Device and method for the continuous production of a shaft that is at least partially hollow and has a varying inner and / or outer diameter

Abstract

Device (1) for the continuous production of a shaft that is at least partially hollow and has varying inner and / or outer diameters (i1, i2, a1, a2) comprising - at least two forging tools (3) arranged symmetrically around a forging axis (2) and driven in the sense of radial working strokes, - a clamping head (4) for holding a cylindrical blank (5) that is at least partially hollow, and - a counterholder (6) for axially supporting the blank (5), wherein the counterholder (6) has a base (7) and a counterholder mandrel (9) attached to the base (7) and extending axially into a central cavity (8) of the blank (5), wherein the counterholder mandrel (9) is formed in at least two parts, wherein a first part of the counterholder mandrel (9) is an inner part (10) and a second part of the counterholder mandrel (9) is an outer part (11) surrounding the inner part (10), characterized in that at least the outer part (11) is designed to be axially movable relative to the inner part (10).

Description

Field of the invention

[0001] The present invention relates to a device for the continuous production of an at least partially hollow shaft with a varying inner and / or outer diameter, comprising at least two forging tools arranged centrally symmetrically around a forging axis and drivable in the sense of radial working strokes, a clamping head for holding an at least partially hollow cylindrical blank, and a counterholder for axially supporting the blank, wherein the counterholder has a base and a counterholder mandrel attached to the base and extending axially into a central cavity of the blank, wherein the counterholder mandrel is formed in at least two parts, wherein a first part of the counterholder mandrel represents an inner part and a second part of the counterholder mandrel represents an outer part surrounding the inner part,wherein at least the outer part is designed to be axially movable relative to the inner part, and a method for the continuous production of an at least partially hollow shaft with varying inner and / or outer diameter using such a device. State of the art

[0002] In the field of mechanical engineering, particularly automotive engineering, shafts and axles are central elements. To reduce weight and conserve resources, shafts and axles are increasingly being manufactured from hollow material, such as tubular blanks as a cost-effective starting material. Radial forging processes, for example, are used to form the blanks. For multiple forming operations, i.e., forming a blank with different inner and / or outer diameters, a blank must generally be re-clamped in separate component fixtures, which leads to increased handling effort, longer cycle times, and, consequently, higher costs.

[0003] Document EP 2 964 407 B1 discloses a continuous process for producing a barrel with a one-piece housing. A two-part hammering mandrel assembly is used, comprising a barrel hammering mandrel and a housing hammering mandrel. The barrel hammering mandrel is held at its rear end by a retaining rod. The housing hammering mandrel is penetrated by the retaining rod of the barrel hammering mandrel, i.e., it is slidably guided in a central bore of the housing hammering mandrel.

[0004] Document DE 195 23 280 C2 discloses a forging machine for internal profiling of tubular workpieces, in particular for forming pipe sections with different inner diameters. The forging machine comprises a forging box for holding the forging tools, a clamping head, a counterholder for clamping the workpiece, and a mandrel that can be inserted into the workpiece. Summary of the invention

[0005] It is an object of the invention to provide a structurally simple device that enables the continuous production of a shaft with a varying inner and / or outer diameter in a simple manner. Furthermore, it is an object of the invention to provide an improved method for the continuous production of a shaft with a varying inner and / or outer diameter using a device according to the invention.

[0006] This need can be met by the subject matter of the present invention according to independent claims 1 and 4. Advantageous embodiments of the present invention are described in the dependent claims.

[0007] The device according to the invention serves for the continuous production of an at least partially hollow shaft with varying inner and / or outer diameter.

[0008] According to the invention, the device comprises at least two forging tools arranged centrally symmetrically around a forging axis and drivable in the sense of radial working strokes, a clamping head for holding an at least partially hollow cylindrical blank, and a counterholder for axially supporting the blank, wherein the counterholder has a base and a counterholder mandrel attached to the base and extending axially into a central cavity of the blank.

