JP2009544887A - Method and apparatus for forming a shaft-hub connection - Google Patents

Abstract

The invention relates in particular to a method for forming a shaft-hub connection (50) of a camshaft (100) or transmission shaft of an internal combustion engine, wherein the accessories (26, 28) are connected to a support shaft tube (34). Each of the arcuate wedge profiles (42) is introduced into the attachments (26, 28) before being attached, and the portion (44) of the support shaft tube (34) to which the attachments (16, 28) are attached. ) Form an arcuate wedge-shaped profile (46) that continuously increases the outer radius of the support shaft tube (34) at the circumference of the portion (44), and the accessory parts (26, 28) It relates to a method in which the tube (34) and the accessory parts (26, 28) are connected by rotating with respect to each other. Within the tool (10), the support shaft tube (34) is locally expanded at the portion (44) to which the attachments (26, 28) are attached, and within the same tool (10), the support shaft tube (34). And the at least two attachment parts (26, 28) are rotated relative to each other until a shape fit between the support shaft tube (34) and the at least two attachment parts (26, 28) occurs. (34) is joined to at least two attachments (26, 28).
[Selection] Figure 2

Description

  The invention relates to a method for forming a shaft-hub connection and an apparatus for carrying out the method, particularly in the case of a camshaft or transmission shaft of an internal combustion engine, as described in the preamble of the independent claim.

  In an internal combustion engine, the camshaft has a function of opening and closing a valve for the gas exchange process as smoothly as possible. Efforts to achieve a light weight configuration to reduce vehicle weight are hampered in so-called assembly camshafts with hollow carrier shafts. What is represented here as a prefabricated camshaft is a camshaft comprising a plurality of assembled parts, i.e. a carrier shaft and accessory parts in the form of cam disks and drive wheels.

  Assembling camshafts have the advantage that functional partitioning can save material costs as a whole. The carrier shaft tube transmits rotational motion to the cam disk located in the carrier shaft tube and essentially performs a bearing function, and the valve drive for engine control from the heavily loaded cam disk. A linear movement of the device is provided. Thus, the carrier shaft tube can be made from a cost-effective ferrous material, while the cam disk is made from tool steel or bearing steel. Several known manufacturing methods are available to optimize the assembly camshaft geometry and for their manufacture, some of which are described in detail in US Pat. ing. In particular, internal high pressure molding methods are generally known for the manufacture of camshafts having a hollow carrier shaft.

  In contrast to passenger car camshafts, multipurpose passenger car camshafts must be able to transmit substantially higher torque than passenger car camshafts. The reason for this is higher gas exchange capacity for larger displacements. In addition, there are specific requirements for multipurpose passenger car engines arising from special applications where, for example, hydraulic equipment is driven by camshafts in agricultural machinery, and where appropriate, auxiliary equipment should be driven by camshafts. is there.

  In this regard, known internal high pressure molding methods have limitations. This method requires a hollow camshaft or tube to receive the cam disk, and the tube thickness of the tube must not be too great so that the required inflation pressure is still controllable. This creates a disadvantage with respect to the raw material for the carrier shaft tube. In the relevant diameter range, pipes that are seamlessly drawn or welded in the longitudinal direction are more expensive than solid circular materials that are rolled. In this case, for strength reasons, the tube must be molded at one end and it must be assumed that a closure cover for oil escape is required on one side. A further aspect is that the tube has a lower moment of resistance to torsional and bending loads compared to a solid shaft, which in the case of a carrier shaft tube is a larger configuration under comparable loads. Sometimes you need to have a size.

  Since the degree of molding cannot be arbitrarily high, technical limitations are imposed on the internal high pressure molding technique. Materials that are displaced radially during internal high pressure molding must be pushed axially. Axial pressing is counteracted by frictional forces, which defines the limit of the internal high pressure produced.

  Furthermore, the known internal high-pressure molding technology has the problem that it is associated with a relatively high capital investment. This is on the one hand associated with the hydraulic assembly required for pressure generation, and on the other hand, due to the very high operating pressure of 2500-3000 bar, safety conditions exist, which affect the equipment costs. A further disadvantageous cost aspect of the internal high pressure molding method is operational management costs. Seals sealing conventional internal high pressure molded lances with respect to the carrier shaft tube are subject to considerable wear and must be replaced periodically, which further limits the degree of equipment utilization. Furthermore, due to the inactive transmission of the actuation force, the internal high pressure molding technique can only be used to a limited extent for the (inactive) shaft-hub connection for multi-purpose passenger car camshafts that are reliable in operation. I can't.

  In known assembled camshafts, each cam disk hole must be pre-machined so that the cam disk can be joined to the carrier tube anyway. In this case, this can only be done efficiently without heat treatment. In order to give the cam disks their final hardness, mainly induction heating of the entire assembled camshaft is required with subsequent quenching in water or oil.

  U.S. Pat. No. 6,053,836 discloses a method for manufacturing a camshaft, wherein a plurality of cam disks and at least one drive wheel are mounted on a carrier shaft for the cam disks. . The outer diameter part of the carrier shaft to which the cam disk is attached has alternately high and low parts, and the cross section of the carrier shaft forms an arcuate wedge shape with the outer diameter continuously expanding as an envelope curve. Yes. On the other hand, a hole adapted to the continuous expansion of the outer diameter of the carrier shaft is drilled in the cam disk. The cam disk and the at least one drive wheel are attached to the carrier shaft by elastically deforming the cam disk and the drive wheel and / or the carrier shaft by rotating the carrier shaft with respect to the hole.

