Assembly system and method for installing a roof module into a vehicle body

An assembly system for automatic installation of a roof module in a vehicle body comprises an adhesive bonding station, in which a cylindrical dose of adhesive is applied to the inside of the roof module, and an assembly robot, whereby the roof module is then inserted into the body delivered on an assembly line. For accurate positioning and fixing of the roof module in the roof opening of the body, the assembly robot is provided with a floatingly mounted assembly tool. On the assembly tool are provided centering tools by which the assembly tool can be positioned with high accuracy relative to the roof module and the body. In addition, fixing hooks are provided on the assembly tool and permit a controlled firm pressing on the roof module into the roof opening of the body.

This application claims the priority of German application 101 43 379.4, filed Sep. 5, 2001, the disclosure of which is expressly incorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to an assembly system for installing a roof module, especially a glass roof, in a roof opening of a vehicle body delivered on an assembly line.

The use of adhesive bonding techniques for fixing vehicle roofs in vehicle bodies is known from German documents DE 40 24 837 A1, DE 44 28 913 A1 and DE 195 02 019 C1. Such adhesive connections guarantee a high degree of crash-proofing, make it possible to compensate for tolerances and ensure that the external region of the body is sealed off from the passenger compartment in a watertight manner. German document DE 40 24 837 A1 also discloses a method for adhesively bonding a sliding roof module to a vehicle body. In this method, a cylindrical dose of adhesive is mechanically and automatically applied to the roof opening of the body. The sliding roof module is then lowered onto the body; the intention is that the cylindrical dose of adhesive will be compressed by the weight of the sliding roof module and a process-proof adhesive bonding of the roof module to the body will be achieved.

However, the method described in German document DE 40 24 837 A1 is time-consuming, as the body must be stationary during the application of the adhesive and the subsequent installation of the roof module until the adhesive has set. Moreover, any error occurring during application of the cylindrical dose of adhesive to the (previously finished) body involves high secondary costs: the body concerned has to be transferred out from the assembly line and carefully cleaned.

It is an object of the present invention to provide an assembly system for the installation of roof modules in vehicle bodies that avoids the abovementioned problems.

This object is achieved, according to the invention, by the claimed assembly system for installing a roof module in a roof opening of a vehicle body delivered on an assembly line. The assembly system includes an adhesive bonding station comprising a bonding robot for applying a cylindrical dose of adhesive to an inside of the roof module, an insertion station comprising an assembly robot for inserting the roof module provided with adhesive into the body, a first handling device for supplying the roof module to the adhesive bonding station and positioning it therein, a second handling device for removing the roof module from the adhesive bonding station and supplying it to the insertion station, and a control system for controlling the bonding robot, the assembly robot, and the handling devices. A roof module installation process is also claimed.

According to certain features of the invention, the cylindrical dose of adhesive is applied not to the vehicle body but to the roof module, which is subsequently positioned with high accuracy relative to the roof opening of the vehicle body and fixed therein. The associated assembly system comprises a bonding robot which applies a cylindrical dose of adhesive to the inside of the roof module. The roof module, provided with the adhesive, is passed by means of a handling device to an assembly robot, which inserts it with accurate positioning into the roof opening of a body delivered on an assembly line. A control system is provided to control and monitor the assembly operation.

Advantageous synchronization of the method steps of delivering the body on the assembly line on the one hand and applying the adhesive to the roof module on the other hand allows a substantial saving of time to result from the assembly system according to the invention as compared with conventional assembly methods. In contrast to the conventional methods, where the assembly system according to the invention is used, the body needs to be stationary only during the insertion of the roof module. The application of the cylindrical dose of adhesive to the roof module and the delivery of the roof module, provided with the adhesive, onto the assembly line can then take place before the point at which the body is transferred by the assembly line to the installation station.

