METHOD AND FORMING DEVICE FOR THE MANUFACTURING OF RING-SHAPED FORMED PARTS

Description

[0001] The present invention relates to a method and a device for producing an inner and an outer annular shaped part from a blank.

[0002] In the production of rolling bearing rings, a pair of rings is typically first produced in a forming device, one of which forms the inner ring and the other the outer ring of a rolling bearing. To produce these rings, known processes first involve cup extrusion from a blank to produce a blank with an inner and an outer annular section and a cup base or slug. These annular sections are then separated from each other and from the cup base and further processed through additional steps such as rolling and expanding to form the inner and outer rings of the rolling bearing, as described, for example, in EP 3 362 204 B1.

[0003] US Pat. No. 6,065,322 A discloses a process in which the blank with the two annular sections and the cup base or slug is produced from the blank in a single forming step by cup extrusion. In this forming process, a stepped forming punch presses against the blank arranged in a forming die, whereby the two annular sections and the cup base are formed from the blank in a single forming step—i.e., in a single forming step with a single die and without modifying the forming step or the die.

[0004] To separate the two annular sections and enable further processing into rolling bearing rings, the annular sections are typically arranged such that they do not overlap in the radial direction and are offset in the axial direction. This requires a stepped profile of the forming die and a corresponding stepped profile of the forming punch of the forming stage.

[0005] One problem is that the stepped profile of the forming punch and die restricts the flow of the blank material during cup extrusion. The material cannot be displaced freely by the forming punch, and the cup base of the molded part cannot therefore be formed as thin as desired. Since the cup base or slug is removed in a subsequent process step and disposed of as scrap, this results in unnecessarily high material waste, which must be reduced as much as possible.

[0006] CN 105057556 B discloses a method in which a cylindrical blank is first pre-formed by cup extrusion into a cup with a cup base and an adjoining continuous cup wall. In a next step, the cup wall and cup base are then further formed into a blank with an inner and an outer annular section and a residual base portion in the center of the inner annular section. This is done, as in the method known from US Pat. No. 6,065,322 A, using a stepped forming punch and a stepped forming die, with the known problem that the flow of material is restricted during forming and the material cannot be displaced unhindered by the forming punch, meaning the residual base portion cannot be formed as thin as desired. In addition, both the pre-formed cup wall and the pre-formed cup base must be further formed after pre-forming.

[0007] Against this background, the object of the invention is to provide a method and a forming device which make it possible to form the cup base of the molding thinner than in the known methods with the known forming devices and thus to minimize material waste.

[0008] This object is achieved by the inventive method and the inventive forming device for producing an inner and an outer annular shaped part from a blank, as defined in independent patent claims 1 and 8. Particularly advantageous developments and refinements of the inventive method and the inventive forming device emerge from the respective dependent patent claims.

[0009] The essence of the invention with regard to the method is that a method for producing an inner and an outer annular shaped part from a blank comprises the following steps: Cup extrusion of the blank into a cup with a shaped cup base and an adjoining stepless cup wall, forming the cup wall such that the formed cup wall comprises an inner annular section and an adjoining outer annular section partially offset in the axial direction, and separating the outer annular section from the inner annular section and separating the inner annular section from the formed cup base, wherein the separated outer annular section forms the outer annular molded part and the separated inner annular section forms the inner annular molded part.

[0010] An advantage of the method according to the invention is that, in the first step of the method, a cup is formed with a shaped cup base and an adjoining stepless cup wall. "Stepless" means that a cross-section of the formed cup wall has no step-like contours. Thus, there are no abrupt transitions between areas of different inner or outer diameters in the cup wall. Such a stepless cup wall can be formed accordingly with stepless forming tools, such as a stepless forming punch and a stepless forming die. As a result, the flow of the blank material is not impeded by step forms, and the forming tool, in particular the forming punch, can displace the blank material largely unhindered during cup extrusion. In this way, a relatively thin cup base can be formed.In the cup extrusion step, the cup base of the cup is essentially completely formed and is not significantly further formed in the subsequent step of forming the cup wall. This also implies that the thickness of the cup base is determined by the cup extrusion step and is largely unchanged during the forming of the cup wall. In the prior art processes discussed above, in which the annular sections of the formed cup wall are formed in the same step as the cup base or the remaining base part, the material flow is impeded due to the required steps in the cross-section of the corresponding forming tools, resulting in a thicker cup base or remaining base part compared to the process according to the invention.

