Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
1998-12-22
2002-02-26
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C428S600000, C428S636000, C428S638000, C228S103000, C228S173400, C073S799000, C073S850000, C073S851000, C029S407010
Reexamination Certificate
active
06350533
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a sheet metal component and a method for manufacturing the same, and more particularly to, a sheet metal component which permits easy and reliable inspection of its weld quality and a manufacturing method thereof.
2. Related Art
Vehicular components such as a frame and a cross member affecting the safety of a vehicle are in some cases are constructed of sheet metal components. Some of these sheet metal components are obtained by welding two metal sheets at their confronting ends and by press-forming a resultant one-piece metal sheet into a desired shape. For example, a side frame of a vehicle is constituted by a front member comprised of a first metal sheet and a rear member comprised of a second metal sheet whose thickness and mechanical strength are larger than those of the first metal sheet, so that it may be deformed to absorb the impact upon head-on collision. The first and second metal sheets are subject to butt welding or lap welding, to be united with each other at their confronting ends, and the resultant one-piece metal sheet is subject to press forming to be formed into a side frame of a desired shape to which important security parts and/or specially guaranteed parts such as suspension unit, engine, transmission unit of a vehicle are attached. Thus, a weld failure caused in the side frame can result in a problem of safety of the vehicle.
In order to determine the weld quality in respect of important sheet metal components, such as side frame, greatly affecting the safety, it is advisable to carry out the total inspection of these components at the stage just after the components are fabricated or after entire cars each incorporating therein the sheet metal component are obtained. Thus, methods for carrying out such total inspection have been investigated.
The weld quality of a sheet metal component can be inspected accurately, if the component can be cut at its weld portion so that the cut portion may be subject to visual inspection for weld quality determination in term of, e.g., a magnifying glass. Although this method is applicable to a sampling inspection, it is of course impossible to apply such method to a total inspection. On the other hand, a weld quality determination of a sheet metal component such as a side frame cannot be made in term of a visual inspection at the stage of obtaining an entire car whose side frame is already painted.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a metal sheet component having a weld portion whose weld quality can be determined easily and accurately in term of appearance inspection and a method for manufacturing such a metal sheet component.
According to one aspect of the present invention, there is provided a sheet metal component comprising a main body which is comprised of one-piece metal sheet obtained by welding two metal sheets at their confronting ends, and an expanding portion which projects from a surface of the main body at a welded portion of the main body and which has an external appearance varying in dependence on a weld state of the welded portion.
Preferably, the expanding portion projects from the surface of the main body by a predetermined amount which is set so as not to produce an unusual appearance, indicative of weld failure, in the expanding portion if the two metal sheets are welded properly at the welded portion and so as to produce the unusual appearance if they are improperly welded.
According to the sheet metal component of this invention, the expanding portion has its external appearance varying in dependence on the weld state of the welded portion of the one-piece metal sheet from which the sheet metal component is fabricated. That is, if the weld state (weld quality) is proper, no unusual appearance such as crack is caused in the expanding portion. On the other hand, if improper welding is made, the expanding portion has such an unusual appearance. Based on the appearance of the expanding portion, therefore, the weld state of the sheet metal component can be determined properly. In this manner, the sheet metal component of this invention permits an easy and accurate determination of the weld quality of the welded portion based only on the appearance inspection. For this reason, the present invention is especially useful to provide a sheet metal component such as an automotive frame to which an important security part or a specially guaranteed part is attached and the weld quality of which affects the safety. Since sheet metal components whose weld quality can be determined positively by means of appearance inspection before and after they are assembled into final products, without the need of cutting the sheet metal components at their welded portions, they can be subject to a 100% inspection or total inspection. For instance, in the case of automotive side frames according to this invention, their weld qualities can be easily and accurately determined in total inspection at one or both of the stages before and after they are respectively assembled into vehicle bodies, whereby the quality assurance and the safety of vehicles can be improved.
In the present invention, the two metal sheets may have different shapes, e.g., different thicknesses. The two metal sheets may be butt-welded or lap-welded at their confronting ends. With these preferred sheet metal components, the two metal sheets are welded into the one-piece metal sheet having a required mechanical property and a desired shape which are suited to mechanical and appearance requirements of the sheet metal component. For instance, it is possible to provide an automotive side frame in which a front member, one of the two metal sheets, is greatly deformed when an impact force is applied thereto, thereby absorbing the impact force.
In the present invention, preferably, the expanding portion is formed into a semi-spherical shape, and has its top formed in alignment with part of the welded portion. With this preferred arrangement, the expanding portion has its external appearance more accurately represents the weld state of the weld portion, and therefore, a more accurate determination of the weld state in term of appearance inspection can be carried out.
According to another aspect of the present invention, there is provided a method for manufacturing a sheet metal component in which two metal sheets are welded at their confronting ends to obtain a one-piece metal sheet which is press-formed into the sheet metal component with use of a first pressing machine.
The manufacturing method comprises the steps of (a) transferring the one-piece metal sheet, which is already press-formed or is not press-formed as yet, between first and second press die halves of a second pressing machine and positioning a metal sheet section of the one-piece metal sheet between a punch formed in the first press-die half and a recess formed in the second press-die half so as to face the punch and permit the punch to intrude thereinto, the metal sheet section including part of a welded portion of the one-piece metal sheet, and (b) causing the punch to press the metal sheet section of the one-piece metal sheet so as to subject the metal sheet section to plastic deformation, to thereby form an expanding portion in the one-piece metal sheet, the expanding portion having its external appearance varying in dependence on a weld state of the welded portion.
Preferably, the step (b) includes causing a predetermined amount of plastic deformation in the metal sheet section, to thereby form the expanding portion. The predetermined amount of plastic deformation is set so as not to produce an unusual appearance, indicative of weld failure, in the expanding portion if the two metal sheets are properly welded and to produce the unusual appearance if they are improperly welded.
With the manufacturing method of this invention, a sheet metal component whose weld state is determinable by appearance inspection can be manufactured properly. Since the sheet metal component has the e
Enomoto Masayuki
Goto Kiyoshi
Komizo Toshiyuki
Jones Deborah
McNeil Jennifer
Mitsubishi Jidosha Kogyo Kabushiki
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