System and method for hemming vehicle sheet metal

Abstract

A vehicle sheet metal hemming system (20) and method for hemming vehicle sheet metal outer and inner members (24 and 26) to each other is performed by prehemming and final hemming operations at a single station in cooperation with robot apparatus (42). A drive mechanism (98) has a rotary actuator (100) that moves a tool table (78) vertically to move tool heads (80) between outer idle positions and inner use positions as well as moving prehem tools (82) and final hem tools (84) of the tool heads so as to perform both the prehemming and the final hemming operations.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a system and method for hemming vehicle sheet metal outer and inner members to each other.

2. Background Art

Vehicle sheet metal components conventionally include outer and inner members having peripheries that are secured to each other by a hemming operation. The outer member of such components defines the vehicle outer surface while the inner member functions to provide structural support and/or attachment of the component to the vehicle or attachment of other vehicle components. Conventionally the hemming is performed by forming the periphery of the outer member around the inside of the periphery of the inner member. The hemming operation is conventionally performed by a linear actuator such as a gas or hydraulic cylinder that provides the forming of the outer member around the inner member and then is reciprocated back to the initial start position in preparation for the next cycle.

Since the forming of the periphery of the outer member around the periphery of the inner member defines a relatively narrow U-shaped final configuration, often the hemming is performed in two steps at two different stations. More specifically, the outer member to be formed is initially provided as a stamping having a perpendicular flange at its periphery. The first hemming step is performed at a “prehem” station to bend the outer member flange approximately 45 degrees around the periphery of the inner member. The partially hemmed assembly is then moved to a final hemming station where the flange is further formed against the periphery of the inner member to complete the hemming operation. The hemmed assembly of the outer and inner members is then delivered from the final hemming station for any other further processing, assembly or other further processing required.

Prior art hemming is disclosed by the following United States Patents which are assigned to the assignee of the present invention. These prior art United States Patents include: U.S. Pat. No. 4,706,489 Dacey, Jr.; U.S. Pat. No. 4,827,595 Dacey, Jr.; U.S. Pat. No. 4,928,388 Dacey, Jr.; and U.S. Pat. No. 5,083,355 Dacey, Jr.

SUMMARY OF THE INVENTION

One object of the present invention is to provide an improved vehicle sheet metal hemming system.

In carrying out the above object, the vehicle sheet metal hemming system according to the invention includes a part supply for providing vehicle sheet metal outer and inner members. A hemming machine of the system cyclically hems a periphery of an outer member to a periphery of an associated inner member. Robot apparatus of the system cyclically transfers an outer member and an associated inner member from the part supply to the hemming machine. A base of the hemming machine has a stationary part mount that receives outer and inner members to be hemmed to each other. A tool table of the machine is supported for vertical movement on the base and has a plurality of tool heads mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount on which the outer and inner members are mounted. Each tool head includes a prehem tool mounted thereon for movement relative thereto between: an inner use position for performing prehemming of the outer periphery of the outer member with respect to the periphery of the inner member, and an outer idle position spaced outwardly from the inner use position. Each tool head also includes a final hem tool for completing the hemming of the periphery of the outer member to the periphery of the inner member. A rotary actuator of the hemming machine has an output that rotates 360 degrees to move the tool table vertically on the base from an upper start position downwardly through a hemming stroke to a lower position and then upwardly back to the upper start position in preparation for another cycle. A first set of cam mechanisms of the hemming machine moves the tool heads from outer idle positions on the tool table to inner use positions during the initial downward movement of the tool table under the impetus of the rotary actuator such that continued downward movement of the tool table then moves the prehemmed tool of each tool head to perform the prehem of the periphery of the outer member to the periphery of the inner member. A second set of cam mechanisms of the hemming machine moves the prehem tools of the tool heads from their use positions to their outer idle positions upon farther downward movement of the tool table to permit the final hem tools to complete the hemming of the periphery of the outer member to the periphery of the inner member under the impetus of the rotary actuator as the tool table reaches the lower position.

The construction and operation of the hemming system and the hemming machine provides hemming of the entire periphery of the outer member to the inner member at a single station and has particular utility in the manufacturing of vehicle fuel doors.

The rotary actuator of the hemming machine includes an electric motor drive, a clutch, and a gear reducer that drive the rotary output for moving the tool table between its upper start and lower positions.

The robot apparatus of the hemming system includes: a first robot for cyclically transferring outer members from the part supply to the part mount of the hemming machine, a second robot for cyclically transferring an inner member from the part supply to the part mount of the hemming machine after prior transfer of the associated outer member thereto, and the second robot subsequently delivering the hemmed outer and inner members from the hemming machine.

Four vertical guides of the hemming machine support the tool table for its vertical movement between the upper start position and the lower position. Two of the guides have upper connections to the tool table and lower connections to the output of the rotary actuator to provide vertical movement of the tool table under the operation of the rotary actuator. These four vertical guides are spaced horizontally around the stationary part mount of the base at approximately 90 degrees from each other. The two vertical guides having the upper and lower connections are spaced from each other 180 degrees with the two other vertical guides therebetween. The other two vertical guides have locators that cooperate with the robot apparatus to locate the inner member with respect to the part mount during the hemming operation. More specifically, the locators are positioned at upper ends of the other two vertical guides and locate an end effector of the second robot to thereby position the inner member during the hemming.