[0011] The separation of the outer annular section from the inner annular section and the separation of the inner annular section from the formed cup base, with the separated outer annular section forming the outer annular molded part and the separated inner annular section forming the inner annular molded part, can take place simultaneously or at different times and independently of one another. For example, in a first separation step, the outer annular section can be separated from the inner annular section, and in a second separation step, the inner annular section can be separated from the formed cup base, or vice versa. The two separation steps can take place in the same forming stage or in different forming stages.

[0012] The inner and outer annular molded parts produced using the inventive method are further processed, for example, in subsequent steps such as rolling and expanding to form an inner ring and an outer ring of a rolling bearing, as described, for example, in EP 3 362 204 B1. Since the cup base is separated and disposed of as scrap, the inventive method reduces material waste due to the thinner cup base. Furthermore, the energy consumption for the forming process is also reduced due to the lower force required.

[0013] Typical materials for the blank for the production of such ring-shaped molded parts for further processing into rolling bearing rings include metals such as steel or rolling bearing steel.

[0014] A blank is particularly well suited for the inventive method if its outer diameter approximately corresponds to the outer diameter of the outer annular molded part. The blank is advantageously disc-shaped.

[0015] Preferably, during the cup extrusion of the blank, the cup base is formed between an end face of a first forming die part and a support surface of an ejector.

[0016] The forming of the cup base between an end face of a first forming punch part and a support surface of an ejector has the advantage that the shape of the forming step can be varied by moving the ejector with the support surface. In particular, in a particularly advantageous embodiment in which the ejector is arranged so as to be movable back, i.e. movable in a direction away from the forming punch, regions of a forming die, in particular a step-shaped region, can be released by moving back the support surface, which enables a multi-stage forming process with only one forming step. Furthermore, after the cup wall has been formed, the formed cup can be easily ejected by means of the support surface arranged on the ejector, without the need for an ejection element in addition to the ejector with the support surface that is already used for forming the cup base.

[0017] Advantageously, during the cup extrusion of the blank, at least a part of a circumferential inner surface of the inner annular molded part is formed by a circumferential outer surface of the first forming die part.

[0018] A circumferential outer surface is understood here as a side surface that surrounds the forming punch part on one side of the forming punch part, projecting away from the end face. A first forming punch part designed in this way is advantageous for displacing the blank material. This ensures that no blank material flows behind the end face of the forming punch part during the cup extrusion process, which would then have to be displaced again in the subsequent step of forming the cup wall. Furthermore, at least part of the circumferential inner surface of the inner annular molded part is already formed, thus avoiding additional forming of this inner surface in the subsequent step of forming the cup wall.

[0019] In an advantageous embodiment, the cup extrusion of the blank takes place in a first forming stage with a stepless forming die and the forming of the cup wall takes place in a second forming stage with a forming die having a step-shaped area.

[0020] Here, after cup extrusion, the cup is transferred from the first forming stage with the stepless forming die to a second forming stage with a forming die that is different from the stepless forming die and has a stepped area. This has the advantage that the method according to the invention can be carried out without the need for movable elements to change the shape of the forming die or to expose parts of the forming die that are inaccessible for cup extrusion of the blank.

[0021] In an alternative advantageous embodiment, the cup extrusion of the blank and the forming of the cup wall are carried out successively in the same forming stage with only one forming die.

[0022] This design variant has the advantage that the cup does not have to be transferred from one forming stage or forming die to another after cup extrusion. This saves the time required for transferring the cup. Furthermore, the gripping tool required for transferring the cup and the space required for the additional forming stage are eliminated.

[0023] Preferably, the forming die comprises a step-shaped region for forming the cup wall and a circumferential inner surface of the step-shaped region of the forming die is released by moving the ejector back with the support surface.

