US20090235712A1

US20090235712A1 - Integrated push pull roller head

Info

Publication number: US20090235712A1
Application number: US12/400,089
Authority: US
Inventors: Ranganathan Padmanabhan; Gerald Erker; Brian Hopkins
Original assignee: Hirotec America Inc
Current assignee: Hirotec America Inc
Priority date: 2008-03-24
Filing date: 2009-03-09
Publication date: 2009-09-24

Abstract

A roller hemming apparatus includes a linear actuator mountable on an end of a multi-axis robotic arm. The linear actuator includes a connector. A roller hemming head is mounted on the linear actuator by the connector. The roller hemming head includes at least one hem roller. The roller hemming head performs both push force and pull force roller hemming operations.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims the priority of U.S. Provisional Application No. 61/070,578 filed Mar. 24, 2008.

TECHNICAL FIELD

This invention relates to roller hemming, and more particularly to an integrated push pull roller head for robotic roller hemming of a set of panels.

BACKGROUND OF THE INVENTION

It is known in the art relating to perform roller hemming utilizing a push-type hem roller to generate hemming pressure by pushing the hem roller against a set of nested panels. For example, a push-type hem roller is used to hem an upturned edge of one or more preformed metal panels to form a hemmed joint or closed panel assembly such as automotive vehicle closure panel assemblies including doors, hoods, decklids, liftgates, and tailgates. However, conventional roller hemming work cells typically require multiple hemming tooling stations in order to complete all of the steps required to hem a set of metal panels.
Also, replacement of hem rollers on conventional roller hemming apparatus is labor intensive and time consuming.

SUMMARY OF THE INVENTION

The present invention provides a push pull roller head that generates hemming pressure both by pushing and pulling, allowing for the utilization of a plurality of roller heads in a single station to act on a panel workpiece using push or pull force roller head orientations. For example, if the panel to be hemmed is in a stand up condition, roller hemming robots may be placed behind the flange area to be hemmed and use the “pull” function of the present roller head to hem the panel, and in the same station, additional robots can perform hemming from the front side of the panel using a “push” force. The present invention provides for the reduction of hemming tooling stations, reduction of plant floor use, and increase in system throughput within one station.
The present roller head may also have a programmable regulator integrated with the head that allows roller head hemming pressure changes to occur during cycle or as needed when switching between specific model requirements.
More particularly, a roller hemming apparatus in accordance with the present invention includes a linear actuator mountable on an end of a multi-axis robotic arm. The linear actuator includes a connector. A roller hemming head is mounted on the linear actuator by the connector. The roller hemming head includes at least one hem roller. The roller hemming head performs both push force and pull force roller hemming operations.
In one embodiment, the connector may be a quick release connector. The linear actuator may include a housing assembly and a piston rod assembly slidable within the housing assembly. The piston rod assembly may include a piston rod extending from the housing assembly and including the connector on a distal end thereof. The housing assembly may include an internal spline and the piston rod may include an external spline cooperable with the internal spline to restrict axial rotation of the piston rod and mounted roller hemming head. The roller hemming head may include a plurality of different hem rollers. One of the hem rollers may be a pull-type hem roller and another of the hem rollers may be a push-type hem roller. Also, one of the hem rollers may be configured to fit into smaller clearances than another of the hem rollers.
A method of roller hemming in accordance with the present invention includes the steps of mounting a linear actuator on an end of a multi-axis robotic arm, the linear actuator including a connector; mounting a roller hemming head on the linear actuator by the connector, the roller hemming head including at least one hem roller; and performing both push force and pull force roller hemming operations with the roller hemming head.
In one embodiment, the connector is a quick release connector, and the method includes the step of exchanging the roller hemming head with another roller hemming head. The method may include the step of restricting axial rotation of the roller hemming head by providing a spline in the linear actuator. The method may include the step of operating the linear actuator to adjust a magnitude of the hemming force applied by the hem roller. The method may include the step of providing a plurality of different hem rollers on the roller hemming head. The method may include the step of mounting a pull-type hem roller on the roller hemming head and mounting a push-type hem roller on the roller hemming head. Also, the method may include the step of mounting a hem roller on the roller hemming head that is configured to fit into smaller clearances than another hem roller mounted on the roller hemming head.
These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an environmental view of a push pull roller hemming head in accordance with the present invention mounted on a multi-axis robotic arm;

FIG. 2 is a side, sectional view of the push pull roller hemming head;

FIG. 3 is a cross-sectional view of the push pull roller hemming head taken along the line 3-3 in FIG. 2;

FIG. 4 is an enlarged, partial view of the push pull roller hemming head as viewed from the direction of arrow 4 in FIG. 2;

FIG. 5 is an environmental view of the push pull roller hemming head performing a pull force hemming operation; and

