The invention relates to a method for the non-cutting production of a rolling bearing with a bearing inner ring and a bearing outer ring and with at least one rolling body row guided between these in raceways. The invention relates, furthermore, to a stamping and deep-drawing tool for applying the method and also to a single-row or multiple-row grooved ball bearing produced according to the method.
It is already known to produce the bearing rings of a rolling bearing in a non-cutting manner according to a cost-effective deep-drawing method. Regions which have been recognized as problematic are the groove-shaped ball raceways or the undercuts required, above all in radial or grooved ball bearings, which cannot be produced by conventional deep-drawing or forming methods.
In order to overcome this problem, instead of grooved ball bearings, axially prestressed four-point bearings or angular ball bearings, both in a single row and in a two-row version, are favored (see DE 2 334 305 A, DE 26 36 903 A1, DE 87 02 275 U1, DE 10 2004 038 709 A1, EP 1 683 978 A1). In four-point bearings, either the bearing inner ring or the bearing outer ring is then divided or produced so as to consist of two drawn components. The undercut in the respective opposite raceway is then generated mostly by roller-burnishing or another identically acting production method. What has become apparent as a disadvantage in four-point bearings with split bearing rings and in angular ball bearings is that, as already indicated above, these bearings have to be prestressed axially. Moreover, the angular ball bearings have comparatively lower load-bearing capacity in applications where mainly radial loads occur.
Further, it is known to manufacture the inner rings and outer rings of the bearings from separate semifinished products, such as sheet bars or else ring elements, and to complete them with at least one rolling body row during assembly. Thus, GB 1,137,313 describes a method for producing a ball bearing, in which the bearing inner ring and the bearing outer ring are manufactured from different sheet bars in a non-cutting manner.
Moreover, it is known to produce both a bearing inner ring and bearing outer ring from a single common semifinished product, with the result that cost savings are to be noted. Thus, DE 21 53 597 A describes a method for the production of rolling bearing rings from sheet metal, according to which, first, a ring of U-shaped cross section, consisting of two essentially axially directed legs of different diameter which are connected to one another by means of a circumferential web, is manufactured in a non-cutting manner, and in which, subsequently, the web is divided so as to give rise to a bearing inner ring and a bearing outer ring. In a following operation, the raceways for the rolling bodies are then formed into the bearing inner ring and bearing outer ring in an extremely complicated manner by means of an elastically expandable punch, that is to say by means of a punch capable of being acted upon with a pressure medium.
Furthermore, DE 602 09 662 T2 discloses a production method for an inner ring and an outer bearing ring of a rolling bearing, first a disk being cut off from a cylindrical bar material, and both a ring for a bearing inner ring and a ring fora bearing outer ring being produced in a non-cutting manner from said disk by cold forging and the subsequent stamping out of a central circular orifice and of an annular groove. The required ring raceways for guiding the rolling bodies are generated by means of subsequent cutting machining.
Finally, patent publication AT 185 664 discloses a method for the simultaneous non-cutting production of an outer and an inner bearing ring for rolling bearings, these bearing rings being worked out of a common disk-shaped blank in a plurality of drawing operations and finally being separated from one another. Thereafter, the bearing rings are provided with raceways, for example by roller-burnishing, and subsequently, completed with at least one rolling body row, are assembled into a rolling bearing.
Proceeding from this, the object on which the invention is based is to present a method for the non-cutting production of a rolling bearing with a bearing inner ring and a bearing outer ring, which method makes it possible, as compared with the known production methods, to have a more cost-effective manufacture of the bearing rings, including their raceways, for the rolling bodies by means of a non-cutting forming method.
According to the features of the main claim, the invention proceeds from a method for the non-cutting production of a rolling bearing with a bearing inner ring and a bearing outer ring and with at least one rolling body row guided between these in raceways. The set object is achieved by means of the following method steps to be carried out:
The subclaims describe preferred developments or refinements of the invention.
Accordingly, with regard to method step a), a metal sheet bar may advantageously be used which, in the region of the ring element to be stamped out, has different material thicknesses as a function of the material flow to be expected and/or of the degree of forming and/or of the material to be processed.
Furthermore, it may be expedient to carry out method steps b) to d) in one single common operation.
Furthermore, with regard to method step c), according to a first advantageous design variant of the method, a predetermined breaking point may be formed in the form of a plurality of segment-like webs of the ring element which are arranged over the circumference and which are themselves separated from one another by means of perforations.
According to a further design variant, with regard to method step c), a predetermined breaking point may be formed in the form of a material weakening continuous or partially segmented over the circumference.
A combination of the above design variants is likewise possible and is therefore also covered by the invention.
In another variant, for method step c), no such predetermined breaking point is formed in the ring element, but, instead, the radially inner portion and the radially outer portion are separated completely from one another.
One advantageous realization of the method provides for method step d), that the axial press forming is executed by means of a simple embossing of the raceways. In embossing, stresses making secondary treatment necessary may arise in the material of the ring elements.
