ADJUSTMENT OF WORK PALLETS FOR VEHICLE BODY ASSEMBLY LINES

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to: vehicle body assembly line apparatus having an adjusting station for adjusting work pallets on which vehicle body formed metal parts are assembled; the work pallets on which adjustable locators are supported for adjustment; and a method for assembling vehicle body formed metal parts by initially adjusting locators on work pallets.

2. Background Art

Vehicle bodies are conventionally manufactured on an assembly line wherein work pallets are moved in a recirculating manner during assembly of formed metal parts to each other. In one type of such assembly formed metal parts are assembled to each other while mounted on the work pallets as the pallets are moved along the assembly line. The assembly is conventionally performed in many different ways such as by the use of fasteners or welding which may either be electric resistance or laser welding, in addition to many other types of connection of the formed metal parts to each other. In one type of assembly, formed sheet metal parts are assembled to each other to provide a rigid vehicle body that also functions as the vehicle frame for mounting of wheel assemblies, the engine, the drivetrain and other vehicle components. In another type of vehicle body construction, longitudinal frame members are assembled to formed sheet metal members that are also secured to each other to provide the mounting of the vehicle body components. ^v

Flexible manufacturing requires that vehicle body assembly lines be capable of manufacturing more than one vehicle model because some models cannot be produced and sold in a sufficient quantity to require a single devoted assembly

line. Since high production vehicle body assembly lines normally have on the order of about 80 to 100 work pallets recirculated during the vehicle body assembly, there is considerable cost in providing the work pallets for any given vehicle model as well as requiring a large storage space for the work pallets when the assembly line is producing a different vehicle body model on another set of work pallets.

Vehicle body work pallets conventionally include a carriage on which locators are mounted. The locators conventionally include locator members having vertical rest surfaces some or all of which have upwardly projecting locator pins. Since different vehicle body models have many different shapes and sizes, the locator members must be mounted at different longitudinal (X), sideways (Y) and vertical (Z) positions, which necessitates the different work pallets for different vehicle body models and the resultant cost and storage space as discussed above. Certain of the locators have the locator pins that provide horizontal positioning in the longitudinal and sideways directions while the vertical rest surfaces provide vertical positioning of the parts being assembled. It is also conventional for the locator pins to have clamps which are selectively operable to provide clamping of the formed metal parts that are supported and positioned by the locator. The construction of such locator pin clamps involves an opening in the locator pin in which a clamp member is selectively movable from an undamped position within the pin to a clamping position projecting outwardly from the pin and clamping the supported formed metal members. As such, the locator pins do not have a solid construction and can be deformed by forces applied to the locator pins.

In attempt to overcome the cost and storage problems involved with providing work pallets for different vehicle models, United States Patent 6,687,971 Nakamura discloses transfer trucks on which adjustable locator jigs are mounted. Adjustment is provided by a jig change-over unit that includes a socket portion engagable with the corresponding locator pin of a locator jig to provide movement for the adjustment. However, the capability of providing such adjustment is limited by the engagement with the locator pin because the locator pin is normally remote from slides along which the adjustment takes place. As such, this adjustment cannot be provided in all three axes of adjustment at the same time.

Other references noted during investigation conducted in connection with the present application is disclosed by United States Patents: 4,594,764

Yamamoto; 4,667,866 Tobita et al.; 4,751,995 Naruse et al.; 4,776,085 Shiiba;

4,939,838 Gatta; 4,951,931 Rossi; 5,203,814 Kushizaki et al.; 5,313,695 Negre et al.; 5,347,700 Tominaga et al.; 5,518,166 Numata et al.; 5,836,068 Bullen et al.;

5,920,974 Bullen; 5,943,768 Ray; 6,065,200 Negre; 6,089,440 Brusha; 6,115,907

Beyer; 6,164,634 Farlow; 6,202,275 Cioletti et al.; 6,378,186 Angel; 6,389,698

Malatier; 6,427,321 Fedato et al.; 6,467,675 Ozaku et al.; 6,546,616 Radowick; and United States Patent Publications: 2001/0013164 Morel et al.; 2002/0023334 Rhoads et al. ; 2002/0038855 Hwang; and 2002/0170160 Savoy et al.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved vehicle body assembly line apparatus including work pallets that can be adjusted for use with different model vehicle bodies for assembling formed metal parts to each other during successive cycles.

