Process for thermal joining of components and device

Abstract

The invention relates to a method for thermally joining components (1, 5) on a camshaft tube (2) of a camshaft (11), in which - two joining tables (3, 4) arranged one above the other are provided, - the components (1, 5) are heated, - a first joining gripper (7) places and aligns the heated first component (1) on the first joining table (3) and at least one further joining gripper (8) places and aligns the at least one heated further component (5) on the at least one further joining table (4), - a centering rod (9) moves upwards through the components (1, 5) and centers the components (1, 5) and, in a return movement together with a guide carriage (10), guides the camshaft tube (2) downwards through the component openings, - the camshaft tube (2) stops at a predefined position, - which moves at least one further joining table (4) apart after a predefined holding time, - the joining grippers (7, 8) open and the camshaft (11) is released.

Description

The present invention relates to a method for the thermal joining of components on a camshaft tube. The invention also relates to a device for the thermal joining of components on a camshaft tube, having a control device for carrying out such a method.A camshaft consisting of a camshaft tube and components, in particular for an internal combustion engine, is usually produced in the so-called thermal joining method, in which the components, in particular cams, are / are heated and / or the camshaft tube is cooled in order to obtain a thermal joining fit after the components have been pushed onto the camshaft tube and a subsequent temperature compensation. Usually, the component is heated, deposited on a joining table by a joining robot and joined onto the camshaft tube both in the axial and in the radial position. After temperature compensation and as a result thereof after the component / cam has been firmly seated on its joining position on the camshaft tube, the joining gripper of the joining robot opens, as a result of which the component is released again and the camshaft can now be moved out of the joining table. The joining process for the next component can now be started.However, the disadvantage of the known thermal joining methods is that a not inconsiderable heat transfer from the heated component into the camshaft tube can occur and, as a result of this heat transfer, the camshaft tube can also expand both in length and in diameter. Due to this heat transfer, an outer diameter of the camshaft tube and, above this, also a joint seat diameter becomes larger, which in turn can reduce a joining clearance during thermal joining of a further component / cam and lead to a higher risk of increased scoring due to contact between the components to be joined during the joining process. The depth of such grooves can become so great that further machining of the camshaft is no longer possible. This ultimately leads to additional waste and to machine downtime, which is absolutely to be avoided.The present invention therefore concerns the problem of specifying an improved or at least one alternative embodiment for a method for the thermal joining of components on a camshaft pipe or generally for the thermal joining of components on a pipe, which at least reduces the disadvantages known in particular in thermal joining processes known from the prior art.This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject of the dependent claims.The present invention is based on the general idea of thermally joining at least two components for the first time, for example cams, simultaneously on an associated camshaft tube or, for the first time, two components simultaneously on an associated tube, as a result of which the disadvantages known hitherto from the prior art in the successive joining of components or components on associated tubes can be avoided in particular. In the method according to the invention, first a first joining table and at least one further joining table arranged above it are provided. Simultaneously or subsequently, a first component and at least one further component are heated or heated, for example inductively, whereupon a first joining gripper places the heated first component on the first joining table and thereby aligns it, and a further joining gripper places and aligns the heated further component on the further joining table. This can take place in particular simultaneously, wherein it is purely theoretically also conceivable that this can take place offset to one another at comparatively short time intervals. The time intervals are of course only so large that both components, for example both cams, can still be joined thermally to a camshaft tube or generally to a tube in a common thermal joining process. Subsequently, a centering rod moves upward through a respective component opening of the components and centers the components / cams, whereupon the centering rod moves downward again and carries along a guide slide with the camshaft tube downward and guides it through the component openings. The camshaft tube stops at a predefined axial and radial position, which is usually effected by stopping the guide slide. A predefined holding time is then allowed, after which temperature compensation and thus a thermal joint fit can be at least partially ensured. After the predefined holding time has elapsed, the further joining table moves apart or is removed, whereupon the joining grippers open and the camshaft with camshaft tube and components is released. With the method according to the invention, it is thus possible, in particular, to at least reduce temperature expansions in the camshaft tube, caused by successive thermal joining of a plurality of components, as a result of which, in particular, waste and also machine downtime can be reduced.It is of course clear that with the method according to the invention not only a first and a further component, but also additional components can be joined thermally to an associated camshaft tube via additional joining tables and additional cam grippers.In an advantageous development of the method according to the invention, the first component and / or the at least one further component are inductively heated. During inductive heating, a coil to which alternating current is applied generates an alternating magnetic field which induces an eddy current in an electrically conductive body, in this case therefore the components / cams. This current induced in the component causes heating of the component at the locations of the current flow due to the electrical resistance of the component. Inductive heating makes it possible, on the basis of a wide variety of adjustable parameters, such as a frequency, to set a penetration depth and also to heat a cam differently at different points, as a result of which particularly uniform heating of the cams, in particular also in the base circle and at the cam crest, can be achieved. A further advantage of the inductive heating is that heating of only the component / cam is effected and no further parts, such as a furnace, have to be preheated. By virtue of such inductive heating, the components can also be heated to their thermal joining temperature comparatively quickly.In a further advantageous embodiment of the method according to the invention, the first component and the at least one further component are heated at different positions. This makes it possible to use smaller and local induction heating devices, wherein it is alternatively of course also conceivable for the first and the at least one further component to be heated in one and the same inductive heating device, whereby the inductive heating device can be designed in a space-optimized and energy-saving manner.In a particularly preferred embodiment of the method according to the invention, the first joining gripper places the heated first component on the first joining table and aligns it, while the at least one further joining gripper simultaneously places and aligns the further component on the further joining table. This allows parallel deposition and alignment of at least two, preferably all, components to be joined thermally on the respective associated joining tables, whereby the cycle time for thermally joining the camshaft can be reduced and cost savings can thereby be achieved.In a further advantageous embodiment of the method according to the invention, the at least one further joining table is supported on the first joining table via a mounting. By means of such a mounting, it is possible to set an axial distance between the first component