[0024] This has the advantage that the ejector with the support surface, which is already used for forming the cup base and for ejecting the formed cup, can also be used to adjust the forming die used for cup extrusion. This means that no additional movable elements are required. This is a simple method for providing a stepped area of ​​the forming die for forming the cup wall after cup extrusion. The stepped area of ​​a forming die is understood to be the area of ​​a forming die whose cross-section has stepped contours due to partial areas with different inner diameters. Such a stepped area of ​​the forming die is necessary to form the respective outer surfaces of the inner and outer annular sections of the formed cup, which have different outer diameters.

[0025] In a preferred embodiment, the blank is cup-extruded and the cup wall is formed by hot forming at temperatures from 500°C.

[0026] Hot forming at the temperatures mentioned above enables easier forming of the blank or bowl compared to cold forming.

[0027] A forming device according to the invention for producing an inner and an outer annular shaped part from a blank comprises: a first forming punch part for cup extrusion of the blank into a cup with a shaped cup base and an adjoining stepless cup wall, a second forming punch part and a forming die having a step-shaped region for forming the cup wall in such a way that it comprises an inner annular section and an adjoining outer annular section partially offset in the axial direction, and a separating tool for separating the outer annular section from the inner annular section and for separating the inner annular section from the formed cup base, wherein the separated outer annular section forms the outer annular shaped part and the separated inner annular section forms the inner annular shaped part.

[0028] The forming device according to the invention offers the same advantages as the method according to the invention.

[0029] "Stepped" and "stepless" are understood as described above. The first and second forming die parts can be different parts of the same forming die, but also parts of two different forming dies. In a preferred embodiment, a suitable cutting tool can be a punching tool. Additional tools, such as a rolling tool or an expanding tool, can be provided.

[0030] Preferably, the forming device comprises an ejector with a support surface and the first forming die part comprises an end face for forming the cup bottom during cup extrusion of the blank.

[0031] The ejector is advantageously designed both for ejecting the formed cup and for providing and holding the support surface during the cup extrusion or forming of the cup wall, and can preferably be moved by means of a hydraulically controlled actuator. A suitable hydraulic system that provides sufficient support force so that the ejector is also suitable for holding the support surface during the cup extrusion or forming of the cup wall is described in EP 3 362 204 B1.

[0032] The support surface of the ejector and the end face of the first forming die part are preferably arranged opposite one another to enable the cup base to be formed between these two surfaces. The distances between the end face and support surface at a thinnest point are preferably in a range of 1 mm to 6 mm to form a cup base of corresponding thickness. In an advantageous embodiment, the first forming die part comprises a first circumferential outer surface for forming at least part of a circumferential inner surface of the inner annular molded part.

[0033] In a further advantageous embodiment, the ejector is arranged to be movable back with the support surface in order to release a circumferential inner surface of the step-shaped region of the forming die for forming the cup wall.

[0034] "Retractable" here means movable in a direction away from the forming die part. For example, the ejector can be retracted due to the force exerted by the first forming die part on the blank or cup.

[0035] In an advantageous embodiment, the first forming punch part, the second forming punch part and the forming die having the step-shaped region are part of a common forming stage.

[0036] In an alternative advantageous embodiment, the first forming punch part and a stepless forming die are part of a first forming stage and the second forming punch part and the forming die having the step-shaped region are part of a second forming stage.

[0037] The method and forming device according to the invention for producing an inner and an outer annular shaped part from a blank are described in more detail below with reference to two exemplary embodiments shown in the drawings. They show: Fig. 1 - a schematic cross-sectional view of a forming stage of a first embodiment of the forming device according to the invention after cup extrusion; Fig. 2 - a schematic cross-sectional view of the forming stage of Fig. 1 after forming the bowl wall; Fig. 3 - a schematic detailed view of Fig. 1 with a cup between a forming die and a forming punch after cup extrusion; Fig. 4 - a schematic detailed view of Fig. 2with a formed cup between the forming die and the forming punch after forming the cup wall; Fig. 5 - a schematic cross-sectional view of a blank; Fig. 6 - a schematic cross-sectional view of a cup formed by cup extrusion; Fig. 7 - a schematic cross-sectional view of a formed cup after forming the cup wall; Fig. 8 - a schematic cross-sectional view of the cup base, the inner annular molded part, and the outer annular molded part after separation; Fig. 9 - a schematic cross-sectional view of a first forming stage of a second embodiment of the forming device according to the invention after cup extrusion; Fig. 10 - a schematic cross-sectional view of a second forming stage of the second embodiment of the forming device according to the invention after forming the cup wall; Fig. 11 - a schematic detailed view of Fig. 9with a cup between a continuous forming die and a forming punch after cup extrusion; and Fig. 12 - a schematic detailed view of Fig. 10 with a formed cup between a forming die having a stepped area and a forming punch after the forming of the cup wall.

