Source: http://www.google.com/patents/US4944445?ie=ISO-8859-1
Timestamp: 2014-09-21 21:13:17
Document Index: 561942594

Matched Legal Cases: ['art 12', 'art 12', 'art 13', 'art 13', 'art 13', 'arts 47', 'arts 37', 'art 38', 'art 38', 'art 37', 'art 43', 'art 43', 'art 44', 'art 44', 'art 44', 'art 43', 'art 44', 'arts 37', 'art 43', 'art 44']

Patent US4944445 - Method for automatic joining and machining - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsThe invention relates to a method and a device for automatically joining and matching assemblies consisting of several components each and retained on a workpiece carrier (4) in a transfer line with retoolable machining stations (3). In the machining station (3), the assembly components are first taken...http://www.google.com/patents/US4944445?utm_source=gb-gplus-sharePatent US4944445 - Method for automatic joining and machiningAdvanced Patent SearchPublication numberUS4944445 APublication typeGrantApplication numberUS 07/422,582Publication dateJul 31, 1990Filing dateOct 17, 1989Priority dateFeb 22, 1985Fee statusLapsedAlso published asDE3506314A1, DE3506314C2, EP0214199A1, EP0214199B1, US4893398, WO1986004871A1Publication number07422582, 422582, US 4944445 A, US 4944445A, US-A-4944445, US4944445 A, US4944445AInventorsErnst ZimmerOriginal AssigneeKuka Schweissanlagen & Roboter GmbhExport CitationBiBTeX, EndNote, RefManPatent Citations (4), Referenced by (10), Classifications (15), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetMethod for automatic joining and machiningUS 4944445 AAbstract The invention relates to a method and a device for automatically joining and matching assemblies consisting of several components each and retained on a workpiece carrier (4) in a transfer line with retoolable machining stations (3). In the machining station (3), the assembly components are first taken off the workpiece carrier, brought into the joining position relative to each other, retained there and machined, in particular tacked or finish-welded. To carry out these various activities and to make the machining station highly flexible, the latter has several tool carriers (22, 23) which can move in at least three axes. The tool carriers (22, 23) are each disposed in a parallel plane above or below the workpiece carrier (4) so they can travel freely. The tool carriers (22, 23) support individual tools which they can change automatically at stationary or movable tool magazines (31, 33, 34). In conjunction with freely programmable actuators for the independent motion of the individual tool carriers (22, 23), new sets of tools can be put together in mosaic fashion for the various activities and in the event of an assembly type change-over.
I claim: 1. A method for the automatic joining and machining of different assemblies, each assembly having at least one component contained in a workpiece carrier having a bearing arm, the method using a transfer line with a retoolable and reconfigurable work station, comprising: presorting parts for the assembly and placing presorted parts on the workpiece carrier bearing arms in positions corresponding generally to a pre-arranged assembly position; delivering the assembly parts on the workpiece carrier bearing arms in a loose and unjoined condition to a work station; employing individual holding and clamping implements, associated with one of a plurality of tool carriers movable in at least two dimensions, at the work station to autmatically position the assembly parts into a precise predetermined joining position relative to other assembly parts; and, securing the assembly parts in a joining position, and thereafter completing at least one of lifting and welding the secured assembly parts.
2. A method according to claim 1, further comprising the step of: automatically exchanging individual tools at a work station.
This is a divisional application Ser. No. 925,000 filed Oct. 22, 1986, now U.S. Pat. No. 4,893,398.
In order to be able to process in such a transfer line different subassemblies, e.g. to a 2-door to a 4-door body type of a vehicle, several side frames with permanently set-up chucking devices fitting the respective body type are provided in the fixing station In the simple case, there are provided in the fixing station itself two different kinds of side frames which can be put into waiting positions when not being used. But is also possible to have a greater number of side frames in readiness via a conveyor and a storage facility and feed them in when needed. This publication further provides for making one side frame suitable for two similar types of body assemblies in that the chucking devices for both types are mounted to the side frame and the chucking devices needed for the respective type are then actuated selectively.
Contrary to the state of the art, in which the assembly, already put together and tacked, was merely finish-welded in the machining station, the method according to the invention provides that the functions of the two preceding stations, namely the setup and the fixing stations, are performed in the machining station also. Accordingly, in the storage facility, the individual parts of the subassembly are merely placed loosely on a work piece carrier, generally a pallet, and brought to the machining station in unjoined condition. There, the precommissioned assembly parts are brought into the proper position relative to each other and welded. Depending on the application, the assembly parts can be finish welded immediately without preceding tacking. However, they may also be tacked first then welded.
The method according to the invention is based on the fundamental idea of assembling in mosaic fashion a completely new set of tools when there is a change in the assembly type to be machined. This is done by exchanging the individual tools in the machining station. This requires considerably less expense than in the state of the art because it is only the individual tools, i.e. the chucks, grippers, welding tongs, etc. which must be kept in stock, and not a complete set of tools individually assembled for each assembly type. For, single tools ar also suited for different assembly types and then need be present only once, according to the invention.