  In order to properly deform the part of the carrier shaft to which the cam disk is to be attached, the carrier shaft is introduced into the tool and such part is sequentially machined with the desired contour. When a carrier shaft tube is used rather than a solid carrier shaft, a corresponding mandrel for support is required during machining.

German Patent Application Publication No. 10 2004 011 815 A1

  An object of the present invention is to provide a method for forming a shaft-hub connection that meets high strength requirements, while this method can be implemented at a relatively low cost and therefore at a low cost. is there. Furthermore, the object of the present invention is to provide an apparatus for carrying out the method.

  This object is achieved according to the invention by the features of the independent claims. Advantageous refinements are described in the further claims.

  The method according to the invention for forming a shaft-hub connection is particularly suitable for a camshaft or transmission shaft of an internal combustion engine. According to the invention, the carrier shaft tube is locally plasticized in the tool at the part to which the attachment is attached and is joined together with at least two attachments in the same tool.

  Here, the accessory parts each have a hole with an arcuate wedge profile, also called a circular spline profile. In the case of a camshaft, the accessory is designed, for example, as a cam disk and drive wheel, and in the case of a transmission shaft, it is designed, for example, as a gear. Advantageously, all accessories to be joined are joined to the carrier shaft tube simultaneously. The joining operation includes relatively rotating the carrier shaft tube and the at least two attachments until a secure connection between the carrier shaft tube and the at least two attachments is obtained.

  A bearing portion that is not deformed is formed in the carrier shaft tube between the accessory parts. In the first process step, the carrier shaft tube is preferably preformed in all parts provided with attachments and then joined to the attachments in these parts. This is done in the same tool, preferably at a constant chucking position. Compared to the prior art, a significant reduction in manufacturing time is obtained. Furthermore, this method is not affected by manufacturing tolerances between the carrier shaft tube as a joining partner and the accessory. Cutting machining of the joint surface can be avoided, and the joint surface is not interrupted by the depression, so that good material utilization is obtained.

  The carrier shaft tube is simply pre-formed in the tool in a first step, preferably by known impulse, gas or hydraulic methods such as internal high pressure forming (IHF) or hot metal gas generation (HMGF). The accessory part in this case already surrounds the corresponding part of the carrier shaft tube. The carrier shaft tube is inflated from the inside by pressure without the attachments being molded and abuts the inner profile of each attachment. The inner contour of the accessory part is now the mold for molding. The active and inactive shaft-hub connection is not realized by the elastic deformation acting on the carrier shaft tube in the radial direction of the attachment partner, but by rotation of the carrier shaft tube relative to the attachment. A suitable material for the carrier shaft tube is a material that can be easily plastically deformed, for example, structural steel such as St52-3. The accessory parts are preferably formed from high strength, advantageously fully annealed steel, for example 100Cr6, considering them as cam disks. The accessory designed as a drive wheel is advantageously also formed from steel, for example from 25MoCr4, preferably in a heat-treated state.

  What can be considered for the arcuate wedge profile is, in addition to the Archimedes or logarithmic spirals, higher order mathematical functions such as Fermat, Galilei, or hyperbolic spirals, sinusoidal spirals, Lemnis skates, circle curves, etc. The function itself is not very important. What is important is simply that the arcuate wedge profile is an open function that widens with a rotation angle in polar coordinates and correspondingly deviates from the circular shape. The center of this function does not necessarily coincide with the axis of rotation of the carrier shaft tube, and thus even an eccentric helix is possible.

  Advantageously, the inner profile of the accessory hole, for example forming a cam disk, is designed to be mirror-symmetric with respect to the inner profile of the accessory hole acting as a drive wheel. Thus, the attachment of the cam disk and the drive wheel to the camshaft tube can be done in a particularly simple manner in which the drive wheel rotates with the cam disk held in a fixed position. The equipment required for this has a particularly simple structure, and the described method can be controlled in a very simple manner. Furthermore, this procedure results in the direction of rotation of the carrier shaft under the operating conditions of the internal combustion engine being directly related to the profile geometry, further increasing the strength of the preferred camshaft. Further, if all cam disks are joined simultaneously with the camshaft drive wheels, the dimensional tolerances that may exist are compensated, so that costly reaming operations are not required in cam disk machining. However, of course, other methods for the relative rotation of the carrier shaft tube with respect to the accessory without drive wheels can also be envisaged.

  Due to the continuous enlargement of the radius of the carrier shaft tube, the accessory part is connected to the carrier shaft tube by radial crimping after rotation, and no special coating of the contact surface (joint surface) is required. This provides attachment fixation in both the radial and axial directions of the carrier shaft tube, without additional material or requiring further method steps.

