CN112041112A

CN112041112A - Assembly welding or splicing production line for automobile body-in-white components

Info

Publication number: CN112041112A
Application number: CN201980026666.5A
Authority: CN
Inventors: 卡罗·帕莱托
Original assignee: Olci Engineering Srl
Current assignee: Olci Engineering Srl
Priority date: 2018-04-20
Filing date: 2019-04-19
Publication date: 2020-12-04
Anticipated expiration: 2039-04-19
Also published as: IT201800004759A1; BR112020021478A2; EP3781350A1; CN112041112A8; WO2019202569A1; CN112041112B

Abstract

A method of assembly welding or splicing vehicle body components in a production line (1), comprising a plurality of robotic work stations (3) arranged in sequence, a plurality of handling robots (6) moving vehicle body components being processed from each work station (3) to the next, a plurality of specific grippers (13) holding and locking vehicle body components in the work stations (3), wherein said specific grippers (13) are configured to produce a determined subassembly vehicle type and are replaceable to produce at least one other vehicle type for the reconfigured assembly welding or splicing production line subassembly (1); the method comprises the step of moving a specific gripper (13) to and from the workstation (3) by means of at least one automatic guided vehicle (55).

Description

Assembly welding or splicing production line for automobile body-in-white components

Cross reference to related citations

The present application claims priority from italian patent application No. 102018000004759 filed on 20/4/2018, the entire disclosure of which is incorporated herein by reference.

Technical Field

The invention relates to a white body process production line for assembly welding, splicing and the like of automobile white body components, such as doors, body side walls, bottom plates and the like.

Background

Assembly and welding of body components by performing a series of operations (mainly welding operations) at successive work stations on a production line is a welding process.

In particular, as a reference to a specific work station, the component being welded or spliced is placed to the next work station by the sheet member gripped by the transfer robot from the previous work station, where the sheet member is operated by a plurality of robots (e.g., welding robots), and is provided to the next work station by the second transfer robot.

The use of such dedicated assembly lines for assembly welding or splicing, welding of individual subassemblies increases the number of dedicated body-in-white production lines, increasing investment costs and space, and the current trend of automotive manufacturers is to use flexible assembly welding or splicing, welding lines that are capable of randomly mixing to produce a given number of different models of bodies-in-white (up to four in general), this type of assembly welding or splicing, welding line being well known, for example from WO2017/109557a 1. These lines allow for flexible "on-demand" production of vehicles.

Flexible production lines solve the above-mentioned problems caused by dedicated production lines, but at the same time flexible production lines currently have some drawbacks. In particular, such a production line requires a large-sized switching mechanism (such as a turntable, a slide table, etc.) for switching different tools for producing different vehicle models, and thus the switching mechanism is very complicated, expensive, and large. The highly complex structure results in a relatively high failure rate, increasing the probability of line stops in the production line.

Another direct consequence of the flexible production line described above is that no matter how many models the initial design plan can produce, a high initial investment is required in the initial construction of the production line, and therefore the cost of the produced vehicle models is high if the assembly or splice line is initially used to produce a single vehicle model.

Another problem caused by the use of known production lines is inefficient use of human resources. Since the operations performed in the workstations of the production line are completely automatic, the operator only needs to assist the manual operations, for example, the loading of the work pieces into the workstations. These operations last only a small fraction of the cycle time, which means that the operator is indifferent in the remaining cycle time waiting for the automation to complete, resulting in a waste of human resources.

Another problem with known assembly or splicing lines is the loss of production due to the long time required to switch tooling, resulting in line stoppages.

Disclosure of Invention

The object of the present invention is to provide a production line for assembly welding or splicing of vehicle body components that solves the above-mentioned problems of the known production lines.

The invention is achieved by a production line according to claim 1.

The use of an Automatic Guided Vehicle (AGV) to replace a particular fixture allows the manufacturer to avoid the use of complex and expensive model changeover mechanisms, thereby minimizing the investment and the possibility of failure dedicated to a single model of fixture.

Furthermore, according to a preferred embodiment of the present invention, all the time of the auxiliary staff of the production line can be operated manually in the logistics area associated with the production line.