The output of the rotary actuator includes a connection bar having opposite ends that include lower connections to the two vertical guides that also have the upper connections to the tool table, and the connection bar has an intermediate portion extending between its opposite ends. The output of the rotary actuator of the hemming machine also includes a rotatively driven eccentric link and a connection link having one end including a pivotal connection to the eccentric link and having another end including a pivotal connection to the intermediate portion of the connection bar between its lower connections to the two vertical guides that also have the upper connections to the tool table.

The tool table is disclosed as including four tool heads spaced at 90 degrees from each other. The two vertical guides that have the upper and lower connections are spaced from each other 180 degrees with the other two vertical guides therebetween, and the tool table includes four tool heads spaced at 90 degrees from each other between the four vertical guides in an alternating relationship.

The construction of the tool table and its tool heads permits the entire periphery of the outer member to be formed for hemming to the periphery of the inner member at a single station with both prehem and final hem forming operations.

The first set of cam mechanisms of the hemming machines includes four slotted cam members mounted on the base and respectively associated with the four tool heads. Four roller cam followers of the first set of cam mechanisms are respectively mounted by the four tool heads and respectively moved by the four slotted cam members on the base to move the tool heads between the outer idle positions and the inner use positions during the vertical movement of the tool table under the impetus of the rotary actuator.

The second set of cam mechanisms includes four roller cams mounted on the stationary part mount of the base and also includes four plate cam followers respectively mounted by the prehem tools of the four tool heads and respectively moved by the four roller cams on the stationary part mount of the base to move the prehem tools relative to the tool heads from the inner use positions to the outer idle positions after continued downward movement of the tool head subsequent to completion of the prehemming. The four roller cams of the second set of cam mechanisms each include two cam rollers spaced from each other such that the associated tool head moves therebetween, the second set of cam mechanisms and the four plate cam followers of the second set of cam mechanisms each includes two cam plates that are respectively moved by the associated two cam rollers on the stationary part mount of the base to provide the movement of the prehem tools relative to the tool heads from the inner use positions to the outer idle positions upon continued downward movement of the tool table subsequent to completion of the prehemming.

Another object of the present invention is to provide an improved method for hemming vehicle sheet metal.

In carrying out the above object, the vehicle sheet metal hemming method is performed by operating robot apparatus to cyclically transfer a vehicle sheet metal outer member and an associated vehicle sheet metal inner member from a part supply to a hemming machine that includes a base having a stationary part mount that receives outer and inner members to be hemmed to each other and that also includes a tool table supported for vertical movement on the base and having a plurality of tool heads mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount on which the outer and inner members are mounted. Operation of a rotary actuator having an output that rotates 360 degrees moves the tool table vertically on the base from an upper start position downwardly through a hemming stroke to a lower position and then upwardly back to the upper start position in preparation for another cycle. During the initial downward movement of the tool table under the impetus of the rotary actuator, a first set of cam mechanisms moves the tool heads on the tool table from outer idle positions to inner use positions such that continued downward movement of the tool table then moves a prehem tool of each tool head to perform a prehem of the periphery of the outer member to the periphery of the inner member. Upon further downward movement of the tool table, a second set of cam mechanisms subsequently moves the prehem tools of the tool heads from inner use positions to outer idle positions to permit final hem tools of the tool heads to complete the hemming of the periphery of the outer member to the periphery of the inner member under the impetus of the rotary actuator as the tool table reaches the lower position.

The hemming method has particular utility in making vehicle sheet metal fuel doors.

The objects, features and advantages of the present invention are readily apparent from the following detailed description of the preferred embodiment for practicing the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan schematic view of a vehicle sheet metal hemming system that is constructed in accordance with the invention and provides the vehicle sheet metal hemming method of the invention.

FIG. 2 is an exploded perspective view illustrating a lower vehicle sheet metal outer member and an upper vehicle sheet metal inner member to be hemmed to each other by the system and method of the invention.

FIG. 3 is a perspective view showing the vehicle sheet member outer and inner members after their peripheries have been hemmed to each other as an assembly.

FIG. 4 is a perspective view of the hemming machine of the hemming system.

FIG. 5 is an elevational view of the hemming machine showing a tool table thereof in an upper start position which corresponds to commencement of a hemming cycle.

FIG. 6 is an enlarged view of a portion of FIG. 1 but with its tool table removed to illustrate the construction of a base, part mount, and first and second cam mechanisms of the hemming machine.

FIG. 7 is a view similar to FIG. 5 but showing the hemming machine with its tool table in a lower position which corresponds to completion of the hemming cycle.

FIG. 8 is a view similar to FIG. 6 showing the hemming machine with the tool table partially removed to facilitate illustration of the machine base, part mount, and first and second cam mechanisms.

FIG. 9 is a top perspective view of the hemming machine shown at the commencement of the hemming cycle which corresponds to the illustrations in FIGS. 5 and 6.

FIG. 10 is a top perspective view similar to FIG. 9 but shown at the completion of the hemming cycle which corresponds to the illustrations in FIGS. 7 and 8.

FIG. 11 is an exploded perspective view showing one of the tool heads and its prehem tool and final hem tool.

FIG. 12 is a perspective view showing a part mount of the machine base on which the outer and inner members are mounted during the hemming cycle.