Preferably, the following steps are performed continuously.
The holes in the accessory parts are aligned with each other so that the accessory part is introduced in a precise position in the tool lower part and the carrier shaft tube can be pushed axially;
-The carrier shaft tube is pushed through the hole in the accessory inserted into the tool. The carrier shaft tube preferably has an annular cross-section, so that the passage through the arcuate wedge profile of the accessory hole is particularly simple. Shorter process times can be realized.
-With the tool closed, the carrier shaft tube is subjected to internal pressure on its inside. The carrier shaft tube is inflated by internal pressure until contact between the carrier shaft tube and the inner peripheral arcuate wedge profile of the accessory is made at the location where the accessory is located.
-With the accessory fixed in place in the tool, the carrier shaft tube is rotated relative to the accessory until an active connection is made between the carrier shaft tube and the accessory. Each attachment may have an inner profile that is designed to be different from the profile of the adjacent attachment, so various geometric parameters of the interface at the carrier shaft tube with different pitches, number of splines, etc. Can be implemented in a simple manner depending on the tool used. The carrier shaft tube can automatically adapt to the local inner profile. The joining surface need not be machined by cutting. Since the joint surface of the carrier shaft tube is not weakened by the depression, a better material utilization can be obtained compared to the prior art. The contact area of the joining partner is relatively long overall.

  A preferred prefabricated shaft that, when installed, consists of a carrier shaft tube and accessories, for example a camshaft, preferably rotates the same as the drive wheel during mounting on the carrier shaft tube under operating conditions. Has a direction. Therefore, transmission of the camshaft driving torque from the driving wheel to the cam disk via the carrier shaft tube is actively performed.

  Preferably, prior to rotation of the carrier shaft tube, the internal pressure spreading inward for expansion and local plasticization of the carrier shaft tube is reduced. Since the carrier shaft tube is simply pre-formed, the elasticity of the carrier shaft tube will recoil somewhat, creating a gap between the carrier shaft tube and the inner profile of the accessory. This gap allows relative rotation between the carrier shaft tube and the accessory.

  The carrier shaft tube may be subjected to an axial upset pressure acting along the longitudinal axis of the carrier shaft tube at one or both of its ends during expansion. As a result, the material can be replenished during plasticization, so that the tube thickness of the carrier shaft tube is excessive in the inflated part, i.e. in the region where the accessory is constructed around the carrier shaft tube. There is no decrease.

  Preferably, the carrier shaft tube can be expanded by an internal high pressure molding process. It can also be envisaged that these carrier shafts are heated before molding and expanded in the heated state, or pulsed expansion is carried out, for example by electrodynamic pulse shaping. The first process step corresponds to the simultaneous pre-forming process of all the arcuate wedge profiles of the carrier shaft tube at the corresponding part where the attachment is to be constructed. It is advantageous if a combined molding tool is used, which is preferably also part of the joining device.

  For joining, advantageously, the attachments forming the drive wheels may be subjected to torque for rotating the carrier shaft tube. For this purpose, a drive device is attached to the carrier shaft tube.

  The carrier shaft tube may be provided as a tube material or may be obtained from a flat sheet metal strip, which is rolled and rolled into a tube before being pushed into the tool. And welded.

  Locally different wall thicknesses can be rolled laterally or longitudinally into the sheet metal strip, which in turn forms the carrier shaft tube. The sheet metal strip can be cut particularly easily into the desired axial length, for example by shearing the sheet metal material. In the case of tubes, a re-machining step is required during shearing, which is not the case with sheet metal strips. In each case, a sheet metal strip having a width corresponding to the circumference of the carrier shaft tube can be rolled, the rolling direction being preferably along the longitudinal axis of the tube. Similarly, a sheet metal strip having a width that is a multiple of the circumference of the carrier shaft tube, preferably at least twice the circumference, may be rolled, and advantageously the rolling direction is transverse to the axis of the tube. Extend in the direction. Thereafter, after length cutting, a sheet metal strip is formed into a tube and closed by a weld seam.

  An apparatus according to the invention for carrying out this method provides a tool lower part having a receiving mold corresponding to the spacing of the accessory parts on the carrier shaft tube, the tool lower part having a matching receiving mold. It can be closed by having a tool upper part. To insert the accessory part, the tool upper part can be lifted or tilted away from the tool lower part. In this state, the rotary drive device can be similarly tilted and removed. The tool is on the one hand a forming tool and on the other hand is part of the joining device. The carrier shaft tube and accessory need not be introduced into a separate tool between the two process steps. The tool preferably comprises two molds, one designed as a holding and fixing device for an accessory designed as a drive wheel and the other as another accessory such as a cam disk or gear and the other Form a holding and fixing device for the part.

  Recesses may be formed on the end surfaces of the tool upper part and the tool lower part, respectively, to form openings in the closed state and guide the carrier shaft tube through these openings. Thus, the passage of the carrier shaft tube through the accessory inserted in the tool and also the application of the molding internal pressure and the application of the upset pressure during molding can be carried out in a very simple manner. .

  Advantageously, a stop and an alignment element may be provided in the receiving mold in order to insert and secure the accessory part with a precise positioning. Accordingly, cam disks as accessories are generally configured on camshafts with an angular offset with respect to each other in the orientation of their rotational positions. The tool receiving provides a corresponding precisely positioned orientation.

