Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
1999-09-17
2001-07-31
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C029S525050, C029S525010, C083S327000, C083S328000, C072S031130, C072S051000
Reexamination Certificate
active
06266865
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is generally directed to a novel method of punching a composite plate.
One prior art method of punching a hole in a composite plate, which is formed of first and second skins with a core sandwiched therebetween, was performed by punching a hole through the plate with a single punch by using a punching apparatus. Due to the spring back qualities of the core material, the core material entered into the hole formed by the punch after the punch was removed from its engagement with the plate. Therefore, the hole created by the punch was not clear and a rivet could not be placed therethrough without first completely clearing the hole by using separate, special tools.
The special tools are used to drill out or remove the excess core material within the hole. These tools are expensive and the process of removing the excess core material is labor intensive.
Another prior art method which is disclosed in this inventor's U.S. Pat. No. 5,774,972, and which is commonly owned by the Assignee herein, uses a novel double punching method to punch the composite plate. This method eliminates the need for special tools to drill out or remove the excess core material within the hole. A problem has been found with this method in that, at times, when the punch is driven completely through the first overlaying skins, the core and the second skin, after breaking the first skins and driving them through the core, the first skins sometimes slipped to the side of the punch, causing the resulting hole to be improperly aligned.
The present invention resolves the problems found in the prior art. The present invention provides a novel method for punching a composite plate which eliminates the step of drilling out or removing excess core material within the hole by using a separate tool and eliminates improper alignment of the resulting hole. In addition, the method of the present invention presents several other advantages and features including the provision of a novel joint structure which will become apparent upon a reading of the attached specification.
OBJECTS AND SUMMARY OF THE INVENTION
A general object of the present invention is to provide a novel method of punching a composite plate to provide a hole through the composite plate which is free of interfering material.
An object of the present invention is to provide a novel method of providing a clear hole through a composite plate without using a separate tool to remove excess material from the hole.
Briefly, and in accordance with the foregoing, the present invention discloses a novel method for forming a clear hole through a composite plate. The composite panel is twice punched by a punching apparatus to form the clear hole. At least two composite plates can be joined together through the clear hole to form a wall panel, such as may be used in a trailer.
Each composite plate is formed from first and second metal skins having a resilient plastic core sandwiched therebetween. The second skin of one plate and the first skin of the adjacent plate each include an integrally formed skin extension which extends past the end of the respective cores and overlaps the respective first or second skin on the adjacent plate.
To perform the method, the following steps are performed: The composite plates are placed adjacent to each other such that the ends of the cores abut against each other and the skin extensions overlap the respective first or second skin of the adjacent composite plate. Thereafter, the punching apparatus is engaged with the plate to be punched to compress the plate core material.
The punching apparatus punches through the extension skin of one plate and the first skin of the adjacent plate, forming a first slug which is slightly pushed into the core material of the adjacent plate. The punching apparatus is then withdrawn from its engagement. The composite plates are flipped over so that the area of the broken extension and first skins are in the direct path of the punching apparatus. Next, the punching apparatus is engaged with the plate to compress the core material. The punching apparatus then punches through the second skin of the plate, forming a second slug which is pushed into the core material of the adjacent plate. The punching motion is continued to punch entirely through the adjacent plate and the extension skin, thereby ejecting the first slug, a portion of the core material and the second slug of the plate, completing the formation of a hole through the plate and the extension skin. The punching apparatus is then withdrawn from its engagement and the core is allowed to expand, due to the spring back qualities of the resilient core material, into the hole. Next, the punching apparatus is re-engaged with the second skin of the plate and compresses the core. The punching apparatus re-punches through the plate and the extension skin in the same location as the punched hole to shear any excess material from within the hole. The punching apparatus is then re-withdrawn from its engagement with the composite plate. After re-punching through the same hole area, the hole is clear and free of any interfering material. A rivet can be easily placed through the hole to join the plates together.
An enlarged shoulder can also be added to the punching apparatus to eliminate the re-punching and re-withdrawing steps from the method. During the withdrawing of the punching apparatus after creating the hole, the shoulder on the punching apparatus will shear any excess core material that has expanded in the hole behind the shoulder from within the hole.
Of course, a composite plate can be punched by using the novel method described herein to form a hole clear of any interfering material by first punching the second skin, then flipping the plate over, and then punching the extension and first skins. Also, a composite plate having only first and second skins and a core can be punched by using the novel method described herein to form a hole clear of any interfering material. That is, a composite plate, without the provision of an overlapping skin can be punched by using this method.
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Hong John C.
Hughes S. Thomas
Trexler, Bushnell Giangiorgi, Blackstone & Marr, Ltd.
Wabash Technology Corporation
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