exception of a region which has the shortest distance radially to the surface of the hollow body, which is aligned as a calibration zone parallel to the longitudinal axis. In each case, the calibration zone first engages in the surface of the hollow body, since this zone is closest to the surface of the hollow body in the machining direction of the stamp. After the penetration of the calibration zone, the remainder of the working surface of the stamp can penetrate into the surface, in particular when the hollow body is pulled, and a first pre-deformation of the hollow body can take place. In the second stage of the procedure, when the punch is moved axially with respect to the hollow body with constant radial infeed, the calibration zone then only needs to carry out the final deformation of the profile. For example, the length of the stamp resp. the length of the working profile longer than the length of the profile to be generated in the hollow body. Thus, for example, in the pulling processing of the hollow body over the entire length of the profile during radial infeed the profile is preformed.

For example, the length of the calibration zone is only a fraction of the total length of the stamp res. the length of the working profile. This calibration zone is ultimately decisive for the shaping and accuracy of the profiling, since only this calibration zone is in contact with the hollow part at the end of the radial infeed.

For example, the stamp will be made of a high-strength material resp. a corresponding

Have surface treatment in order to achieve the longest possible service life and thus to ensure a high accuracy of the profiling created over a longer production period.

For example, the device has at least two profiling tools arranged opposite each other with respect to the longitudinal axis of the hollow body. In order for an optimal force introduction and distribution is ensured on the hollow part, and also the forces in the device itself can be optimally absorbed and distributed. Conceivable, of course, other arrangements, for example, each symmetrical arrangements of profiling tools.

• Fig. 1 schematisch den prinzipiellen Aufbau einer herkömmlichen Schlagwalzvorrichtung mit auf einer Kreisbahn umlaufenden Profilierungsrollen;
• Fig. 2 schematisch den prinzipiellen Aufbau einer Vorrichtung zur Durchführung des Verfahrens;
• Fig. 3 den Längsschnitt durch einen auf einem Dorn aufgesetzten topfförmigen Hohlkörper vor der Bearbeitung mit einem Profilierungswerkzeug;
• Fig. 4 den Längsschnitt von Figur 3 nach dem ersten Verfahrensabschnitt der Verfahrens;
• Fig. 5 den Querschnitt durch den Bearbeitungsbereich des Längsschnittes von Figur 4;
• Fig. 6 den Längsschnitt durch einen auf einem Dorn aufgesetzten topfförmigen Hohlkörper vor der alternativen Bearbeitung mit einem Profilierungswerkzeug; und
• Fig. 7 den Längsschnitt eines Profilierungswerkzeuges.

An embodiment of the present invention will be explained in more detail with reference to figures. Show it

• Fig. 1 schematically shows the basic structure of a conventional impact rolling device with circulating on a circular path profiling rollers;
• Fig. 2 schematically the basic structure of a device for carrying out the method;
• Fig. 3 the longitudinal section through a cup-shaped hollow body placed on a mandrel prior to machining with a profiling tool;
• Fig. 4 the longitudinal section of FIG. 3 after the first stage of the process;
• Fig. 5 the cross section through the processing area of the longitudinal section of FIG. 4 ;
• Fig. 6 the longitudinal section through a cup-shaped hollow body placed on a mandrel before the alternative machining with a profiling tool; and
• Fig. 7 the longitudinal section of a profiling tool.

FIG. 1 schematically shows the basic structure of a conventional impact rolling device for generating internal and external teeth on a cylindrical hollow body 1. The hollow body 1 is formed as a thin-walled pot, which on a profiled mandrel. 2 is postponed and processed from outside by means of arranged on a circular path K profile rollers 3 beating. The profile rollers 3 are thereby delivered radially against the axis A of the hollow body until the desired tread depth has been achieved on the hollow body 1. From this representation it can be seen that the profiles 4 are produced on the hollow body 1 at the front end with a straight end, while the profile ends tapering, with a radius corresponding to the shape of the circular path K ends. Now, if the profiles 4 must be formed close to a protruding radially outwardly of the hollow body 1 shoulder, so this process can be resp. do not use this device.