Furthermore, where the assembly system according to the invention is used, errors in the application of the adhesive, such as smearing, premature setting of the adhesive, etc., are associated with much lower costs than in the case of conventional methods: in the event of defective application of the adhesive, the roof module in question is transferred out and at the same time a new roof module is provided with adhesive and inserted into the body. This is much less costly than the outward transfer of a contaminated body from the assembly line, cleaning and return to the assembly line that are necessary in the case of the conventional methods. The transferred roof module is cleaned and delivered again, without the assembly cycle or the assembly sequence of vehicle bodies being affected thereby.

The assembly system according to the invention permits fully automated assembly of the roof module even under the very cramped conditions in the immediate vicinity of an assembly line. The roof modules are advantageously delivered to the assembly system in load carriers that contain a plurality of roof modules. In a first step, they are separated and laid in templates with the inside upwards, so that they are already in an advantageous attitude for the application of the cylindrical dose of adhesive. To fix the roof modules in this attitude, the templates are expediently provided with automatic tensioning elements (e.g. suction cups which grip onto the outside of the roof module).

In order to deliver the roof modules laid in the templates to the adhesive bonding station, the assembly system comprises a first handling device. In order to avoid soiling of the joint regions of the roof modules during transfer and handling, the joint regions are in many cases covered with protective adhesive tapes directly after production of the roof module. Before the roof modules are delivered to the adhesive bonding station, these protective adhesive tapes have to be removed in order to expose the joint regions on the roof modules. For this purposes, a fully automated stripping device can be used. In that event, the protective adhesive tapes are expediently provided with projecting gripping loops; the stripping device grips these loops and strips off the protective adhesive tapes. Alternatively, the protective adhesive tapes can be stripped off manually. In that event, for ergonomic reasons, the roof module should be tilted in order to permit easy access to the protective adhesive tapes in all marginal areas of the roof module. Therefore, in this case, a pivoting device is provided by means of which the roof module fixed on the template is pivoted through approximately 80° about its longitudinal axis; after removal of the protective adhesive tapes by an operative, the roof module is pivoted back again into its initial position.

Immediately after the removal of the protective adhesive tapes, the roof module fixed on the template—with the inside upwards—is delivered to the adhesive bonding station where cylindrical doses of adhesive are applied to the joint regions. The adhesive is applied by means of a bonding robot, which travels along a pre-programmed bonding path with the aid of a CNC control system and in so doing deposits a cylindrical dose of adhesive on the joint regions by means of an adhesive nozzle. In order to ensure process-proof application of the cylindrical dose of adhesive, the adhesive nozzle is pressed by means of a spring against the roof module. The state of tension of the spring is continuously monitored, so that a defective contact between the adhesive nozzle and the roof is detected immediately and suitable counter-measures can be taken.

After application of the cylindrical dose of adhesive, the roof module is removed from the template by means of a further handling device and delivered to the assembly robot. For this purpose, the roof module is first advantageously tilted through 180° about its longitudinal axis in order to bring it in the installation position. In this attitude, the roof module is gripped by the assembly robot, by means of which the roof module is inserted into the roof opening of the body.

The insertion of the roof module into the body has to take place with extreme precision in order to ensure a high-quality visual impression made by the finished vehicle. In particular, the roof module must be oriented with high precision in the transverse direction of the body coordinate system relative to the roof opening in order to produce uniform gaps on both sides between the edges of the roof module and the roof struts of the body, into which clip-on trim strips are introduced in a subsequent assembly step. In order to guarantee such precise positioning of the roof module in the body, it is advantageous to install the roof module by means of an assembly tool which is mounted floatingly relative to the assembly robot. The tracking movement of the assembly robot corresponds to a permanently programmed CNC path; the floating mounting then permits compensation for tolerance-induced inaccuracies in the geometric dimensions and/or position of the roof module and/or of the body delivered on the assembly line, so that precise orientation of the roof module relative to the body can be achieved.

A precondition for this is that the roof module can be received in the assembly tool in a manner such that a high-precision orientation of the roof module relative to the assembly tool is ensured. For this purpose, the assembly tool is provided with (first) centering tools, whereby centering of the roof module relative to the assembly tool is achieved. Furthermore, the assembly tool is provided with additional (second) centering tools, by means of which accurate positioning of the assembly tool relative to the roof opening of the vehicle body is achieved. Thus, the roof module is gripped in a defined position relative to the assembly tool of the assembly robot, transferred to the body and inserted there in a defined position relative to the roof opening.