In carrying out the above object, the vehicle body assembly line apparatus of the invention for use in cyclically assembling formed metal parts for vehicle bodies of different models during successive cycles includes a plurality of work pallets that are sequentially movable along an assembly line to support formed metal parts being assembled to each other. Each work pallet includes a carriage supporting a plurality of adjustable locators each of which includes a locator member for mounting a vertical rest surface with a plurality of the rest surfaces including a locator pin extending upwardly therefrom for providing part positioning during the assembly. Each locator member has a grab member located at a remote location below the mounting location of its vertical rest surface. A linear bearing supports each locator member on the carriage for adjusting movement along a linear axis. Each locator includes a brake having a locked condition for holding its locator member in an adjusted position and having an unlocked condition where the locator member thereof is freely movable for adjustment along the axis of its linear bearing.

An adjusting station of the apparatus is located at an upstream end of the assembly line to which the work pallets are successively moved to begin the assembly of formed metal parts for each cycle. At the adjusting station, the grab members of the locator members of the locators on the work pallets are grasped and with the brakes thereof in their unlocked condition moved as necessary to provide adjustment of the locator pins along their linear bearings to the proper positions for the particular vehicle body model to be assembled on each work pallet during the next cycle.

The vehicle body assembly line apparatus as disclosed has the adjusting station including an adjuster for adjusting the locators. The adjuster station includes at least one programmable robot for providing the locator adjustment, and for greater production levels the adjuster station includes a plurality of programmable robots for providing the locator adjustment.

Each locator member as disclosed has a positioning target at a known location with respect to where its vertical rest surface is mounted. The adjusting station includes a sensor for sensing the adjusted position of the positioning target on the locator member to determine whether the positioning target thereof is positioned within a design tolerance range and for generating a deviation signal when the positioning target is not located within the design tolerance range. The adjusting station includes a control for operating the adjuster to readjust the appropriate locator in response to the deviation signal to provide positioning of the associated locator positioning target within the design tolerance range.

A plurality of the locators on each work pallet have linear bearings that provide at least vertical locator adjustment on the carriage, and for all positions of required adjustment a plurality of the locators on each work pallet have linear bearings that provide longitudinal, sideways and vertical locator adjustment on the carriage. More specifically, the linear bearings for providing longitudinal and sideways adjustment each include a pair of spaced rails and at least one rail brake, and the linear bearings for providing vertical adjustment each include a vertical rod and a rod brake. Furthermore, the linear bearings for providing longitudinal and sideways adjustment each include a pair of rail brakes for respectively locking and

unlocking to the associated pair of spaced rails to provide the longitudinal and sideways adjustment.

The vehicle body assembly line disclosed is specifically designed to assembly formed sheet member parts to each other.

Another object of the present invention is to provide an unproved work pallet for use in a vehicle body assembly line to cyclically assemble formed metal for vehicle bodies of different models during movement through the assembly line.

In carrying out the immediately preceding object, the vehicle body work pallet of the invention includes a carriage and a plurality of adjustable locators each of which includes a locator member for mounting a vertical rest surface with a plurality of the rest surfaces having a locator pin extending upwardly therefrom to provide part positioning during assembly on the pallet. Each locator member has a grab member located at a remote location below the mounting location of its vertical rest surface. Each locator includes a linear bearing for supporting its locator member on the carriage for adjusting movement along a linear axis. A brake of each locator has a locked condition for holding its locator member in an adjusted position and has an unlocked condition where the locator member thereof is freely movable by grasping of its grab member at its remote location below its vertical rest surface.