The method according to the invention and the associated device are primarily suited for welding transfer lines. The basic inventive idea of carrying out the joining and machining operations in one station, however, may also find applications in other field, e.g. in assembly lines or in complex machining lines where the machining operations also comprise forming operations with and without chip removal, in addition to welding. Additionally, the inventive idea is not restricted to transfer lines, but can also be used in single stations.
The machining station according to the invention contains several tool carriers which are singly movable in three dimensions and whose tools can approach any point of the subassembly. The tool carriers may carry different tools, e.g. grippers or chucks which, themselves, may be designed as individual tools or tools of a set. In addition, welding tongs, chip removing cutting tools,assembly tools like screwdrivers or the like or any other type of tool may be provided as tools. The tools themselves may also have other, additional shafts with appropriate drives.
The tool carriers are freely movable in space. According to the embodiment examples, shown, the tool carriers have three translatory degrees of freedom for this purpose. But in order embodiments they may also have more degrees of freedom or also two translatory and one rotary ones. The number and kind of the degrees of freedom depends primarily on the requirements inherent in the workpiece, i.e. the assembly.
The tool carriers are controllable individually, and their tools can reach any point of the assembly. The motion of the tool carriers and the function of their tools are controlled by an appropriate program. Mutual collision of the tool carriers is prevented by direct or by overriding control measures. When there is a change-over to another assembly to be machined, the control program is exchanged. In many cases, the tools of the tool carriers will then be changed also. But is also possible to use universal tools suited to handle and machine different assemblies. This then requires only a control program change, which means very low cost, associated only with the software.
The tool carriers may be combined into groups and mounted in one or several planes. Within their group they possess, now as before, the same free mobility in space. Only, within the group that tool carriers move in the same plane, i.e. they have two identical axes. As to the third and possibly additional axes, the tool carriers may differ individually.
In the embodiment examples shown, two or three planes of motion are provided for the tool carriers. In other embodiment examples, more or fewer planes may be present. It is recommended to arrange at least one plan of motion of the tool carriers parallel to the workpiece carrier plan, especially to the plan of a pallet. In variation of the embodiment examples, the workpiece carrier may also be moved in a vertical or oblique plane, in accordance with which at least one tool carrier plan is also aligned vertically or obliquely.
The embodiment example in which the tool carriers can travel in two parallel planes above and below the workpiece carrier makes a very high degree of flexibility possible already because every point of the assembly is accessible by appropriate tools from the top, from the bottom and from the sides. For special handling tasks such as turning or erecting individual parts of the assembly, a third or even a fourth vertical plan of motion may be provided according to another embodiment example.
According to the embodiment examples it is recommendable to mount to each crossbeam at least two tool carriers of opposite sides. They can then travel along the crossbeam without hindering each other. But additional tool carriers may also be mounted to a crossbeam.
According to the invention, pallets with bearing arms on which the individual parts of the assemblies are deposited next to each other are used as workpiece carriers. In order to hold these parts securely when transporting the pallet, and still be able to remove automatically and transport them with the tool carriers without much energy consumption it is recommendable to provide snap connections between the bearing arms and the individual parts of the assembly
BRIEF DESCRIPTION OF THE DRAWINGS. In the drawings:
From the setup station 2, the pallets 4 are brought to one of the three paralleled, juxtaposed machining stations 3. In the machining station 3, the assembly components are removed from their seats on the pallet and are brought and held in a joining position relative to each other. Then the assembly parts are centered and chucked in the final position relative to each other and welded or otherwise machined. The finished assemblies are then transported out of the machining stations 3 on their pallets 4 and newly assembled to other body parts on new pallets, or else temporarily stored and treated otherwise.
The pallet 4 has a closed frame, from which project into the free interior bearing arms 14 on which the components 7, 8, 12 are deposited and held. To be welded to the bottom part 12, the roof spars 7, 8 must be removed from their seating position next to the bottom part 12 and conjuqated to the latter. To make this removal easy, the roof spars 7, 8 are detachably held on the bearing arms 14 by snap connections. The components 7, 8 12 are deposited near the edge of the pallet 4 which is of sufficiently large size to form a relatively big inner space free of bearing arms. The bearing arms 14 are designed as relatively inaccurate single seats and perform merely a supporting and holding function for the components 7, 8 and 12 without precise adjustment. After the transport and the exact centering and chucking of the components in the machining station are concluded, only a few bearing arms 14 are sufficient to merely support the components 7, 8, 12 and hold them so that the total carriers can grip and chuck them. In this process, the components 7, 8 and 12 may also sag in their deposited position or otherwise deform elastically without suffer-damage. As FIG. 2 shows, the pallet 4 initially still has free bearing arms 14 which will later support the finish-machined assembly.
The toothed belt or rack drives used for this purpose are provided with a cover and are the subject of the older, not prepublished, national German Patent Application No. P 34 20 936.0.
