POSITIONING AND HOLDING APPARATUS

Abstract: On a production line, component parts to be connected together are first loosely assembled, then fed to a framing station. At the framing station there are pillars 18 at either side of a path 11 through the station. These pillars carry tools 24,26. The tools are adapted to position and hold the various component parts of the assembly whilst welding or glueing takes place. Each of the pillars carries tools which will cooperate with more than one different assembly type, and each pillar can be rotated about its vertical axis to present either one set or a different set of these tools to the path through the apparatus, so that different assemblies can follow one another sequentially on the production line, and all such assemblies will be correctly positioned and held whiist the component parts are secured together.

Description: Title: Positioning and hold in apparatus DESCRIPTION Field of invention l This invention relates to apparatus for positioning and holding components during assembly of the components on a production line. The apparatus is particularly, but not exclusively, suitable for positioning and holding the parts of a vehicle body shell for welding. Background to the invention I When welding together components to produce a vehicle body shell, difficulties arise in holding the component pieces, ie underbody, roof and two sides, in correct relative positions for welding. One attempt to overcome this problem when welding vehicle sides to the underbody is to provide three co-operating intermittent endless conveyors: a central conveyor carrying a series of so-called trucks, each substantially identical and adapted to receive a vehicle underbody; and two side conveyors, one on each side of the central conveyor, each carrying a series of so-called gates, the gates on each side conveyor being substantially identical and each adapted to receive an appropriate vehicle side. In use, an underbody and two sides are fed on the conveyors to a working station and the conveyors are stopped. The parts are then assembled, generally by manual welding, and the welded body is then conveyed away. In practice, certain problems arise with this arrangement as follows: 1) the arrangement is slow and not suitable for automation; 2) the trucks and beds are liable to be bent or otherwise damaged in use, resulting in production of distorted and non-uniform products; 3) a particular arrangement is suitable for production of only one body model and is not variable. In an attempt to overcome these problems alternative systems have been devised. Firstly, the so-called Robogate system involves use of only one or two shuttle beds in place of a series of trucks, and a unique pair of gates for each body model. In a typical embodiment of this system there is provided a shuttle bed with two pairs of gates, each pair for producing a different body model. In use, the underbody, sides and roof are initially secured together in approximately correct positions by so-called toy-tabbing, ie by providing metal tabs which pass through appropriate holes, with the ends of the tabs then being twisted. The toy-tabbed assembly is lifted onto the shuttle bed and an appropriate pair of gates moved inwardly to hold the pieces in appropriate relative positions. Welding can then be carried out, eg using robots. After welding is completed the gates are moved out and the welded shell is removed. If an alternative body is to be produced, eg a hatchback model rather than a notchback, in practice it is commonly possible to use the same shuttle bed because a common underbody is used, but different gates are required. The second pair of gates is accordingly moved into position in place of the first pair, and operation is resumed. Such an embodiment thus enables two body models to be produced, with a typical time of fifteen seconds required for changing the gates for different body models. Because the arrangement can use a unique shuttle bed and unique pair of gates for a particular model, problems of producing non-identical bodies do not arise. Further, a similar arrangement is provided by the socalled Fatagate system. A typical embodiment comprises a single shuttle bed, with three pairs of gates located on a vertically movable conveyor. Such an arrangement permits three model variations, with a typical changeover time of about 26 seconds. This arrangement can occupy less space than is required by the Robogate system, but greater vertical space is required. Further, because the gates typically weigh about 2 tons each, bulky complex machinery#is required to move them vertically for changeover. Summary of the Invention According to the invention there is provided apparatus for use in a production line for positioning the individual parts of assemblies of parts and for holding the parts in their correct relative positions, the apparatus comprising a path for movement of assemblies through the apparatus, and a plurality of pillars at one or both sides of the path, the pillars supporting sets of tools for positioning and holding parts of the assemblies, at least some of the pillars supporting more that one tool set and being rotatable between a position where one tool set is presented to the path of movement for cooperation with an assembly and another position where a different tool set is presented for cooperation with a different assembly. This apparatus makes it possible to pass different assemblies along a production line, for example hatchback and notchback variants of a car body. One set of tools will be presented to the path of movement for one variant and another set will be presented for the other variant, with the pillars rotating between positions as one body moves out of the apparatus, and the other moves in. The invention finds particular application in connection with spot-welding and/or glueing together metal and other components where it is important that the various components are held accurately in place during welding or glueing. The invention is thus particularly useful in the production of vehicle bodies, and also other sheet metal articles such as washing machines and filing cabinets. A particularly important application of the invention is in vehicle body-framing, ie the assembly of sides, underbody and roof to produce a vehicle body shell. Apparatus in accordance with the invention may also be used for side