Method for rotationally fixed joining of camshaft components onto a hollow camshaft

Abstract

The invention relates to a method for joining several camshaft components (3) to a hollow camshaft (2) in a rotationally fixed manner, comprising the following measures: a) Arranging of form matrices (4) on predetermined axial sections (5) of the camshaft (2), b) Inserting a pressurization device (6) into an interior space (7) bounded by the camshaft, c) Introducing a pressurized fluid (F) into the interior (7) by means of the pressurization device (6), so that the axial sections (5) of the camshaft (2) in the area of ​​the forming dies (4) are pressed radially outwards against the forming dies (4) and thereby expanded, d) Rotationally fixed joining of the camshaft components (3) onto the widened axial sections (5), in particular by pressing.

Description

[0001] The present invention relates to a method for rotationally fixed joining of at least one camshaft component to a hollow camshaft. The invention further relates to a device configured for carrying out this method.

[0002] DE 10 2014 106 924 A1 discloses a method for manufacturing a camshaft for controlling the valves of an internal combustion engine, comprising a carrier shaft on which a single component is arranged and several cam elements that are fixedly mounted on the carrier shaft. To ensure the fixed mounting of these individual components on the carrier tube, the tube is provided with a profile forming the mounting positions for these individual components by grinding, and each mounting position is provided with a surface profile before the respective individual components are pressed onto it. Grinding the tube to create a pre-profiling represents an additional manufacturing step that incurs additional costs.

[0003] EP 0 213 529 A1 describes a method by which a large number of camshaft components are attached to a hollow shaft in one operation by hydraulically expanding the tube beyond its plasticity limit.

[0004] The object of the present invention is to demonstrate new methods for the rotationally fixed joining of a camshaft component to a camshaft. In particular, a particularly simple and therefore cost-effective method is to be created.

[0005] This problem is solved by the subject matter of the independent patent claims. Preferred embodiments are the subject matter of the dependent patent claims.

[0006] The basic idea of ​​the invention is therefore to expand the camshaft radially outwards in the axial section in which the camshaft component is to be joined to the outer circumference of a camshaft, using a pressurized fluid introduced into the camshaft and a die arranged radially outside the camshaft, in order to join a camshaft component to the outer circumference of a camshaft.

[0007] This results in the outer diameter of the partially formed camshaft being larger in the area of ​​the joining surface than in the unformed area of ​​the camshaft. This prevents a situation where, when joining a camshaft component with a diameter of the opening forming the joining surface that is slightly smaller than the diameter of the expansion area forming the joining surface on the shaft, this opening in the camshaft component comes into contact with the unexpanded tube. Thus, tolerance-related difficulties during the axial sliding of the camshaft component onto the camshaft, caused by an excessively large diameter of the camshaft tube during the joining process, are avoided.

[0008] The essential feature of the method presented here is that the radial expansion of the camshaft occurs prior to the actual rotationally fixed joining of the camshaft component to the camshaft. This advantageously prevents, after the removal of the pressurized fluid, not only the camshaft but also the camshaft component mounted on it from experiencing an elastic radial springback, which would result in a disadvantageously reduced overlap between the two joining partners, i.e., between the camshaft and the camshaft component.

[0009] Instead, the solution presented here allows the elastic springback of the expanded camshaft to be taken into account when determining the diameter of the opening in the camshaft, thereby achieving a greater overlap between the two joining partners. This results in a better torsional-resistant connection when the camshaft component is subsequently joined to the camshaft in the area of ​​its expanded axial section, typically by pressing or thermal joining.

[0010] The method according to the invention serves for the rotationally fixed joining of several, i.e., at least two, preferably at least three, camshaft components onto a hollow camshaft. For this purpose, the method comprises at least four measures a) to d).

[0011] At least one camshaft component can be a cam, which in turn can comprise a cam body with a through-hole. However, at least one camshaft component with a cam body and through-hole can also be a flange, a bearing sleeve, a pulse generator wheel, a sprocket, or a gear.

[0012] In measure a) of the method according to the invention, forming dies are arranged radially on the outside of predetermined axial sections of the camshaft. In measure b), a pressurization device is introduced into an interior space bounded by the camshaft.