FIG. 13 is a view that illustrates the vehicle sheet metal outer and inner members just before downward movement of the tool heads has commenced the prehem operation.

FIG. 14 is a view similar to FIG. 13 but after completion of the prehem operation.

FIG. 15 is a view similar to FIG. 14 after outward movement of the prehem tool and continued downward movement of the tool head has moved the final hem tool to preform the final hemming that completes the hemming operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, a schematically indicated vehicle sheet metal hemming system is indicated generally by 20 and is constructed in accordance with the invention as well as performing a vehicle sheet metal hemming method according to the invention as is hereinafter more fully described. The hemming system 20 and the hemming method of the invention will be described in an integrated manner to facilitate an understanding of all aspects of the invention.

The hemming system 20 includes a part supply collectively indicated by 22 for providing vehicle sheet metal outer and inner members 24 and 26 as shown in FIG. 2. As illustrated in FIG. 1, the outer members 24 are provided by an outer member subsupply 28 and the inner members 26 are provided by an inner member subsupply 30.

With continuing reference to FIG. 1, a hemming machine 32 of the hemming system 20 cyclically hems a periphery 34 of the outer member 24 to a periphery 36 of an associated inner member 26 as shown in FIG. 3 to provide an assembled vehicle sheet metal component 38 as shown in FIG. 3. As is hereinafter more fully described, the specific assembled vehicle sheet metal component 38 illustrated is a fuel door whose inner member 36 provides attachment to an associated hinge for moving the fuel door between open and closed positions through the assistance of a thumb hold 40 in the outer member 34 which provides the continuation of the vehicle outer surface around the associated fuel door opening. The inner member 26, as shown in FIGS. 2 and 3, includes two or more deformations at its periphery 36 for contacting the outer member 24 to assist in preventing movement of the inner member with respect to the outer member after the hemming. It should also be appreciated that not all fuel doors have thumb holds, since some fuel doors have spring assisted opening after release by an internal actuator within the vehicle occupant compartment. In such cases the outer member will provide continuity of the outer vehicle surface around the fuel door opening.

The hemming machine 32 has particular utility in providing the hemming of the entire periphery 34 of the outer member 24 to the periphery 36 of the inner member 26 during a single hemming operation which consists of an initial prehemming step and a subsequent final hemming step performed at a single location so as to facilitate the assembling of the outer and inner members to each other.

With reference back to FIG. 1, robot apparatus collectively indicated by 42 cyclically transfers an outer member 24 and an associated inner member 26 from the part supply 22 to the hemming machine 32. More specifically, the robot apparatus includes a first robot 44 having an arm 46 that supports an end effector 48 for cyclically moving the outer members from the subsupply 28 to the hemming machine 32 as the robot arm 46 is moved between its solid and phantom line positions. After such transfer, the robot arm 46 is then moved back to its solid line position to start the next cycle. The robot apparatus 42 also includes a second robot 50 having an arm 52 which supports an end effector 54 that cyclically moves the inner members from the second subsupply 30 to the hemming machine after the first robot 44 has moved the associated outer member to the hemming machine. The second robot 50 maintains its arm 52 at the hemming machine positioning the inner and outer members with respect to each other and after the hemming operation moves the hemmed sheet metal assembly 38 to a delivery station 56 which may be a bin, conveyor, etc.

As illustrated in FIGS. 4-8, the hemming machine includes a base that is generally indicated by 58 and has lower feet 60 mounted on the factory floor 62, a lower base member 64, vertical columns 66 that extend upwardly from the lower base member, an upper base member 68 supported by the column 66 above the lower base member in a spaced relationship, and a part mount 70 best illustrated in FIG. 12 and mounted on the upper base member 68 to receive the sheet metal outer and inner members to be hemmed to each other as previously described in connection with the robot apparatus. More specifically with reference to FIG. 12, the part mount 70 has an upper surface 72 including a peripheral depression 74 where the thumb hold of the outer member is positioned. In addition, locators 76 project upwardly from the upper surface 72 to provide peripheral positioning of the outer member which then receives the inner member as previously described. The part mount 70 may also have an upwardly projecting peripheral die ring, instead of the locators 76, for positioning the outer member 24 during the hemming. The inner member positioning is also achieved in cooperation with the end effector 54 of the second robot 50 shown in FIG. 1 as previously described and, after the hemming operation, the sheet metal assembly 38 is moved upwardly from the part mount 70 and moved to the delivery station 56 as the first robot 44 moves the next outer member from the first substation 28 to the part mount as previously described in preparation for the next cycle. The second robot 50 then is operated so that its end effector 54 moves another inner member from the second subsupply 30 to the part mount for the next hemming operation.