aperture construction and engine compartment construction. When used for vehicle body-framing, there may be two, three or four pillars for each side of the vehicle, on each side of the path. In a further aspect the present invention thus provides a vehicle framing station comprising a track, means for transporting a vehicle underbody along the track through the station, and one or more pillars at each side of the track, each of which pillars may be individually rotated to bring a selected one of two or more sets of tools carried thereby into an operative position for holding parts to be welded together and the underbody in the correct relative positions for welding. The body panels to be welded together may be loosely assembled on the underbody before the underbody enters the station. This loose assembly can be held together by toytabbing. Alternatively, the underbody may enter the station without the side panels and roof panel. The pillars can be swung out to a horizontal or near horizontal position, the side panels loaded onto the faces of the pillars in contact with the appropriate tools on the pillars, and the pillars can then swing back to their upright position to position the side panels relative to the underbody. If this procedure is used, the roof panel will be lowered into place in a downstream working station. With this alternative procedure, it is possible to dispense with the toy-tabbing stage. When the body sides, roof and underbody are pre-assembled in approximately correct positions, eg by toy-tabbing, the assembled shell is moved into the station, and the pillars are then moved in to locate and hold the side panels in appropriate position relative to the other panels for welding. Welding is then carried out, eg using robots. After welding has been completed the pillars are then moved back and the welded body shell is removed. The process is then repeated as appropriate. As each pillar is independently rotatable and carries two or more sets of tools, many combinations of tools in the operative position are possible, giving great versatility. The tools conveniently comprise fixtures and clamps. The fixtures provide precise reference points in space, and the clamps ensure that the parts to be secured together are held together with adequate pressure during the welding process. The pillars may also carry locating means for bringing the parts into correct positions in space, if necessary. The pillars are preferably rotatable about a vertical axis, but horizontal or inclined axes of rotation are also possible. The pillars are preferably also movable towards and away from the path. They can be moved away from the path to allow an assembly to enter or leave the apparatus, and can be moved toward the path to take up their operative positions. In a preferred embodiment , this movement of the pillars takes place by hinging the pillars at their bases, so that the pillars can be swung back away from the path. In another embodiment the pillars can slide in and out while remaining in a substantially vertical orientation. The position of the pillars in the apparatus can be adjustable to allow the apparatus to be set up for use with a particular assembly or range of assemblies. The bases of the pillars may be mounted on tracks which extend parallel and/or at right angles to the path. Where pivotable pillars are used, the pillars may be held in the vertical position by a locating pin such as a shot pin or wedge action pin to give precise working orientation. When used in vehicle body-framing, the number of sets of tools carried by each pillar is selected according to body variants required. Four sets of tools is suitable, providing good scope for variants without undue complexity. It is to be noted that such an arrangement enables, say, variants of body rear configuration (eg hatchback, notchback or estate) to be clamped by altering only the relevant pillar or pillars on each side. Each pillar is preferably securable in position after rotation by a locating pin, eg a shotpin or a wedge-action pin, to ensure precise indexing. When the pillar is located in position, a pneumatic supply is conveniently operatively connected with the appropriate set of tools for that index position. The locating pin and pneumatic supply are conveniently carried by a beam which may extend between the tops of aligned pillars, eg forming the side arrangement of the vehicle body-framing apparatus. This beam may also provide a lead-in slot which receives the top end of the pillar when the pillar moves to its operating position. Each pillar preferably includes its own computer control means having a program for each tool set, the correct program being selected by the indexing means. Each pillar is preferably provided with a grid pattern of holes so that tools are replaceable. Tool replacement may be necessary when the apparatus is to be used for different assemblies, or for maintenance purposes. The base of each pillar is conveniently removably attached to a station base for substitution or changeover. The pillar bases may be movably, eg slidably attached to a station base for repositioning for different models. If any tool is bulky, then it is conveniently hingeably mounted to the pillar so that it may be moved, eg by pneumatic means, to a position where it will not hinder securing operations when not in use. It will be apparent that the present invention, in preferred embodiments at least, can provide a vehicle body-framing station which has several advantages as compared with the prior art systems discussed above. 1. Rapid tool selection is possible because only a simple rotation of one or more pillars is required. This feature reduces the time required between working on one variant of an assembly and another variant. A change time of under five seconds is possible, ie within the time generally taken to transfer an assembly in and out of the station. This means that model variants can be handled on a single production line without having any effect on production rate. 2. The equipment required to produce a ranye of model variants is far more compact, and can use up to one-third to one-fifth of the manufacturing space required for prior art equipment. 