In FIG. 2 is now also schematically illustrated the basic structure of a device for machining cylindrical, thin-walled hollow bodies. Here, too, a profiled mandrel 2 is used, on which the hollow body 1 to be profiled is placed. The hollow body 1 here now has an outwardly projecting shoulder 1 '. The profiles 4 should now be carried out from the front side to close to the shoulder. For this purpose, profiling tools 5 are now used, which can be delivered radially with respect to the axis A of the hollow body 1. The profiling tools 5 are driven by means of an eccentric drive (not shown for clarity) in a linear oscillating movement exactly radially to the axis A.

In FIG. 3 the longitudinal section through the mandrel 2 is shown with attached hollow body 1, wherein the profiling tool 5 is in the starting position for the processing of the shoulder 1 'of the hollow body 1. The hollow body 1 is pressed firmly against the mandrel 2 in the axial direction. The mandrel 2 has in particular a toothing resp. Longitudinal profiling on which the hollow body 1 rests with its inner side before machining. Next, the mandrel 2 a shoulder 2 'on.

The profiling tools 5 are now placed in the first process section in a sudden hammering action on the surface of the hollow body 1. Simultaneously with this oscillating movement of the profiling tools 5, these are now in the first process section radially against the axis A of the hollow body 1 to a previously defined resp. set depth, as shown in the longitudinal section FIG. 4 evident. At the end of this first process section, the profile is now formed in the region of the shoulder 1 ', while it is first preformed to the left to the front edge of the hollow body 1, but not yet fully formed.

By an axial relative displacement of the hollow body 1 with respect to the profiling tool 5 in the second process section, in which the profiling tool 5 is pulled out at a constant feed depth quasi from the hollow body 1, the profile 4 is now fully formed over its entire length. In FIG. 5 is in the Cross-section of the profiling tool 5 in its defined feed depth in the lowest Bearbeitungsresp. Engagement position shown in the hollow body 1. Here is particularly clearly the cross-section finished shaped profile 4 of the hollow body 1 can be seen.

Typically, the profiling tools 5 may be operated at a speed of over 1000 beats per minute, for example even over 1500 beats per minute. In this case, the profiling tools 5 can be delivered in each case for each complete hollow body revolution in the radial direction in each case by at least about 0.1 mm until the desired tread depth is reached.

In FIG. 6 the longitudinal section through a hollow body 1 is analogous to FIG. 3 shown, in which case the profiling tool 5 is shown in its alternative starting position for processing. The profiling tool 5 is located axially in front of the end face of the hollow body 1, and is delivered radially in the predefined feed depth. For the actual processing of the hollow body 1, the profiling tool 5 is now pushed axially in the direction of the shoulder 1 'of the hollow body 1 until reaching the desired profile length. The hollow body 1 is for example close to the end face of the mandrel 2, and the shoulder 1 'has against the shoulder 2' of the mandrel 2 on a small game. Thus, the material of the hollow body 1 during processing in the direction of this shoulder 2 'expand. It is clear to the skilled person that this relative movement in the device itself by displacement of the hollow body 1, respectively. of the mandrel 2 relative to the profiling tool 5 can take place.

In FIG. 7 is still the longitudinal section of a profiling tool 5 shown, as it can be used for example for the claimed method. The profiling tool 5 is designed as a punch and has on its machining side 6 a cross-section to the profile 4 to be generated of the hollow body 1 corresponding shape, for example, a trapezoidal shape. The lower edge 7 of the machining side 6 is thereby arranged in relation to the axis A of the hollow body at an acute angle φ. Depending on the shape and depth of the profile 4 to be produced, this angle is between 0.5 ° and 10 °.

The lower edge 7 extends for example straight, but may also have a slight curvature. At the right end of the profiling tool 5 after FIG. 7 a calibration zone 8 is formed. In the region of this calibration zone 8, the lower edge 7 is aligned parallel to the axis A of the hollow body 1, and the contour of the machining side 6 corresponds to the cross section of the profile to be produced on the outside of the hollow body 1. The lower edge 7 extends from the calibration zone 8 at an angle or possibly in an arc to the opposite end of the profiling tool 5. This angle resp. Arc corresponds to the contour of the preforming region of the profile 4 to be produced. It has been found that it can be advantageous if the length of the calibration zone 8 is only one Fraction of the total length of the profiling tool 5 corresponds.