Each locator of the work pallet includes a positioning target at a known location with respect to where its vertical rest surface is mounted to permit sensing of the locator member positioning and any necessary readjustment upon sensing an out of tolerance position after the initial adjustment. A plurality of the locators on the work pallet each includes a linear bearing that supports the locator member thereof on the carriage for vertical adjustment, and for all positions of required adjustment a plurality of the locators on the work pallet each includes linear bearings that support the locator member thereof on the carriage for longitudinal and sideways and vertical adjustment. The linear bearings of the pallet for providing

longitudinal and sideways adjustment each include a pair of spaced rails and at least one rail brake, and the linear bearings of the pallets for providing vertical adjustment each include a vertical rod and a rod brake. More specifically, the linear bearings of the pallets for providing longitudinal and sideways adjustment each include a pair of rail brakes for respectively locking and unlocking to the associated rails to provide the longitudinal and sideways adjustment.

Another object of the present invention is to provide an improved method for cyclically assembling formed metal parts for different model vehicle bodies.

In carrying out the immediately preceding object, the method for cyclically assembling formed metal parts of different model vehicle bodies is performed by cyclically moving work pallets to an upstream adjusting station of an assembly line, and adjustable locators are unlocked on each work pallet to permit adjustment of locator members thereof for freely movable adjustment of the locator members and vertical rest surfaces thereof as well as locator pins on a plurality of the locator members along at least one linear axis on a carriage of the work pallet. A grab member on each locator member at a remote location below its vertical rest surface is grasped to adjust the position of the locator member and its vertical rest surface as necessary for the vehicle body model formed metal parts to be assembled during the next cycle.

As disclosed, the location of a positioning target on each locator member is sensed after the adjustment to determine whether the positioning target, which is at a known position with respect to the vertical rest surface is within a design tolerance range to thereby determine whether the locator member is properly located. Thereafter readjusting and sensing of the location of the positioning targets is performed as necessary until the locator members and are all properly positioned.

At least one programmable robot is operated to provide the adjustment of the locator members on the carriage, and as disclosed a plurality of

programmable robots are operated to provide the adjustment of the locator members on the carriage.

The locator members are adjusted along a vertical axis and for all required positioning are adjusted along longitudinal, sideways and vertical axes. More specifically, the locator members are each adjusted longitudinally and sideways along associated pairs of spaced rails and selectively locked by at least one rail brake, and the locator members are each adjusted vertically along an associated rod and selectively locked by a rod brake. Furthermore, the locators are each locked in longitudinal and sideways directions by an associated pair of rail brakes that respectively operate on the associated pair of spaced rails.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is a schematic top plan view of a vehicle body assembly line that embodies the present invention and performs a method of vehicle body assembly in accordance with the invention.

FIGURE 2 is a perspective view of a work pallet for use in assembling vehicle body formed metal parts in accordance with the invention.

FIGURE 3 is a top plan schematic view for illustrating the operation of adjustable locators on the work pallets of the assembly line.

FIGURE 4 is a perspective view taken from an outboard direction of one of the adjustable locators of the work pallets.

FIGURE 5 is a perspective view of the adjustable locator taken from an inboard direction.

FIGURE 6 is a schematic view that illustrates a control brake utilized with linear bearings of the adjustable locators.

FIGURE 7 is a schematic view illustrating a sensor used to provide any required locator positioning adjustment.

FIGURE 8 is a perspective view that is partially broken away and partially shown in schematic to show the manner in which the locator members are supported by a pair of spaced rails and one or a pair of rail brakes to provide longitudinal and sideways adjustment.

FIGURE 9 is a perspective view that is partially broken away to illustrate the manner in which the locator members are supported by a vertical rod and a rod brake to provide vertical adjustment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to Figure 1 of the drawings, a vehicle body assembly line generally indicated by 10 includes a schematically indicated conveyor 12 for conveying work pallets 14 during assembly of formed metal parts to each other to provide vehicle bodies. During such assembly, the work pallets 14 are conveyed by the conveyor 12 in a clockwise direction starting at an initial adjusting station 16 where adjustable locators 18 (Figure 2) are adjusted as is hereinafter more fully described. From the adjusting station 16 shown in Figure 1 , the work pallets 14 are conveyed toward the right to a front floor panel supply station 20, then to a center floor panel supply and assembly station 22, then to a rear floor panel supply and assembly station 24 where the assembly is completed, and finally to an unload station 26 prior to continued clockwise movement to the left along a return run back to the adjusting station 16. The adjustment of the locators 18 of work pallets 14 at the adjusting station 16 permits the assembly line to accommodate vehicle body assembling of different models and can also provide adjustment of each work pallet after each assembly cycle so as to ensure that the locators are properly located in preparation for the next cycle.

