Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
2000-09-05
2001-10-16
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C029S465000, C029S243500, C029S514000
Reexamination Certificate
active
06301768
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to hemming two preformed metal panels together to form a closure panel and more particularly to an improved method that does not require conventional press means rather the hemming dies are drawn together.
BACKGROUND OF THE INVENTION
It is known in the automotive industry to join two metal preformed panels into a unitary hollow structural unit. Typical units of this type include vehicle doors, hoods, and trunk lids. Collectively, these units are referred to as closure panels.
A conventional process of joining the two panels together is referred to as hemming and results in a flange of the outer panel being folded over and gripping the edge of the inner panel. The process is well known. A conventional method and apparatus for joining two metal preformed panels is disclosed in U.S. Pat. No. 5,150,508 and its disclosure is incorporated herein by reference.
Conventional press style hemming machines require a tall press system having a base and platens on which upper and lower dies are mountable. The press system is actuated by a hydraulic cylinder having a limited stroke. Metal panels are nested together between the dies and the dies are moved toward each other to edge hem the two panels together. These conventional machines typically have a single hydraulic cylinder to drive the upper and lower dies, making it difficult to control pressing the corners of the panels together. Hydraulic fluid used in the hydraulic system is flammable.
These conventional hemming machines are costly and large requiring significant floor space and ceiling height. In addition, these machines require significant maintenance yet are difficult to maintain because of the limited stroke of the hydraulic cylinder which allows limited access between the upper and lower dies.
SUMMARY OF THE INVENTION
The present invention provides a hemming apparatus and method that eliminates the conventional press system.
The present invention also provides a hemming apparatus and method that improves control during edge hemming of two preformed panels.
In addition, the present invention provides a hemming apparatus and method that is less costly, eliminates the use of hydraulics and is easier to maintain.
More specifically, the closure panel hemming apparatus comprises a lower support supporting a lower hemming die and an upper support spaced from and mounted above the lower support and supporting an upper hemming die. The upper and lower supports are relatively vertically moveable for bringing the dies toward and away from one another. Guide posts interconnect the upper and lower supports and maintain alignment of the upper and lower supports during movement thereof. A plurality of actuators each of the ball screw or rack and pinion type is driveably connected to draw together the upper and lower supports bringing the dies together for hemming.
In one embodiment each actuator is a ball screw actuator including a ball screw mounted on the lower support and a ball nut mounted on the upper support. A drive motor is provided for driving the ball screw. A controller electrically connected to the drive motor controls motor operation.
Preferably the closure panel hemming apparatus includes a plurality of guide posts and ball screw actuators. The closure panel hemming apparatus can include synchronous drive means for driving the plurality of actuators from the drive motor. Spring units associated with ball screw actuators assure an even application of force by the actuator limited to a preset level. Alternatively, the closure panel hemming apparatus can include a plurality of drive motors corresponding to the number of ball screw actuators wherein each ball screw actuator is independently driven.
In another embodiment each actuator is a rack and pinion actuator including a rack mounted on a guide post otherwise fixed relative to one of the supports. A pinion fixedly mounted relative to the other support is driven by a drive motor to cause relative movement between upper and lower supports. A controller electrically connected to the drive motor controls motor operation.
In either embodiment, the upper support and upper die as well as the lower support and lower die can be of integral construction.
A method for forming a vehicle closure panel assembly from outer and inner metal panels, includes the steps of:
supporting the lower hemming die on the lower support;
supporting the upper hemming die on the upper support;
disposing preformed metal panels between the lower and upper hemming dies;
maintaining alignment of the upper and lower dies during relative movement thereof by means of guide posts extending between the supports; and
drawing the dies together, through the operation of a plurality of actuators drawing together the supports, to hem the metal panels.
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.
REFERENCES:
patent: 3422658 (1969-01-01), Michelson
patent: 4726273 (1988-02-01), Miceli
patent: 4756069 (1988-07-01), Morikawa
Blount Steven
Fildes & Outland, P.C.
Hughes S. Thomas
Tesco Engineering, Inc.
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