CN112041112B - Assembly welding or splicing production line for automobile body-in-white components - Google Patents

Abstract

A method of assembling 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 a vehicle body component being processed from each work station (3) to the next, a plurality of specific grippers (13) holding and locking the vehicle body components in the work stations (3), wherein said specific grippers (13) are configured to produce a determined subassembly vehicle type and, alternatively, to produce at least one other vehicle type for the re-configured assembly 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 one (55).

Description

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

Cross reference to related citations

The present application claims priority from italian patent application No. 102018000004759, filed on 2018,month 4, andday 20, 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 automobile doors, automobile 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 WO2017/109557A1. 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 fraction of the cycle time, which means that the operator is indifferent to the remaining cycle time waiting for the automation to be completed, resulting in a waste of human resources.

Another problem with known assembly or splicing lines is lost production due to the long time required to switch tooling, resulting in production 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 toclaim 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 vehicle 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 perform the auxiliary manual operation 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 condition;

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.

Theproduction line 1 comprises aninitial loading station 2 for loading the vehicle body subassemblies to be welded or spliced, a plurality ofwork stations 3 and afinal unloading station 4 from which the welded subassemblies are taken out. Theproduction line 1 may further comprise one or moreintermediate loading stations 2, which may be arranged at other suitable possible positions in the line if not all components can be loaded at theinitial loading station 2.

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

Since the plate members carried by the carrier robot 6 (fig. 1) are all the same, the carrier gripper of the carrier robot can be made a universal gripper 7 (fig. 2).

Each work station 3 (fig. 2 and 3) comprises awork area 11 containingfixed holding clamps 12, which is the same for all work stations, and adapted to apply special tooling clamps 13 (hereinafter designated as special clamps 13) of the vehicle type being produced, the details of which will be described in detail hereinafter. Thestation 3 also comprises a waiting area one 14 adjacent to theworking area 11, in which aparticular clamp 13 can wait for a subsequent tool clamp to be switched.

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

The platform 17 and thegantry 18 have, in addition to the respective workingrobots 15 and 16, a plurality of control cabinets for controlling the workingrobots 15, 16 and the handlingrobots 6 associated with thework stations 3, as well as acontroller cabinet 19 for use in the welding process.

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

Fig. 2 shows theworkstation 3 without specific clamps and grippers.

Fig. 3 shows theworkstation 3 loaded with a specific jig one 13A (designed for the model a) set on thefixing jig 12 in thework area 11 and a specific jig two 13B (designed for the model B) set in the waiting area one 14.

Thespecial fixture 13 is shown in fig. 4 and 5 (exploded view) and comprises abase 20, thebase 20 being identical for all vehicle models, one or morecontrol system boxes 21, thecontrol system boxes 21 being vehicle model specific, a positioning andlocking fixture 22, adapted to support and position the vehicle model being worked on. The switching of thespecific 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 andlocking clamp 22 mounted on therectangular support surface 23, except that thebase 20 comprises therectangular support surface 23, the fourclamp positioning mechanisms 24, thecontrol system box 21, is not described in detail herein, as the positioning andlocking clamp 22 is not part of this invention.

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

More specifically, thefixing jig 12 includes a pair ofparallel support plates 25 facing each other and fixed to the floor, and acrosspiece 26 perpendicular to thesupport plates 25 and connecting respective ends of the plates. In use, thefixing clamps 12 are fixed in thework area 11 of theworkstation 3 by means ofbolts 28, with thecrosspieces 26 aligned parallel to the horizontal axis X, longitudinal with respect to the production line, and thesupport plates 25 parallel to the horizontal axis Y, perpendicular to the axis X.

Thesupport plate 25 has respectiveindependent supports 27 at the ends opposite thecrosspieces 26 for positioning thesupport base 20.

Eachsupport plate 25 has, adjacent to crosspiece 26, arespective centring assembly 30 consisting of an upwardly taperedconical pin 31 and a pair ofrollers 32 having axes C and X parallel to each other and supported by respective centring pins 33 fixed toparallel support plates 25, higher thanparallel support plates 25.

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

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

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

The taperedpin 31 of thecentring assembly 30 fits into a groove machined in a centring element (not shown) fixed in a corresponding position under thebase 20 and extending in the X direction.

