Electric heating – Metal heating – By arc
Reexamination Certificate
2002-08-28
2004-10-12
Elve, M. Alexandra (Department: 1725)
Electric heating
Metal heating
By arc
C219S121650, C219S121820
Reexamination Certificate
active
06803538
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to processing systems and more particularly, but not necessarily exclusively to welding systems to manufacture tailored blanks.
2. Description of the Related Art
The automobile industry has, over the years, achieved significant improvements in the operating efficiency of the automobiles they produce. This has, in large part, been achieved by the reduction in the weight of the vehicle while maintaining its structural integrity. A major proportion of the weight of the vehicle is from its steel components, such as the chassis and doors, hood and trunk lids. Often, there are areas in the structure of these components that need to remain of a greater thickness, such as in the region of the door hinges, while there are other areas, such as in the door frame, that can be of relatively thinner wall. It is common in this case to reinforce the otherwise relatively thin door frame in the regions to carry the hinges with a stiffener to provide the necessary reinforcement. However, this step increases the parts count and is a source for additional cost.
The automobile industry has, in recent years, been working to implement a welding process to fabricate what is popularly known as a tailored blank which has a relatively thick portion which is welded to a relatively thin portion, so that it can be later stamped into a part with a thick portion being in place to provide strength, reduce the overall part count and weight.
A significant improvement to laser welding lines is disclosed in U.S. Pat. No. 6,204,469 entitled LASER WELDING SYSTEM, assigned to HONDA GIKEN KOGYO KABUSHIKI KAISHA. The subject matter of this patent is incorporated herein by reference. This will be referred to as the Honda '469 patent.
While the system described in the '469 patent has provided a substantial increase in the speed, accuracy and integrity of tailored blanking welds, there is a continuing need to make further improvements, particularly in the speed of the operation.
Accordingly, the present invention seeks to improve certain aspects of the welding processes such as those used to form tailored blanks.
SUMMARY OF THE INVENTION
In one of its aspects a laser welding system, comprising:
a travel path to carry a first blank and a second blank, the first blank having a first weld surface and the second blank having a second weld surface, the first and second blanks being ready to be welded together to form a weld seam along the first and second weld surfaces;
an upstream clamp assembly and a downstream clamp assembly positioned on the travel path;
each of the upstream and downstream clamp assemblies being movable to an open position to allow the first blank to pass through the upstream clamp assembly to a first location within the downstream clamp assembly;
a laser welding source directed at a weld location on the travel path between the upstream and downstream clamp assemblies;
at least one locating means operable to locate the first weld edge adjacent the weld location;
first displacement means to displace the first weld edge against the locating means;
the downstream clamp assembly being movable from the open position to a closed clamped position to clamp the first blank with the first weld edge adjacent the weld location;
the locating means being operable to be withdrawn from the travel path;
the upstream clamp assembly being movable from the open position to an intermediate position, which is selected to guide the second blank to pass through the upstream clamp assembly in a substantially coplanar relationship with the first blank so that the second weld edge makes contact with, but not past, the first weld edge;
second displacement means to displace the second blank to a location adjacent the weld location where the second weld edge abuts the first weld edge;
the upstream clamp assembly being movable from the intermediate position to a closed clamped position to clamp the second blank;
the laser welding unit operable to fuse the first and second weld edges blanks together.
In one embodiment, the system further comprises first and second lateral positioning means for respectively positioning the first and second blanks relative to the travel path. Each blank has a pair of side edges and each lateral positioning means includes a pair of lateral abutment members, each for engaging a corresponding side edge, and a lateral servo positioner for positioning each lateral abutment member. Lateral control means is provided for incrementally controlling the lateral servo positioners. Each of the lateral abutment members includes an upwardly directed flange and a plurality of stop members mounted on the flange.
In one embodiment, each of the claim assemblies includes an upper clamp beam and a lower clamp beam, a plurality of clamp elements fastened to the upper beam and a clamp drive unit for displacing the upper clamp beam relative to the lower clamp between the open and closed positions.
In one embodiment, the first displacement means includes at least one first engagement portion for engaging the first blank and a first drive portion for driving the first engagement portion. The first engagement portion includes a first engagement member, in the form of an upwardly directed flange and a blank abutment member mounted on the flange, for engaging an edge on the first blank opposite the first weld edge and the first drive portion includes a first servo positioner which is aligned for movement along the travel path for displacing the first engagement member; and first control means for incrementally controlling the first servo positioner. A first actuator unit is provided for actuating the blank abutment member between an operable position in the travel path and an inoperable position below the travel path.
In one embodiment, the second displacement means includes at least one second engagement portion for engaging the second blank and a second drive portion for driving the second engagement portion. The second engagement portion includes a second engagement member, in the form of an upwardly directed flange and a blank abutment member mounted on the flange, for engaging an edge of the second blank opposite the second weld edge and the second drive portion includes a second servo positioner which is aligned for movement along the travel path for displacing the second engagement member; and second control means for incrementally controlling the second servo positioner. A second actuator unit is provided for actuating the blank abutment member between an operable position in the travel path and an inoperable position below the travel path.
In one embodiment, the locating means includes a locating member movable between an operable position in the travel path and an inoperable position below the travel path and a locating drive assembly for driving the locating member between the operative and inoperative positions. The locating drive assembly has a carriage member mounted for lateral movement relative to the travel path on a third servo positioner, the carriage supporting a vertically oriented actuator with an output shaft coupled to the locating member. A third control means is also provided for incrementally controlling the third servo positioner.
In still another of its aspects, the present invention provides a method of welding a pair of blanks, comprising:
a step for providing a travel path to carry a first blank and a second blank;
a step for providing an upstream clamp assembly and a downstream clamp assembly positioned on the travel path;
a step for opening the upstream and downstream clamp assemblies;
a step for conveying a first blank along the travel path and through the upstream clamp assembly to the downstream clamp assembly;
a step for positioning a laser welding unit at a weld location between the upstream and downstream clamp assemblies;
a step for interrupting the travel path at the weld location with at least one blank locator;
a step for displacing the first blank until its trailing to-be-welded edge abuts the loc
Perry Warren
Wright Christopher J.
Elve M. Alexandra
Honda Canada Inc.
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