[0009] According to the present invention, the counterholder mandrel is formed in at least two parts, wherein a first part of the counterholder mandrel represents an inner part and a second part of the counterholder mandrel represents an outer part surrounding the inner part, wherein at least the outer part is designed to be axially movable relative to the inner part.

[0010] The inner part therefore has a smaller outer diameter than the outer part. The outer part therefore has a larger outer diameter than the inner part.

[0011] In this context, the term "axial" refers to a direction along or parallel to the forging axis. The term "radial" refers to a direction perpendicular to the forging axis.

[0012] The counterholder and / or the clamping head and / or the forging tools can be axially movable along a guide bed.

[0013] The counterholder mandrel of the counterholder preferably has a greater axial extension than the central cavity of the blank. This means that the counterholder mandrel is longer than the central cavity.

[0014] The method according to the invention for producing an at least partially hollow shaft with different inner and / or outer diameters is carried out using the device according to the invention and comprises at least the following steps: - Providing a cylindrical blank with a through-hole at least partially penetrating this blank, which forms a central cavity of the blank, - Clamping the blank in a clamping head so that an opening of the central cavity is located on a front side of the blank facing away from the clamping head, - Axial advance of a counterholder or axial movement of the clamping head so that a counterholder mandrel, namely an inner part and an outer part of the counterholder mandrel, axially penetrates the central cavity of the blank completely up to a defined stop, whereby the blank is pre-tensioned via the outer part, - Radial feeding of the forging tools to a first section of the blank, - forging a first shaft section having a first inner diameter in the region of the first section of the blank, wherein the first inner diameter is defined by an outer diameter of the outer part, - Radial opening of the forging tools, - Axial movement of the outer part towards the base of the counterholder out of the central cavity of the blank, whereby the blank is pre-tensioned at the front side via the outer part, - Axial movement of the clamping head with the clamped blank so that the inner part lies in the area of ​​a second section of the blank and only partially breaks through the cavity, - Radial feeding of the forging tools to the second section of the blank, - forging a second shaft section having a second inner diameter in the region of the second section of the blank, wherein the second inner diameter is defined by an outer diameter of the inner part, - Radial opening of the forging tools - Axial movement of the inner part towards the base of the counterholder out of the central cavity of the blank, whereby the blank is released at the front via the outer part, - Axial pulling of the blank, now the finished shaft, from the clamping head.

[0015] The improved design of the device according to the invention makes it possible to realize a radial forging process which is characterized in particular by low handling effort, shorter cycle times and, consequently, also lower costs. Brief description of the drawings

[0016] The invention is described below by way of example with reference to the drawings. Fig. 1 shows a schematic representation of an exemplary blank before a forging process. Fig. 2 shows a schematic representation of an exemplary blank according to Fig. 1 after a first forging process with a first inner diameter and a first outer diameter. Fig. 3 shows a schematic representation of a finished shaft, i.e. an exemplary blank according to Fig. 1 after a first and a second forging process Fig. 4 shows a schematic sectional view of a device in an initial position. Fig. 5 shows a schematic sectional view of a device during a first forging process. Fig. 6 shows a schematic sectional view of a device between the first forging process and the second forging process. Fig. 7 shows a schematic sectional view of a device during a second forging process. Fig. Figure 8 shows a schematic sectional view of a device after the two forging processes. Fig. 9 shows a perspective view of a blank and the forging tools. Fig. 10 shows a frontal view of Fig. 9 in the direction of the direction arrow 12. Detailed description of the invention

[0017] Fig. 1 to Fig. 3 each show schematic representations of a blank 5 in different forging stages. Fig. 1 a blank 5 before the forging processes, Fig. 2 shows a blank 5 after a first forging process and Fig. 3 shows a blank 5, now a finished shaft, after a first and a second forging process. In Fig. 4 to Fig. 8 shows a device 1 in the corresponding forging stages.