The vehicle body assembly line construction, the work pallet construction and the vehicle body assembling method of the invention will be

described in an integrated manner to facilitate an understanding of all aspects of the invention. Also, it is should be appreciated that while the assembly line is disclosed as assembling front, center and rear formed sheet metal floor parts 28, 30 and 32 as shown in Figure 3, the assembly can also be performed with other formed sheet metal parts, such as, for example, assembly of longitudinal frame members to formed sheet metal body panels, etc.

As shown in Figure 3, each work pallet 14 includes a carriage 34 on which the adjustable locators 18 are mounted. Each locator as shown in Figures 4 and 5 and schematically in Figure 7 includes a locator member 36 having a vertical rest surface 37 mounted thereon and a locator pin 38 also mounted thereon and extending upwardly from vertical rest surface 37 mounted on the locator member to be capable of providing part positioning of the assembly. More specifically, the vertical rest surface 37 of each locator member 36 is adjustable vertically and supports the parts being assembled to provide positioning in a vertical direction, i.e. the Z direction shown in Figure 3. Furthermore, the locator member 36 is horizontally adjustable so the locator pin 38 mounted thereon is capable of providing positioning of the parts in longitudinal and sideways directions as respectively illustrated by X and Y in Figure 3. Each locator member 36 as shown in Figure 4 has a grab member 40 that is located at a remote position below its vertical rest surface 37 to provide the adjustment as is hereinafter more fully described. A linear support bearing 42 _Z shown in Figures 4 and 5 supports the locator member 36 for vertical adjusting movement of its vertical rest surface and associated locator pin 38. As specifically shown in Figure 5, the locator member 36 is directly supported by a vertical linear bearing 42z which is in turn supported by a sideways linear support bearing 42y that is supported by a longitudinal support bearing 42x. The linear support bearing 42z as shown in Figures 6 and 9 includes a rod 44 and a brake 46 that has a locked condition for holding its locator member in an adjusted position along its vertical direction and also has an unlocked condition where the locator member thereof is freely movable for adjustment along the vertical axis of its linear bearing. The linear bearings 42x and 42y have a construction described below.

For some low production vehicle body assembly lines, it is possible to utilize manual grasping of the grab member 40 of each locator member 36 as shown in Figure 4 to permit adjustment to the required position along the vertical Z axis and, as shown, likewise along the sideways Y axis and the longitudinal X axis. For higher production assembly lines, it is preferable to utilize an adjuster 48 as shown in Figure 1 at the adjusting station. Regardless of whether a manual or automatic adjuster is utilized, the remote location of the grab member 40 from the vertical rest surface 37 and locator pin 38 of the locator member 36 facilitates the adjustment. As specifically shown in Figure 4, the grab member 40 is located vertically below the locator pin 38 relatively close to the sideways linear bearing 42y and longitudinal linear bearing 42x. Each linear bearing includes a pair of linear bearing slides or rails 50 extending parallel to its bearing rod. The remote location of the grab member 40 from the vertical rest surface 37 and locator pin 38 of the locator member 36 facilitates the adjustment without binding of these bearing rails 50 and permits adjustment in all three directions by a single movement without the requirement of initial adjusting in one direction and then subsequent adjustment in two other directions as has been required in the prior art.

Each of the horizontal and linear bearings 42x and 42y for providing adjustment along the longitudinal and sideways directions has a construction as illustrated in Figure 8 wherein the spaced slides or rails 50 provide support for movement along the associated direction with each bearing including at least one rail brake 51 and preferably including a pair of rail brakes 51 respectively associated with the pair of spaced rails. These rail brakes 51 like the rod brake 46 shown in Figure 9 have an unlocked condition for permitting adjustment along the direction of the associated pair of rails and have a locked condition for holding the adjusted position along the associated axis.