Once the roof module has been inserted into the roof opening of the body, the cylindrical dose of adhesive is compressed under the dead weight of the roof module. Experience suggests that it is extremely difficult here to dimension the quantity of adhesive applied or the distance between the regions of the roof module and of the roof opening to be bonded in such a way that the roof module sinks under its dead weight into the vehicle body in a process-proof manner and by exactly the right distance. In order to achieve a high-precision vertical orientation of the roof module relative to the roof opening, it is therefore advantageous to increase the size of the quantity of adhesive to be applied (or reduce the size of the distance between roof module and roof opening in the connection region) and to press the roof module with additional force while it is being inserted into the roof opening. For this purpose, the assembly tool is provided with fixing hooks which—after the roof module has been inserted into the vehicle body—engage into the window openings of the body and pull down the assembly tool to a level relative to the body roof that has been previously defined with high precision. In this manner, a reproducible vertical orientation of the roof module relative to the surrounding body roof can be achieved. The exertion of force by means of the fixing hooks is typically maintained for a few seconds until initial setting of the adhesive takes place and the roof module is fixed in that position.

In order to carry out a rapid quality control on the bodies—especially at the start of line production or in the event of equipment or design modifications—in relation to the size of the gaps between roof opening and roof module, it is advisable to provide the assembly system with a sensor system for detecting relevant measured parameters of the body and the roof module. Particularly advantageous is the use of optical sensors—for example, light-section sensors—by means of which a rapid contact-free detection and analysis of the gap sizes can be carried out before insertion of the roof module has ended; in the event of defective insertion, the position of the roof module can be adjusted immediately—i.e. before the adhesive has set—with the aid of the assembly tool.

The assembly system is particularly suitable for use on assembly lines on which different versions of motor vehicles are assembled, only selected motor vehicles needing to be provided with a roof module to be installed in the course of assembly whereas other vehicles have already been provided with a (welded-in) solid roof at the carcass stage. In order to ensure a smooth assembly of the different versions, it is advantageous to feed early information to the control system of the roof module assembly system on the points within the assembly sequence where vehicle bodies are present which have to be fitted with a roof module. This permits prompt commencement of the application of adhesive to the roof module to be inserted at the same time as the body in question is being delivered to the assembly line, so that the body reaches the assembly station at the same time as the adhesive-coated roof module. As a result, the time requirement associated with the bonding-in of the roof module is minimized. Furthermore, the adhesive is here prevented from being applied to the roof modules too early (or at the wrong time), which can result in setting of the adhesive before the roof module has been inserted into the body and hence increased reject rates or remedial work.

In an advantageous embodiment of the invention, the bodies are provided on the assembly line with electronically or optically readable mobile data storage media which contain information on the equipment of the particular vehicle body. The data from these mobile data storage media are read out with the aid of a sensor located at a suitable distance from the roof module assembly station at the edge of the assembly line and transmitted to the control system of the assembly system which analyses them to determine whether or not the installation of a glass roof is necessary. If a data set reaching the control system contains the requirement that a roof module is to be inserted, the control computer triggers the application of adhesive and the delivery of the roof module so that the roof module reaches the assembly station (as nearly as possible) simultaneously with the body.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a system layout of an assembly system1according to the invention for the installation of roof modules2in vehicle bodies3. The vehicle bodies3are delivered to the assembly system1on an assembly line4, whose direction of movement is indicated by an arrow5in FIG.1.

The roof modules2are supplied to the assembly system1on load carriers (not shown in FIG.1), in each of which a plurality of roof modules2are contained, stacked one above the other in the installation position. In the case of complex roof modules2(for example, glass sliding roofs) each load carrier typically contains from six to ten roof modules2, which are stacked one above the other in the installation position on the load carrier. By means of a first handling device6the roof modules2are delivered to an adhesive bonding station7in which their insides8are provided with cylindrical doses of adhesive16. For this purpose, in a first method step, the roof modules2are unstacked from the load carriers and introduced individually into mobile templates9. This unloading may take place manually or with the aid of an automated unstacking device (not shown in FIG.1).