[0018] The blank 5 according to Fig. 1 represents the starting material for producing a shaft with a varying inner diameter i1, i2 (and a varying outer diameter a1, a2) and is cylindrical, partially hollow, with a central cavity 8. In the present embodiment, the blank 5 is a one-sidedly closed extrusion blank. The blank 5 is thus closed on a first end face and open on a second end face opposite this first end face, wherein the opening on the second end face is part of the central cavity 8 of the blank 5.

[0019] The device 1 comprises four forging tools 3, namely forging hammers, arranged centrally and symmetrically around a forging axis 2 and drivable in the sense of radial working strokes. These forging hammers and their arrangement relative to the blank 5 are particularly Fig. 9 and Fig. 10 shown.

[0020] Furthermore, the device 1 comprises a clamping head 4 for holding the blank 5, wherein the blank 5 is held on its closed end face on the clamping head 4.

[0021] The device 1 also includes a counterholder 6 for axially supporting the blank 5, wherein the counterholder 6 has a base 7 and a counterholder mandrel 9 attached to the base 7. The counterholder mandrel 9 is designed such that it can extend partially axially into the central cavity 8 of the blank 5.

[0022] The counterholder mandrel 9 is formed in two parts, wherein a first part of the counterholder mandrel 9 represents an inner part 10 and a second part of the counterholder mandrel 9 represents an outer part 11 surrounding the inner part 10.

[0023] The outer part 11 is designed to be axially movable relative to the inner part 10.

[0024] The inner part 10 thus has a smaller outer diameter than the outer part 11. The outer part 11 thus has a larger outer diameter than the inner part 10.

[0025] In this context, the direction "axial" refers to a direction along or parallel to the forging axis 2. In this context, the direction "radial" refers to a direction normal to the forging axis 2.

[0026] The counterholder 6 and / or the clamping head 4 are axially movable along a guide bed. The forging tools 3, i.e., the forging hammers, are radially movable.

[0027] The counterholder mandrel 9 of the counterholder 6 has a greater axial extension than the central cavity 8 of the blank 5.

[0028] The method according to the invention for producing an at least partially hollow shaft with different inner diameters i1, i2 and different outer diameters a1, a2 is carried out using the device 1 described above and comprises at least the following steps: - Providing a cylindrical blank 5 with a through-hole at least partially penetrating this blank 5, which forms a central cavity 8 of the blank 5 (one-sided closed extrusion blank: Fig. 1), - Clamping the blank 5 in a clamping head 4, so that an opening of the central cavity 8 is located on a front side of the blank 5 facing away from the clamping head 4 ( Fig. 4), - Axial feeding of a counterholder 6, so that a counterholder mandrel 9, namely an inner part 10 and an outer part 11 of the counterholder mandrel 9, axially completely break through the central cavity 8 of the blank 5 up to a defined stop, wherein the blank 5 is prestressed via the outer part 11 ( Fig. 4), - Radial feeding of the forging tools 3 to a first section of the blank 5 ( Fig. 4, Fig. 5), - Forging a first shaft section with a first inner diameter i1 in the region of the first section of the blank 5, wherein the first inner diameter i1 is defined by an outer diameter of the outer part 11 ( Fig. 5), - Radial opening of the forging tools 3 ( Fig. 6), - Axial movement of the outer part 11 in the direction of the base 7 of the counterholder 6 out of the central cavity 8 of the blank 5, whereby the blank 5 is prestressed on the front side via the outer part 11 ( Fig. 6), - Axial movement of the clamping head 4 with the clamped blank 5, so that the inner part 10 lies in the area of ​​a second section of the blank 5 and only partially breaks through the cavity 8 ( Fig. 7), - Radial feeding of the forging tools 3 to the second section of the blank 5 ( Fig. 7), - forging a second shaft section with a second inner diameter i2 in the region of the second section of the blank 5, wherein the second inner diameter i2 is defined by an outer diameter of the inner part 10 ( Fig. 7), - Radial opening of the forging tools 3 ( Fig. 8), - Axial movement of the inner part 10 in the direction of the base 7 of the counterholder 6 out of the central cavity 8 of the blank 5, whereby the blank 5 is released at the front via the outer part 11 ( Fig. 8), - Axial removal of the blank 5, now the finished shaft, from the clamping head 4 ( Fig. 3). List of reference symbols 1 device 2 forged axles 3 blacksmith tools 4 clamping head 5 blank 6 counterholders 7 Base 8 Central cavity 9 Counterholder mandrel 10 First part (inner part) 11 Second part (outer part) 12 Direction arrow i1 First inner diameter i2 Second inner diameter a1 First outer diameter a2 Second outer diameter