Alternatively or additionally to this, one advantageous realization of the method provides for method step d), that the axial press forming comprises deep-drawing or extrusion. In these method steps, a material flow occurs which compensates mechanical stresses. Furthermore, the material flow may be utilized not only for transferring the raceway to that side of the ring element which points toward the tool, but also for causing that side of at least one of the two annular portions which points away from the tool to acquire a contour.
In particular, for this purpose, at least one of the two ring elements may be introduced into a die, so that, during axial press forming, the ring element is pressed into the die and that side of the ring element which points away from the tool acquires a contour which corresponds to the cross-sectional configuration of the die. In this case, in a single method step, both the raceway on the side which points toward the tool and the contour on that side of the ring element which points away from the tool can be obtained. At the same time, during axial press forming, the material flow reduces the occurrence of mechanical stresses in the ring element.
As the invention further provides, with regard to method step e), the forming of the ring element is carried out by the axial application of force to the annular portions, for example in the connection region or in the region of the formed predetermined breaking point, preferably in a plurality of forming stages.
As the invention also provides, with regard to method step e), a deep-drawing tool with a drawing punch which is annular or has at least part-annular portions and with an annular drawing die is used.
Advantageously, in this case, a drawing punch is used, with a portion tapering in cross section toward the workpiece in the form of the ring element and having radially inwardly and radially outwardly pointing junction surfaces which, in turn, penetrate into the ring element in the region of the predetermined breaking point and thereby implement forming as a result of a combination of a radial driving apart of the two annular portions and of a simultaneous axial introduction of these into the annular drawing die.
With regard to method step f), the introduction of the at least one cage element equipped with the at least one rolling body row into the axial spacing forming between the two annular portions moving toward one another may take place manually, semi-automatically or fully automatically.
With regard to method step g), there may be a provision whereby, advantageously, at the latest after the end position has been reached, the predetermined breaking point between the two annular portions in the form of the produced bearing inner ring and bearing outer ring breaks.
Advantageously, further, there may be provision whereby the complete captively mounted rolling bearing subassembly is subjected to heat treatment in order to eliminate structural stresses in the bearing inner ring and the bearing outer ring which have occurred due to the forming process.
Alternatively to the method steps described hitherto, there may be provision whereby, according to the method, a rolling bearing without a cage is produced for the rolling bodies. In this case, method step f) comprises the introduction of rolling bodies into the radial spacing forming between the two annular portions moved toward one another, and method step g) comprises the final transfer of the two annular portions, including the rolling bodies, by the further application of force to the end faces of the annular portions and/or to the rolling bodies into an end position such that a complete captively mounted subassembly, consisting of a bearing inner ring and of a bearing outer ring, with annular raceways which are arranged radially opposite one another and in which the at least one rolling body row is received positively, is formed.
Finally, alternatively to the method sequence described hitherto, there may be provision whereby only one of the two said ring elements is produced according to the method steps mentioned, whereas the second ring element is produced according to the same or another, for example conventional, forming process and is conveyed to the manufacturing device before being filled with the rolling bodies.
Finally, the subject of the invention includes a stamping and deep-drawing tool for carrying out the method described above and also a single-row or multiple-row grooved ball bearing produced according to the above method.
The proposed method for producing a rolling bearing has the essential advantage, in relation to conventional production methods, that the bearing inner ring and the bearing outer ring, including the undercut for the rolling body raceways, are produced as it were simultaneously in one production process by the non-cutting forming method. Furthermore, this method makes it possible, even while the bearing rings are being produced by said non-cutting forming method, to equip these with at least one cage element having at least one rolling body row or, without a cage, with the necessary rolling bodies and finally to connect them positively to form a complete captively mounted subassembly. This method therefore results in a considerable potential for savings in terms of material and work time.
The invention is explained in more detail below by means of some embodiments, with reference to the accompanying drawing in which:
As already mentioned, according to
The radially inner annular portion 3a is, in future, to form the bearing inner ring 3a′ and the radially outer annular portion 3b the bearing outer ring 3b′ of a rolling bearing 5 (
During forming by stamping, in the connection region between the two annular portions 3a and 3b of the ring element 3 according to
By contrast, it may also be expedient to provide (not illustrated in any more detail) a continuous or partially segmented material weakening only over the circumference in the ring element 3. A combination of the two above design variants is likewise possible and is therefore also covered by the invention.
According to another variant, it is also possible that no such predetermined breaking point 6 is formed in the ring element 3, but, instead, the radially inner portion 3a and the radially outer portion 3b are separated completely from one another. Such a procedure is to be preferred when the ring element 3 according to
After the method steps explained with reference to
A person skilled in the art, with knowledge of the invention, can comprehend that it is expedient to carry out all the method steps described above in one single common operation, for which purpose the forming tool merely has to be adapted correspondingly, that is to say equipped both with a stamping means and with a press-forming means (not illustrated in any more detail).
Furthermore, it has proved highly appropriate in investigations to use a metal sheet bar 1 which, in the region of the ring element 3 to be stamped out, has different material thicknesses as a function of the material flow to be expected and/or of the degree of forming and/or of the material to be processed. The profiling of the ring element 3, in particular of the raceways 8a, 8b, is therefore designed in such a way that uniform raceways 8a, 8b are produced in a finally formed part.