The axial feed of the hollow body 1 resp. of the mandrel 2 is to be tuned, for example, to the length of the calibration zone 8 and is when using two radially opposite profiling tools 5, for example, a maximum of twice this length in a full revolution of the hollow body. 1

The stroke of the profiling tools 5 of the oscillating movement is dimensioned such that it is greater than the maximum radial infeed depth of the first method section. Thus, the profiling tools 5 arrive at each stroke once outside the contour of the surface of the hollow body 1. Then, the hollow body 1, respectively. the mandrel 2 in the same frequency as the oscillation of the profiling tool and synchronized to this movement, for example, intermittently rotated. In this case, the rotational movement is carried out, for example, exactly by a pitching step of the profiling, so that successive abrupt actions of the profiling tools 5 in adjacent profiles 4 of the hollow body 1 take place. Thus, a very precise and uniform profiling can be generated on the entire circumference of the hollow body 1.

Very high production rates can be achieved by the already mentioned high rate of impact, which is particularly advantageous for mass production, for example in the automotive industry.

Claims (19)

1. A method for profiling of cylindrical, thin-walled, hollow workpieces (1) by cold-forming, for producing inner and outer toothings in the hollow workpieces having profiles running essentially parallel to a longitudinal axis (A) of the hollow workpiece, characterized in that

   - for being worked on, the hollow workpiece (1) is placed onto a mandrel having a profiling, the mandrel being movable along the longitudinal axis (A) of the workpiece (1) relative to the profiling tool (5),

   - a profiling tool (5) which is operationally connected to an eccentric drive produces, in a direction radial to said longitudinal axis (A), hammering impacts from the outside against the hollow workpiece (1),

   - the profiling tool (5) acts on the surface of the hollow workpiece (1) in an oscillating fashion solely in an essentially perpendicular direction,

   - the oscillating thrust motion of the profiling tool (5) is selected to be greater than the maximum radial depth of impression of the profiling tool (5) into the hollow workpiece (1),

   - the hollow workpiece (1) is intermittently rotated about said longitudinal axis (A), wherein said intermittent rotation of the hollow workpiece (1) is synchronized with the oscillating thrust motion of the profiling tool (5), in particular each time by an amount corresponding to a pitch of the profiling to be made, and

   - the profiling tool (5), while operating in a uniform radial depth oscillation, is caused to move axially relative to the hollow workpiece (1), until a desired length of the profiling is achieved,

   wherein the profiling tool (5) is designed as a metal working die comprising an active operational side (6) and has at its active operational side (6) a shape corresponding in a cross-section to the contour of the profile of the hollow workpiece (1) to be created, and wherein the active operational side (6) has a lower edge (7) which in a longitudinal section is inclined at an acute angle relative to said longitudinal axis (A), except for a calibration zone (8) forming an end portion of the profiling tool (5), wherein said lower edge (7), in a longitudinal section, is in the range of the calibration zone (8) aligned parallel to the longitudinal axis (A), and wherein, in a cross-section, a contour of the operational side (6) corresponds to the profile to be created in the external surface of the hollow workpiece (1), and wherein in the calibration zone (8) the lower edge (7) is located closest to the surface of the hollow workpiece (1).
2. The method according to claim 1, wherein previous to the axial movement, the profiling tool (5) is adjusted to a predetermined profiling depth setting radial to the longitudinal axis (A) of the hollow workpiece (1).
3. The method according to claim 1 or claim 2, wherein at least once a change of direction of said axial movement of said profiling tool (5) relative to said hollow workpiece (1) takes place, for example back to an initial position after achieving a desired length of the profile.
4. The method according to one of claims 1 to 3, wherein after a respective completion of said axial relative movement of said profiling tool (5), the profiling tool (5) is retracted out of the profile (4) in the hollow workpiece (1).
5. The method according to one of claims 1 to 4, wherein the profiling of the mandrel (2) extends from a free end of the mandrel up to a shoulder (2') of the mandrel protruding radially outward, and wherein a hollow workpiece (1) is placed onto the mandrel which is pot- or jar-like and has a rim or a shoulder (1').
6. The method according to claim 5, wherein firstly, the profiling tool (1) is radially engaged in a region of the shoulder (2') of the mandrel (2) and a region of the rim (1') of the hollow workpiece (1), respectively, and thereafter, the mandrel (2) and the hollow workpiece (1), respectively, are axially moved relative to the profiling tool (5) in a direction pointing away from the shoulder (2') and from the rim (1'), respectively, for example until the profiling tool (5) can no longer operate on the workpiece.
7. The method according to claim 5, wherein firstly, in a region of said free end of the of the hollow workpiece (1) and of the mandrel (2), respectively, the profiling tool (5) is radially adjusted to a predetermined profiling depth setting, and thereafter, the mandrel (2) is axially moved relative to said profiling tool (5), for example until the profiling tool (5) is engaged in proximity of the shoulder (2') of the mandrel (2) and of the rim (1') of the hollow workpiece (1), respectively.
8. The method according to one of claims 1 to 7, wherein at least two profiling tools (5) are used which lie radially opposite to one another, for example wherein they are driven in a mutually synchronized manner with respect to their radial profiling depth setting and with respect to their oscillating movement.
9. The method according to one of claims 1 to 8, wherein an adjustment of the profiling depth setting of the profiling tool (5) radial to the hollow workpiece (1) is carried out continuously or in discrete adjustable steps, until the specified depth of the profile (4) of the hollow workpiece (1) is reached.
10. An apparatus for carrying out a method according to one of claims 1 to 9, comprising