Advantageously, the roof modules2—if they are delivered in the installation position—are tilted through 180° about their longitudinal axes in the course of their removal from the load carriers, so that they are each laid in the templates9with the inside8upwards. This has the advantage that the roof modules2are then already in an attitude favorable for the application of the cylindrical dose of adhesive.FIG. 2shows a detailed view of the inside8of a roof module2laid on a template9. For the exact positioning of the roof module2, the template possesses stops10, which are shown diagrammatically in FIG.2. To fix the attitude of the roof module in the template9, the latter is also provided with tensioning elements11(for example, suction cups, which engage on the outside of the roof module, or alternative elements engaging on the edge39of the roof module2). To move the templates9, use is made of a fully automatic conveyor device12, by means of which loaded templates9are fed to an adhesive bonding station7in a selected sequence, moved singly into and out of waiting positions and transferred back again in the unloaded state into the starting position, where they stand ready to receive a new roof module.

As is shown inFIG. 2, the inside8of the roof module2possesses joint regions13, in the region of which cylindrical doses of adhesive are to be applied; these joint regions are shown by hatching in FIG.2. In the present embodiment, a peripheral joint region13′ is provided on the roof module2; the cylindrical dose of adhesive16′ to be applied in this region, indicated by broken lines inFIG. 2, both fixes the roof module2in the roof opening24and seals the interior of the vehicle against the external environment. Furthermore, an additional joint region13″ is provided both at the rear and at the front in the direction of the vehicle; in this region13″ a supporting cylindrical dose of adhesive16″, indicated in broken lines inFIG. 2, is applied, whereby increased stability and rigidity of the complete body3is achieved. The cylindrical doses of adhesive16′,16″ may be of one-piece form or may consist of a plurality of partial doses.

The roof modules2delivered are provided in the joint regions with protective adhesive tapes14which are intended to protect these regions13from soiling during transfer. Before the cylindrical doses of adhesive16are applied to the roof modules, these protective adhesive tapes14are manually removed. For this purpose, the roof module2is pivoted in a pivoting station15, together with the template9, through approximately 80° about its longitudinal axis; when this occurs, the inside8of the roof module2is turned towards the operative responsible for stripping off the protective adhesive tape14, so that the regions of the adhesive tapes14are easily accessible to the operative. The stops10and/or the tensioning elements11ensure here that the roof module2does not unintentionally slip out of the template9during the swinging. The operative now strips off the protective adhesive tapes14. Thereafter, the roof module2is pivoted back again into its starting position and fed to the adhesive bonding station7. As an alternative to the protective adhesive tapes14, the joint regions13may also be masked, for example, by a protective layer sprayed on as a liquid (for example, a PVC composition) which must be removed before the (manual or mechanical) application of the adhesive.

In the adhesive bonding station7, cylindrical doses of adhesive16are applied to the joint regions13on the inside8of the roof module2. For this purpose, a (five- or six-shafted) bonding robot17is used, which deposits the cylindrical dose of adhesive16via an adhesive nozzle18on the joint region13(see FIG.3). In the embodiment shown inFIG. 1, a second (replacement) bonding robot17′ is also provided in addition to this (main) bonding robot17; this bonding robot17′ serves as a back-up in order to prevent failure of the complete system1as a result of failure of the (main) bonding robot17.

The bonding robot17follows a programmed-in CNC path which corresponds to the desired position of the cylindrical doses of adhesive16on the inside8of the roof module2. The outlet aperture18′ of the adhesive nozzle18has a triangular profile and is pressed by means of a spring19onto the inside8of the roof module2.