In summary, when thebase 20 is placed on top of the holding fixture, the first andsecond rollers 32, 36 are first relatively centered in the directions X and Y, and then the tapered pins 31 fit into the holes and not shown grooves of the centeringelements 37, respectively.

A centeringassembly 30, in the sequence of fig. 6-10, wherein thefirst roller 32 and taperedpin 31 are not aligned with the sides to avoid overlap.

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

The centeringassembly 30 is machined to ensure that the taperedpin 31 can only enter the hole of the centering element 37 (fig. 10) when in the relatively correct position. Thus ensuring the relative position determination between the base 20 and the holdingclamp 12, in the hole of the centeringelement 37 the taperedpin 31 is progressively engaged (figure 11) until the hole of the centeringelement 37 is engaged to the bottom of the taperedpin 31 without any clearance in between (figure 12), when thebase 20 is on the holdingclamp 12.

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

As described above, the vehicle body subassembly parts are transferred from one work station to another by theuniversal transfer robot 6. In order to design the standard "gripper" of thetransfer robot 6 in a special fashion, it is necessary to use atransfer gripper 40 or "gripping device" (described in fig. 4 and 5), which transfergripper 40 is provided with aninterface flange 41 adapted to cooperate with the hand of thetransfer 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.

Thetransfer gripper 40 consists essentially of agripper frame 42 having a gripping andsupport mechanism 43 that provides the assembly being processed. Theparticular gripper 13 is adaptable to thetransfer gripper 40 as shown in fig. 4, except that in the assembly, when thetransfer 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 orsplicing line 1 and which may conveniently be located 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 thespecific 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 afine positioning trolley 48, which is brought to theloading station 2 in theproduction line 1 with an AGV.

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

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

Theloading station 2 is provided with anupper work area 53 and asecond waiting area 54 which are adapted to store respective fine positioning trolleys 48 (figure 19).

Theupper work area 53 has afine positioning skip 48 positioning mechanism similar to the position positioning reference for aparticular fixture 13 in the work area of theworkstation 3 described above. Theupper work area 53 contains the specificfine positioning skip 48 of the vehicle type being produced.

Thesecond waiting area 54 is adapted to storefine positioning trolleys 48 for the currently produced vehicle type to accommodate the impending vehicle type changeover, or to replace emptyfine positioning trolleys 48 with full ones in theupper work area 53 as shown in fig. 19.

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

Thespecial gripper 13 is moved by a first AGV of flat and rectangular shape, automatic guided vehicle one 55 (fig. 13 and 14), which can move under thebase 20 of thespecial gripper 13 and lift it.

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

The bottom of the AGV, i.e. the automated guided vehicle (55), is provided with four sets of independent travelling steering wheels (56) and a sensor (57) (e.g. an optical sensor) for detecting a path.

The AGV, i.e., theautomatic guide vehicle 55, is provided withlifters 58 on the top, parallel to each other, that extend laterally to the outside dimensions of the AGV. Thelifters 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 aloading area 59 is met.

The AGV, i.e., the automated guidedvehicle 55, also includes atool identification sensor 60, such as an optical sensor, which is adapted to read a corresponding identification code disposed below thebase 20 of aparticular fixture 13 to properly identify the fixture.

The vertical space occupied by the AGV, i.e. thejack 58 in the first automatic guidedvehicle 55, during standby is slightly less than the free height below therectangular support surface 23 of thebase 20.

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

Fig. 15, 16 and 17 illustrate an AGV, i.e., an automatic guided vehicle, 55, disposed under thechassis 20. Referring to FIG. 15, the AGV, i.e., the automatic guidedvehicle 55, occupies substantially the same space in plan view as therectangular support surface 23.

In FIG. 16, the AGV is in a standby state wherein thebase 20 of aparticular gripper 13 is resting on thegripper positioning mechanism 24. In fig. 17, the AGV, i.e., the automatic guided vehicle one 55, is in a raised state in which thechassis 20 is raised from the floor, and the AGV, i.e., the automatic guided vehicle one 55, can transport thespecific gripper 13 to other areas.