  The tool upper part may be formed from two parts that are arranged relative to each other in the longitudinal direction. As a result, the two molds can be opened individually and different axial regions of the carrier shaft tube can be exposed.

  The tool lower part may be formed from two parts that are arranged relative to each other in the longitudinal direction, or may be formed in one piece.

  It is advantageous if the individual parts of the tool upper part can be released individually from the tool lower part due to the action of torque in the second process step joining by rotation.

  In addition, it is beneficial to provide at least one hydraulic ram on the end face of the tool so that further upset pressure can be exerted on the carrier shaft tube during expansion of the carrier shaft tube. Preferably, hydraulic rams are provided on both end faces.

  A drive unit may be provided for rotation, and the drive unit may be in operative connection with the installed carrier shaft tube at one end face. The drive unit can be pivoted off or pulled off when not needed.

  In the case of long, thin-walled carrier shaft tubes and many accessories, the torque required for splicing that is introduced via the drive wheels exceeds the torsional strength of the carrier shaft tubes Can happen. Thus, in an alternative embodiment of the present invention, the drive unit required for such joining by rotation so that each individual accessory or pair of accessory pairs combined as a group is individually rotated or clamped Is integrated into the mold. This provides the advantage that the torque required to join each individual accessory or each group of accessories can be electronically monitored and recorded. As a result, higher resolution or higher sensitivity quality control can be performed during the bonding operation. A further advantage can be seen in that the joining torque does not have to be all introduced into the carrier shaft tube via the drive wheels. Thus, in this embodiment, the joint torque required in each case is locally introduced at each joint point, and the carrier shaft tube is locally exposed to lower loads, so that the carrier shaft tube The number of attachments to be joined is not critical.

  Preferably, the carrier shaft tube operably connected to the drive unit may be rotatable with respect to an accessory fixed in the tool until an active connection is obtained.

  Further advantages and details of the invention are explained in more detail below with reference to preferred exemplary embodiments described in the drawings, but are not limited to these exemplary embodiments.

FIG. 6 shows a preferred tool before insertion of an accessory part. FIG. 6 shows a closed preferred tool with an attached accessory. FIG. 4 shows a closed preferred tool with a carrier shaft tube penetrated. FIG. 2 shows a detail of the carrier shaft tube according to FIG. 1 guided through two attachments. FIG. 2 shows the carrier shaft tube with the preferred tool after the first step according to FIG. 1 with pre-forming of the carrier shaft tube with a hydraulic ram arranged on the end face. FIG. 2 shows the carrier shaft tube in the preferred tool according to FIG. 1 in a second step with relative rotation of the carrier shaft tube with respect to an accessory fixed in the tool. FIG. 2 shows the carrier shaft tube with the preferred tool according to FIG. 1 in the removal stage after the second step, with a fixed shaft-hub connection. FIG. 6 is a side view of an alternative rotational configuration with a preferred tool. FIG. 3 shows various shaft-hub connections before the first step with a carrier shaft tube threaded through an attachment. FIG. 5 shows various shaft-hub connections after pre-forming. FIG. 4 shows various shaft-hub connections after the second step with a rotated carrier shaft. FIG. 3 shows various shaft-hub connections before the first step with a carrier shaft tube threaded through an attachment. FIG. 5 shows various shaft-hub connections after pre-forming. FIG. 4 shows various shaft-hub connections after the second step with a rotated carrier shaft. It is a figure which shows the alternative manufacturing method for the carrier shaft pipe | tube of pipe | tube thickness change. It is a figure which shows the carrier shaft pipe | tube of the pipe | tube thickness change manufactured from a sheet metal strip, Comprising: It is the perspective view of the pipe which was rolled and welded in the longitudinal direction. FIG. 8b is a perspective cross-sectional view of the tube of FIG. 8a showing a carrier shaft tube of varying tube thickness produced from a sheet metal strip. FIG. 4 shows a carrier shaft tube of varying tube thickness produced from a sheet metal strip, showing a shaped carrier shaft that is tube thickness varied and has a circular spline profile. FIG. 8b is a perspective sectional view of the carrier shaft of FIG. 8c, showing a carrier shaft tube of varying tube thickness produced from a sheet metal strip. It is the schematic of a rolling apparatus. 1 is a schematic view of an endless belt capable of producing a camshaft tube. FIG.

  In the following drawings, the same reference numerals are used for functionally identical or identically acting components for the sake of clarity. In that respect, the preceding description is referenced in each case.

  The method according to the invention provides two emphasis. That is, the carrier shaft tube is pre-formed in the tool, and at the same time the circumferential profile of the carrier shaft tube is pre-determined by the inner profile of the accessory part where the accessory part is fixed, and the carrier shaft pipe Are rotated with respect to the attachment in the same tool to make a fixed shaft-hub connection.

  FIGS. 1 a-1 c outline the preparatory steps for performing the preforming of the carrier shaft tube 34.

  A preferred multi-part tool 10 comprises a tool lower part 12 and a tool upper part 16. In this example, the tool lower part 12 and the tool upper part 16 are formed of two parts 12a and 12b and two parts 16a and 16b that are adjacent to each other in the longitudinal direction 48, respectively. The longitudinal direction 48 is also the longitudinal direction of the carrier shaft tube 34. The component 12a and the component 16a form a first mold G1 of the tool 10, and the component 12b and the component 16b form a second mold G2 of the tool 10.