3. The weight of components to be moved during changeover is low, so that the operating mechanism can be simple, light, compact and cheap. The invention will be further described, by way of example, with reference to the accompanying drawings, in which: In the drawings Figure 1 is a schematic perspective view of one embodiment of a vehicle body-framing station; Figure 2 is a view similar to Figure 1 of an alternative embodiment. Figure 3 is a detail view of one pillar: and Figure 4 is a schematic plan view of a production line. Detailed description of the drawings Figure 1 illustrates an automated vehicle body-framing station comprising a framework 10 having a base 12, upright corner pillars 14 and upper cross-beams 16. The upper beams 16 may be omitted. A bed (not shown) is located on the base for receiving a vehicle body shell made up from an underbody, a roof and two sides, loosley secured together in approximately correct positions for welding, eg by toy-tabbing. Before this body shell can be welded, the underbody, roof and sides must be securely clamped in their correct relative positions. Three pillars 18 are provided on each side of a transfer path through the station, for locating and holding the parts of the vehicle body in their correct relative positions, so that they can be welded. The transfer path is defined by two parallel rails 11. The pillars 18 are mounted on bases 40. Each base has a lower part 44 which can slide sideways on rails 42 and an upper part 46 which can slide in and out on the lower part 44. The pillars can be easily moved to any position, as required when setting up the station to handle a particular assembly. Once the pillars have been set to a particular position, by moving their bases which are then locked in place, the pillars are able to move in two senses. Firstly the pillars can move towards and away from the path 11 to allow a vehicle body 39 to move in or out of the station. This movement is accomplished in Figure 1 by pivoting the pillars about an axis 41. This pivoting action is effected by an electric motor 50 (see Figure 3) which drives a worm gear 52 meshing with a spur gear 54 fixed to the bottom of the -pillar. This drive mechamism is used because it is quick acting and because a pneumatic ram will not lift the pillar. A pneumatic piston/cylinder unit 56 acts between the pillar 18 and the floor of the station to act as an air spring and cushion the movement and assist lifting of the pillar. When the pillar moves to its erect position, the top is received in a guide 58 formed in a bar 60 attached to the framework 10 of the station. This bar is not shown in Figure 1. When the pillar reaches its end position, it contacts a switch 62 at the bottom of the guide, and when these switches show that all the pillars are vertical, a subsequent stage of operation can take place. The mouth of the guide 58 is wider than the bottom, to guide the pillar home. When the pillar is in its erect position as indicated by the switch 62, an air feed nozzle 64 descends into a hole 66 in the top of the pillar. By means of suitable nonreturn valving, the interior of the pillar which forms an air pressure chamber can be pressurised to operate the selected tools 24 or 26. In the illustrated embodiment, each pillar 18 is of square cross-section and can carry up to four sets of tools each for producing a different body model, models A, B, C and D. In the illustrated embodiment only two sets of tools 24 and 26 are shown, for producing models A and B. Each pillar 18 is arranged for independent indexed rotation by hydraulic or mechanical means (not shown) about its vertical axis for selectively bringing each set of tools into an operative position, adjacent the body to be welded. Each pillar carries its own computer control means 32 having a program for each tool set, the correct program being selected by the indexing means. Each pillar is securable in the selected rotational position by a locating pin (not shown) to ensure precise indexing. The framework 10 carries two overhead robots 34, adjustably movable on upper beams of the framework. Freestanding robots 36 are also provided on the framework base, two robots 36 being illustrated in the Figure, with areas such as area 38 being provided for extra freestanding robots if required. The sets of tools 24,26 include fixtures to provide precise reference points in space and clamps to ensure that the parts to be secured are held together with adequate pressure. Locating means may also be provided for bringing the parts into correct position and space if necessary. With the component parts appropriately located, welding is then carried out under computer control by the robots. When welding has been completed, the sub-frameworks are moved outwardly, the welded body shell is moved from the framework along the tracks 11 and a new body to be welded is moved in its place. The process is repeated as appropriate. If the next body is of a different style, then the relevant pillar or pillars 18 are rotated by the action of the local computer control means to bring a different set of tools into the operative position as appropriate. Such rotation takes about five seconds, and is within the time generally taken to transfer a vehicle body in and out, so that model changes need have no effect on production rate. The embodiment illustrated in Figure 2 is generally similar to that of Figure 1. The main area of difference is that the pillars 18 are mounted in sub-frameworks 20, and the whole sub-framework 20 on each side moves in out out as indicated by arrows A. The beam 22 forming the top of each sub-framework corresponds to the beam 60 of Figure 3. Figure 4 shows an alternative way of working. In this Figure, an underbody 72 Is loaded on a production line 70 moving in the direction of an arrow 74. The underbody 72 may have the engine compartment already built up at the front end. When the underbody enters the framing station 10, the pillars 18 are pivoted fully outwards into substantially horizontal positions. Side panel assemblies 76 are delivered to the station and are laid on the pillars, where they will fit in with, and be gripped by, tools 24 or 26 on the upper faces of the pillars. The pillars are then swung up, and when they are erect the side panels will be correctly positioned relative to the underbody where they can be first clamped and then welded, to produce a body shell. The pillars 18 are lowered again and the shell 78 moved out of the station by the production line. At a subsequent working station, the roof panel can be dropped down and welded to the body.