This spring19guarantees a permanent contact between the adhesive nozzle18and the roof module2(and hence a uniform profile of the cylindrical dose of adhesive16) and simultaneously permits the monitoring of the adhesive bonding process. By means of a sensor56, which in the example shown inFIG. 3is in the form of an inductive proximity sensor, the vertical deviation57of the adhesive nozzle18relative to a stop58on the bonding robot17is continuously checked. If the vertical deviation57differs from a predetermined target value (for example, because of an absence of contact between the adhesive nozzle18and the roof module2), this is immediately detected by the sensor56. Advantageously, a warning signal is triggered in such a case, so that suitable counter-measures (replacement of the adhesive nozzle18, correction of the attitude of the roof module2, etc.) can be taken.

After application of the cylindrical dose of adhesive16, the roof module2is removed from the mobile template9by means of a second handling device20and passed to an insertion station21. In the present embodiment, the roof module2is tilted through 180° about its longitudinal axis by means of the handling device20and inserted, in the installation position, into a transfer template22, from which it is them picked up by an assembly robot23which inserts the roof module2into the roof opening24of the body3. The mobile template9is transferred back by means of the conveyor device12to the starting position and held available there to pick up a further roof module.

The assembly robot23carries an assembly tool25for the high-precision gripping, positioning and fixing of the roof module2in the roof opening24of the body3. During pick-up of the roof module2from the transfer template22and transfer of the roof module2, the assembly tool25is in a fixed position relative to the assembly robot23, which follows a programmed-in CNC path. The transfer template22for transferring the roof module2is floatingly mounted relative to the factory floor by means of roller bearings, so that dimensional inaccuracies of the roof module2can be compensated during pick-up of the roof module2by the assembly tool25by means of horizontal movements of the transfer template22. For the high-precision pick-up of the roof module2, the assembly tool25is provided with centering tools27, whose function is described below. During the insertion of the roof module2into the body3, the assembly tool25is floatingly mounted relative to the assembly robot23; this floating mounting permits flexible high-precision positioning of the assembly tool25relative to the roof opening24with the aid of further centering tools27′, whose function is likewise described below.

FIG. 4ashows a detailed view of the side of the assembly tool25facing the roof module2; the outer edging39of the roof module2is indicated by a broken line in this figure.FIG. 4bshows a section in the transverse direction of the vehicle through the assembly tool25, the roof module2and the roof opening24of the vehicle body3.

For lifting and transferring the roof module2, the assembly tool25is provided with vacuum suction cups26, which permit controlled raising and dropping of the roof module2. Furthermore, the assembly tool25is provided with a (first) pair of centering tools27, which—as described below—permit positionally accurate reception of the roof module2in the assembly tool25. Each centering tool27comprises a rotating element28, which is fixed on the assembly tool25to rotate about a center of rotation29. Two arms30are fixed on each rotating element28to be freely rotatable, the articulation points31of the two arms30on the rotating element28being diametrally opposite to one another and being at the same distance from the center of rotation29. At the ends of the arms30remote from the rotating element28are fixed, in a freely rotatable manner, rollers33(or mouldings of any desired shape, especially adapted to the marginal contour39of the roof module2). The lengths of the two arms30of each centering tool27and the radii of the two rollers33are so dimensioned that the distances34between the regions of the rollers33lying nearest to the center of rotation29and the center of rotation29on each arm are of identical length. As a result of a controlled rotation of the rotating element28, the distances34between the regions of the rollers33lying nearest to the center of rotation29and the center of rotation29—and hence also the distances apart of the rollers33—can be selectively varied.

In addition, the assembly tool25possesses a further (second) pair of centering tools27′, which—as described below—serve for the positionally accurate positioning of the assembly tool25relative to the roof opening24of the body3. Their structural form corresponds to that of the centering tools27, and their centers of rotation29′ are located on the axis35extended by the two centers of rotation29(of the first pair of centering tools27). The effect of this is to ensure that the alignment by means of the first centering tools27and the alignment by means of the second centering tools27′ always take place in accordance with the same axis35. For details of the structure and mode of operation of the centering tools, reference is made to German application DE 198 17 056 A1, the content of which is hereby incorporated by way of reference into the present application.