  As can be seen in the open tool 10 in FIG. 1 a, receiving dies 20 and 22, each having depressions, stops, alignment aids, etc., are respectively contact surfaces 14 of the tool lower part 12 and the tool upper part 16. , 18. The attachments 26, 28 can be inserted into the receiving mold 20 of the tool lower part 12 with precise positioning, ie these attachments 26, 28 already have an angular position and on the carrier shaft tube 34. Can be inserted with a mutual spacing corresponding to the relative position after each other. The receiving dies 20, 22 predetermine the relative angular position of the attachment 26.

  The attachments 26 (only some of which are referenced for clarity) are designed, for example, as cam disks, while the attachment 28 preferably has a drive wheel with an outer tooth profile. Constitute. At this time, the carrier shaft tube 34 forms the cam carrier shaft of the camshaft. A highly loaded cam with carrier shaft tube 34 transmitting rotational motion to an attachment 26 located on carrier shaft tube 34 and designed as a cam disk and performing essentially a bearing function The disc provides a linear movement of the valve drive for engine control.

  The mold G1 in the closed state forms a holding and fixing device for the accessory 28 designed as a drive wheel, and the mold G2 is a holding and fixing device for the accessory 26, i.e. a cam disk or the like. Form.

  In addition to the two-part design of the tool lower part 12, the parts 12a, 12b can be connected together to form a single component.

  FIG. 1b shows the attachment 26, 28 inserted and the tool upper part 16 and the tool lower part 12 closed and secured relative to each other. At this time, the tool 10 forms a closed mold and adjusts all attachments 26, 28 to be joined.

  Between the upper tool part 16 and the lower tool part 12 is formed a tubular cavity 24 which is provided for receiving a carrier shaft tube 34. Further, each of the two end faces of the tool 10 is provided with a preferably circular opening 30, 32 through which the carrier shaft tube 34 can be introduced into the tool 10.

  A closed tool 10 having an inserted attachment 26, 28 and an introduced carrier shaft tube 34 is illustrated in FIG. 1c. The attachments 26, 28 have internal holes that are aligned with the openings 30, 32, and thus can pass the carrier shaft tube 34. The carrier shaft tube 34 projects on both sides and protrudes from the openings 30 and 32. In a further procedure, in accordance with the known internal high pressure molding (IHU), if appropriate and also using a high temperature carrier shaft tube 34 (HMGF, high temperature metal gas molding), for the internal expansion of the carrier shaft tube 34, the molding The required pressure medium is supplied to the end of the carrier shaft tube 34.

  Prior to the joining operation, and also before the carrier shaft tube 34 is pre-formed, the carrier shaft tube 34 is a tubular section of circular cross-section, and the pre-manufactured attachments are circular. With a suitable internal hole with an arcuate wedge profile.

  This is illustrated in FIG. 2 by way of an example of the details in which the carrier shaft tube 34 of circular cross-section is guided in the direction 36 through two attachments 26 having an arcuate wedge profile 42, corresponding to the situation of FIG. It becomes clear by doing. There is play 40 between the surface 38 of the carrier shaft tube 34 and the arcuate wedge-shaped profile 42 of the attachment 26 so that the carrier shaft tube 34 can be easily pushed through the attachment 26.

  FIG. 3 shows the tool 10 of FIGS. 1a-1c with the carrier shaft tube 34 depressed. At the end of the carrier shaft tube 34, not only is the pressure medium supplied for internal expansion, but also the material is transferred from the end of the carrier shaft tube 34 by the hydraulic ram 52 within the tool 10. Is pushed into. Thus, during molding with local radial expansion at the portion 44 where the attachments 26, 28 are located, the carrier shaft tube 34 is simultaneously subjected to length reduction or upset.

  The operating pressure required for this method depends, inter alia, on the material properties of the carrier shaft tube 34 and its wall thickness and is typically between 2000 and 4000 bar. As a result of this first process, the preforming of the carrier shaft tube 34 and the formation of the arcuate wedge-shaped profile 46 (or circular spline profile) in the interior bores of the attachments 26,28. This is done at a certain axial position or portion 44. For clarity, only some of the portions 44 are referenced.

  The arcuate wedge-shaped profiles that can each be formed at the junction (portion 44) of the carrier shaft tube 34 are pre-determined by the individual profiles of the internal bores of the relevant attachments 26,28. Therefore, the attachments 26, 28 are already provided with corresponding inner contours during their manufacturing process.

  As is known from German Offenlegungsschrift 10 2004 011 815 A1, this is preferably done directly during forging without the additional expenditure for drilling deviating from a circular cross section. May be. In accordance with the present invention, molding occurs only at the portion 44 of the carrier shaft tube 34 where the attachments 26, 28 are finally secured in the second process step. Otherwise, with the bearings located between the attachments 26, 28 or other carrier shaft portions, the receiving dies 20, 22 on the tool 10 prevent significant molding.

