HK1118501B - System for welding motor-vehicle bodies - Google Patents

Description

System for welding motor vehicle bodies

Technical Field

The present invention relates to a system for welding structures consisting of stamped sheet-metal elements, such as motor vehicle bodies or their subcomponents, said system being designed to operate on a plurality of different types of structures to be welded (for example bodies of different models of motor vehicles, or bodies of different types of motor vehicles, such as dining cars, station wagons, vans, etc., of the same model, or, moreover, individual subcomponents of different models of motor vehicles, such as floors or sides, for example).

Background

Some systems of the above type are known (see, for example, GB- ｃA-2172555 and EP- ｃA-0642878 in the name of the present applicant) which comprise:

-a welding station;

-a transfer line for transferring the structure to be welded or at least a part thereof through a welding station; and

a plurality of pairs of side frames provided with means for clamping the structure to be welded during welding and guidable along the conveying line, the clamping means being provided on the side frames of each pair and matching the configuration of the respective type of structure to be welded.

In the known system described above, the side frames are movable on guides arranged laterally of the conveying line, so as to effect the displacement of a pair of side frames arranged close to the welding station, according to the type of structure to be welded. Each side frame is movable between a first position proximate to the welding station and at least a second position relatively remote from the welding station.

Furthermore, when each pair of side frames is in the above-mentioned first position proximate to the welding station, it is movable between an open condition and a closed condition, in the latter of which the clamping device of the respective side frame is operable to clamp the welded structural portion in the welding station into the welding configuration. The system also includes means for moving the sideframe between the respective first and second positions.

In order to facilitate the use of different types of side frames, it is also known to equip the system with a magazine of one or more side frames, each comprising one or more parking stations (with reference to the direction of advance along the work line) both upstream and downstream of the welding station, each station comprising a track portion designed to support the side frame in a sliding manner.

Due to the pre-arrangement of the storage magazine of the side frames, it is possible for one station to operate in a flexible manner on many different types of structures being welded.

The object of the present invention is to further improve the known systems by further increasing their flexibility and the production capacity of the line. A further object is to provide a system that can achieve the above object in a relatively simple and reliable way.

Disclosure of Invention

In order to achieve the above and further objects, the subject of the invention is a welding system of the type already described above, further characterized in that it comprises auxiliary guide means directly connecting at least one rail portion of the magazine located upstream of the welding station with a rail portion of the magazine located downstream of the welding station, so as to facilitate the transfer of the side frames directly from the upstream magazine to the downstream magazine and vice versa.

Thanks to the above features, it is possible to ensure, during the operation of the welding station, whatever the continuity of the different types of structures being welded, which are in any operating condition and in particular advance through the welding station, the system will always be able to find at a time a pair of side frames which must be in the most advantageous position to achieve that the respective structure being welded reaches this working position before it reaches the station, so as to ensure that there is no dead time for the prearrangement of the frames which must be in the welding position, and to replace the previous side frame with a new pair of side frames whose replacement time must not exceed the replacement time of the welded body at this station, when a member of a type different from the previous one enters the welding station.

Drawings

The invention will be described in conjunction with the appended drawings, in which:

fig. 1 is a schematic view of a first example of an embodiment of a system according to the invention; and

fig. 2 is a perspective schematic view of a variation of the system of fig. 1.

Detailed Description

Figure 1 shows ｃA welding system for motor vehicle bodies, which corresponds to ｃA large extent to the system known from the previous european patent application No. ep- ｃA-1611991, filed in the name of the present applicant.

The system comprises a welding station 1 arranged along a conveying line (indicated only schematically by arrow 2) for conveying welded bodies through the welding station 1. The welding station 1 is not shown in detail, since it has a concept that is generally known, except for some of its specific innovative aspects, which will be described below. The welding equipment provided in the welding station 1 can be constituted by robots of known type, the control unit of which comprises a set of different operating programs, each time selected according to the type of body to be welded.