In that regard, preferably both the material flow to be expected and the degree of forming during forming must previously be simulated mathematically and taken into account correspondingly. Thus, during the further forming, still to be described below, by the axial shaping of the ring element 3 or its annular portions 3a, 3b, the regions which are upset must have smaller material thicknesses, while the regions which are stretched therefore have greater material thicknesses. A possible stretching of the raceways 8a, 8b during said shaping must therefore be taken into account and be allowed for in the initial profiling.
As already indicated above, the ring element 3 is then subjected to axial forming by deep drawing, according to
The drawing punch 10a is designed with a portion 11 tapering in a wedge-shaped manner in cross-section toward the workpiece or toward the ring element 3 and having radially inwardly and radially outwardly pointing junction faces 12a, 12b which, in turn, penetrate in the region of the predetermined breaking point 6 between the annular portions 3a, 3b of the ring element 3 into the latter and thereby implement forming as a result of a combination of a radial driving out of the two annular portions 3a, 3b and of a simultaneous axial introduction of these into the drawing die 10b.
In this case, the ring element 3 is supported on the drawing die 10b both via a region near its inside diameter and via regions near its outside diameter, as a result of which, because of the axial application of force, described in more detail above, to the predetermined breaking point 6 and to the adjacent surfaces of the annular portions 3a, 3b of the ring element 3, these and their raceways 8a, 8b are pivoted toward one another about the predetermined breaking point 6. The predetermined breaking point 6 or the material still present in this region in this case forms as it were a kind of solid state joint.
According to
When a specific predetermined degree of forming of the ring element 3 or its annular portions 3a, 3b is reached at the time point ts, according to
On account of a subsequent further application of force to the adjacent end faces 14 of the annular portions 3a, 3b and/or to the rolling bodies 9 by means of a drawing punch 10a now designed with obtuse pressure surfaces 15, the composite component structure to be generated is transferred at a time point t6 into an end position within the drawing die 10b such that finally, at a time point t7, a complete and captively mounted subassembly in the form of a rolling bearing 5 is formed, consisting of a bearing inner ring 3a′ and of a bearing outer ring 3b′ with annular raceways 8a, 8b which are arranged radially opposite one another and in which the rolling bodies 9, together with the cage element 13, are received positively (see,
At the latest when the end position shown in
As illustrated in more detail in
As may be gathered from
As has already been indicated briefly in the summary of the invention, a rolling bearing may also be produced so as to be cageless, that is to say, for example, with a full set of balls, according to the basic principles of the method presented. For this purpose, the rolling bodies 9 without a cage 13 are introduced into the radial spacing forming between the two annular portions 3a and 3b moved toward one another. This is followed by the transfer of the two annular portions 3a, 3b, including the rolling bodies 9, by a further application of force to the end faces 14 of the annular portions 3a, 3b and/or to the rolling bodies 9 into an end position such that a complete captively mounted subassembly, consisting of a bearing inner ring 3a′ and of a bearing outer ring 3b′, with annular raceways 8a and 8b which are arranged radially opposite one another and in which the at least one rolling body row is received positively, is formed. In that regard, reference is made to
Moreover, alternatively to the method variant described in detail with reference to the figures, there may be provision whereby only one of the two said ring elements for forming the bearing inner ring 3a′ or the bearing outer ring 3b′ is produced according to the method steps mentioned, whereas the second ring element is produced according to the same or another, for example conventional, forming process and is conveyed to the manufacturing apparatus before the introduction of the rolling bodies 9 and before the joint forming into the rolling bearing to be produced. In that regard,
In the exemplary embodiment described above, a press-forming tool 7 was provided for the method step d) (see,
Alternatively or additionally to this, for method step d) there may be provision for carrying out the axial press forming by means of deep drawing or extrusion or for superposing deep drawing or extrusion upon the pressing indicated in
As illustrated in the upper part image of
Axial press forming is carried out by means of a tool which on its end face has in each case a dome-shaped protuberance 23 which in each case bears centrally on the two portions 3a, 3b. By axial force (arrow 24) being exerted on the tool, the domes 23 are pressed onto the portions 3a, 3b which, in turn, are pressed into the cross-sectional contour 18 of the die 17. In this case, a material flow in the direction of the axial force 24 and perpendicularly thereto takes place, so that the portions 3a, 3b fill the cross-sectional contour 18 of the die 17 (see,
Further machining takes place after the steps described above with regard to the first exemplary embodiment.
In the second exemplary embodiment, the raceways 8a, 8b and the contour 25 were produced in a single method step d), so that secondary machining, even thermal secondary machining for the reduction of mechanical stresses which have occurred in the material, can be avoided.
Number | Date | Country | Kind |
---|---|---|---|
10 2007 027 216.4 | Jun 2007 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/DE2008/000241 | 2/7/2008 | WO | 00 | 12/11/2009 |