  As can be clearly seen after the arcuate wedge profile 46 has been pre-formed into the carrier shaft tube 34 in the first process step, the carrier shaft tube 34 still remains in the tool 10 initially. After the reduction and reduction of the internal pressure required for pre-forming, the carrier shaft tube 34 is deformed and returned in the radial direction by its elasticity. A slight radial play is established between the attachments 26, 28 and the carrier shaft tube 34. At this time, therefore, there is still no inactive connection, in contrast to other known shaft-hub connections by internal high pressure molding.

  The mold G1 of the tool 10 was then opened which had the accessory 28 forming the drive wheel fixed in place substantially during molding of the carrier shaft tube 34. In contrast, the mold G2 of the tool 10 remains closed.

  This is illustrated in FIGS. 4a and 4b. At this time, a lateral access 56 of the drive unit 54 to the accessory 28 designed as a drive wheel is made possible.

  As is known from German Offenlegungsschrift 10 2004 011 815 A1, the orientation of the arcuate wedge-shaped profile 42 in the attachment 28 designed as a drive wheel is that in the remaining attachment 26. Constructed in reverse. The drive unit 54 has an electric or hydraulic rotary drive with an integral angle decoder. The drive unit 54 is connected to a control device (not shown), which allows a programmed rotational movement or angular tightening in a pre-set amount, similar to known screw control devices. At this time, the attachment 28 can be rotated by an active connection, preferably via an external tooth profile incorporated in the attachment 28 designed as a drive wheel or through an opening for weight reduction. Thus, the drive unit 54 is positioned relative to the accessory 28 designed as a drive wheel. The predetermined rotational movement of the attachment 28 designed as a drive wheel results in all the attachments 26 including the attachment 28 designed as a drive wheel being joined to the carrier shaft tube 34.

  After this rotational movement of the attachment 28 designed as a drive wheel with respect to the other attachment 26 fixed in place, then in a first process step an arc shape preformed on the carrier shaft tube 34. The wedge-shaped profile 46 forms a shaft-hub connection 50 with all attachments including the attachment 28 designed as a drive wheel (FIG. 4b). The attachments 26, 28 to be joined are fixed to the carrier shaft tube 34 by a single rotational movement. With respect to the exemplary camshaft, the geometry of the arcuate wedge-shaped profiles 44, 46 is fixed so that the shaft-hub connection 50 acts actively in the direction of rotation, which is the direction of later rotational motion in the internal combustion engine. .

  At the end of the second process step, the tool G2 mold G2 is opened and the assembled shaft 100 can be removed.

  FIG. 5 outlines a tool 10 that uses only one mold with a tool lower part 12 and a tool upper part 16. This mold has receiving molds 20 and 22 (FIG. 1) having positioning elements and the like necessary for final positioning of the attachments 26 and 28, and within the receiving mold, the attachments 26 and 28 Arranged at the final position. As described above, the carrier shaft tube 34 is introduced into a closed mold and passed through the attachments 26, 28 in the tool 10 and, as described above, hydraulic, gas or pulsed. Depending on the method, it is preformed in the corresponding part 44.

  In this case, the accessory part 28 designed as a drive wheel is rotated by a rotating device comprising an outer race 64, a rotating body 62, an inner race 66 having a gear housing, and an electric motor (not shown). The The accessory 28 designed as a drive wheel is received by the outer race with its rotation fixed by the inner race 66. To remove the assembled shaft 100, the tool upper part 16 is lifted or tilted away from the tool lower part 12.

  During molding of the carrier shaft tube 34, the rotating device is held in a restrained position. After pre-forming of the local arcuate wedge profile on the carrier shaft tube 34, the rotating device is released and a drive unit 54 (FIG. 4a) for introducing the torque required for joining is engaged with the opening 60 of the rotating device. It is made into a joint state. Transmission of torque to the carrier shaft tube 34 is effected by an opening 60, an inner race 66, and rotational interlocking by the outer tooth profile of the accessory 28 designed as a drive wheel.

  If appropriate, additional torque may be generated by additional drives acting on the carrier shaft tube 34. Again, the arcuate wedge-shaped profile 42 of the attachment 28 is oriented opposite to the profile of the attachment 26. Accordingly, the carrier shaft tube 34 is joined by the prescribed rotational movement of the inner race 66.

  FIGS. 6 a-6 f again illustrate the procedure of this method by the cross section of the carrier shaft tube 34 with the attachment 26. The attachment 26 has an internal hole with an arcuate wedge profile 42. A circular carrier shaft tube 34 is guided through the attachment 26 (FIGS. 6a and 6d). The carrier shaft tube 34 is expanded as described above, in which case the arcuate wedge profile of the accessory 26 is formed at the portion 44 by forming an arcuate wedge profile 46 imitating the arcuate wedge profile 42 therein. 42. After removal of the internal molding pressure, a small play is formed between the arcuate wedge profile 46 of the carrier shaft tube 34 and the arcuate wedge profile 42 of the accessory 26. The carrier shaft tube 34 is rotated to make an active shaft-hub connection 50. The arcuate wedge profile 42 may be designed in a completely different manner, for example with different pitches and / or different numbers of splines (e.g. the number of splines is 2 in FIGS. It is clear that the number of may have 3).

  A further advantageous development of the assembled shaft 100 in terms of its weight is possible when the carrier shaft tube 34 is formed from a precision steel tube with a non-uniform tube thickness.