The transfer line 2 and the means along which the movement of the bodies is obtained are assumed to be of any known type, said elements not being shown in the figures, as long as they do not belong to the scope of the present invention. Their removal from the drawings also renders the latter more directly understandable. It is obvious in any case that the way in which the bodies to be welded are formed in the welding station can be of any type. For example, the body can be completely preassembled upstream of the welding station in a temporary manner. Otherwise, the different sub-components forming the body are conveyed on the conveying line 2, in an as yet unassembled condition, to the welding station, where they are assembled themselves before welding is carried out. Alternatively, the conveying line 2 conveys only the body parts, such as the floor, into the welding station, in which the assembly of the complete body is carried out in such a situation when the remaining parts of the body that reach here are obtained. Furthermore, the system of the invention can of course also be used for welding individual sub-components of a vehicle body, or in theory also for any other type of welded sheet metal structure manufactured in different types or models or patterns. Regardless of the manner in which the bodies are assembled, when the bodies are subjected to a welding operation in the welding station 1, the parts of each body must be clamped in a precise position. The clamping is achieved by means of a positioning and clamping tool which can be carried by pairs of side frames operatively interchangeable with each other, indicated in fig. 1 by 3a, 3b, 3c and 3d, which can be operated on longitudinal bottom rails or rails 4. In the case where a detailed description of the operation of the system according to the invention is not absolutely necessary, the side frames 3a, 3b, 3c and 3d will be identified only by reference numeral 3.

In the illustrated condition, the rails 4 extend parallel to the line 2 for conveying the bodies, and the rails 4 are fixed directly to the floor, except for their respective intermediate portions, indicated by 4a, provided in a position corresponding to the welding station 1. As will be apparent from the following, the portion 4a of the rail 4 is able to translate in a direction substantially perpendicular to the longitudinal development of the rail itself for carrying the pair of side frames 3 in use in the respective closed condition into the welding station 1.

The pair of frames 3 can be moved along the rails 4 to transport the pair of side frames corresponding to the type of body being welded into a position equivalent to the welding station 1. The side frame pairs located at the welding station can be rapidly replaced by sliding on the respective rails 4 immediately before the body arrives at the welding station 1, of a type different from the type of body that the welding station has directly operated, as will appear from the following description.

In order to enhance the flexibility of the welding station and in particular to increase the number of different types of bodies that can be operated by the welding station, in the case of the example, two frame stores are provided, respectively upstream and downstream of the welding station (with reference to the direction of advance along the firing line 2). Each of the two frame stores comprises a series of stations 6a and 6b arranged on either side of the transfer line 2 and the rail 4, wherein each station comprises a rail portion 7 having a shape similar to the rail 4 and is thus designed to support the respective side frame in a sliding manner. In the illustrated case, the rail section 7 extends substantially parallel to the rail 4.

In the example illustrated, the upstream and downstream repositories each have two sections of repositories on either side of the transfer line 2, each section comprising three distinct stations 6a, 6b corresponding to the maximum total of six different types of frame 3 operating on the same number of body types. Of course, in any case, both repositories can be provided with a number of parking stations, with the limitations shown below.

The different frames 3 carry, in a per se known manner, respective positioning tools (not shown) for clamping, designed to engage the sides and the top of the body in such a way as to clamp it in a precise position during the execution of the welding operation in the welding station 1. The bottom of the body is instead clamped with other positioning means for clamping, previously provided on the bottom of the welding station 1. Each pair of side frames 3 is provided in particular with positioning means for clamping, which are adapted to the specific structure of the respective type of bodywork.

During use of the system, each time on the rails 4 is placed a first pair of side frames 3 in the working position, which correspond to the type of car body each time placed in the welding station 1, and a second pair of side frames 3 in the waiting position, which correspond to the type of car body to be welded immediately thereafter. When a following vehicle body enters the welding station 1, the first frame 3 is conveyed to a waiting position and the second frame 3 is conveyed into a working position with simultaneous movement in the longitudinal direction along the guide rails 4.

Arranged in positions corresponding to both longitudinal ends of the guide rail 4 are respective translatable guide rail elements 8a, 8b having a shape of the type of the guide rail 4. The translatable guide rail elements 8a, 8b are equipped with respective motor drives 9 to be able to move between a first position and a plurality of second positions, in a direction perpendicular to the longitudinal extension of the guide rail 4, for example laterally on respective pairs of guide rails 10a, 10 b. In the first position described above, each translatable guide rail element 8a, 8b is longitudinally aligned with a respective guide rail 4 so as to constitute an extension thereof. By means of the above-mentioned transverse translation, each extension 8a, 8b can enter a position corresponding to the corresponding parking station 6a, 6b, i.e. to the guide rail portion 7.