FIG. 6 is an environmental view of the push pull roller hemming head performing a push force hemming operation.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in detail, numeral 10 generally indicates a roller hemming apparatus in accordance with the present invention. The roller hemming apparatus can perform both push force type and pull force type hemming operations using a single roller hemming head. The roller hemming apparatus also provides for quick and easy exchange of the roller hemming head.
With reference to FIGS. 1 through 4, the roller hemming apparatus 10 includes a linear actuator 12 that is mountable on an end 14 of a multi-axis robotic arm 16 by a tool exchanger or similar. The linear actuator 12 includes a housing assembly 18 and a piston rod assembly 20. The piston rod assembly 20 is movable between a retracted position (as illustrated in FIG. 2) and an extended position (not shown). As discussed in more detail below, the piston rod assembly 20 carries a hemming roller end effector such as roller hemming head 22 or similar.
The housing assembly 18 includes a body 24, an internal spline housing 26, and a rear end cap 28. The body 24 of the housing assembly 18 includes a centrally located cylindrical throughbore 30 that extends through the body.
The piston rod assembly 20 fits within and slides with respect to the housing assembly 18. The rear end portion of the piston rod assembly 20 includes an external spline 32 cooperable with the internal spline of the internal spline housing 26. The external spline 32 fits inside the internal spline housing 26 and slides relative to the internal spline. The cooperation of the internal spline 26 with the external spline 32 prevents axial rotation of the piston rod assembly 20. This is important for roller hemming, in which axial rotation of the roller head is undesirable.
The piston rod assembly 20 includes a piston rod 34 that slides within the throughbore 30 of the body 24. The piston rod 34 has a distal end portion 36 that includes a connector 38 for securing the roller hemming head 22 thereto as described in more detail below. The piston rod assembly 20 also includes a generally annular piston 40 having a central opening 42 and a collar 44. The piston rod 34 fits through the central opening 42 and the collar 44, and is mounted to the piston 40. The piston 40 carries a pair of circumferential seals 46. The seals 46 ride against the internal chamber 50 surface of the body 24 so that fluid pressure applied to one side of the piston 40 causes the piston rod assembly 20 to move in one direction or the other without leakage between the piston 40 and the internal surface of the body 24. The end of the piston rod 34 opposite the distal end portion 36 includes the external spline 32.
The rear end cap 28 forms a sealed chamber 48 surrounding the external spline 32. When pneumatic pressure is introduced into the chamber 48, the piston 40 is forced outward (to the right in FIG. 2) to move to its extended position. Opposite the chamber 48, the throughbore 30 defines a chamber 50 which surrounds the piston rod 34. When pneumatic pressure is introduced into the chamber 50, the piston 40 is forced to its retracted position (to the left as shown in FIG. 2) by the action of the pneumatic pressure on the piston. Pneumatic supply lines 52 may be connected to passages 54 and 56 to supply air under pressure to chambers 48 and 50, respectively.
The roller hemming head 22 is mounted to the linear actuator 12. For example, as shown in FIG. 4, the roller hemming head 22 is mounted via the connector 38 located on the distal end 36 of the piston rod 34. The connector 38 may be a simple attachment, quick release connector that allows the roller hemming head 22 to be quickly mounted on and dismounted from the piston rod 34. This facilitates quick change of the roller hemming head 22, either to replace the roller hemming head when the roller(s) become worn or to exchange the roller hemming head for a different roller head (for example, a roller hemming head including a final hem roller may be exchanged for a roller hemming head including a pre-hem roller). In the embodiment shown in FIGS. 2 and 4, the connector 38 includes a through hole in the distal end 36 of the piston rod 34, and the roller hemming head 22 is secured to the piston rod by a keeper 58 and fastener 60 extending through the roller hemming head and the through hole of the piston rod 34.
The roller hemming head 22 may include a plurality of different hem rollers 62, 64 for performing different roller hemming operations. For example, one of the rollers 62 may be utilized for push-type roller hemming operations while the other roller 64 may be utilized for pull-type roller hemming operations. Also, one of the rollers 64 may be configured to fit into locations with small clearances, while the other roller 62 may be configured to hem locations having larger clearances. Further, the rollers may be configured to perform different types of hems, such as flat hems and rope hems. The hem rollers 62, 64 are mounted on the roller hemming head 22 via bearings to allow for smooth rotation of the rollers. Although, the roller hemming head 22 is shown having two hem rollers, the roller hemming head may have one roller or a plurality of rollers.
Turning to FIG. 5, the roller hemming head 22 is shown performing a pull force type roller hemming operation. Outer panel 66 and inner panels 68, 70 are supported on an anvil 72. The hem roller 64 engages a bent edge 74 of the outer panel 66 on a side opposite the anvil 72, and the hem roller 64 is pulled against the outer panel 66 by the roller hemming head 22. The linear actuator 12 applies a selectable predetermined force exerted on the outer panel bent edge through the hem roller 64 when the chamber 50 is filled with fluid pressure and chamber 48 is exhausted of fluid pressure. This is carried out by toggling a valve that diverts the fluid pressure from passage 54 to passage 56. When fluid pressure is applied to chamber 50 and chamber 48 is exhausted, the piston rod assembly 20 is moved and held in a retracted position as shown in FIG. 2. The robotic arm 16 then positions the hem roller 64 to be in contact with the bent edge 74. After positioning the hem roller 62, the robotic arm then moves the linear actuator 12 in a direction along the axis of piston rod assembly 20 causing the piston rod assembly to become extended by a predetermined amount. When the desired amount of hemming force is obtained, the robotic arm 16 moves the roller hemming head along the edge portion of the outer and inner panels 66, 68, and the hem roller 64 pulls the bent edge 74 of the outer panel 66 against the inner panel 68 to hem the outer panel 66. The hemming force may be regulated as the hem roller 64 moves along the bent edge 74 of the outer panel 66 to provide a generally constant hemming force through the hemming operation. It should also be appreciated that due to the spline construction of the linear actuator, axial rotation of the piston rod 34 is restricted, and therefore the orientation of the hem roller 64 relative to the edges of the outer and inner panels 66, 68 is rigidly maintained.
Turning to FIG. 6, the roller hemming head 22 is shown performing a push force type roller hemming operation on the outer and inner panels 66, 70. The hem roller 62 engages a bent edge 76 of the outer panel 66 on a side opposite the anvil 72, and the hem roller 62 is pushed against the outer panel 66 by the roller hemming head 22. The linear actuator 12 applies a predetermined force exerted on the outer panel bent edge 76 through the hem roller 62 when the chamber 48 is filled with fluid pressure and chamber 50 is exhausted, thereby moving and holding the piston rod assembly 20 in the extended position. The robotic arm 16 then positions the hem roller 62 to be in contact with the bent edge 76 of the outer panel 66. After positioning the hem roller 62, the robotic arm 16 moves the linear actuator in a direction along the axis of the piston rod assembly 20 to become retracted by a predetermined amount. When the desired amount of hemming force is obtained, the robotic arm 16 moves the roller hemming head 22 along the edges of the outer and inner panels 66, 70, and the hem roller 62 pushes the bent edge 76 of the outer panel 66 against the inner panel 70 to hem the inner and outer panels. The hemming force may be regulated as the hem roller 62 moves along the bent edge 76 of the outer panel 66 to provide a generally constant hemming force through the hemming operation. It should also be appreciated that due to the spline construction of the linear actuator, axial rotation of the piston rod 34 is restricted, and therefore the orientation of the hem roller 62 relative to the edges of the outer and inner panels 66, 70 is rigidly maintained.
Although the invention has been described by reference to a specific embodiment, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiment, but that it have the full scope defined by the language of the following claims.