Claims

[1] Device (1) for the continuous production of an at least partially hollow shaft with varying inner and / or outer diameter (i1, i2, a1, a2) comprising - at least two forging tools (3) arranged centrally and symmetrically around a forging axis (2) and drivable in the sense of radial working strokes, - a clamping head (4) for holding an at least partially hollow cylindrical blank (5), and - a counterholder (6) for axially supporting the blank (5), wherein the counterholder (6) has a base (7) and a counterholder mandrel (9) attached to the base (7) and extending axially into a central cavity (8) of the blank (5), wherein the counterholder mandrel (9) is formed in at least two parts, wherein a first part of the counterholder mandrel (9) represents an inner part (10) and a second part of the counterholder mandrel (9) represents an outer part (11) surrounding the inner part (10), characterized bythat at least the outer part (11) is designed to be axially movable relative to the inner part (10). [2] Device (1) according to claim 1, characterized by that the counterholder (6) and / or clamping head (4) and / or the forging tools (3) are axially movable along a guide bed. [3] Device (1) according to claim 1 or 2, characterized by that the counter-holder mandrel (9) has a greater axial extension than the central cavity (8) of the blank (5). [4] Method for the continuous production of an at least partially hollow shaft with varying inner and / or outer diameter (i1, i2, a1, a2) using a device (1) according to one of claims 1 to 3, comprising at least the following steps: - Providing a cylindrical blank (5) with a through-bore which at least partially penetrates this blank (5) and forms a central cavity (8) of the blank (5), - clamping the blank (5) in a clamping head (4) so ​​that an opening of the central cavity (8) is located on a front side of the blank (5) facing away from the clamping head (4), - axially advancing a counterholder (6) or axially moving the clamping head (4) so ​​that a counterholder mandrel (9), namely an inner part (10) and an outer part (11) of the counterholder mandrel (9), axially completely break through the central cavity (8) of the blank (5) up to a defined stop, wherein the blank (5) is pre-tensioned via the outer part (11), - Radial feeding of the forging tools (3) to a first section of the blank (5), - forging a first shaft section having a first inner diameter (i1) in the region of the first section of the blank (5), wherein the first inner diameter (i1) is defined by an outer diameter of the outer part (11), - Radial opening of the forging tools (3), - axial movement of the outer part (11) in the direction of the base (7) of the counterholder (6) out of the central cavity (8) of the blank (5), wherein the blank (5) is prestressed at the end face via the outer part (11), - axial movement of the clamping head (4) with the clamped blank (5) so that the inner part (10) lies in the area of ​​a second section of the blank (5) and only partially breaks through the cavity (8), - Radial feeding of the forging tools (3) to the second section of the blank (5), - forging a second shaft section having a second inner diameter (i2) in the region of the second section of the blank (5), wherein the second inner diameter (i2) is defined by an outer diameter of the inner part (10), - Radial opening of the forging tools (3), - axial movement of the inner part (10) in the direction of the base (7) of the counterholder (6) out of the central cavity (8) of the blank (5), whereby the blank (5) is released at the front via the outer part (11), - Axial pulling of the blank (5), now the finished shaft, from the clamping head (4).

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