    - at least one eccentrically operated drive and

    - at least one profiling tool (5) operationally connected to said at least one eccentrically operated drive for producing the oscillating thrust motion, and

    - a workpiece holder in the form of a mandrel (2) for a hollow workpiece (1), said workpiece holder being movable relative to said profiling tool (5) along a longitudinal axis (A) of the mandrel;

    - a drive for intermittently rotating said mandrel (2) about its longitudinal axis (A), in a fashion synchronized with the oscillatory thrust motion,

    wherein

    - the profiling tool (5) is designed as a metal working die comprising an active operational side (6) and has at its active operational side (6) a shape corresponding in a cross-section to the contour of the profile of the hollow workpiece (1) to be created,

    - the active operational side (6) has a lower edge (7) which in a longitudinal section is inclined at an acute angle relative to said longitudinal axis (A), except for a calibration zone (8) forming an end portion of the profiling tool (5), wherein said lower edge (7), in a longitudinal section, is in the range of the calibration zone (8) aligned parallel to the longitudinal axis (A), and wherein, in a cross-section, a contour of the operational side (6) corresponds to the profile to be created on the outside of the hollow workpiece (1), and wherein in the calibration zone (8) the lower edge (7) is located closest to the longitudinal axis (A).
11. The apparatus according to claim 10, wherein the length of the die (5) and a length of the working profile, respectively, is longer than the length of the profile (4) to be created in the hollow workpiece (1).
12. The apparatus according to claim 10 or 11, wherein the length of the calibration zone (8) is only a fraction of the length of the die and of the length of the produced profile, respectively.
13. The apparatus according to one of claims 10 to 12, comprising at least two profiling tools (5), wherein said tools lie, with respect to the longitudinal axis (5) of the hollow workpiece (1), opposite to one another.
14. The apparatus according to claim 10, wherein the profiling of the mandrel (2) extends from a free end of the mandrel up to a shoulder (2') of the mandrel protruding radially outward.
15. The apparatus according to claim 14, wherein the mandrel (2) is designed such that a hollow workpiece (1) can be placed onto it which is pot- or jar-like and has a rim or a shoulder (1').
16. The apparatus according to claim 10, wherein the acute angle amounts to between 0.5° and 10°, depending on form and depth of the profile (4) to be produced.
17. The apparatus according to claim 10, wherein the lower edge (7) runs in an angle or along an arc from the calibration zone (8) to the opposite end of the profiling tool (5).
18. The apparatus according to claim 17, wherein this angle and this arc, respectively, corresponds to a contour of a pre-shaping area for the profile (4) to be produced.
19. Use of a method according to claim 5 or of an apparatus according to claim 14, for profiling of cylindrical, thin-walled, hollow workpieces (1) by cold-forming, for producing inner and outer toothings in the hollow workpieces having profiles running essentially parallel to a longitudinal axis (A) of the hollow workpiece (1), wherein the hollow workpieces (1) are pot- or jar-like and have a shoulder or a rim and are hollow workpieces which find application in transmission manufacturing, serving for the transfer of rotary motion and torque in automatic transmissions.

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