[0013] In step c), a pressurized fluid is introduced into the interior by means of the pressurization device. This presses the axial sections of the camshaft against the forming dies and expands them radially. After removing the forming dies from the camshaft, in particular by adjusting them radially outwards, in step d) the camshaft components are each fitted onto the corresponding and expanded axial sections and preferably pressed or thermally joined.

[0014] In a preferred embodiment of the method according to the invention, at least two, preferably several, and particularly preferably all, axial sections are widened simultaneously. This reduces the time required to carry out the method.

[0015] Particularly preferably, at least two, and preferably all, camshaft components can be joined or pressed on simultaneously. Specifically, camshaft components are also joined simultaneously to all simultaneously expanded axial sections, so that after joining, a camshaft component is arranged on each axial section and rotationally fixed to it. This results in a further reduction in machining time.

[0016] Preferably, in measure c) at least two (first) axial sections can be widened simultaneously and then, in measure d), a camshaft component can be added to each of these (first) axial sections, wherein the addition of all camshaft components to the first axial sections takes place simultaneously.

[0017] Particularly advantageous in this variant is the ability to repeat measures c) and d) for at least two second axial sections. This variant achieves a reduced machining time compared to successively joining all camshaft components. Since not all camshaft components are joined simultaneously, a forming die is not required for each individual camshaft component. This allows the design of the device to be kept comparatively simple.

[0018] In another preferred embodiment, in measure c), an axial section is widened for each camshaft component to be joined. This widening is performed simultaneously for all these axial sections. Particularly preferably, in the embodiment described above, in measure d), a camshaft component can be joined to each of the widened axial sections. In this variant, the joining of all camshaft components to the axial sections is performed simultaneously. This variant allows for maximum time savings in the process.

[0019] Alternatively, in the preferred embodiment described above, the expanded axial sections can be divided into first and second axial sections. In this variant, in measure d), first camshaft components are simultaneously joined to the first axial sections. Only afterwards, i.e., not simultaneously with the joining of the first camshaft component, are second camshaft components simultaneously joined to the second axial sections. This approach allows for both a structurally simpler pressurization device and a simpler assembly device for the camshaft components to be joined or pressed on.

[0020] The invention further relates to a device for carrying out the above-presented method according to the invention, so that the advantages of the method according to the invention explained above are transferred to the device according to the invention.

[0021] The device according to the invention comprises a storage device for receiving the camshaft component to be added next, in which a through-opening is formed for guiding the camshaft along an axial direction.

[0022] Furthermore, the device includes an axially adjustable holding device for holding and moving the camshaft relative to the storage device and preferably along the axial direction.

[0023] Furthermore, the device comprises at least two, preferably several, forming dies for arrangement radially outward on the axial section of the camshaft that is to be widened. The forming dies are preferably radially adjustable.

[0024] Finally, the device includes a pressurization unit that can be inserted along the axial direction into an interior space bounded by the camshaft. The pressurization unit allows the pressurized fluid required to expand the axial section to be introduced into this interior space.

[0025] According to an advantageous embodiment of the device according to the invention, the storage device can have a flat storage surface on which the camshaft component is arranged, or at least can be arranged, in a joining position. This allows the camshaft component to be stably supported in the storage device.

[0026] In a preferred embodiment of the device according to the invention, the holding device can be designed with a receiving element similar to a chuck and have a centering device axially opposite the receiving element for radially centering the camshaft, between which the camshaft can be axially clamped. This allows the camshaft to be held stably and adjusted for joining the respective camshaft components.

[0027] In another preferred embodiment, the pressurization device can have a lance that can be inserted axially into the interior and extends axially, with a fluid outlet for introducing the fluid into the interior. Advantageously, the fluid outlet can be arranged radially so that the fluid exiting the outlet directly impinges radially on the axial section of the camshaft to be expanded.

[0028] In another preferred embodiment, the pressurization device comprises a pressure head with a fluid outlet arranged radially outward on the outside. Through this fluid outlet, the fluid can exit the pressurization device into the interior of the camshaft in such a way that it exerts a radially outward adjusting force on the camshaft, causing it to expand the axial section. This presses the axial section radially outward into the die and expands it radially outward as desired.