In a substantially similar manner, the transfer of thefine positioning skip 48 is accomplished, in accordance with the preferred embodiment of the present invention, by a second type of AGV, automatic guided cart two 61 (fig. 20 and 21), which can be arranged under thefine positioning skip 48 and lift it.

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

Four independent sets of second runningsteering wheels 62 and a second sensor 63 (e.g., an optical sensor) for detecting a path are provided at the bottom of the AGV, i.e., the second automatic guidedvehicle 61.

On top of the AGV, i.e. the automatic guidedvehicle 55, there is arranged aring jack 64 which is lifted by the thrust of an electric actuator (not shown here) and which is provided with athird sensor 68 for correct recognition of thefine positioning skip 48.

The vertical space occupied by theannular jack 64 in the AGV, i.e., the automatic guidedvehicle 55, during standby is reduced to slightly less than the free height below thesupport plane 49 of thefine positioning skip 48.

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

As described above, the AGVs, i.e., the first automatic guidedvehicle 55, the second automatic guidedvehicle 61, are responsible for moving thespecific jigs 13 and the fine positioning jigs 48 to between the logistics area 45 and thework station 3, and to theloading stations 2 in theproduction line 1, respectively.

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

Theproduction line 1 finally comprises a control system 66 which can be programmed to control the AGVs, i.e. the first 55 and the second 61 automatic guided vehicles.

The control system 66 includes aline controller 67, whichline controller 67 is connected to the controllers of theindividual workstations 2, 3, 4 via a field network, while the control system 66 is connected to the AGVs, i.e. the first automatic guidedvehicle 55 and the second automatic guidedvehicle 61, by wireless. Theline controller 67 controls the transport and replacement of specific clamps between the clamp storage area and theworkstation 3.

The AGV, i.e., the second automatic guidedvehicle 61, may be controlled by theline controller 67, or may be controlled by different controllers for sharing different lines as necessary, and in this case, the control is performed by a factory wireless network.

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

when producing component vehicle types (e.g. vehicle type a), the respectivefine positioning skip 48 with the vehicle type components is placed in theupper work area 53 in theloading station 2. Inworkstation 3, the AGV places the required gripper 13A to be produced inworkstation 11.

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

Thefirst transfer robot 6 transfers the sheet metal part from theloading station 2 to thefirst work station 3 by means of thetransfer grippers 40. In theworkstation 3, the sheet metal parts are positioned onspecific fixtures 13 for the purpose of performing the welding work. Thetransfer gripper 40 is then moved back to theloading station 2 for the next cycle.

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

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

In the waiting area one 14 of theworkstation 3 there is a special fixture two 13B for the new vehicle type to be produced. In thesecond waiting area 54 of theloading station 2 there is afine positioning trolley 48 for the new vehicle type to be produced, and if the number of sheet metal parts on thefine positioning trolley 48 in theupper work area 53 is not sufficient to complete a batch, the same type of sheet metal parts can also be used in thesecond waiting area 54.

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

Fig. 18 shows in detail an operation sequence required for switching the vehicle type. The sequence begins at 25 with two AGVs, automatic guided vehicles one 55, positioned under respective specific grippers one 13A, two 13B. Thus, for clarity, the AGVs are hereinafter referred to as AGV55A and AGV55B (AGVs being standard, non-specific equipment).

The operation sequence is as follows:

1) The twoAGVs 55A/55B respectively lift the firstspecific clamp 13A and the secondspecific clamp 13B;

2) The secondspecific gripper 13B moves to the AGV passage 65 by theAGV 55A;

3) The secondspecific clamp 13B moves along the AGV passage 65 by the AGV55B to avoid the traveling path of the firstspecific clamp 13A;

4) The specific gripper one 13A is moved to the AGV lane 65 by theAGV 55A;

5) The two first 13A, second 13B specific grippers pass overrespective AGVs 55A, theAGVs 55B travel along the AGV path 65 with the second 13B specific grippers aligned with the axis of the workstation;

6) The specific gripper two 13B is moved to thework area 11 by theAGV 55A;

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

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

9) The AGV55A moves out of the special fixture one 13A and moves to the AGV aisle 65;

10 AGV55A travels along AGV aisle 65;

11 The AGV55A is removed from the particular fixture one 13A and moved to the AGV aisle 65.

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

At this time, theAGVs 55A, 55B can move to thenext workstation 3 and be placed under the specific jig one 13A, the specific jig two 13B. This step is not shown in fig. 18, since it occurs during the blocked time, when bothworkstations 3 are in operation. The stop time of the subsequent workstation starts from operation 1).