The hemming machine 32 also includes a tool table 78 supported for vertical movement on the upper base member 68 of base 58 from the upper start portion of FIG. 5 to the lower position of FIG. 7 as is hereinafter more fully described. The tool table 78 includes a plurality of tool heads 80, four as shown, mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount 70 on which the outer and inner members are mounted for the hemming operation. Each tool head 80 as shown in FIG. 11 includes a prehem tool 82 and a final hem tool 84. Bolts 86 extend through holes in the final hem tool 84 and into holes 88 in the tool head 80 to fixedly mount the final hem tool thereon. The prehem tool 82 has a mounting portion 90 that is received within a downwardly opening slideway 92 in the final hem tool 84 to support the prehem tool for movement between an inner use position as illustrated in FIGS. 13 and 14 and an outer idle position as illustrated in FIG. 15. The prehem tool 82 has a tool surface 94 that is curved for approximately 90 degrees about the central axis of the part mount and has an inclination of approximately 45 degrees with respect to the horizontal. During downward movement of the tool heads as is hereinafter described, the prehem tool 82 is moved from the position of FIG. 13 to the position of FIG. 14 in its inner use position to preform prehemming of the outer periphery 34 of the outer member 24 with respect to the periphery 36 of the inner member 26. Thereafter as is hereinafter more fully described, outward movement of the prehem tool 82 to the idle position of FIG. 15 and continued downward movement of the tool head moves a tool surface 96 of the final hem tool 84 into engagement with the outer member periphery 36 and downwardly into the final position shown to complete the hemming operation. This tool surface 96 of the final hem tool 84 extends with a curved shape around the central axis of the part mount for approximately 90 degrees with a horizontal orientation to provide the final hemming step.

As shown in FIGS. 4, 5 and 7, a drive mechanism 98 of the hemming machine includes a rotary actuator 100 having an output 102 that moves the tool table 78 vertically on the upper base member 68 of base 58 from an upper start position as shown in FIG. 5 through a hemming stroke to a lower position as shown in FIG. 7 and then upwardly back to the upper start position in preparation for another cycle. More specifically, the rotary output 102 rotates in the direction of arrow 104 in FIG. 5 for 180 degrees to move the tool table through the hemming stroke as is hereinafter more fully described until reaching the lower position of FIG. 7 which corresponds to the final hemming illustrated in FIG. 15. Thereafter, continued rotation of the rotary output 102 in the direction of arrow 106 shown in FIG. 7 for 180 degrees moves the tool table back upwardly to the position of FIG. 5 in preparation for the next cycle. In this upper position, the rotary operation dwells for a predetermined time to permit unloading of the hemmed sheet metal assembly and loading of the next outer and inner members to be hemmed to each other.

As best illustrated in FIGS. 9 and 10, the hemming machine 32 includes a first set of cam mechanisms 108 for moving the tool heads 80 from outer idle positions as shown in FIG. 9 to inner use positions as shown in FIG. 10 during the initial downward movement of the tool table 78 under the impetus of the rotary actuator 100 of the drive mechanism. This initial movement corresponds with the movement of the FIG. 6 right cam mechanism 108 from its solid line indicated position to its phantom line indicated position and positions the tool heads for the prehemming operation during the downward movement from the position of FIG. 13 to the position of FIG. 14, as previously described, and for the subsequent final hemming during the downward movement to the position shown in FIG. 15. After completion of the hemming operation, subsequent upward movement of the tool table 78 back to its upper position causes the cam mechanisms 108 to move the tool heads 80 back to their outer positions as shown in FIGS. 5 and 6. Linear bearings 110 best shown in FIGS. 6, 8 and 11 mount the tool heads 84 for their inward and outward movement under the operation of the cam mechanisms 108 whose construction is hereinafter more fully described.

As illustrated in FIGS. 6, 8, 11 and 12, a second set of cam mechanisms 112 move the prehem tools 82 of the tool heads 80 from their inner use positions illustrated in FIGS. 6, 13 and 14 to their outer idle positions illustrated in FIGS. 8 and 15 upon farther downward movement of the tool table to permit the final hem tools to complete the hemming of the periphery 34 of the outer members to the periphery 36 of the inner members 24 as previously described in connection with FIG. 15. This movement is under the impetus of the rotary actuator 100 of drive mechanism 98 as the tool table 68 reaches the lower position illustrated in FIG. 8. The construction of the second set of cam mechanisms 112 as well as the first set of cam mechanisms 108 is hereinafter more fully described in detail.

As illustrated in FIG. 4, the rotary actuator 100 of drive mechanism 98 includes an electric motor drive 114, a clutch 116, and a gear reducer 118 that rotatively drive the rotary output 102 for moving the tool table between its upper start position of FIG. 5 and its lower position of FIG. 7. The clutch 116 disengages to prevent any machine damage in case of malfunction while the gear reducer 118 reduces the speed of rotation of the electric motor drive 114.

As shown by combined reference to FIGS. 4, 5, 9 and 10, the hemming machine includes two vertical guides 120 spaced diametrically opposite each other from the central axis of the part mount and two other vertical guides 122 spaced diametrically opposite each other with respect to the part mount, with the vertical guides 120 and 122 alternating with each other and being spaced circumferentially about the central axis of the part mount at 90 degrees from each other. The two vertical guides 120 are linear bearings that provide a guiding function of the tool table 78 on the upper base member 68 of the base 58. These two vertical guides 120 have upper locators 123 that locate the end effector 54 of the second robot 50 to locate the inner member 26 with respect to the part mount 70 during the hemming operation. The other two vertical guides 122 in addition to providing such vertical guiding also provide connection of the tool table 78 to the rotary actuator 100 of the drive mechanism 98 in order to provide the actuation of the tool table vertical movement.