[0038] The following definition applies to the following description: If reference symbols are provided in a figure for the purpose of clarity but are not mentioned in the directly related description, reference is made to their explanation in preceding or subsequent description sections. Conversely, to avoid graphic overload, reference symbols that are less relevant for immediate understanding are not shown in all figures. For this purpose, reference is made to the other figures.

[0039] The Figures 1 and 2show a schematic cross-sectional view of a forming stage of a first embodiment of the forming device according to the invention at the end of two working steps, the Figures 3 and 4 two corresponding schematic detail views and the Figures 5 to 8 a workpiece, typically made of metal, processed with the forming device in four different processing phases.

[0040] Fig. 1 shows the forming stage in a first arrangement at the end of a cup extrusion of a disc-shaped blank 3 (see Fig. 5) to a cup 3' with a cup wall 31. The forming device comprises a machine body 5 and a forming die 1 fastened thereto, in which the cup 3' formed from the blank 3 by cup extrusion is arranged. The forming die 1 is delimited on a side facing the machine body 5 by a support surface 45 of a movably arranged ejector 41. Furthermore, the forming device comprises a forming punch 2 driven by a punch drive 6. The punch drive 6 comprises a punch drive crank 60 driven by a punch drive shaft 64, which is connected via an articulated connection 63 to a punch drive rod 62, which in turn is connected via a further articulated connection 61 to the forming punch 2.For cup extrusion, the punch drive crank 60 is rotated by the punch drive shaft 64 in the direction of rotation indicated by the arrow and the forming punch 2 is pressed against the blank 3 arranged in the forming die 1 and the blank 3 is formed into the cup 3' by the force of the forming punch 2.

[0041] The arrangement further comprises a hydraulically operated actuator 70, which is movably mounted in the machine body 5 and supports the ejector 41, which is also movably mounted in the machine body 5. To move or adjust the actuator 70, a piston 74, which is firmly connected to the actuator 70, is moved forward (toward the forming die 1) and backward (in the direction away from the forming die 1) in a hydraulic chamber 76 of a hydraulic system 7 by means of a hydraulic medium, in particular hydraulic oil. The actuator 70, the piston 74, and the hydraulic chamber 76 are each circular-cylindrical, but can also have other shapes in alternative embodiments. Furthermore, the hydraulic system 7 comprises a position measuring device with measuring electronics as well as other hydraulic elements such as a hydraulic source, lines, hydraulic accumulators, and collecting tanks. These elements are graphically combined in a hydraulic block 73.Of the elements relevant to the hydraulic system 7, for the sake of clarity, only the two servo valves 72 for supplying and discharging the hydraulic medium to and from the hydraulic chamber 76 are shown. To move the piston 74 and the actuator 70 towards the forming die 1 or to exert a force in this direction, the hydraulic medium is supplied via the servo valves 72 into an area of ​​the hydraulic chamber 76 behind the piston 74 (i.e. on the side of the piston 74 facing away from the forming die 1) and is discharged from an area of ​​the hydraulic chamber 76 in front of the piston 74. Accordingly, for a movement of the piston 74 in the opposite direction, the hydraulic medium is supplied via the two servo valves 72 into the area of ​​the hydraulic chamber 76 in front of the piston and is discharged from the area of ​​the hydraulic chamber 76 behind the piston.The movement of the piston 74 and the actuator 70 firmly connected thereto in a hydraulic system 7 corresponds to the state of the art and requires no further explanation. Further details on such a hydraulic system 7 are described, for example, in WO 2017 / 072173 A1.

[0042] By means of the actuator 70, a force can be exerted on the ejector 41 in the direction of the forming die 1. The hydraulic system 7 used here is, like the system described in WO 2017 / 072173 A1, designed, on the one hand, to support the blank 3 during cup extrusion or the cup 3' during the forming of the cup wall 31 and, on the other hand, to support a formed cup 3" (see Figures 2 and 7 ) from the forming die 1.