Drawings

For a better understanding of the present invention, the following detailed description of preferred embodiments is provided by way of non-limiting example and with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view, partly in elevation, from the top of a group weld or splice line according to the present invention;

FIG. 2 is a perspective view of the top of the workstation of FIG. 1;

FIG. 3 is a side view of the workstation of FIG. 2;

FIG. 4 is a perspective view of the top of the clamp holding and locking the body assembly in the workstation;

FIG. 5 is an exploded perspective view of the clamp of FIG. 4;

FIGS. 6, 7, 8, 9 and 10 are diagrams showing the steps of placing the jig in FIG. 5;

FIG. 11 is a schematic perspective view of the top of the logistics area of the assembly welding or splicing line of FIG. 1;

FIG. 12 is a schematic perspective view of the top of the upper and lower regions of the manual work piece;

FIGS. 13 and 14 are top and bottom perspective views, respectively, of a first automated guided vehicle for use in the assembly welding or splicing line of the present invention;

figures 15 and 16 are a top view and a side view, respectively, of the base supporting and contacting the clamp and the automatic guided vehicle associated therewith;

FIG. 17 is a front view corresponding to FIG. 16, in a different operational state;

FIG. 18 schematically illustrates a train type change operation of a welding or splicing line workstation;

FIG. 19 shows details of a build-up or splice line loading station;

fig. 20 and 21 are top and bottom perspective views, respectively, of a second automated guided vehicle for use in the assembly welding or splicing line of the present invention.

Detailed Description

With reference to fig. 1, numeral 1 indicates as a whole a multifunctional production line for assembling, welding or splicing, welding bodywork components. The production line is capable of producing different vehicle models (e.g., quarter inner panel/quarter outer panel; mid-floor/rear floor) according to production logic, as described in detail below. The production line can also be used for producing different vehicle types under the condition that the technological parameters are compatible.

Hereinafter, the term "subassembly" means a state of assembly welding or splicing of body-in-white body constituent members, i.e., physical products. On the other hand, the term "vehicle type" refers to the type of sub-assembly, not to a vehicle type that can be used for production line production.

The production line 1 comprises an initial loading station 2 for loading the vehicle body subassemblies to be welded or spliced, a plurality of work stations 3 and a final unloading station 4 from which the welded subassemblies are taken out. The production line 1 may further comprise one or more intermediate loading stations 2, which may be arranged at other suitable possible locations in the line body if not all components can be loaded at the initial loading station 2.

The components being welded or spliced are transferred from one station to the next by a transfer robot 6, which is arranged between the two work stations.

Since the pieces to be handled by the robot 6 (fig. 1) are all identical, the handling grippers of the handling robot can be made as universal grippers 7 (fig. 2).

Each work station 3 (fig. 2 and 3) comprises a work area 11 containing fixed holding clamps 12, which is the same for all work stations, and is adapted to apply special tooling clamps 13 (hereinafter designated as specific clamps 13) of the vehicle type being produced, the details of which will be described in detail hereinafter. The station 3 also comprises a waiting area 14 adjacent to the working area 11, in which a particular clamp 13 can wait for the subsequent switching of the tooling clamps.

The workstation 3 comprises two series of working robots 15, 16 (three in the example shown here for each series), arranged on both sides of the workstation. The first series of working robots 15 are arranged on a platform 17 located on the opposite side of the working area 11 from the waiting area 14; the second series of working robots 16 are arranged on a gantry 18 above one side of the waiting area 14. The working robot 16 is thus in a higher position, above the waiting area, in order to allow a specific gripper 13 to be carried from the waiting area 14 to the working area 11 and vice versa.

The platform 17 and the gantry 18 have, in addition to the respective working

robots

15 and 16, a plurality of control cabinets for controlling the working

robots

15, 16 and the handling robots 6 associated with the work stations 3, as well as a controller cabinet 19 for use in the welding process.

Platform 17 and gantry 18 are designed as pre-assembled welded or spliced modules, equipped with robots and related system accessories.

Fig. 2 shows the workstation 3 without specific clamps and grippers.

Fig. 3 shows the workstation 3 loaded with a specific jig 13A (designed for the vehicle type a) provided on the fixing jig 12 in the work area 11, and a specific jig 13B (designed for the vehicle type B) provided in the waiting area 14.