The gripper 54 of the upper tool carrier 23 fetches the rear roof spar 11 from its location on the pallet 4, brings it into the position shown in broken lines in FIG. 5 opposite the bottom part 13 and places the roof spar 11 next to the bottom part 13 and into the two still empty jaws of the chuck 28. In the same manner, the other upper tool carrier 23a, by means of the gripper 55 exchanged for the welding tons 29 (FIG. 4), places the door spar 10 next to the bottom part 13 and into the still empty individual jaw of the chuck 28a and a free individual jaw of the chuck 28b. Subsequently, the gripper 54 of the tool carrier 23, free again after having deposited the roof spar 11, grips the front roof spar 9 and places it into the still empty individual jaws of the chucks 28b and 28c. When all chucks 28 and 28c are closed, the components 9, 10, 11 and 13 are in the correct position relative to each other and can be welded at the seams. For this purpose, the grippers 54, 55 on the upper tool carriers 23, 23a are exchanged for the welding tons 29, 29a. Thus, the assembly can be finish-welded in the machining station without prior tacking.
In other applications, the assignment of functions may be different. For instance, the various tasks may not only be divided according to planes of motion, but may also be assigned to individual tool carriers within the plans of motion.
The demanded flexibility of the machining station 3 requires in most cases that when there is an assembly change, not only the control program for the tool carrier motion, but also their tools need changing. Towards this end, several tool magazine 31, 31a are provided in the machining station 3. In the embodiment example of FIGS. 3 to 5, an upper tool magazine 31a is assigned to the upper tool carriers 22 to 22c. Each tool magazine 31, 31a consists of a number of tool seats 34 rigidly mounted on top of or under the pallet carrier 30 in longitudinal direction 39. The tool seats 34 project from the side into the machining station 3. To exchange tools, the tool carriers must approach the tool seats 34, deposit the tool no longer needed in a free seat and couple the new tool at another seat. For this purpose, the tool seats 33 project into the path of motion of the tool carriers However, in order not to interfere with the free mobility of the tool carriers, the tool seats 33 may also have swivel arms, by means of which they can be pivoted out of the sphere of motion of the tool carriers.
In contrast thereto, FIGS. 6 and 7 show a variation of the tool magazines 31, 31a. They are here formed by a closed row of tool sets 34 which are movable along a rigid oval track 35 transverse to the transport direction 39. The oval tracks 35, in turn, are mounted on the longitudinal beams 17, 17a so as to be movable in transport direction 39, and they have an open inner area so that they can traverse the tool carriers. In this case, the tool magazines 31, 31a are positioned opposite the tool carriers to longitudinal direction, and the old tools are transferred to the rotating tool seats 34, and new ones are coupled. As may be seen in FIG. 7, if the tool seats 34 are correctly aligned, one tool magazine 31 can equip both the vertically aligned tool carriers 22 and the horizontally aligned tool carriers 41. Moreover, the lower tool magazine 31 can equip the tool carriers 23 of the upper plane if the coupling of the tools 37a points upwardly.
In variation of FIGS. 3 to 5, FIGS. 6 and 7 also show a passenger car floor assembly 53 as assembly to be welded which also gets holes depending on type variants The holes are produced by a stamping tool (not shown) to be exchanged.
The coupling 37, 37a, 38 is designed as straight plug-in coupling in which the connecting parts 47 are introduced into each other, opening each other up when liquid or gaseous media are being connected. The connections 47 are automatically closed in this case when the coupling is open. The coupling parts 37, 37a, 38 are connected through a threaded bayonet arrangement 42. For coupling, the coupling part 38 is turned into the coupling position, and the carrier head then feeds it to the coupling par 37, 37a to the point where the threaded bayonet arrangement 42 gets into ready position and an antirotation device 46 on the coupling part 38 engages a corresponding hole in the coupling part 37. This assures straight guidance which is needed to plug the connections 47 into each other. Subsequently, the inner part 43 is turned to cause the threaded bayonet arrangement 42 to engage. For this purpose, the inner part 43 is rotatably mounted in an outer part 44 which supports the antirotation device 46 and is connected to the outer part 44 in the initial and final positions of the rotary motion by spring-loaded, unlockable detents 45. The antirotation device 46 prevents the outer part 44 from corotating, in consequence of which the detent 45 will let go when the inner part 43 is turned relative to the stationary outer part 44 and the threaded bayonet arrangement 42 connects the coupling parts 37, 37a and 38 firmly to each other. For uncoupling, the above described process takes plane in reverse order. By means of their couplings 37, the tools are prepositioned in coupling positions in the tool seats 34 and retained secure against rotation.
If there is the danger that, due to greater torsional forces exerted on the tools about the center axis 52, the threaded bayonet arrangement 42 could disengage, and e.g. electropneumatically controlled locking arrangement 48 is provided either alone or additionally. The piston, designed as locking bolt 49, is pulled out of the locking hole 50, or pushed into it for locking, by double-acting solenoids 51 by means of compressed air at the beginning or end of the rotary motion of the inner part 43 in the outer part 44.
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