[0043] Fig. 1 shows the forming device in an arrangement in which the blank 3 has just been formed into the cup 3'. Fig. 2shows the forming device in an arrangement in which the cup wall 31 of the previously formed cup 3' has been formed in a step of the process following the cup extrusion. As in Fig. 2 As shown, the actuator 70 was moved back, which also allows the ejector 41 to be moved back to expose a stepped area of ​​the forming die 1 for forming the cup wall. Furthermore, the forming punch 2 was pressed further against the cup 3' arranged in the forming die 1 and formed into the formed cup 3" by forming the cup wall 31. The forming punch 2 was moved by further rotating the punch drive crank 60 in the direction of rotation indicated by the arrow.

[0044] The process for producing an inner and an outer annular shaped part from the blank 3 will now be described using the Figures 3 and 4 , which show detailed views of the forming die 1, the forming punch 2 and the ejector 41, as well as the Figures 5 to 8 , which illustrate the blank 3, the bowl 3', the formed bowl 3" as well as an inner annular molded part 39 and an outer annular molded part 38 in a cross-sectional view, are explained in more detail.

[0045] Fig. 3 shows a cross-sectional view of the ejector 41, the forming punch 2 and a forming die 1 with the cup 3' arranged in the forming die 1. The arrangement corresponds to that in Fig. 1 shown arrangement, in which the blank 3 was formed into the cup 3' by cup extrusion. Such a disc-shaped blank 3 is shown in Fig. 5 The blank 3 is shown here, like all the others in the Figures 6 to 8 Objects or workpieces shown in cross-sectional views are rotationally symmetrical around the respective dashed line.

[0046] The bowl 3' is in Fig. 6shown enlarged. It comprises the stepless bowl wall 31, which has a circumferential inner surface 35", and a shaped bowl bottom 30. The shape of the bowl 3' is essentially determined by the support surface 45 of the ejector 41, a Fig. 3a stepped surface 15 of the forming die 1 arranged in the same plane as the support surface 45 and surrounding it in a ring shape, a continuously variable circumferential inner surface 12 of the forming die 1, an end face 23 of a first forming punch part 20 of the forming punch 2, and a first circumferential outer surface 21 of the first forming punch part 20. The cup base 30 is formed between the support surface 45 of the ejector 41 and the end face 23 of the first forming punch part 20. The distance between the support surface 45 and the end face 23 is preferably in a range of 1 mm to 6 mm and is approximately 3 mm in this exemplary embodiment, whereby the cup base 30 is formed to a thickness corresponding to this distance. The first circumferential outer surface 21 of the first forming die part 20 forms the circumferential inner surface 35" of the cup 3'. This in turn forms part of a circumferential inner surface 35' of the Fig. 8illustrated inner annular molded part 39. The first forming die part 20 has a first outer diameter AD1 in a range of 10 mm to 150 mm.

[0047] Fig. 4 shows a cross-sectional view of the same elements as Fig. 3 , but in the Fig. 2 shown arrangement, in which the bowl 3' has already been formed into the formed bowl 3" by forming the bowl wall 31. The formed bowl 3" is in Fig. 7 It comprises an inner annular section 32 and an outer annular section 33.

[0048] The ejector 41 with the support surface 45 was moved back, thereby releasing a region of the forming die 1 with a first circumferential inner surface 11. The region of the forming die 1 with the first circumferential inner surface 11 has a first inner diameter ID1. The region of the forming die 1 with the second circumferential inner surface 12 has a second inner diameter ID2, wherein the first inner diameter ID1 is smaller than the second inner diameter ID2. The first inner diameter ID1 is in a range from 16 mm to 170 mm, and the second inner diameter ID2 is in a range from 22 mm to 190 mm. Due to the two different inner diameters ID1, ID2, a step with the step surface 15 is formed at the transition between the first and the second circumferential inner surface 11, 12. The first circumferential inner surface 11 together with the second circumferential inner surface 12 forms a step-shaped region 13 of the forming die 1.