More specifically, the two vertical guides 122 have upper connections 124 to the tool table 78 as shown in FIGS. 9 and 10 and have lower connections 126 to the rotary actuator 100 as shown in FIGS. 5 and 7. The four vertical guides 120 and 122 are thus spaced horizontally around the stationary mount 70 on the upper base member 68 of base 58 at approximately 90 degrees from each other with the two vertical guides 122 having the upper and lower connections 124 and 126 being spaced from each other 180 degrees with the two vertical guides 122 therebetween. The output 102 of the rotary actuator 100 includes a connection bar 128 shown in FIGS. 5 and 7 as having opposite ends 130 that include the lower connections 126 to the vertical guides 122 that also have the upper connections 124 to the tool table 78. This connection bar 128 also has an intermediate portion 132 extending between its opposite ends. The output 102 of the rotary actuator 100 includes a rotatively driven eccentric link 134 and a connection link 136 having one end 138 including a pivotal connection 140 to the eccentric link and having another end 142 including a pivotal connection 144 to the intermediate portion 132 of the connection bar 128 between its lower connections 126 to the two vertical guides 122 that also have the upper connections to the tool table.

As illustrated in FIGS. 9 and 10, the four tool heads 80 of the tool table 78 are spaced at 90 degrees from each other between the four vertical guides 120 and 122 in an alternating relationship. Four tool head slideways 146 are respectively associated with the tool heads 80 and each has lower mounts 148 fixedly secured to the tool table 78 as well as each having an upper support 150 that extends between the lower mounts and is slidably engaged by the final hem tool 84 of the associated tool head to prevent upward movement thereof during both the prehemming and final hemming operations previously described in connection with FIGS. 12-15.

As illustrated in FIGS. 4-10, the first set of cam mechanisms 108 includes four slotted cam members 152 mounted on the upper base member 68 of the base 58 and respectively associated with the four tool heads 80. Each of the cam members 152 has a slot 154 having an outwardly inclined upper end and a vertical lower end best shown in FIGS. 6 and 8. The first set of cam mechanisms also includes four roller cam followers 156 respectively mounted by the four tool heads 80 and received by the slots 154 of the four cam members 152 on the base to move the tool heads between the outer idle positions and the inner use positions during the vertical movement of the tool table under the impetus of the rotary actuator 100 previously described.

The second set of cam mechanisms 112 as shown in FIG. 12 includes four pairs of roller cams 158 that are mounted on the stationary part mount 70 on the upper base member 68 of the base 58 and respectively associated with the four tool heads. The roller cams 158 of each pair are spaced from each other such that the four tool heads move therebetween during the inward and outward movement under the operation of the first set of cams as described above. The second set of cam mechanisms 112 also includes four pairs of plate cam followers 160 with each pair being mounted on one of the prehemmed tools 82, as shown in FIG. 11, on opposite sides of its tool surface 94. Each prehem tool 82 also includes a threaded adjuster that is engaged with a gas spring 164 of the associated tool head 80 to bias the prehem tool to its inner use position. After the rotary actuator 100 has moved the tool table 78 downwardly sufficiently so that the prehemming has been performed as illustrated in FIG. 14, the plate cam followers 160 engage the roller cams 158 and move the prehem tools 82 outwardly against the bias of gas springs 164 as illustrated in FIG. 11 to the outer idle position shown in FIG. 15 so that the final hem tools 84 can complete the hemming operation as previously described.

The sheet metal hemming system 20 of the invention thus provides efficient loading of the inner and outer members by the robot apparatus for both the prehem and final hemming operations as well providing delivery of the sheet metal assembly after the hemming from the single station where both the prehem and final hemming operations are performed by rotary actuation of the drive mechanism.

While the best mode for practicing the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.

Claims

1. A vehicle sheet metal hemming system comprising:

a part supply for providing vehicle sheet metal outer and inner members;

a hemming machine for cyclically hemming a periphery of an outer member to a periphery of an associated inner member;

robot apparatus for cyclically transferring an outer member and an associated inner member from the part supply to the hemming machine;

the hemming machine including a base having a stationary part mount that receives outer and inner members to be hemmed to each other;

a tool table supported for vertical movement on the base and having a plurality of tool heads mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount on which the outer and inner members are mounted;

each tool head including a prehem tool mounted thereon for movement relative thereto between: an inner use position for preforming prehemming of the periphery of the outer member with respect to the periphery of the inner member, and an outer idle position spaced outwardly from the inner use position;

each tool head also including a final hem tool for completing the hemming of the periphery of the outer member to the periphery of the inner member;

a drive mechanism including a rotary actuator having an output that rotates 360 degrees to move the tool table vertically on the base from an upper start position downwardly through a hemming stroke to a lower position and then upwardly back to the upper start position in preparation for another cycle;

a first set of cam mechanisms for moving the tool heads from outer idle positions on the tool table to inner use positions during the initial downward movement of the tool table under the impetus of the rotary actuator such that continued downward movement of the tool table then moves the prehem tool of each tool head to perform the prehem of the periphery of the outer member to the periphery of the inner member; and

a second set of cam mechanisms for moving the prehem tools of the tool heads from their inner use positions to their outer idle positions upon farther downward movement of the tool table to permit the final hem tools to complete the hemming of the periphery of the outer member to the periphery of the inner member under the impetus of the rotary actuator as the tool table reaches the lower position.

2. A vehicle sheet metal hemming system as is claim 1 wherein the rotary actuator of the drive mechanism includes an electric motor drive, a clutch, and a gear reducer that drive the rotary output for moving the tool table between its upper start and lower positions.