The special fixture 13 is shown in fig. 4 and 5 (exploded view) and comprises a base 20, the base 20 being the same for all vehicle models, one or more control system boxes 21, the control system boxes 21 being vehicle model specific, a positioning and locking fixture 22 adapted to support and position the vehicle model being worked on. The switching of the specific jig 13 can be used not only for the specific vehicle type but also for various vehicle types because its function depends on the progress state of the assembly.

The positioning and locking clamp 22 mounted on the rectangular support surface 23, except that the base 20 comprises the rectangular support surface 23, the four clamp positioning mechanisms 24, the control system box 21, is not described in detail herein, as the positioning and locking clamp 22 is not part of this invention.

The base 20 fits over the mounting fixture 12 and the locating pins in the mounting fixture 12 are all substantially C-shaped (fig. 5), with the relative unidirectional positioning being ensured by the centering and locating system, as described below.

More specifically, the fixing jig 12 includes a pair of parallel support plates 25 facing each other and fixed to the floor, and a crosspiece 26 perpendicular to the support plates 25 and connecting respective ends of the plates. In use, the fixing clamps 12 are fixed in the work area 11 of the workstation 3 by means of bolts 28, with the crosspieces 26 aligned parallel to the horizontal axis X, longitudinal with respect to the production line, and the support plates 25 parallel to the horizontal axis Y, perpendicular to the axis X.

The support plate 25 has respective independent supports 27 at the ends opposite the crosspieces 26 for positioning the support base 20.

Each support plate 25 has, adjacent to crosspiece 26, a respective centring assembly 30 consisting of an upwardly tapered conical pin 31 and a pair of rollers 32 having axes C and X parallel to each other and supported by respective centring pins 33 fixed to parallel support plates 25, higher than parallel support plates 25.

A pair of rollers 32 are machined to engage bosses 34 (not visible in fig. 5, but shown in fig. 6-10) on the base 20 for centering in the Y direction.

Similarly, crosspiece 26 has a centering assembly 35 along its centerline, comprising a pair of rollers 36, identical to rollers 32 but having an axis parallel to axis Y, and designed to cooperate with a projection (not shown) on base 20 so as to obtain a centering in the X direction.

The tapered pin 31 of one of the centering assemblies 30 is machined to fit in a hole machined in a centering element 37 (fig. 6-10), the centering element 37 being fixed in a corresponding position below the base 20 and having a mating face that allows it to mate with the tapered pin 31 on the base without clearance.

The tapered pin 31 of the centring assembly 30 fits in a groove machined in a centring element (not shown) fixed in a corresponding position under the base 20 and extending in the X direction.

In summary, when the base 20 is placed on top of the fixture, the rollers 32, 36 are first relatively centered in the directions X and Y, and then the tapered pin 31 fits into the hole 37 and the groove, not shown, respectively.

A centering assembly 30, in the sequence of fig. 6-10, wherein the rollers 32 and tapered pins 31 are not aligned with the sides to avoid overlap.

After the first stage of approaching a relatively undetermined position (fig. 6), if the projection 34 on the base 20 is misaligned, it will contact one of the rollers 32 (fig. 7) and tend to drag to a centered position because the base 20 is lower relative to the holding fixture 12.

The centering assembly 30 is machined to ensure that the tapered pin 31 can only enter the hole of the centering element 37 (fig. 10) when in the relatively correct position. Thus ensuring the relative positioning between the base 20 and the holding clamp 12, in the hole 37 the tapered pin 31 is progressively engaged (figure 11) until the engagement of the hole 37 to the bottom of the tapered pin 31, without any clearance in between (figure 12), when the base 20 is on the holding clamp 12.

Note that in the other centering assembly 30 is an elliptical slot rather than a hole, and that there is no tapered pin in the centering assembly 35, thereby allowing equal static constraint between the base 20 and the holding fixture 12.

As described above, the vehicle body subassembly parts are transferred from one work station to another by the universal transfer robot 6. In order to design the standard "gripper" of the robot 6 in a special fashion, it is necessary to use a handling gripper 40 or "gripping device" (described in fig. 4 and 5), the handling gripper 40 being provided with an interface flange 41 adapted to cooperate with the hand of the handling robot 6, in fact an extension of this own hand, to allow the use of a common hand for picking up and placing different vehicle models.