[0029] According to another advantageous embodiment, the storage device or a container surrounding a container interior can comprise at least one camshaft component to be attached to the camshaft. In this container, the camshaft components to be attached can be "stored" before being attached and can also be successively removed from the container interior for successive attachment to the camshaft.

[0030] For this purpose, the container can particularly preferably have a container opening that can be closed by means of a container closure of the container, through which a camshaft component arranged in the interior of the container can be transported from the interior of the container to the joining position.

[0031] The storage area can be particularly advantageous as part of the container closure.

[0032] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0033] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0034] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0035] They show, schematically: Fig. 1 an example of a device according to the invention when carrying out the method according to the invention, Fig. 2 a flowchart illustrating the method according to the invention, Fig. 3a-d Illustrations which depict the device of Fig. 1 show snapshots taken during the execution of the method according to the invention.

[0036] The Fig. Figure 1 shows a schematic representation of an example of a device 1 according to the invention for rotationally fixed joining of a camshaft component 3 to a hollow camshaft 2 extending along an axial direction A. In this example, the camshaft component 3 is a cam 21 with a cam body 22 in which an opening 23 is formed. However, the camshaft component 21 with cam body 22 and opening 23 can also be a flange, a bearing sleeve, a pulse generator wheel, a sprocket, or a gear (not shown).

[0037] In the Fig. 1 further camshaft components 3* are already rotationally fixed to the camshaft 2, which in the example are also designed as cams 21*.

[0038] In the example shown in the figures, the axial direction A extends along a central longitudinal axis M of the hollow cylindrical camshaft 2. A radial direction R extends perpendicular to the axial direction A away from the central longitudinal axis M.

[0039] A circumferential direction U runs perpendicular to both the axial direction A and the radial direction R around the central longitudinal axis M.

[0040] The device 1 further comprises a storage device 10 for receiving the camshaft component 3 to be joined, in which a through-opening 8 is formed for guiding the camshaft 2 along the axial direction A. The storage device 10 can, as shown, have a flat storage surface 11 on which the camshaft component 3 to be joined can be arranged in a joining position FP.

[0041] Furthermore, the device 1 comprises an axially adjustable holding device 9 for holding and moving the camshaft 2 along the axial direction A and relative to the storage device 10. The holding device 9 can, as shown, have a receiving element 18 in the form of a chuck and a centering device 19 axially opposite the receiving element 18 for radially centering the camshaft 2, between which the camshaft 2 can be axially clamped.

[0042] Furthermore, the device 1 comprises several forming matrices 4 for their respective arrangement on a radially widened axial section 5 of the camshaft 2. In the example of the Fig. Figure 1 shows only one such forming matrix 4, which can be composed of two half-shells 4a, 4b. The forming matrices 4 are radially adjustable.

[0043] Finally, the device 1 comprises a pressurizing device 6 that can be inserted along the axial direction A into an interior space 7 bounded by the camshaft 2. By means of the pressurizing device 6, the pressurized fluid F, preferably a hydraulic oil, required for expanding the axial section 5, can be introduced axially into the interior space 7 in the region of the axial section.

[0044] For this purpose, the pressurization device 6 can, as shown, have a lance 16 that can be inserted axially into the interior 7 and extends along the axial direction A and through which the fluid F can flow.

[0045] The pressurization device 6 can also include a pressure head 20 that communicates fluidically with the lance 16 and extends axially to the lance 16, and on which fluid outlets 17 are arranged radially outside. The fluid F can exit the pressurization device 6 into the interior 7 via the fluid outlets 17 in such a way that a radially outward adjusting force is exerted on the camshaft 2 to expand the axial section 5 in the region of the axial section 5. This causes the axial section 5 to expand as described in Fig. 1. The area is indicated as being widened radially outwards.

[0046] The device 1 according to the invention, as explained above, serves to carry out the method according to the invention presented above and thus for the rotationally fixed joining of at least one camshaft component 3 onto a hollow camshaft 2.

[0047] The inventive method is described below using the Fig. 1 and 3a - 3d are explained by way of example. The procedure comprises, according to the section in Fig. The flowchart shown in section 2 shows four measures a) to d).