Claims

1. A roller hemming apparatus comprising:

a linear actuator mountable on an end of a multi-axis robotic arm, said linear actuator including a connector;

a roller hemming head mounted on said linear actuator by said connector, said roller hemming head including at least one hem roller;

whereby the roller hemming head performs both push force and pull force roller hemming operations.

2. The roller hemming apparatus of claim 1, wherein said connector is a quick release connector.

3. The roller hemming apparatus of claim 1, wherein said linear actuator includes a housing assembly and a piston rod assembly slidable within said housing assembly, said piston rod assembly including a piston rod extending from said housing assembly and including said connector on a distal end thereof.

4. The roller hemming apparatus of claim 3, wherein said housing assembly includes an internal spline and said piston rod includes an external spline cooperable with said internal spline to restrict axial rotation of said piston rod and mounted roller hemming head.

5. The roller hemming apparatus of claim 1, wherein said roller hemming head includes a plurality of different hem rollers.

6. The roller hemming apparatus of claim 5, wherein one of the hem rollers is a pull-type hem roller and another of the hem rollers is a push-type hem roller.

7. The roller hemming apparatus of claim 5, wherein one of the hem rollers is configured to fit into smaller clearances than another of the hem rollers.

8. A method of roller hemming comprising the steps of:

mounting a linear actuator on an end of a multi-axis robotic arm, said linear actuator including a connector;

mounting a roller hemming head on said linear actuator by said connector, said roller hemming head including at least one hem roller;

performing both push force and pull force roller hemming operations with the roller hemming head.

9. The method of claim 8, wherein said connector is a quick release connector, and said method includes the step of exchanging said roller hemming head with another roller hemming head.

10. The method of claim 8, including the step of:

restricting axial rotation of said roller hemming head by providing a spline in said linear actuator.

11. The method of claim 8, including the step of:

operating said linear actuator to adjust a magnitude of the hemming force applied by said hem roller.

12. The method of claim 8, including the step of:

providing a plurality of different hem rollers on said roller hemming head.

13. The method of claim 12, including the step of:

mounting a pull-type hem roller on said roller hemming head and mounting a push-type hem roller on said roller hemming head.

14. The method of claim 12, including the step of:

mounting a hem roller on said roller hemming head that is configured to fit into smaller clearances than another hem roller mounted on said roller hemming head.