In addition, the assembly tool25disposes of four fixing hooks36, by means of which the roof module2is selectively pressed into the roof opening24of the body3after installation, in order to ensure precise vertical adjustment and a process-proof adhesive bonding of the roof module2in the roof opening24. The fixing hooks36are fixed via pivots41on the assembly tool25, the pivot axes42extending approximately parallel to the longitudinal axis of the vehicle. During the gripping of the roof module2in the transfer template22, during the transfer to the vehicle body3and during the positioning of the roof module2in the roof opening24, the fixing hooks36—as indicated in broken lines inFIG. 4b—are swung out laterally over the assembly tool25in order to avoid reductions of available space. Each fixing hook36is mounted relative to the assembly tool25via a controllable hydraulic or pneumatic pressure cylinder47; by means of this cylinder47—as indicated by arrows38inFIG. 4b—the fixing hooks36can be displaced in the vertical direction relative to the assembly tool25.

A description is given below of the individual steps during removal of the roof module2from the transfer template22and subsequent insertion into the body3.

First, the assembly tool25is lowered onto the roof module2laid in the transfer template22. The assembly tool25is at this time fixed in a firm attitude (in other words, not floating) on the assembly robot23. The fixing hooks36are swung away upwards in order to prevent collisions between fixing hooks36and roof module2. Furthermore, the angular position of the rotating elements28,28′ of the centering tools27,27′ is set so that the rollers33,33′ project laterally beyond the edges39of the roof module2. Now the two rotating elements28of the first centering tools27are rotated in a controlled manner in the direction of the arrow40(FIG. 4a), as a result of which, on each of the two centering tools27, the distance34of the rollers33from the respective centers of rotation29is reduced. As a result, the transfer template22mounted floatingly relative to the factory floor is rotated (together with the roof module2fixed thereon) relative to the assembly tool25. The rotating elements28are rotated until all rollers33lie on the edges39of the roof module2, so that no further rotation is possible; the roof module2is then so oriented relative to the assembly tool25that the axis of symmetry of the roof module2coincides with the axis35of the two centers of rotation29on the assembly tool25. In this position, the suction cups26are activated, so that the roof module2is now fixed in that orientation relative to the assembly tool25. The centering tools27can then be swung out of the plane of the roof module2in order to avoid reductions of available space during the installation of the roof module2in the roof opening24.

The roof module2aspirated against the assembly tool25is now raised out of the transfer template22and transferred to the vehicle body3delivered by the assembly line4. During the installation of the roof module2, the body3is lifted out of the assembly line4in a defined position, so that it is in a stationary position relative to the assembly robot23. The assembly tool25, mounted floatingly relative to the assembly robot23, with the roof module2fixed thereon, is now oriented with high precision relative to this stationary body3. During this orientation, the roof module2—as shown inFIG. 4b—is raised in the vertical direction relative to the body3, so that the cylindrical doses of adhesive16do not contact the flanges44of the roof opening24that lie opposite to them.

For the centering of the assembly tool25(and hence also of the roof module2) relative to the body3, the centering tools27′ are used. The rotating elements28′ of these centering tools27′ are first located in a position of rotation in which the rollers33′ and the end of each arm30′ rest on the roof edges39(seeFIG. 4b), so that the rollers33′ can be introduced between the two roof struts45of the body3. The two rotating elements28′ are then rotated in a controlled manner in the direction of the arrow40′ (seeFIG. 4a). When this occurs, the two arms30′ are moved into an extended position and the rollers33′ (or mouldings) are splayed away from the center of rotation29′ until all rollers33′ rest on the insides46of the roof struts45. The assembly tool25with the roof module2fixed thereon is then positioned between the roof struts in such a way that the axis35of the centers of rotation29,29′ (and hence also the axis of symmetry of the roof module2) are disposed precisely centrally relative to the roof struts45.