The transfer gripper 40 consists essentially of a gripper frame 42 having a gripping and support mechanism 43 that provides the assembly being processed. The particular gripper 13 is adaptable to the transfer gripper 40 as shown in fig. 4, except that in the assembly, when the transfer gripper 40 is not in use, it resembles a magazine of grippers.

Fig. 10 shows a logistics area 45, which is part of the assembly or splicing line 1 and which may conveniently be arranged at the end of the assembly or splicing line.

The flow area 45 is divided into two areas in sequence:

a jig storage area 46 for storing the specific jig 13 when the relevant vehicle model is not produced or is about to be produced.

A manual parts loading or "assembly welding or splicing" area, indicated by the numeral 47, shown in greater detail in figure 12.

The assembly welding or splicing area 47 is used for manually loading parts onto a fine positioning trolley 48, which is brought to the loading station 2 in the production line 1 with an AGV.

The fine positioning skip car 48 (see also fig. 19) is provided with a support plane 49, and the support plane 49 is provided with a plurality of sheet metal part positioning mechanisms 50 for positioning the sheet metal parts. The fine positioning skip 48 is further provided with support feet which allow the support plane 49 to be separated from the ground.

The sheet metal parts are manually taken from the work area 53 and loaded in a layered arrangement onto the fine positioning trolley 48 for gripping by one or more handling robots in the loading station 2. Each fine positioning skip 48 is adapted for a single vehicle type and provides multiple layers of sheet metal parts on the fine positioning skip for successive grasping by the robot.

The loading station 2 is provided with an upper work area 53 and a waiting area 54, which are adapted to store respective fine positioning trolleys 48 (fig. 19).

The upper work area 53 has a fine positioning skip 48 positioning mechanism similar to the position positioning reference for a particular fixture 13 in the work area of the workstation 3 described above. The upper work area 53 contains the specific fine positioning skip 48 of the vehicle type being produced.

The waiting area 54 is adapted to store fine positioning trolleys 48 for the currently produced vehicle type to accommodate an imminent vehicle type change, or to replace empty fine positioning trolleys 48 with full ones in the upper work area 53, as shown in fig. 19.

According to the present invention, the specific gripper 13 is moved by an automatic guide vehicle, hereinafter simply referred to as "AGV" for the sake of brevity.

The particular gripper 13 is moved by a first AGV55 (fig. 13 and 14) of a flat and rectangular shape that is able to move under the foot 20 of the particular gripper 13 and lift it.

The illustrated AGV is an AGV from a company having model number MR-Q9-LD300A (H).

The bottom of the AGV55 is provided with four independent sets of first running wheels 56 and with a first sensor 57 (e.g., an optical sensor) for detecting the path.

The AGV55 is provided with jacks 58 on the top that are parallel to each other and extend laterally to the outside dimensions of the AGV. The lifters 58 are driven by an electric actuator (not shown) to lift the workpiece.

The pair of lifters are respectively arranged at two ends of each lifter, and the space requirement of a loading area 59 is met.

AGV55 also includes a tool identification sensor 60, such as an optical sensor, that is adapted to read a corresponding identification code disposed below the base 20 of a particular fixture 13 to properly identify the fixture.

The vertical space occupied by the lift 58 of AGV55 while on standby is slightly less than the free height below the rectangular support surface 23 of the pedestal 20.

The bearing capacity of the AGV is about 3000 kilograms, and the lifting stroke is about 100 millimeters.

FIGS. 15, 16, and 17 illustrate an AGV55 being disposed under a dock 20. Referring to FIG. 15, AGV55 occupies substantially the same space in plan view as rectangular support surface 23.

In FIG. 16, the AGV is in a standby state wherein the base 20 of a particular gripper 13 is resting on the gripper positioning mechanism 24. In FIG. 17, the AGV55 is in a raised position, where the chassis 20 is raised from the floor, and the AGV55 can transport a particular clamp 13 to other areas.

In a substantially similar manner, in accordance with a preferred embodiment of the present invention, the fine positioning skip 48 is diverted by a second AGV61 (fig. 20 and 21) that can be arranged under the fine positioning skip 48 and lift it.

The illustrated AGV is a Hangzhou Haikang robotics, Inc. (China) model MR-Q7-LR050C AGV.