[0049] The forming punch 2 is pressed against the cup 3' arranged in the forming die 1, whereby the stepless cup wall 31 is formed into the inner annular section 32 and the outer annular section 33 of the formed cup 3". The first circumferential inner surface 11 of the forming die 1 forms the circumferential outer surface 37 of the inner annular section 32 and the second circumferential inner surface 12 forms the circumferential outer surface 36 of the outer annular section 33. The circumferential inner surface 35 - which corresponds to a part of the circumferential inner surface 35' of the inner annular mold part 39 - was already formed in the previous step as part of the circumferential inner surface 35" of the cup 3'. Furthermore, the forming punch 2 comprises a second forming punch part 24 with an outer diameter AD2 in a range of 16 mm to 170 mm.A second circumferential outer surface 22 of the second forming punch part 24 forms the circumferential inner surface 34 of the outer annular section 33. The radial dimensions of the formed cup 3" are thus predetermined by the first and second outer diameters AD1, AD2 of the respective forming punch part and the first and second inner diameters ID1, ID2 of the respective regions of the forming die 1.

[0050] The cup extrusion of the blank 3 into the cup 3' and the forming of the cup wall 31 are carried out by hot forming at temperatures starting at 500°C. In an alternative embodiment, these forming processes can also be carried out by cold forming.

[0051] After the cup wall 31 has been formed, the forming punch 2 is moved away from the formed cup 3" and from the forming die 1 by means of the punch drive 6 by further rotating the punch drive crank 60. The formed cup 3" is then ejected from the forming die 1 by means of the ejector 41.

[0052] After ejection, in a further step not shown in the figures, the outer ring-shaped molded part 38 and the inner ring-shaped molded part 39 are produced from the formed cup 3", see Fig. 8For this purpose, the outer annular section 33 is separated from the inner annular section 32, and the inner annular section 32 is separated from the cup base 30 using a suitable separating tool, in particular a punching tool. The separated outer annular section 33 forms the outer annular molded part 38, and the separated inner annular section 32 forms the inner annular molded part 39. In addition, the outer annular molded part 38 and the inner annular molded part 39 are usually rolled or expanded after separation. The punched-out cup base 30 is disposed of as scrap.

[0053] The Figures 9 and 10 show schematic cross-sectional views of a first and a second forming stage of a second embodiment of the forming device according to the invention at the end of two working steps and the Figures 11 and 12 two corresponding schematic detail views. As in the first embodiment, the Figures 5 to 8a workpiece processed with the forming device in four different processing phases.

[0054] Fig. 9shows the first forming stage of the forming device at the end of the cup extrusion process of the blank 3 into a cup 3'. The first forming stage comprises a machine body 105 and a continuously variable forming die 101 attached thereto, in which the cup 3' formed from the blank 3 by cup extrusion is arranged. The forming die 101 is delimited on a side facing the machine body 105 by a support surface 145 of an ejector 141. Furthermore, the forming device comprises a forming punch 102 driven by a punch drive 106. The punch drive 106 comprises a punch drive crank 160 driven by a punch drive shaft 164, which is connected via an articulated connection 163 to a punch drive rod 162, which in turn is connected to the forming punch 102 via another articulated connection 161.For cup extrusion, the punch drive crank 160 is rotated by the punch drive shaft 164 in the direction of rotation indicated by the arrow, and the forming punch 102 is pressed against the blank 3 arranged in the forming die 101, and the blank 3 is formed into the cup 3' by pressing the forming punch 102. In the embodiment shown in . Fig. 9 In the arrangement shown, in which the bowl 3' has just been formed, the forming punch 102 is already deflected to its maximum and cannot be moved further in the direction of the bowl 3' or the forming die 101 even by further rotation of the punch drive crank 160.

[0055] Instead, the forming punch 102 is moved away from the cup 3' and the continuously variable forming die 101 by further rotating the punch drive crank 160 and the cup 3' can be ejected by means of the ejector 141.

[0056] To form the bowl wall 31, the bowl 3' is transferred to a second forming stage, which Fig. 10is shown.

[0057] The second forming stage is structurally identical to the first forming stage with the exception of the forming die. The stepless forming die 101 is replaced in the second forming stage by a forming die 110 comprising a stepped region. In this exemplary embodiment, the forming punch 102 is also structurally identical to the forming punch 102 of the first forming stage and is therefore provided with the same reference numeral. In alternative embodiments, two different forming punches could also be used.