Moving the different pairs of side frames 3 can be implemented in a number of ways. In a first embodiment corresponding to what is shown in fig. 1, the movement of the different pairs of side frames 3 can be achieved by means of independent tractors, each of which can cooperate with a different side frame 3 in order to pick them up from the respective station 6a and 6b and bring them into the working position corresponding to the position of the station 1, and vice versa. In the example shown in fig. 1, two pairs of tractors, indicated by 11a and 11b, are provided, which can be selectively connected to different side frames.

The welding system described above corresponds to what is shown in the previous european patent application No. ep- ｃA-1611991, filed in the name of the present applicant. The general operation of the system will be described hereinafter. We assume that in the welding station 1 there is a body of a first type, called type a, part of which is clamped in a precise position during the welding operation by positioning means carried by a pair of side frames 3 a. The bodies located in the welding station 1 are followed by a second type of bodies, called type B, in which positioning tools, predisposed to clamp different portions of the type B bodies, are predisposed on the pair of side frames 3B during the execution of the welding. Likewise, we will assume that a body of type B is followed by a body of the third type C, and then by a body of the fourth type D, each of which is associated with a respective type of side frame 3C and 3D.

The replacement of one body with a different type of body in the welding station 1 is accompanied by the replacement of a pair of side frames used by the station itself along the rails 4 in such a way as to bring one pair of side frames 3 into a waiting position and the other pair of side frames 3 into a working position corresponding to the welding station.

Once each pair of side frames has reached the working position, it can be moved between an open condition, in which the entry of a new welded body into the welding station 1 is effected, and a closed condition, in which the positioning tools of the side frames engage the sides and the top of the body to clamp them in a precise position. As mentioned above, the above movement is achieved by translation of the portion 4a of the guide 4. The clamping of the side frame 3 in the closed condition with respect to the welding station is achieved by means known per se.

In fig. 1, the vehicle body advancing along the line is not shown for clarity. As soon as the bodies of types a and B advance along the line, they are welded each time after the previous longitudinal sliding of the two pairs of side frames 3a and 3B in such a way that one of said pairs reaches the working position and the other one enters the waiting position (upstream and downstream of the welding station, respectively). In the situation shown in fig. 1, the two side frames 3a are in the working position, which means that the car body in the welding position is a type a car body. If, for example, a body of type C is to be welded behind said body, the two side frames 3b do not remain stationary in the waiting position, but instead advance longitudinally along the guide rails 4 up to the position shown in fig. 1. In said condition, the rails 8b are moved laterally along the rails 10b until they are aligned with the respective rails 7 of the two stations 6b of the magazine. In this way, the side frame 3b can be brought into the inactive position in the magazine, after which the rail portions 8b are aligned with the portions 7, which wait for the side frames 3 c. Thus, the sideframes 3c can be loaded onto the track sections 8b, which again move laterally until they are aligned with the tracks 4. In this way, the side frames 3C can be moved into the waiting position, immediately downstream of the welding station, so that at the end of the welding of the bodies of type a they are ready to be translated longitudinally along the rails 4 and moved into the working position for intervention in the bodies of type C entering the welding station.

As already described, the above structure and operation are known from the previous european patent application No. ep- ｃA-1611991, filed by the applicant's name. The embodiment of the invention shown in fig. 1 differs from previously known applications in that in the example shown, the repositories arranged upstream and downstream of the welding system are directly connected together by a rail section 70. In the particular example shown, only two rail sections 70 are provided, which connect the two rail sections 7 together on both sides of the welding station. However, it is not excluded to provide a larger number of connecting portions 70 for connecting more than two rail portions 7 together. As can be seen, the prearrangement of the track portions 70 enables the transfer of the side frames from the upstream magazine of the station directly to the downstream magazine, or vice versa, without the need to transfer the side frames through the longitudinal tracks 4 arranged on both sides of the welding station, the track portions 70 being directly connected together with the track portions 7 belonging to the storage silos arranged upstream and downstream of the welding station. In other words, the guide rail line 70 is provided to constitute a bypass with respect to the longitudinal guide rail 4. Said solution allows a considerable increase in the productivity of the system and in particular again ensures the possibility of quickly positioning a pair of side frames in the working position, whether said side frames are arranged in any station of the storage magazine.