The bottom of AGV61 is provided with four independent sets of running wheels 62 and sensors 63 (e.g., optical sensors) for detecting the path.

On top of the AGV55, a ring lift 64 is provided, which is lifted by the thrust of an electric actuator (not shown here) with a third sensor 68 for correct recognition of the fine positioning skip 48.

The vertical space occupied by the ring lift 64 of AGV55 while on standby is reduced to slightly less than the free height below the support plane 49 of the fine positioning cart 48.

The load capacity of the AGV is about 500 kg and the lifting stroke is about 60 mm.

As described above,

AGVs

55,61 are responsible for moving a particular fixture 13 and fine positioning cart 48 between logistics area 45 and workstation 3 and to loading station 2 in production line 1, respectively.

The running of the AGVs is along a dedicated lane 65 which is arranged beside the production line 1 and which allows the passage of operators, hereinafter referred to as AGV lane 65 (fig. 2 and 11).

Line 1 finally includes a control system 66 that can be programmed to control

AGVs

55, 61.

The control system 66 includes a line controller 67, the line controller 67 being connected to the controllers of the

individual workstations

2, 3, 4 via a field network, while the control system 66 is connected to the

AGVs

55,61 via wireless. The line controller 67 controls the transport and replacement of specific clamps between the clamp storage area and the workstation 3.

The AGV61 may be controlled by the line controller 67 or may be controlled by different controllers sharing different lines as necessary, in which case the control is over the plant wireless network.

The operation of the line 1 has been partly shown in the above description, as follows:

when producing a component vehicle type (for example vehicle type a), the respective fine positioning skip 48 with the vehicle type component is placed in the upper part work area 53 in the loading station 2. In workstation 3, the AGV places a gripper 13A, which is required to produce, in workstation 11.

In the loading station 2, the components are loaded onto the handling grippers 40; the bonding is performed by adhesive or welding by a dedicated robot as needed.

The first transfer robot 6 transfers the sheet metal part from the loading station 2 to the first work station 3 by means of the transfer grippers 40. In the workstation 3, the sheet metal parts are positioned on specific fixtures 13 for the purpose of performing the welding work. The transfer gripper 40 is then moved back to the loading station 2 for the next cycle.

At the end of the welding operation, the next handling robot 6 picks up the sheet from the work station 3 and passes on to the next work station, as is the case for all work stations 3.

At the off-line station 4, the vehicle models are unloaded from the assembly or splice line.

In the waiting area 14 of the workstation 3 there is a special fixture 13B for the new vehicle type to be produced. In the waiting area 54 of the loading station 2 there is a fine positioning trolley 48 for the new vehicle type to be produced, and the waiting area 54 can also be used for sheet metal parts of the same type if the number of sheet metal parts on the fine positioning trolley 48 in the upper work area 53 is not sufficient to complete a batch.

In preparation for switching the model, for example, from model a to model B, the specific jig 13A in the workstation 3 must be replaced with the specific jig 13B in the waiting area. The change is made to all workstations by two AGVs 55 in succession.

Fig. 18 shows in detail the sequence of operations required for switching the vehicle types. The sequence begins at 25, where two AGVs 55 are positioned under respective

specific grippers

13A, 13B. Thus, for clarity, the AGVs are hereinafter referred to as AGVs 55A and AGVs 55B (AGVs are standard, non-specific devices).

The operation sequence is as follows:

1) two AGVs 55A/55B each lift their respective

specific grippers

13A, 13B;

2) the specific gripper 13B is moved to the AGV passage 65 by the AGV 55A;

3) the specific gripper 13B is moved along the AGV passage 65 by the AGV55B to avoid the traveling path of the specific gripper 13A;

4) the specific gripper 13A is moved to the AGV passage 65 by the AGV 55A;

5) the two

particular grippers

13A, 13B pass over respective AGVs 55A, the AGVs 55B move along the AGV path 65 with the particular gripper 13B aligned with the axis of the workstation;

6) the specific gripper 13B is moved to the work area 11 by the AGV 55A;

7) the particular gripper 13A is moved along the AGV aisle 65 by the AGV55A, aligned with the workstation axis.