3. A vehicle sheet metal hemming system as is claim 1 wherein the robot apparatus includes: a first robot for cyclically transferring outer members from the part supply to the part mount of the hemming machine, a second robot for cyclically transferring an inner member from the part supply to the part mount of the hemming machine after prior transfer of the associated outer member thereto, and the second robot subsequently delivering the hemmed outer and inner members from the hemming machine.

4. A vehicle sheet metal hemming system as in claim 3 further including locators that cooperate with the second robot to locate the inner member with respect to the part mount during the hemming.

5. A vehicle sheet metal hemming system as is claim 1 wherein the hemming machine includes four vertical guides that support the tool table for its vertical movement between the upper start position and the lower position, and two of the guides having upper connections to the tool table and lower connections to the output of the rotary actuator to provide vertical movement of the tool table under the operation of the rotary actuator.

6. A vehicle sheet metal hemming system as is claim 5 wherein the four vertical guides are spaced horizontally around the stationary part mount of the base at approximately 90 degrees from each other, the two vertical guides having the upper and lower connections being spaced from each other 180 degrees with the other two vertical guides therebetween, the output of the rotary actuator including a connection bar having opposite ends that include the lower connections to the two vertical guides that also have the upper connections to the tool table, and the connection bar having an intermediate portion extending between its opposite ends.

7. A vehicle sheet metal hemming system as in claim 6 wherein the two other vertical guides have upper ends including locators that cooperate with the robot apparatus to locate the inner member with respect to the part mount during the hemming operation.

8. A vehicle sheet metal hemming system as is claim 6 wherein the output of the rotary actuator also includes a rotatively driven eccentric link and a connection link having one end including a pivotal connection to the eccentric link and having another end including a pivotal connection to the intermediate portion of the connection bar between its lower connections to the two vertical guides that also have the upper connections to the tool table.

9. A vehicle sheet metal hemming system as is claim 6 wherein the output of the rotary actuator also includes a rotatively driven eccentric link and a connection link having one end including a pivotal connection to the eccentric link and having another end including a pivotal connection to the intermediate portion of the connection bar between its lower connections to the two vertical guides that also have upper connections to the tool table, and the rotary actuator including an electric motor drive, a clutch and a gear reducer that drive the eccentric link to move the tool table between its upper start and lower positions.

10. A vehicle sheet metal hemming system as is claim 5 wherein the four vertical guides are spaced horizontally around the stationary part mount of the base at approximately 90 degrees from each other, the two vertical guides having the upper and lower connections being spaced from each other 180 degrees with the other two vertical guides therebetween, and the tool table including four tool heads spaced at 90 degrees from each other between the four vertical guides in and alternating relationship.

11. A vehicle sheet metal hemming system as is claim 10 wherein the first set of cam mechanisms includes: four slotted cam members mounted on the base and respectively associated with the four tool heads, and four roller cam followers respectively mounted by the four tool heads and respectively moved by the four slotted cam members on the base to move the tool heads between the outer idle positions and the inner use positions during the vertical movement of the tool table under the impetus of the rotary actuator.

12. A vehicle sheet metal hemming system as is claim 10 wherein the second set of cam mechanisms includes: four roller cams mounted on the stationary part mount of the base, and four plate cam followers respectively mounted by the prehem tools of the four tool heads and respectively moved by the four roller cams on the stationary part mount of the base to move the prehem tools relative to the tool heads from the inner use positions to the outer idle positions after continued downward movement of the tool head subsequent to completion of the prehemming.

13. A vehicle sheet metal hemming system as is claim 12 wherein the four roller cams of the second set of cam mechanisms each includes two cam rollers spaced from each other such that the associated tool head moves therebetween, and the four plate cam followers of the second set of cam mechanisms each including two cam plates that are respectively moved by the associate two cam rollers on the stationary part mount of the base to provide the movement of the prehem tools relative to the tool heads from the inner use positions to the outer idle positions upon continued downward movement of the tool table subsequent to completion of the prehemming.

14. A vehicle sheet metal hemming system as is claim 10 wherein the first set of cam mechanisms includes: four slotted cam members mounted on the base and respectively associated with the four tool heads, and four roller cam followers respectively mounted by the four tool heads and respectively moved by the four slotted cam members on the base to move the tool heads between the outer idle positions and the inner use positions during the vertical movement of the tool table under the impetus of the rotary actuator; and wherein the second set of cam mechanisms includes: four roller cams mounted on the stationary part mount of the base, and four plate cam followers respectively mounted by the prehem tools of the four tool heads and respectively moved by the four roller cams on stationary part mount of the base to move the prehem tools relative to the tool heads from the inner use positions to the outer idle positions after continued downward movement of the tool table subsequent to completing the prehemming.