In this orientation, the assembly tool25is lowered onto the vehicle body3. The cylindrical doses of adhesive16are so dimensioned here that the roof module2sinks incompletely into the roof opening24under its own dead weight, in other words so that the edges39of the roof module2project in the height direction (vertical direction) beyond the roof struts45.

Whereas in the embodiment shown inFIGS. 4aand4bthe first pair of centering tools27(for orienting the assembly tool25relative to the roof module2) and the second pair of centering tools27′ (for orienting the assembly tool25relative to the roof struts45) represent separate components, the two functions can also be combined in a single pair of centering tools27″. These centering tools27″ have the same structure as the centering tools27,27′. For the orientation of the assembly tool25relative to the roof module2, they are placed under tractive stress (in the direction of the arrow40inFIG. 4a), whereas for orientation of the assembly tool25relative to the roof struts45they are placed under compressive stress (in the direction of the arrow40′ inFIG. 4a).

After the lowering of the roof module2onto the flanges44of the roof opening24, in a subsequent step the roof module2is now pressed into the roof opening24of the body3to the desired depth by means of the assembly tool25. For this purpose, the fixing hooks36are swung into the window openings37of the body3about their pivot axes42. The pressure cylinders47of the fixing hooks36are then subjected to pressure, so that the fixing hooks36are pulled in the direction of the assembly tool25and forces build up between the upper sides48of the fixing hooks36, engaging into the window openings37, and the assembly tool25, which forces pull down the assembly tool25onto the body3and so press the roof module2into the roof opening24of the body3.

The forces applied by the pressure cylinders47are adjusted by means of force adjusters which guarantee that the roof module2is pressed into the roof opening24with the same force by all fixing hooks36. Alternatively, sensors may be provided, by means of which the height of the roof module2relative to the body3is detected; the force of the four pressure cylinders47is increased repeatedly until such time as the desired height of installation is reached. In this position, the fixing hooks36hold the roof module2for a few seconds in order to ensure fixing of this installed position.

In addition to the sensors by means of which—as mentioned above—the height of the inserted roof module2by comparison with the roof opening24can be measured, further sensors49are provided in the assembly system1which serve to verify the correct position of the roof module2in the roof opening24; these sensors49serve in particular to measure the gap dimensions between the outer edges39of the roof module2and the inner edges46of the roof struts45. The measurement takes place immediately after insertion of the roof module2into the roof opening24. In the event of defective insertion, the position of the roof module2can be readjusted immediately—in other words, before setting of the adhesive—by means of the assembly tool25. Alternatively, inaccuracies in the insertion of the roof module2may be corrected manually. Optical light-section sensors are used as the sensors49. They permit rapid, contact-free online measurement; the measured results are in electronic form and can be used directly as a control parameter for automatic correction of the position of the roof module2.

After installation of the roof, the vehicle body3is moved away in the direction of the arrow5by means of the assembly line4. In addition to the automatic insertion station21, a trolley conveyor60is also provided, by means of which the roof modules2provided with adhesive are manually transferred to the assembly line4and can be manually introduced there into the body3.

The control of the assembly system1is provided by means of a control system50, which controls the individual steps of the individual components of the assembly system1and matches them to one another.

In particular, by means of the control system50, the individual steps for the application of adhesive to the inside8of the roof module2on the one hand and the passing of the body3to the insertion station21on the other hand are so coordinated in time that synchronization of these operations is achieved. As a result of a prompt commencement of the application of adhesive it is possible to ensure that the roof module2, provided with cylindrical doses of adhesive16, is gripped and raised by the assembly tool25at exactly that point in time at which the associated body3on the assembly line4enters the insertion station21. In order to achieve this, a sensor52is provided at a point51in the assembly line4upstream of the roof module assembly system1, by means of which sensor52the arrival of a body3at that point51is detected. A measurement signal from the sensor52then triggers the start of the adhesive application operation.