8) The specific gripper 13B is moved to the waiting area 14 by the AGV 55B;

9) the AGV55A moves out of the particular gripper 13A and moves to the AGV aisle 65;

10) AGV55A travels along AGV aisle 65;

11) the AGV55A moves out of the particular gripper 13A and onto the AGV path 65.

At the end of this operation, the workstation 3 is running and work on a new vehicle model can be started. The total production downtime required to complete the above operations 1) -10) does not exceed 90 s.

At this point, the AGV55A, AGV55B, may move to the next workstation 3 and be placed under a

particular gripper

13A, 13B. This step is not shown in fig. 18, since it occurs during the blocked time, when both workstations 3 are in operation. The stop time of the subsequent workstation starts from operation 1).

Since during the clamp change of one station 3 the other stations remain working properly, the total production standstill time is equal to the standstill time of one station (the standstill time is a discontinuity from station to station).

The exchange of the fine positioning skip 48 between the upper work area 53 and the waiting area 54 and the replacement of an empty fine positioning skip 48 with a full one is performed by two AGVs 61 in a manner similar to that described for the particular fixture 13. The order of the acts of the operations is not described in detail herein.

A careful analysis of the assembly welding or splicing method according to the invention of the production line 1 reveals the advantages of the invention with respect to the prior art:

using an AGV to move a specific gripper 13 can greatly simplify the structure of the production line because a complicated vehicle type switching mechanism such as a rotary table, a slide device, etc. is not required.

Therefore, the initial cost of the production line structure is reduced, and the cost of the fixing device is dispersed over different models. Thus, if the production line is initially used to produce a single vehicle model, the later added vehicle models are not subject to high cost.

The introduction of new models does not imply long production interruptions, which are the case in the prior art. Switching vehicle models is performed in a very fast manner by the AGV described above once a particular gripper for a new vehicle model is available in the gripper storage area. Since the production line structure is absolutely flexible, the number of vehicle models that can be produced is unlimited.

Production pauses caused by switching vehicle types can be compared with cycle times. Thus, the production line 1 is not designed for production in a "random mixing" mode, but it is suitable for mass production.

However, considering that the production line is simpler than the prior art, the production line failure rate can be greatly reduced. The higher number of assemblies per batch (corresponding to at least one hour of production, for example), the smaller production losses due to technical problems compensate for the production losses due to the switching of models, compared to the known flexible production lines.

Finally, since the operator works in a separate logistics area from the workstation 3, the present invention can eliminate 10 times of waiting time due to the limitation of machine time, thereby making full use of human resources.

Claims

1. A method of assembling or splicing vehicle body components in a production line (1), comprising:

-arranging a plurality of robotic workstations (3) in a sequence one after the other;

-a plurality of handling robots (6), each handling robot (6) being arranged between a first and a second work station (3) adjacent to each other for moving a body component under process from the first work station to the second work station;

-a plurality of specific jigs (13) for supporting and locking subassemblies in the workstation (3), said specific jigs (13) being configured to produce a determined subassembly vehicle type and, alternatively, to produce at least one other subassembly vehicle type for the reconfigured assembly welding or splicing line (1);

characterized in that the specific gripper (13) is moved to or from the workstation (3) by means of at least one automatic guide vehicle (55).

2. Method according to claim 1, characterized in that the step of moving a specific gripper (13) comprises the following operations: for each work station, a first specific jig (13) is arranged for a first vehicle body assembly type in a work area (11) of the work station, a second specific jig (13) is arranged for a second vehicle body assembly type in a waiting area (14) of the work station, and the first specific jig (13) is replaced by the second specific jig (13) when the assembly welding or splicing production line (1) is switched from a first set of configurations for producing the first vehicle body assembly type to a second set of configurations for producing the second vehicle body assembly type.

3. Method according to claim 1, characterized in that, for each work station (3), the step of transporting the specific gripper (13) comprises the operation of transporting the specific gripper (13) between the work station and the gripper storage area (46).

4. A method as claimed in claim 3, characterised in that said transporting operation is carried out by using a tunnel (65) dedicated to the automatic guide trolley (55,61) and arranged beside the assembly or splicing line (1).

5. A method according to any one of claims 1 to 4, characterized by comprising the step of moving by at least one automatic guide vehicle (61) a fine positioning skip (48) loaded with components to be group welded or spliced in a loading station (2) in a group welding or splicing line (1).