15. A vehicle fuel door sheet metal hemming system comprising:

a part supply for providing vehicle sheet metal fuel door outer and inner members;

a hemming machine for cyclically hemming a periphery of a fuel door outer member to a periphery of an associated fuel door inner member;

robot apparatus for cyclically transferring a fuel door outer member and an associated fuel door inner member from the part supply to the hemming machine;

the hemming machine including a base having a stationary part mount that receives fuel door outer and inner members to be hemmed to each other;

a tool table supported for vertical movement on the base and having a plurality of tool heads mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount on which the fuel door outer and inner members are mounted;

each tool head including a prehem tool mounted thereon for movement relative thereto between: an inner use position for preforming prehemming of the periphery of the fuel door outer member with respect to the periphery of the fuel door inner member, and an outer idle position spaced outwardly from the inner use position;

each tool head also including a final hem tool for completing the hemming of the periphery of the fuel door outer member to the periphery of the fuel door inner member;

a drive mechanism including a rotary actuator having an output that rotates 360 degrees to move the tool table vertically on the base from an upper start position downwardly through a hemming stroke to a lower position and then upwardly back to the upper start position in preparation for another cycle;

a first set of cam mechanisms for moving the tool heads from outer idle positions on the tool table to inner use positions during the initial downward movement of the tool table under the impetus of the rotary actuator such that continued downward movement of the tool table then moves the prehem tool of each tool head to perform the prehem of the periphery of the fuel door outer member to the periphery of the fuel door inner member; and

a second set of cam mechanisms for moving the prehem tools of the tool heads from their inner use positions to their outer idle positions upon farther downward movement of the tool table to permit the final hem tools to complete the hemming of the periphery of the fuel door outer member to the periphery of the fuel door inner member under the impetus of the rotary actuator as the tool table reaches the lower position.

16. A vehicle sheet metal hemming system comprising:

a part supply for providing vehicle sheet metal outer and inner members;

a hemming machine for cyclically hemming a periphery of an outer member to a periphery of an associated inner member, and the hemming machine including a base having a stationary part mount that receives outer and inner members to be hemmed to each other;

robot apparatus including: a first robot for cyclically transferring outer members from the part supply to the part mount of the hemming machine, a second robot for cyclically transferring an inner member from the part supply to the part mount of the hemming machine after prior transfer of the associated outer member thereto, and the second robot subsequently delivering the hemmed outer and inner members from the hemming machine;

the hemming machine including a tool table supported for vertical movement on the base and having a plurality of tool heads mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount on which the outer and inner members are mounted;

each tool head including a prehem tool mounted thereon for movement relative thereto between: an inner use position for preforming prehemming of the periphery of the outer member with respect to the periphery of the inner member, and an outer idle position spaced outwardly from the inner use position;

each tool head also including a final hem tools for completing the hemming of the periphery of the outer member to the periphery of the inner member;

a drive mechanism including a rotary actuator having an output and also including an electric motor, a clutch and a gear reducer that drive the rotary output 360 degrees to move the tool table vertically on the base from an upper start position downwardly through a hemming stroke to a lower position and then upwardly back to the upper start position in preparation for another cycle;

a first set of cam mechanisms for moving the tool heads from outer idle positions on the tool table to inner use positions during the initial downward movement of the tool table under the impetus of the rotary actuator such that continued downward movement of the tool table then moves the prehem tool of each tool head to perform the prehem of the periphery of the outer member to the periphery of the inner member; and

a second set of cam mechanisms for moving the prehem tools of the tool heads from their inner use positions to their outer idle positions upon farther downward movement of the tool table to permit the final hem tools to complete the hemming of the periphery of the outer member to the periphery of the inner member under the impetus of the rotary actuator as the tool table reaches the lower position.

17. A vehicle sheet metal hemming system comprising:

a part supply for providing vehicle sheet metal outer and inner members;

a hemming machine for cyclically hemming a periphery of an outer member to a periphery of an associated inner member, and the hemming machine including a base having a stationary part mount that receives outer and inner members to be hemmed to each other;

robot apparatus including: a first robot for cyclically transferring outer members from the part supply to the part mount of the hemming machine, and a second robot for cyclically transferring an inner member from the part supply to the part mount of the hemming machine after prior transfer of the associated outer member thereto, and the second robot subsequently delivering the hemmed outer and inner members from the hemming machine;

the hemming machine including a tool table having a plurality of tool heads mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount on which the outer and inner members are mounted;

four vertical guides that support the tool table for vertical movement between an upper start position and a lower position, and two of the vertical guides having upper connections to the tool table;

each tool head including a prehem tool mounted thereon for movement relative thereto between: an inner use position for preforming prehemming of the periphery of the outer member with respect to the periphery of the inner member, and an outer idle position spaced outwardly from the inner use position;

each tool head also including a final hem tool for completing the hemming of the periphery of the outer member to the periphery of the inner member;

a drive mechanism including a rotary actuator having an output that rotates 360 degrees, and said two vertical guides having the upper connections to the tool table also having lower connections to the output of the rotary actuator to move the tool table vertically on the base from an upper start position downwardly through a hemming stroke to a lower position and then upwardly back to the upper start position in preparation for another cycle;

a first set of cam mechanisms for moving the tool heads from outer idle positions on the tool table to inner use positions during the initial downward movement of the tool table under the impetus of the rotary actuator such that continued downward movement of the tool table then moves the prehem tool of each tool head to perform the prehem of the periphery of the outer member to the periphery of the inner member; and

a second set of cam mechanisms for moving the prehem tools of the tool heads from their inner use positions to their outer idle positions upon farther downward movement of the tool table to permit the final hem tools to complete the hemming of the periphery of the outer member to the periphery of the inner member under the impetus of the rotary actuator as the tool table reaches the lower position.