[0048] The method according to the invention serves for the rotationally fixed joining of several camshaft components 3 onto a hollow camshaft 2. For this purpose, the method comprises four measures a) to d).

[0049] In a first step a), the forming dies 4 are arranged on predetermined axial sections 5 on the outer circumference 24 of the camshaft 2. In a second step b), the pressurization device 6 is placed in an interior space 7 bounded by the camshaft 2. In a third step c), a pressurized fluid F is introduced into the interior space 7 by means of the pressurization device 6, so that the axial sections 5 of the camshaft 2 are each pressed against a forming die 4 and thereby radially expanded.

[0050] In a fourth measure d), the camshaft components 3 are each joined to the associated and widened axial sections 5 in a rotationally fixed manner and are pressed on or thermally joined for this purpose.

[0051] The following will be based on the Fig. Sections 3a to 3d illustrate various preferred variants of the method according to the invention by way of example.

[0052] The Fig. Figures 3a to 3d show a further development of the device 1 in the form of snapshots taken at different times during the execution of the method according to the invention. In this variant, several axial sections 5 are simultaneously expanded using the forming dies, and several camshaft components 3 are simultaneously joined or pressed onto the camshaft 2 in a rotationally fixed manner.

[0053] Specifically, in the example of the Fig. 3a Three first axial sections 5, 5a are simultaneously widened by arranging three forming matrices 4 in these three first axial sections 5 on the outer circumference 24 of the camshaft 2, as described in measure a). Likewise, as described in measure b), the pressure application device 6 with three printheads 20 is introduced into the interior 7, such that one printhead 20 is arranged in each of the first axial sections 5a.

[0054] Then, as in Fig. 3b shows the three form matrices 4 moved radially outwards away from the camshaft (see arrows X).

[0055] As also in Fig. As shown in Figure 3b, the camshaft 2 is then adjusted along the axial direction A (see arrow Y). This causes the expanded axial sections 5 to be inserted into the openings 23 of the camshaft component 3. In this way, as measure d) of the procedure, a camshaft component 3 is fitted onto each of the first axial sections 5a, 5a. Thus, the fitting of all camshaft components 3 onto the first axial sections 5a, 5a occurs simultaneously.

[0056] In this variant, measures c) and d) are repeated for three further axial sections 5 - hereinafter referred to as second axial sections 5b - and three further camshaft components 3.

[0057] This scenario is in the Fig. 3c and Fig. Shown in 3D. According to Fig. 3c the second axial sections 5b are expanded radially outwards by means of the forming matrices 4 arranged in the area of ​​the second axial sections 5b on the outer circumference 24 of the camshaft 2 and the pressure application device 6 with the three print heads 20 arranged in the area of ​​the second axial sections 5b according to measure c).

[0058] Then, as in Fig. 3D shows the form matrices 4 moved radially outwards away from the camshaft 2 (see arrows X in Fig. 3d).

[0059] As also in the Fig.As shown in Figure 3d, the camshaft 2 is then axially adjusted. This causes the expanded second axial sections 5b, 5 to be axially inserted into the openings 23 in the camshaft component 3. In this way, as measure d), a camshaft component 3 is also added to each of the second axial sections 5b, 5. Thus, the joining of the three camshaft components 3 to the second axial sections 5, 5b also occurs simultaneously, but with a time offset from the first axial sections 5, 5a.

[0060] In another variation of the example described above, it is conceivable to carry out the widening of the axial sections 5 according to measure c) simultaneously for all axial sections 5 to be widened. In this variation of the example described above, the first and second axial sections 5a, 5b would therefore be widened simultaneously. Likewise, in this variation, in accordance with measure d), all camshaft components 3 to be added can then be pressed onto the widened axial sections 5a, 5b simultaneously and thus joined to the camshaft 2 in a rotationally fixed manner.