Claims: Claims 1. Apparatus for use in a production line for positioning the individual parts of assemblies of parts and for holding the parts in their correct relative positions, the apparatus comprising a path for movement of assemblies through the apparatus, and a plurality of pillars at one or both sides of the path, the pillars supporting sets of tools for positioning and holding parts of the assemblies, at least some of the pillars supporting more than one tool set and being rotatable between a position where one tool set is presented to the path of movement for cooperation with an assembly and another position where a different tool set is presented for cooperation with a different assembly. 2. An assembly as claimed in claim 1, wherein the pillars are moveable towards and away from the path. 3. Apparatus as claimed in claim 1 or claim 2, wherein the pillars are hinged at their bases, and can be moved about this hinge axis to move towards and away from the path. 4. Apparatus as claimed in claim I or claim 2, wherein the pillars on each side of the path are mounted on a common sub-framework, and the sub-framework is slideable towards and away from the path. 5. Apparatus as claimed in any preceeding claim, wherein each pillar has a base, and wherein the base is moveable transversely and/or parallel to the direction of the path. 6. A vehicle framing station comprising a track, means for transporting a vehicle underbody along the track through the station, and one or more pillars at each side Of the track, each of which pillars may be individually rotated to bring a selected one of two or more sets of tools carried thereby into an operative position for holding parts to be welded together and to the underbody in the correct relative positions for welding. 7. A vehicle framing station as claimed in claim 6, having three pillars on each side of the path. 8. A vehicle framing station as claimed in claim 6 or claim 7, wherein one set of tools carried by the pillars is adapted to position and hold parts of one vehicle body type, and another set of tools carried by the pillars is adapted to position and hold the parts of a different vehicle type. 9. A vehicle framing station as claimed in any one of claims 6 to 8, including a plurality of robot welders. 10. A vehicle framing station as claimed in any one of claims 6 to 9, wherein the tools carried by the pillars are pneumatically operated, and the interior of each pillar comprises an air pressure chamber. 11. A vehicle framing station as claimed in claim 10, wherein the air pressure chamber in each pillar is pressurised from a compressed air source at the station each time a vehicle underbody is positioned in the station. 12. A vehicle framing station as claimed in any one of claims 6 to 11, wherein the pillars are pivotably mounted for movement between a substantially horizontal position in which they can receive a body side panel and a vertical or substantially vertical position in which they hold the vehicle parts together. 13. A vehicle framing station as claimed in claim 12, wherein the pillars are locked in their vertical positions. 14. A vehicle framing station as claimed in any one of claims 6 to 13, wherein each pillar carries four sets of tools. 15. A vehicle framing station as claimed in any one of claims 6 to 14, wherein each pillar has its own computer control means having a program for each tool set. 16. A vehicle framing station as claimed in any one of claims 6 to 15, wherein each pillar is provided with a grid pattern of holes for receiving tool fastenings, so that the tools are replaceable. 17. A method of vehicle framing, wherein a vehicle underbody is delivered to a framing station, body side panels are loaded onto laterally extended, generally horizontal arms extended from the framing station, the arms are brought to a vertical position so that the body side panel is correctly positioned relative to the underbody, and the body is welded. 18. A method as claimed in claim 17, wherein the vehicle roof is fitted at a subsequent framing station. 19. A vehicle framing station substantially as herein described with reference to and as shown in the accompanying drawings.

Inventors: PIGOTT, NORMAN BRIAN
Applicants: LITTON U.K. LIMITED
Application year: 1984
Main classification: B62D65
IPC codes: B23K37, B62D65