[0058] To form the cup wall 31 of the cup 3' arranged in the forming die 110, the punch drive crank 160 is again rotated by the punch drive shaft 164 in the direction of rotation indicated by the arrow and the forming punch 102 is pressed against the cup 3' arranged in the forming die 101. The cup 3' is formed by forming the cup wall 31 into the formed cup 3". In the Fig. 10In the arrangement shown, in which the formed cup 3" has just been formed, the forming punch 102 is already deflected to its maximum and cannot be moved further in the direction of the formed cup 3" or the forming die 110 even by further rotation of the punch drive crank 160.

[0059] In this second embodiment, the ejector 141 can also be moved by an actuator 170, but only to eject the cup 3' or the formed cup 3" from the forming die 101 or from the forming die 110. In this embodiment, the ejector 141 does not have to be arranged so that it can be moved back any further. Such an ejection mechanism corresponds to the prior art and will not be described further here. In alternative embodiments, the forming dies 101, 110 can also be delimited by an immovable boundary wall instead of the support surface 145 of the ejector 141, and the cup 3' or the formed cup 3" can be removed from the respective forming die 101, 110 from the side facing the forming punch 102.

[0060] Fig. 11 shows a cross-sectional view of the ejector 141, the forming punch 102 and the continuously variable forming die 101 with the cup 3' arranged therein. The arrangement corresponds to that shown in Fig. 9illustrated arrangement of the first forming stage, in which the blank 3 was formed into the cup 3' by cup extrusion.

[0061] The shape of the cup 3' is essentially determined by the support surface 145 of the ejector 141, a support surface arranged in accordance with Fig. 11a bottom surface 115 of the forming die 101 arranged in the same plane as the support surface 145 and surrounding it in a ring shape, a continuously circumferential inner surface 114 of the forming die 101, an end face 123 of a first forming punch part 120 of the forming punch 102, and a first circumferential outer surface 121 of the first forming punch part 120. The cup bottom 30 is formed between a support surface 145 of the ejector 141 and the end face 123 of the first forming punch part 120. In an alternative embodiment, the support surface 145 can also be a surface of a non-movable boundary wall. The first circumferential outer surface 121 of the first forming die part 120 forms the circumferential inner surface 35" of the cup 3'. This in turn forms part of the circumferential inner surface 35' of the inner annular formed part 39.

[0062] Fig. 12shows a cross-sectional view of the ejector 141, the forming punch 102 and a forming die 110 comprising a step-shaped area 113 with the formed cup 3" arranged in the forming die 110. The arrangement corresponds to that in Fig. 10 illustrated arrangement of the second forming stage, in which the bowl 3' has already been formed into the formed bowl 3" by forming the bowl wall 31.

[0063] The forming die 110 comprises a region with a first circumferential inner surface 111 having a first inner diameter ID1' and a region with a second inner diameter ID2', wherein the first inner diameter ID1' is smaller than the second inner diameter ID2'. A step forms at the transition between the first circumferential inner surface 111 and the second circumferential inner surface 112, and the first circumferential inner surface 111 and the second circumferential inner surface 112 form a stepped region 113.

[0064] The forming punch 102 is pressed against the cup 3' arranged in the forming die 110, whereby the stepless cup wall 31 is formed into the inner annular section 32 and the outer annular section 33 of the formed cup 3". The first circumferential inner surface 111 of the forming die 110 forms the circumferential outer surface 37 of the inner annular section 32 and the second circumferential inner surface 112 forms the circumferential outer surface 36 of the outer annular section 33. The circumferential inner surface 35 - which corresponds to a part of the circumferential inner surface 35' of the inner annular mold part 39 - was already formed in the previous step as part of the circumferential inner surface 35" of the cup 3'. Furthermore, the forming punch 102 comprises a second forming punch part 124 with an outer diameter AD2' that is larger than the first outer diameter AD1'.A second circumferential outer surface 122 of the second forming die part 124 forms the circumferential inner surface 34 of the outer annular portion 33.

[0065] The outer diameters AD1', AD2' and the inner diameters ID1', ID2' correspond to the outer diameters AD1, AD2 and the inner diameters ID1, ID2 of the first embodiment.