It is often necessary, in addition to the bodies3which are to be provided with a roof module2in the course of assembly, also to assemble on the same assembly line4bodies3′ in which no roof module is to be installed (because, for example, they already have a solid roof2′). In this case, the bodies3,3′ are provided with electronic data storage media53, on which the equipment of the respective body3,3′ is stored. The sensor52provided on the assembly line4is then so designed that it reads the data from the electronic data storage medium53. From these data, it is determined whether a solid roof2′ has already been installed in a body3,3′ which is passing the sensor52at that time or whether a roof module2is to be installed. If a roof module2is to be installed, the application of adhesive to a roof module2and the subsequent installation of the roof module2in the body3are triggered via the control system50. If this is not the case, the preparation of the roof module for the body3′ in question is omitted. The positioning of the sensor52relative to the assembly system1depends upon the speed of the assembly line4and on the lead time necessary for the preparation of the roof module2to be installed (for feeding it to the adhesive bonding station7, applying the adhesive and transferring it to the assembly tool25). Advantageously, a further sensor59(for example, a light barrier) is provided to check the bodies3, by means of which a check is conducted to determine whether the particular body3delivered already has a (fitted) roof; in this case, the control system50receives a pulse that suppresses the installation of a (possibly incorrectly prepared) roof module2.

As an alternative to the use of the sensor52for detecting the assembly sequence, the assembly sequence may also be stored in a production control system55and transmitted by that production control system55to the control system50of the assembly system1.

The control system50also monitors the period elapsing between the start of application of adhesive to the joint regions13of the roof module2and the insertion of that roof module2into a vehicle body3to ensure that the “potlife” of the adhesive is not exceeded. The potlife depends, inter alia, on the chemical composition and processing temperature of the adhesive used and described the interval of time within which the adhesive must be used up after its emergence from the adhesive nozzle18in order to achieve sufficiently good adhesion properties. If the potlife is exceeded on a particular roof module2(for example, because of a breakdown of the assembly line4or because of the outward transfer of a vehicle body3), the roof module2in question is singled out; if appropriate, a new roof module2is prepared immediately and is then bonded into the next body3instead of the singled-out roof module2. The singled-out roof module2is initially laid on a standby support54and can subsequently be cleaned and reused.

The control system50continuously monitors the interval of time since the last release of adhesive from the adhesive nozzle18of the bonding robot17. If that period exceeds a particular, preset maximum value, a cylindrical dose of adhesive of a predetermined length is emitted from the adhesive nozzle18and disposed of immediately. This is particularly important if several body variations3,3′ are being transported on the assembly line4, only some of which are to be provided with a bonded-in roof module2; in this case, such a long time may elapse between two consecutive modular roof requirements that the adhesive hardens in the adhesive nozzle18, which may result in the blocking of the adhesive nozzle18and/or reduced adhesive quality.

In addition, the control system50monitors the buffer stock of unstacked roof modules2, in other words the number of mobile templates9loaded with a roof module2. If the control system50detects insufficient coverage, a signal is emitted which alerts the machine supervisor to the fact that additional roof modules2require loading. If different roof modules are available for installation, depending on the version to be produced, a check is carried out prior to the delivery of each new body3to determine whether a roof module2corresponding to the required version is being held ready in one of the mobile templates9; that template9is then transferred in so that the roof module2in question is delivered to the insertion station21in synchrony with the arrival of the body3.

Whereas only the installation of a single version of the roof module2in the bodies3passing on the assembly line4has hitherto been considered, it is fundamentally possible, with the roof module assembly system1described above, to fit different types and versions of roof modules. Thus, for example, a glass roof may be inserted into a first delivered body3while a slatted roof of the same length/breadth is installed in a second body3and a solid roof of the same length/breadth in a third body3. In this case, different roof versions2are held ready in the templates9and, as required, are transferred by the first handling device6to the adhesive bonding station7, provided with adhesive and inserted into the body3at the insertion station21. In order to prepare the roof module2needed in each case promptly, the version of the body3arriving is detected sufficiently ahead of time by means of the sensor52located on the assembly line4and reported to the control system50; the control unit50then triggers the inward transfer of a template9loaded with the desired roof type, so that the roof module2required arrives at the right time at the adhesive bonding station7and the insertion station21.