and the at least one further component extremely exactly, as a result of which camshafts of the highest quality can be produced. By means of such a mounting, it is also possible to achieve different axial distances between two adjacent joining tables and thus also between two adjacent components by means of different mounting changes.The present invention is further based on the general idea of specifying a device for the thermal joining of components on a camshaft tube, which device has a first joining table and at least one further joining table arranged above it, and also a first joining gripper and at least one further joining gripper. Furthermore, the device according to the invention has a vertically displaceable centering rod for centering the components and a vertically displaceable guide carriage for moving the camshaft tube. By means of a control device, which is likewise a component of the device, the thermal joining method according to the invention described in the preceding paragraphs can be carried out. The advantages described with respect to the method according to the invention can thus be transferred to the device by means of the device according to the invention, so that with this device a waste rate of camshafts can be reduced just as well as machine downtime. This is particularly due to the fact that at least two components can be thermally joined in parallel with an associated camshaft tube with the device according to the invention, whereby in particular a formation of grooves due to a temperature expansion of the camshaft tube, caused by a successive joining of the components, can be avoided.The device according to the invention expediently has an inductive heating device for heating the components. Such an inductive heating device can be a collective heating device in which not only the first component but also the at least one further component can be heated simultaneously. This allows the creation of an inductive heating device which is optimized in terms of installation space and which can also be operated in an energy-saving manner. Alternatively, it is of course also conceivable that an individual inductive heating device is provided for heating each component, as a result of which such heating devices can be made smaller and can also be positioned at different locations. This offers the great advantage that the joining grippers under certain circumstances have more freedom of movement and do not interfere with one another.Expediently, the device has a mounting by means of which the further joining table is mounted on the first joining table. With such a mounting, it is possible to set an exact axial distance between the first joining table and the at least one further joining table, by means of which an extremely exact axial distance between the first component and the at least one further component can also be set indirectly. By means of changes in impact of different magnitude, it is also possible to realize different axial distances.Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention. The above-mentioned components of a superordinate unit, such as a device, a device or an arrangement, which are designated separately, can form separate components or components of this unit or can be integral regions or sections of this unit, even if this is illustrated differently in the drawings.Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally the same components.They show, in each case schematically FIG. 1 shows individual method steps of a method according to the invention, FIG. 2 shows a possible embodiment of a device according to the invention.According to FIG. 1, a method according to the invention for the thermal joining of components 1, 5 on a camshaft tube 2 (compare FIG. 2 ) has a first method step A, in which a first joining table 3 and at least one further joining table 4 arranged above it are provided.In a subsequent method step B, a first component 1 and at least one further component 5 are heated, for example by means of an inductive heating device 6, as is shown in FIG. 2. The inductive heating can be carried out simultaneously in a common inductive heating device 6 or else in separate inductive heating devices 6. In method step C, a first joining gripper 7 now grasps the heated first component 1 and deposits it on the first joining table 3 and aligns it there. At the same time or at least only slightly offset in time, a further joining gripper 8 grasps the heated further component 5 and deposits it on the further joining table 4 and aligns it there.Subsequently, in method step D, a centering rod 9 (compare FIG. 2 ) moves upward through a respective component opening of the components 1, 5 and centers the components 1, 5 and, in the process, carries along a guide slide 10 together with the camshaft tube 2 in a downward direction and guides the camshaft tube 2 through the associated component openings of the respective components 5, 1. In method step E, the guide slide 10 stops at a predefined axial and in particular also radial position, whereupon the camshaft tube 2 also stops at the predefined axial and in particular also radial position. A holding time is now waiting, after which the further joining table 5 moves apart or is removed in method step F and the joining grippers 7, 8 open and the joined camshaft 11 together with the camshaft tube 2 and the components 1, 5 thermally joined thereon is thereby released and can be removed.The first component ( 1) and / or the further component ( 5) can be designed, for example, as a cam, signal generating wheel, sprocket wheel or gearwheel.According to FIG. 2, a device 13 according to the invention for the thermal joining of components 1, 5 on a camshaft tube 2 of a camshaft 11 has a first joining table 3 and at least one further joining table 4 arranged above it. Furthermore, the device 13 has a first joining gripper 7 and at least one further joining gripper 8, wherein the first joining gripper 7 can grip and position and align the heated first component 1 and the further joining gripper 8 can grip and position and align the heated further component 5. In addition, the device 13 according to the invention has a vertically movable centering rod 9 for centering the components 1, 5 and a likewise vertically movable guide slide 10 for moving the camshaft tube 2 and for pushing it through the components 1, 5.The device 13 can have an inductive heater device 6 for heating the components 1, 5, wherein the inductive heating device 6 is designed for heating or heating all the components 1, 5 or only one associated component 1, 5, wherein in the latter case a plurality of such inductive heating devices 6 are provided. A predefined axial distance a between the first joining table 3 and the further joining table 4 can be preset exactly via a mounting 12, wherein the axial distance a is measured in each case between surfaces of the joining tables 3, 4 on which the associated components 1, 5 are placed.If FIG. 2 is further considered, it can be seen that the at least one further joining table 8 is supported on the first joining table 7 via a stand 12, as a result of which a predefined axial distance a between the two joining tables 3, 4 can be set exactly. By means of the exactly adjustable axial distance a between the two joining tables 3, 4, an exactly predefined axial distance a between two components 1, 5 can be achieved after the camshaft 11 has been manufactured.The stand 12 can be present at different heights, wherein a height corresponds to the axial distance a. Due to the different height changes 12, camshafts 11 with components 1, 5 arranged thereon at different axial distances from one another can be produced comparatively easily and nevertheless exactly.All in all, with the device 13 according to the invention and the method according to the invention for thermally joining components 1, 5 on a camshaft tube 2, thermal joining that is significantly faster with respect to cycle time can be achieved, wherein at the same time waste of camshafts 11 can be reduced just as machine downtime, since, owing to the parallel joining of at least two components 1, 5, it is not necessary for the further component 5 to be thermally joined to a camshaft tube 2, on which the first component 1 has already been thermally joined and the diameter of the camshaft tube 2 thereby increases in a thermally induced manner, which reduces a joining clearance when the further component 5 is pushed on, and can lead, for example, to the digging-in of grooves on the camshaft tube 2, which can subsequently hardly be eliminated by means of post-processing.