  By rolling the sheet metal blank or sheet metal strip 68 to be formed, the future carrier shaft tube 34 can be “designed” by its plate thickness with respect to the corresponding loads and stresses on the assembled shaft. For this purpose, as illustrated in FIG. 7, a rolling roller 80 having an upper roller 82 and a lower roller 84 is used. The feed of the rollers 82, 84 (indicated by double-headed arrows) affects the initial material, for example, the minimum sheet thickness 72 and the maximum sheet thickness 74 of the thin sheet, and hence the thickness 72, 74 of the future carrier shaft tube 34. be able to. Advantageously, the width 86 of the sheet metal strip 68 corresponds to the circumference of the future carrier shaft tube 34.

  Figures 9a and 9b show a further variation of the carrier shaft tube 34 formed by rolling and welding. At one end, for example in the region of the accessory 28 designed as a drive wheel, the carrier shaft of a defined length L having a larger tube thickness 74 than in the region of the accessory 26 and bearing part designed as a cam disk. In order to manufacture the tube 34, the sheet metal strip 68 is subjected to flexible rolling.

  The preferred process steps in semi-finished product manufacturing are flexible rolling, length cutting, tube forming, and butt welding. A length cut immediately after rolling is advantageous because the flat material can be separated by shearing much more simply than by separating the tubes, for example by sawing or framing. Shearing can not be applied to tubes because the cross section is crushed at the cutting point.

  Further, it may be possible to produce very long and thin sheet panels having a relatively long length 86 and varying sheet thickness. Thereby, as can be seen in FIG. 9b, the roll sheet is utilized more effectively. After this sheet metal panel is further cut into strips, a sheet panel blank whose width substantially corresponds to the axial length L of the finished carrier shaft tube 34, in each case a plurality of carrier shaft tubes, For example, in FIG. 9b, five carrier shaft tubes 34 can be manufactured in the longitudinal direction.

  Obviously, the handling costs are sometimes increased compared to the continuous production of the sheet metal strip 68 (FIG. 7). However, this is simplified because the sheet metal strip can be rolled such that the upper roller 82 in the rolling roller 80 is designed with a step corresponding to the desired change in wall thickness ( FIG. 9a). As a result, the plate thickness change in the thin sheet occurs in the transverse direction with respect to the rolling direction, while the sheet thickness does not change in the rolling direction. The sheet metal strip 68 of varying thickness, like the sheet metal strip 68 of constant thickness, can be formed into a tube according to known forming methods, for example by bending or rounding with a mandrel, after which the tube Welded in a known manner with a longitudinally extending butt surface (FIG. 8a).

  Thus, in the region of the carrier shaft tube 34 where the attachment 28 designed as a drive wheel is to be constructed, other axial sections of the carrier shaft tube 34 where the attachment 26, bearings, gaps, etc. are located. It is possible to provide a greater tube thickness than inside. Depending on the feed of the rollers 82, 84, various construction variants of the blank of the initial material (thin sheet) are possible. If the distance between the two rollers 82 and 84 located opposite each other is changed in the same manner, the change in the plate thickness occurs on both sides in the direction transverse to the longitudinal direction 48. In contrast, the movement of only one roller 82 or 84 that moves transversely to the rolling direction results in only a change in thickness on one side. In this case, in each case, the other roller 84 or 82 performs the support function.

  The sheet metal strip 68 to be formed is typically wound by a supplier into a so-called coil and made available in this form.

  The sheet metal strip 68 for manufacturing the carrier shaft tube may be continuously formed sequentially. Subsequent shearing process cuts the desired sheet metal blank as sheet metal strip 68 to a length L suitable for manufacturing carrier shaft tube 34. The rolled sheet metal strip 68 is joined by a precision weld seam 70 using, for example, laser beam welding, direct current welding, or intermediate or high frequency welding methods to form a welded precision steel pipe, The carrier shaft tube 34 is formed and pre-formed and joined in the manner described above. In this case, as before, the carrier shaft tube 34 has a circular outer periphery and the thickness protrudes inward as is apparent from FIG. 8b. 8c and 8d show a configuration (circular spline profile) in which the thickness of the material is oriented both inside and outside (tube thickness change) for comparison.

  The assembled shaft 100 can provide different arcuate wedge profiles 42 along the carrier shaft tube with the possibility of being able to configure the tube thickness and with respect to the various attachments 26,28. Can be made available according to the size.

Claims (24)