[0066] The subsequent work steps for producing the outer annular molded part 38 and the inner annular molded part 39 correspond to those of the first embodiment and are therefore not repeated here.

Claims

1. Method for producing an inner (39) and an outer (38) ring-shaped formed part from a blank (3), comprising the steps: - cup extrusion of the blank (3) to form a cup (3') having a drawn-out cup base (30) and an adjoining stepless cup wall (31), - forming of the cup wall (31) in such a way that the formed cup wall comprises an inner ring-shaped section (32) and an adjoining outer ring-shaped section (33) which is partly offset in an axial direction, and - separation of the outer ring-shaped section (33) from the inner ring-shaped section (32) and separation of the inner ring-shaped section (32) from the drawn-out cup base (30), the detached outer ring-shaped section constituting the outer ring-shaped formed part (38) and the detached inner ring-shaped section constituting the inner ring-shaped formed part (39).

2. Method according to claim 1, characterised in that during the cup extrusion of the blank (3) the cup base (30) is shaped between an end face (23, 123) of a first forming punch portion (20, 120) and a support face (45, 145) of an ejector (41, 141).

3. Method according to claim 2, characterised in that during the cup extrusion of the blank (3) at least a part of a peripheral inner surface (35') of the inner ring-shaped formed part (39) is shaped by a peripheral outer surface (21, 121) of the first forming punch portion (20, 120).

4. Method according to any one of claims 1 to 3, characterised in that the cup extrusion of the blank (3) is effected in a first forming station with a stepless forming die (101) and the forming of the cup wall (31) is effected in a second forming station with a forming die (110) having a stepped region (113).

5. Method according to any one of claims 1 to 3, characterised in that the cup extrusion of the blank (3) and the forming of the cup wall (31) are carried out in succession in the same forming station with only one forming die (1).

6. Method according to claims 2 and 5, characterised in that the forming die (1) comprises a stepped region (13) for forming the cup wall (31), and a peripheral inner surface (11) of the stepped region (13) of the forming die (1) is exposed by retraction of the ejector (41) having the support face (45).

7. Method according to any one of claims 1 to 6, characterised in that the cup extrusion of the blank (3) and the forming of the cup wall (31) are effected by hot-forming at temperatures of 500°C and above.

8. Forming device for producing an inner (39) and an outer (38) ring-shaped formed part from a blank (3), the forming device comprising: - a first forming punch portion (20, 120) for cup extrusion of the blank (3) to form a cup (3') having a drawn-out cup base (30) and an adjoining stepless cup wall (31), - a second forming punch portion (24, 124) and a forming die (1, 110) having a stepped region (13, 113) for forming the cup wall (31) in such a way that it comprises an inner ring-shaped section (32) and an adjoining outer ring-shaped section (33) which is partly offset in an axial direction, and - a separating tool for separating the outer ring-shaped section (33) from the inner ring-shaped section (32) and for separating the inner ring-shaped section (32) from the drawn-out cup base (30), the detached outer ring-shaped section constituting the outer ring-shaped formed part (38) and the detached inner ring-shaped section constituting the inner ring-shaped formed part (39).

9. Forming device according to claim 8, characterised in that it comprises an ejector (41, 141) having a support face (45, 145), and the first forming punch portion (20, 120) comprises an end face (23, 123) for shaping the cup base (30) during the cup extrusion of the blank (3).

10. Forming device according to claim 8 or 9, characterised in that the first forming punch portion (20, 120) comprises a first peripheral outer surface (21, 121) for shaping at least a part of a peripheral inner surface (35') of the inner ring-shaped formed part (39).

11. Forming device according to claim 9 or 10, characterised in that the ejector (41) having the support face (45) is arranged to be retractable in order to expose a peripheral inner surface (11) of the stepped region (13) of the forming die (1) for forming the cup wall (31).

12. Forming device according to any one of claims 8 to 11, characterised in that the first forming punch portion (20), the second forming punch portion (24) and the forming die (1) having the stepped region (13) are part of a common forming station.

13. Forming device according to any one of claims 8 to 11, characterised in that the first forming punch portion (120) and a stepless forming die (101) are part of a first forming station, and the second forming punch portion (124) and the forming die (110) having the stepped region (113) are part of a second forming station.