18. A vehicle sheet metal hemming system comprising:

a part supply for providing vehicle sheet metal outer and inner members;

a hemming machine for cyclically hemming a periphery of an outer member to a periphery of an associated inner member, and the hemming machine including a base having a stationary part mount that receives outer and inner members to be hemmed to each other;

robot apparatus including: a first robot for cyclically transferring outer members from the part supply to the part mount of the hemming machine, a second robot for cyclically transferring an inner member from the part supply to the part mount of the hemming machine after prior transfer of the associated outer member thereto, and the second robot subsequently delivering the hemmed outer and inner members from the hemming machine;

the hemming machine including a tool table having four tool heads mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount on which the outer and inner members are mounted;

four vertical guides that support the tool table for vertical movement between an upper start position and a lower position, the four tool heads being mounted between the four vertical guides in an alternating relationship, two of the vertical guides having upper connections to the tool table, and the other two vertical guides having upper locators that cooperate with the second robot to locate the inner member during the hemming operation;

each tool head including a prehem tool mounted thereon for movement relative thereto between: an inner use position for preforming prehemming of the periphery of the outer member with respect to the periphery of the inner member, and an outer idle position spaced outwardly from the inner use position;

each tool head also including a final hem tool for completing the hemming of the periphery of the outer member to the periphery of the inner member;

a drive mechanism including a rotary actuator having an output that rotates 360 degrees, an electric motor drive, a clutch and a gear reducer that drive the rotary output, the rotary output including a rotatively driven eccentric link and a connection link having opposite ends one of which is connected to the rotatively driven eccentric link, a connection bar having opposite ends and an intermediate portion connected to the other end of the connection link, and said two vertical guides having the upper connections to the tool table also having lower connections to the opposite ends of the connection bar to move the tool table vertically on the base from an upper start position downwardly through a hemming stroke to a lower position and then upwardly back to the upper start position in preparation for another cycle;

a first set of cam mechanisms each of which includes: four slotted cam members mounted on the base and respectively associated with the four tool heads, and four roller cam followers respectively mounted by the four tool heads and respectively moved by the four slotted cam members on the base to move the tool heads from outer idle positions on the tool table to inner use positions during the initial downward movement of the tool table under the impetus of the rotary actuator such that continued downward movement of the tool table then moves the prehem tool of each tool head to perform the prehem of the periphery of the outer member to the periphery of the inner member; and

a second set of cam mechanisms each of which includes: four roller cams mounted on the stationary part mount of the base, and four plate cam followers respectively mounted by the prehem tools of the four tool heads and respectively moved by the four roller cams on stationary part mount of the base to move the prehem tools relative to the tool heads from their inner use positions to their outer idle positions after continued downward movement of the tool head subsequent to completing the prehemming to permit the final hem tools to complete the hemming of the periphery of the outer member to the periphery of the inner member under the impetus of the rotary actuator as the tool table reaches the lower position.

19. A method for hemming vehicle sheet metal comprising:

operating robot apparatus to cyclically transfer a vehicle sheet metal outer member and an associated vehicle sheet metal inner member from a part supply to a hemming machine that includes a base having a stationary part mount that receives outer and inner members to be hemmed to each other and that also includes a tool table supported for vertical movement on the base and having a plurality of tool heads mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount on which the outer and inner members are mounted; and

operating a drive mechanism including a rotary actuator having an output that rotates 360 degrees to move the tool table vertically on the base from an upper start position downwardly through a hemming stroke to a lower position and then upwardly back to the upper start position in preparation for another cycle, with a first set of cam mechanisms moving tool heads on the tool table from outer idle positions to inner use positions during the initial downward movement of the tool table under the impetus of the rotary actuator such that continued downward movement of the tool table then moves a prehem tool of each tool head to perform a prehem of the periphery of the outer member to the periphery of the inner member, and with a second set of cam mechanisms subsequently moving the prehem tools of the tool heads from inner use positions to outer idle positions upon farther downward movement of the tool table to permit final hem tools of the tool heads to complete the hemming of the periphery of the outer member to the periphery of the inner member under the impetus of the rotary actuator as the tool table reaches the lower position.

20. A method for hemming vehicle sheet metal fuel door comprising:

operating robot apparatus to cyclically transfer a vehicle sheet metal fuel door outer member and an associated vehicle sheet metal fuel door inner member from a part supply to a hemming machine that includes a base having a stationary part mount that receives fuel door outer and inner members to be hemmed to each other and that also includes a tool table supported for vertical movement on the base and having a plurality of tool heads mounted thereon for movement relative to the table inwardly and outwardly with respect to the part mount on which the outer and inner members are mounted; and

operating a drive mechanism including a rotary actuator having an output that rotates 360 degrees to move the tool table vertically on the base from an upper start position downwardly through a hemming stroke to a lower position and then upwardly back to the upper start position in preparation for another cycle, with a first set of cam mechanisms moving tool heads on the tool table from outer idle positions to inner use positions during the initial downward movement of the tool table under the impetus of the rotary actuator such that continued downward movement of the tool table then moves a prehem tool of each tool head to perform a prehem of the periphery of the fuel door outer member to the periphery of the fuel door inner member, and with a second set of cam mechanisms subsequently moving the prehem tools of the tool heads from inner use positions to outer idle positions upon farther downward movement of the tool table to permit final hem tools of the tool heads to complete the hemming of the periphery of the fuel door outer member to the periphery of the fuel door inner member under the impetus of the rotary actuator as the tool table reaches the lower position.