[0061] In another variation of the examples described above, in measure c), all first axial sections 5a, 5 are widened simultaneously, and then, also in measure c), all second axial sections 5b, 5 are widened simultaneously. Thus, the widening of the second axial sections 5b is staggered in time compared to the first axial sections 5a. In measure d), in this variation, a camshaft component 5 is then added simultaneously to each of the axial sections 5, i.e., to both the first axial sections 5a and the second axial sections 5b. Reference symbol list 1 Device 2 camshafts 3 Camshaft component 4 Forming die 5, 5a, 5b (first / second) axial section 6. Pressurization device 7 Interior 8 Through opening 9 Holding device 10 Storage unit 11 storage space 16 lance 17 Fluid outlet 18 Recording element 19 Centering device 20 printhead 21 cams 22 cam bodies 23 Breakthrough 24 External circumference F Fluid FP joining position M Central longitudinal axis A axial direction U circumferential direction R radial direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 106 924 A1

[0002] EP 0 213 529 A1

[0003]

Claims

[1] Method for joining several camshaft components (3) to a hollow camshaft (2) in a rotationally fixed manner, comprising the following measures: a) Arranging of form matrices (4) on predetermined axial sections (5) of the camshaft (2), b) Inserting a pressurization device (6) into an interior space (7) bounded by the camshaft, preferably axially in the area of ​​the axial sections (5), c) Introducing a pressurized fluid (F) into the interior (7) by means of the pressurization device (6), so that the axial sections (5) in the area of ​​the molding dies (4) are pressed radially outwards against the molding dies (4) and thereby radially expanded, d) Rotationally fixed joining of the camshaft components (3) to the widened axial sections (5), in particular by pressing or by thermal joining. [2] Method according to claim 1, characterized by, that at least two, preferably all, axial sections (5, 5a, 5b) are widened simultaneously. [3] Method according to claim 1 or 2, characterized by , that at least two, preferably all, camshaft components (3) are simultaneously joined or pressed onto the camshaft (2). [4] Method according to one of claims 1 or 2, characterized by , that in measure c) at least two (first) axial sections (5, 5a) are widened simultaneously and then in measure d) a camshaft component (3) is added to each of these (first) axial sections (5a, 5), wherein the addition of all camshaft components (3) to the first axial sections (5, 5a) is carried out simultaneously. [5] Method according to claim 4, characterized by , that measures c) and d) are repeated for at least two second axial sections (5, 5b). [6] Method according to one of claims 1, 2 and 4, characterized by, that in measure c) for each of the camshaft components (3) to be added an axial section (5) is widened, the widening being carried out simultaneously for all these axial sections (3). [7] Method according to one of claims 1, 2 and 4 or 6, characterized by , that in measure d) a camshaft component (3) is added to each of the widened axial sections (5), the addition of all camshaft components (3) to the axial sections (5) is carried out simultaneously. [8] Method according to any one of claims 1, 2 and 4 to 5, characterized by , that the axial sections (5) are subdivided into first (5a) and second axial sections (5b), - in measure d) first camshaft components (3) are simultaneously added to the first axial sections (5a) and then second camshaft components (3) are simultaneously added to the second axial sections (5b). [9] Apparatus (1) for carrying out the method according to any of the preceding claims, - with a storage device (10) having a through-opening (8) for receiving the camshaft component (4) to be added, - with an axially adjustable holding device (9) for holding and moving the camshaft (2) relative to the storage device (10), - with form matrices (4) for arranging on the axial sections (5) of the camshaft (2) to be widened, - with a pressurizing device (6) that can be inserted axially into an interior space (7) bounded by the camshaft (2) for introducing a pressurized fluid (F) into the interior space (7). [10] Device according to claim 9, characterized by , that the holding device (9) has a receiving element (18), in particular a chuck, and a centering device (19) axially opposite the receiving element (18) for radially centering the camshaft (2), between which the camshaft (2) can be axially clamped. [11] Device according to claim 9 or 10, characterized by , that the pressurization device (6) has a lance (16) that can be inserted axially into the interior (7) and extends axially, with a fluid outlet (17) for introducing the fluid (F) into the interior (7), in particular axially in the area of ​​the axial sections (5). [12] Device according to any one of claims 9 to 11, characterized by , that the pressurization device (6) comprises a pressure head (20) on which the fluid outlet (17) is arranged radially outside, through which the fluid (F) can exit the pressurization device (6) in such a way that it exerts a radially outward adjusting force on the camshaft (2) in the interior (7), preferably axially in the area of ​​the axial section (5), to widen the axial sections (5).

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