Fig. 1 relates to an example, as in the previous patent application filed in the name of the applicant, in which the movement of the side frames is effected by means of separate tractors 11a, 11b, which can be moved on the rails 4 and rail portions 7 and can be engaged with the side frames.

Fig. 2 shows a similar welding station, where each side frame is provided with its own independent motor drive. Also in the example of fig. 2, the robot R carrying the welding heads required for each welding operation carried out on the bodies located in the welding station is not shown, and the bodies advancing through the welding station shown are also not shown. Fig. 2 shows in particular a situation in which two pairs of side frames are provided along the rails 4 at both sides of the line, all remaining types of side frames being provided in a magazine downstream of the welding station. In the case of the example shown in fig. 2, a total of four pairs of side frames are again provided that can operate on four different types of vehicle bodies. In the example shown in fig. 2, the type a vehicle body is located in the welding station, engaged by the pair of frames 3a, while the pair of side frames 3d is waiting. The upstream magazine is completely empty, and the side frame 3b in the downstream magazine is in the process of being transferred from the downstream magazine to the upstream magazine via the rail portion 70.

Fig. 2 then differs from fig. 1 in that in the system shown therein no frame 3 is transported by a self-propelled cart.

As shown, the principle underlying the present invention consists in creating a direct connection between the magazine upstream of the welding station and the magazine downstream of the welding station, so as to make it possible to transport directly the side frames provided in one of said magazines into the other magazine and vice versa, without having to pass through the rails 4 provided at both sides of the welding station.

Of course, the details of construction and the embodiments may vary widely with respect to what is described and illustrated herein without departing from the principles of the present invention.

In particular, the structure, construction and operation of the welding station may also differ from what is described above, and this is also true of the number, construction and arrangement of the side frame stores.

Claims (3)

1. A system for welding a structure made of pressed sheet-metal elements for motor vehicle bodies or sub-components, the system being adapted to operate on a plurality of different types of welded structures, the system comprising:

a welding station;

a transfer line for transferring the welded structure or at least a portion thereof through the welding station;

a plurality of pairs of side frames (3) provided with means for clamping the structure to be welded, the clamping means on each pair of side frames being adapted to the respective type of construction of the structure to be welded,

wherein the pairs of side carriages are movable at both sides of the line on the longitudinal main guide (4) between a work position at the welding station and either of two waiting positions, which are longitudinally spaced apart from the work position and are respectively upstream and downstream of the work position,

so that the respective pairs of side frames can be arranged at the working positions in the welding station according to the type of structure to be welded,

wherein a given pair of side frames is also movable between an open position and a closed position when in said operative position at the welding station, in the closed position said given pair of side frames being operable to clamp portions of a welded structure in a welding configuration at the welding station (1),

the system further comprises:

at least one first frame magazine located upstream of the welding station and at least one second frame magazine located downstream of the welding station, each magazine comprising one or more parking stations, each parking station having a rail portion (7) located at a lateral distance from the main rail (4) and on which a side frame can slide,

a translatable guide rail element (8a, 8b) having a shape of the type of the main guide rail (4) and arranged in a position corresponding to both longitudinal ends of the main guide rail (4);

the translatable rail elements (8a, 8b) are equipped with motor drive means (9) capable of being moved transversely in a direction perpendicular to the longitudinal extension of the main rail (4) between a first position close to the welding station (1), in which each translatable rail element (8a, 8b) is longitudinally aligned with the respective main rail (4), so as to constitute an extension thereof for enabling the side frame to be transferred along the translatable rail elements (8a, 8b) between said first position and said second position,

separate tractors (11a, 11b) movable on the main rail (4) and rail portions (7) and engageable with the side frames to effect movement of different pairs of side frames (3); and is

Wherein the system further comprises at least one auxiliary rail (70) positioned at a lateral distance from the main rail (4) and operatively connected to the two laterally distant rail portions of the first and second frame magazine to enable directly shifting one sideframe on said auxiliary rail from one magazine to the other, bypassing the main rail at both sides of the firing line.

2. The system for welding structures formed by stamped sheet-metal components according to claim 1, characterized in that said tractors (11a, 11b), which are independent with respect to said side frames (3a, 3b, 3c, 3d), each tractor (11a, 11b) is selectively and automatically connected to a different pair of side frames to move them.

3. System for welding structures made of pressed sheet-metal elements according to claim 1, characterised in that each side frame (3) is provided with its own independent motor drive.