A method for forming a shaft-hub connection (50) of an internal combustion engine camshaft (100) or transmission shaft, wherein attachments (26, 28) are attached to a carrier shaft tube (34); Each arcuate wedge profile (42) is introduced into the attachment (26, 28) prior to attachment, and the portion (44) of the carrier shaft tube (34) to which the attachment (16, 28) is attached. Forms an arcuate wedge-shaped profile (46) that continuously expands the outer radius of the carrier shaft tube (34) around the circumference of the portion (44), wherein the attachments (26, 28) are: In a method in which the carrier shaft tube (34) and the accessories (26, 28) are connected by mutual rotation;
Within the tool (10), the carrier shaft tube (34) is locally expanded at the part (44) to which the attachments (26, 28) are attached,
Within the tool (10), the relative rotation of the carrier shaft tube (34) and the at least two attachments (26, 28) causes the carrier shaft tube (34) and the at least two attachments ( 26, 28), wherein the carrier shaft tube (34) is joined to at least two attachments (26, 28) by being performed until an active connection is obtained.   During the local expansion of the carrier shaft tube (34), all parts (44) of the carrier shaft tube (34) to which the attachments (26, 28) are attached are expanded simultaneously. The method according to claim 1.   All the attachment parts (26, 28) are simultaneously joined to the carrier shaft pipe (34) during relative rotation of the carrier shaft pipe (34) and the attachment parts (26, 28). The method according to claim 1 or 2, characterized in that The accessory (26, 28) is introduced into the tool (10) with precise positioning so that the carrier shaft tube (34) can be pushed axially (36). The holes of the accessory parts (26, 28) are aligned with each other;
The carrier shaft tube (34) being pushed through the hole of the accessory (26, 28) inserted into the tool (10);
With the tool (10) closed, the carrier shaft tube (34) is subjected to internal pressure inside the carrier shaft tube (34);
The carrier shaft tube (34) is a portion (44) where the attachment parts (26, 28) are located, and the inner circumference of the carrier shaft tube (34) and the attachment parts (26, 28). Inflated by internal pressure until contact with the arcuate wedge profile (42) is made;
With the attachment (26) fixed in place in the tool (10), the carrier shaft tube (34) is connected to the carrier shaft tube (34) and the attachments (26, 28). The method according to any one of claims 1 to 3, characterized in that it is rotated with respect to the attachment (26, 28) until an active connection is made.   5. The internal pressure spreading inside the carrier shaft tube (34) is reduced before the rotation of the carrier shaft tube (34). 6. the method of.   The carrier shaft tube (34) acts along the longitudinal axis (48) of the carrier shaft tube (34) at one or both ends of the carrier shaft tube (34) during expansion. The method according to claim 1, wherein the upset pressure is applied in the axial direction.   A method according to any one of the preceding claims, characterized in that the carrier shaft tube (34) is expanded by an internal high pressure molding process.   8. A method according to any one of the preceding claims, characterized in that the carrier shaft tube (34) is heated prior to molding and expanded in the heated state.   9. A method according to any one of the preceding claims, characterized in that the accessory (28) forming the drive wheel is subjected to a torque for rotation of the carrier shaft tube (34).   10. The carrier shaft tube (34) is manufactured from a shaped flat sheet metal strip (68) before being pushed into the tool (10). The method according to one item.   Locally different plate thicknesses are rolled into the sheet metal strip (68) of the carrier shaft tube (34), and the sheet metal strip (68) is cut to a desired axial length into the tube. 11. A method according to claim 10, characterized in that it is formed and closed by a weld seam (70).   The sheet metal strip (68) is designed with a width (86) transverse to the longitudinal axis (48) and corresponding to the circumference of at least two carrier shaft tubes (34). The method according to claim 10 or 11, characterized in that: Device for carrying out the method according to any one of claims 1 to 12, comprising a tool (10),
The carrier shaft tube (34) is locally inflatable and the carrier shaft tube (34) rotates with respect to the attachment (26, 28) inserted into the tool (10). And can be joined to the accessory parts (26, 28).   The tool (10) comprises a tool lower part (12) having a receiving mold (20) corresponding to the spacing of the accessory parts (26, 28), the tool having a matching receiving mold (22). 14. Device according to claim 13, characterized in that it can be closed by means of a tool upper part (16).   Recesses are formed in the end faces of the tool upper part (16) and the tool lower part (12), respectively, to form openings (32, 30) in the closed state of the tool (10), and the openings (32 , 30) through which the carrier shaft tube (34) can be guided and further passed through the inserted attachment (26, 28).   16. A stop and an alignment element are provided in the receiving mold (20, 22) for inserting and securing the accessory (26, 28) in a precise position. The device described in 1.   17. The tool upper part (16) is formed from two parts (16a, 16b) arranged relative to each other in the longitudinal direction (36). Equipment.   18. The tool lower part (12) is formed from two parts (12a, 12b) arranged relative to each other in the longitudinal direction (36). The device described.   19. A device according to any one of claims 14 to 18, characterized in that the tool lower part (12) is integrally formed.   20. The individual tool (16a, 16b) of the tool upper part (16) can be individually released from the tool lower part (12) according to any one of claims 14-19. The device described.   15. At least one hydraulic ram (52) is provided on the end face, the hydraulic ram (52) being able to exert upset pressure on the installed carrier shaft tube (34). The apparatus as described in any one of -20.   Device according to any one of claims 14 to 21, characterized in that at one end, a drive unit (54) can be in operative connection with the installed carrier shaft tube (34).   The carrier shaft tube (34) operably connected to the drive unit (54) rotates with respect to the accessories (26, 28) secured in the tool (10) until an active connection is obtained. 23. The apparatus of claim 22, wherein the apparatus can be.   The drive unit required for joining is such that each individual accessory (26, 28) can be individually rotated with respect to the carrier shaft tube (34) having a fixed rotational position, 15. Device according to claim 14, characterized in that it is integrated in the tool (10).

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