Since during the clamp change of onestation 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 thefine positioning skip 48 in theupper work area 53 and the waiting area two 54 and the replacement of an emptyfine positioning skip 48 with a full one are performed by two AGVs, i.e., the automatic guided cart two 61, in a manner similar to that described for thespecific gripper 13. The order of the acts of the operations is not described in detail herein.

A careful analysis of the assembly or splicing method by theproduction line 1 according to the invention reveals the advantages of the invention over the prior art:

using an AGV to move aspecific 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, theproduction line 1 is not designed for production in a "random mix" 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 theworkstation 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 (15)

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 guided vehicle (55);

the step of moving the specific gripper (13) comprises the following operations: arranging a first specific jig (13) for a first vehicle body component model in a working area (11) of the workstation, arranging a second specific jig (13) for a second vehicle body component model in a waiting area one (14) of the workstation, and replacing the first specific jig (13) with 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 component model to a second set of configurations for producing the second vehicle body component model;

the workstation (3) comprises two series of working robots (15, 16), a first series of working robots (15) being arranged on a platform (17) located on one side of the working area (11) opposite to the waiting area one (14); the second series of working robots (16) are arranged on a gantry (18) above one side of the waiting area one (14); the working robot (16) is in a higher position than the waiting area so as to allow the specific jig (13) to be carried from the waiting area one (14) to the work (11); -a special fixture comprising 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; the work area comprises a fixed holding jig (12), said holding jig (12) comprising 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 the respective ends of the plates; in use, the fixing clamp (12) is 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 supporting plate (25) has at the end opposite to the crosspiece (26) respective independent supports (27) for positioning the supporting base (20); each support plate (25) has, adjacent to the crosspiece (26), a respective centring assembly (30) consisting of a tapered pin (31) tapered upwards and a pair of rollers (32) having axes C and X parallel to each other and supported by respective centring pins (33) fixed to the parallel support plates (25) higher than the parallel support plates (25).

2. 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).

3. Method according to claim 2, characterized 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).

4. A method according to any one of claims 1 to 3, comprising the step of moving by at least one second automatic guide vehicle (61) a fine positioning skip (48) loaded with components to be assembled or spliced in a loading station (2) in an assembly or splicing line (1).

5. A method according to claim 4, 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).

6. The method of claim 5, 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 II (54) of the loading station, and when the assembly welding or splicing production line (1) is switched from a first configuration for producing the vehicle type of the first type of vehicle body components to a second configuration for producing the vehicle type of 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).

7. Method according to any one of claims 5 to 6, 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).

8. An assembly or splice production line for assembly welding or splicing of vehicle body components, comprising:

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

-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 holding and locking subassemblies in a workstation (3), said specific jigs (13) being configured to produce determined subassembly vehicle models and, alternatively, other subassembly vehicle models for a 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 one (55);

-a control system (66) for controlling the automatic lead-vehicle one (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.

9. The assembly welding or splicing line according to claim 8, 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 skip (48);

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

10. Group welding or splicing line according to claim 8 or 9, 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.

11. Group welding or splicing line according to claim 10, wherein said specific clamp (13) comprises a base (20), which base (20) is identical for all clamps 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.

12. Assembly or splicing line according to claim 9 or 11, 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).

13. Group welding or splicing line according to claim 10, wherein in each work station (3) a work area (11) and a waiting area one (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 one (14), and at least one further work robot, said further work robot being arranged on the other side of the work area (11) beside the waiting area one (14), said work station (3) comprising an elevated structure on which at least one further robot is mounted and being configured to allow passage of a specific clamp (13) from the work area (11) to the waiting area one (14) and vice versa.

14. Group welding or splicing line according to claim 9, 11 or 13, comprising at least one loading station (2), the loading station (2) being provided with a work area (53) and a second waiting area (54) configured to receive a respective fine positioning skip (48) in a predetermined reference position.

15. Group welding or splicing line according to claim 14, 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).

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