6. A method according to claim 5, characterized in that the step of providing the components to be group welded or spliced in the loading station (2) comprises the step of manually loading the components on a fine positioning trolley (48) in a logistics zone (45) of the group welding or splicing line (1), and the step of moving the fine positioning trolley (48) between the logistics zone (45) and said loading station (2).

7. The method of claim 6, wherein the step of moving the fine positioning skip (48) comprises: a first type of fine positioning skip car (48) for loading parts of a first type of vehicle body components is arranged in a working area (53) of a loading station (2), a second type of fine positioning skip car (48) for loading parts of a second type of vehicle body components is arranged in a waiting area (54) of the loading station, and when a welding or splicing production line (1) is switched from a first configuration for producing the first type of vehicle body components to a second configuration for producing the second type of vehicle body components, the first type of fine positioning skip car (48) is replaced by the second type of fine positioning skip car (48).

8. A method according to any one of claims 5 to 7, characterized in that the step of moving the fine positioning trolley (48) comprises an operation of transporting an empty fine positioning trolley (48) from the loading station (2) back to the logistics zone (45).

9. An assembly welding or splicing production line for assembly welding or splicing vehicle body components, comprising:

-a plurality of robotized workstations (3) arranged in sequence;

-a plurality of specific jigs (13) for holding and locking subassemblies in the workstation (3), said specific jigs (13) being configured to produce determined subassembly vehicle types and, alternatively, other subassembly vehicle types for the reconfigured assembly welding or splicing line (1);

the method is characterized in that:

-a jig storage area (46) for accommodating specific jigs (13) of the model of the assembly vehicle to be made;

-a number of automatic guided vehicles (55);

-a control system (66) for controlling the automatic guiding cart (55), the control system being programmable to control the transport of specific grippers (13) between the gripper storage area and the workstation (3), and to replace specific grippers (13) of the assembly or splicing line (1) for reconfiguration.

10. The assembly welding or splicing production line of claim 9, wherein:

-at least one loading station (2) for loading the components to be assembled or spliced;

-a number of fine positioning trolleys (48), each configured to load a component of a determined vehicle type;

-a logistics area (45) for storing and manually loading said fine positioning trolleys (48);

a programmable automatic guided vehicle control system for controlling the transport of fine positioning trucks (48) between the logistics area (45) and said at least one loading station (2), and for replacing the fine positioning trucks (48) in said at least one loading station (2).

11. Group welding or splicing line according to claim 9 or 10, wherein each work station (3) comprises a work area (11) and a waiting area one (14) for receiving a respective specific gripper (13), said work area (11) being provided with position reference elements for cooperating with corresponding position reference elements in the specific gripper (13) to determine the position of the latter in a unique way.

12. Group welding or splicing line according to claim 11, wherein said specific clamp (13) comprises a base (20), which base (20) is identical for all tools and is provided with position reference elements, and a plurality of positioning and locking clamps (22) arranged on the base to cooperate with the respective body components.

13. The assembly welding or splicing line according to any one of claims 10 to 12, wherein said specific gripper comprises a handling gripper (40) for holding the body component and gripping it by a handling robot (6) for transporting the body component from the work station (3) to the subsequent work station (3).

14. Group welding or splicing line according to any one of claims 11 to 13, wherein in each work station (3) a work area (11) and a waiting area (14) are arranged opposite each other, said work station (3) comprising at least one work robot (15), said work robot (15) being arranged on the side of the work area (11) opposite the waiting area (14), and at least one further work robot, said further work robot being arranged on the other side of the work area (11) next to the waiting area (14), said work station (3) comprising an elevated structure on which at least one further robot is mounted and being configured to allow the passage of a specific clamp (13) from the work area (11) to the waiting area (14) and vice versa.

15. Group welding or splicing line according to any one of claims 10 to 14, comprising at least one loading station (2), the loading station (2) being provided with a work area (53) and a waiting area (54) configured to receive a respective fine positioning skip (48) in a predetermined reference position.

16. Group welding or splicing line according to claim 15, comprising a moving channel (65) of automatic guide cars (55,61) adjacent to the waiting areas (14,54) of the work station (3) and of the loading station (2).