The adjuster 48 of adjusting station 16 shown in Figure 1 includes at least one robot 52 whose arm 54 as schematically identified in 54 has an end effector for grabbing the grab member 40 and providing the locator member adjustment as described above. Preferably there are a plurality of the adjusting robots 52 with one

robot dedicated to each of two of the adjustable locators 18 shown in Figure 2 so as to provide a more rapid adjusting cycle.

As illustrated in Figure 7, each of the locator members 36 on which the locator pins 38 are mounted has a positioning target 56 at a known location with respect to the vertical rest surface and hence also with respect to the locator pin. The positioning target 56 is most preferably constructed with a sharp edge such as provided by a hole to facilitate sensing of its position by a sensor 58 that projects a sensing signal 59. Since the locator pins often have hollow interiors to receive clamp members used for providing part clamping, it is preferably for the positioning target to be remote from the locator pin although in some constructions the positioning target can be on the locator pin. The sensing signal 59 from the sensor 58 senses the location of the positioning target 56 to determine whether the positioning target is positioned within a design tolerance range. A deviation signal is generated by the sensor 58 when the positioning target 56 and thus the vertical rest surface 37 and the locator pin 38 are not located within the design tolerance range. It should be noted that the sensing of the location of the positioning target 56 senses its position in the longitudinal X, sideway Y and vertical Z directions regardless of whether the locator member 36 also has a positioning pin 38 or not.

Adjusting station 16 shown in Figure 1 includes a control 60 that senses the deviation signal from the sensor 58 and through connections 62 to the adjusting robots 52 provides readjusting of the appropriate locator in response to the deviation signal to provide positioning of the associated locator positioning target within the design tolerance range. The sensing and readjustment can be performed as many times as necessary until the positioning is within the design tolerance range. Control 60 also has a connection 64 as shown in Figures 1 and 6 to the linear bearing brakes 46 so as to provide their locked and unlocked conditions as previously described. Furthermore, control 60 has connections 66 to supply and assembly robots 68 of the front, center and rear part stations 20, 22 and 24 previously described.

With reference to Figure 3, the assembly line has the adjustable locators positioned on the work pallet carriages 34 along their lengths at each lateral side along the longitudinal X direction. On the upper side as illustrated, the adjustable locator 18 farthest to the left and the second from the right have close tolerance spacing of the locator pins 38 and positioning holes in the floor parts 28, 30 and 32 being assembled. Furthermore, the locator 18 farthest to the right and the second locator from the left have close tolerance locator pin and part hole positioning in the sideways Y direction so as prevent rotation of the parts 28, 30 and 32. On the other lateral side of the work pallet carriage 34, the locators 18 only provide vertical part positioning on their vertical rest surfaces since the locator pins 38 of the locators have a greater tolerance spacing with the associated positioning holes in the parts 28, 30 and 32 and thus provide only an initial rough horizontal part positioning without any binding with the positioning provided by the locator pins and part holes on the other lateral side of the work pallet as described above. In fact, these locators 18 that provide only vertical part positioning and do not provide horizontal part positioning do not necessarily have to have positioning pins mounted thereof projecting upwardly from their vertical rest surfaces.

It should be appreciated that the locator members 36 which mount the vertical rest surfaces 37 for providing vertical positioning and the locator pins 38 for providing longitudinal and sideways positioning can be provided as separate units apart from the locator members. In fact, there is a protocol in the industry for mounting of the units having the vertical rest surface and locator pin. Thus, it is possible for the present invention to be sold without the vertical rest surfaces and locator pins to customers who wish to purchase these units which will be mounted on the locator members.

As illustrated in Figure 8, the rail brakes 51 each include a driven actuator 70, ball bearings 72, a backing plate and facing assembly 74, a bias spring

76, a driving wedge support 78, a driving wedge 80, pistons 82 and 83 the latter of which is biased by spring 76, a main spring 84 that biases the piston 82, and a bearing retainer 86.

The rod lock 46 illustrated in Figure 9 includes an anodized aluminum housing 88, a high performance guide bushing 90, a steel clamping collar 92, an O-ring seat 94, an air chamber 96, an air inlet 98, a piston and outer collar 100, a breather 102, piston biasing springs 104, and ball bearings 106.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.