Claims

Method for the thermal joining of components (1, 5) on a camshaft tube (2) of a camshaft (11), in which - a first joining table (3) and at least one further joining table (4) arranged above them are provided, - a first component (1) and at least one further component (5) are heated, - a first joining gripper (7) places and aligns the heated first component (1) on the first joining table (3) and at least one further joining gripper (8) places and aligns the at least one further component (5) on the at least one further joining table (4), - a centring rod (9) moves upwards through a respective opening of the components (1, 5) and centres the components (1, 5) and drives the camshaft tube (2) downwards together with a guide slide (10) in a return movement and guides it through the opening, the camshaft tube (2) stops at a predefined axial and radial position, the at least one further joining table (4) moves apart after a predefined holding time has elapsed, the joining grippers (7, 8) open and the camshaft (11) is released.Method according to Claim 1, characterized in that the first component (1) and / or the at least one further component (5) are heated inductively.Method according to claim 1 or 2, characterised in that the first component (1) and the at least one further component (5) are heated at different positions.Method according to one of the preceding claims, characterized in that the first joining gripper (7) places and aligns the heated first component (1) on the first joining table (3) and the at least one further joining gripper (8) simultaneously places and aligns the at least one heated further component (5) on the at least one further joining table (4).Method according to one of the preceding claims, characterized in that the at least one further joining table (4) is supported on the first joining table (3) via a mounting (12).Method according to one of the preceding claims, characterized in that at least one of the following components is selected as the first component (1) or as the further component (5), a cam, a signal generating wheel, a sprocket wheel, a toothed wheel.Device (13) for the thermal joining of components (1, 5) on a camshaft tube (2) of a camshaft (11), having - a first joining table (3) and at least one further joining table (4) arranged above it, - a first joining gripper (7) and at least one further joining gripper (8), - a vertically displaceable centering rod (9) for centering the components (1, 5), - a vertically displaceable guide slide (10) for moving the camshaft tube (2), - a control device (14) for carrying out the method according to one of the preceding claims by means of the device (13).Device according to claim 7, characterised in that the device (13) has an inductive heating device (6) for heating the components (1, 5).Device according to claim 7 or 8, characterised in that the device (13) has a stand (12), by means of which the further joining table (4) is placed on the first joining table (3).

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