Material or article handling – Apparatus for moving intersupporting articles into – within,... – Stack forming apparatus
Reexamination Certificate
1998-09-29
2001-02-06
Krizek, Janice L. (Department: 3652)
Material or article handling
Apparatus for moving intersupporting articles into, within,...
Stack forming apparatus
C269S054500, C269S903000, C414S792900, C414S796600
Reexamination Certificate
active
06183190
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of stacking packs of printed circuit boards; to a pack loading and unloading device and pack unpinning mechanism for a machine tool; and to a pack of printed circuit boards stackable using the method according to the invention.
As is known, for machining on a machine tool, packs of printed circuit boards are normally provided with two locating pins along the center line and adjacent to two opposite edges of the pack, which pins project from one face of the pack and are essential for aligning and securing the pack to the table of the machine tool.
The pins, however, prevent the packs from being stacked contacting one another, e.g. for storage, and, to prevent the pins of one pack from damaging the adjacent pack, the packs must be separated by a distance greater than the length of the pins. For this reason, the packs are normally stacked in special trays for protecting the pins and maintaining the necessary distance between the packs. Such trays, however, take up an enormous amount of space, thus increasing the storage cost of the packs.
Moreover, the pins seriously complicate loading and unloading of the packs on and off the machine tool. One known machine with a number of machining heads comprises an automatic pack loading and unloading device, wherein two mechanisms are provided on either side of the machine for vertically moving two racks, one for loading and the other for unloading packs of printed circuit boards.
By means of push actuators associated with each machining head, the packs are moved along the X axis on two guides parallel to the X axis, and which are movable vertically to keep the pins detached from the table during transport; and the packs are then fed in steps to the various machining heads. As a result, the loading and unloading device is extremely complicated, expensive and slow-operating.
Another known machine provides for feeding the machining head by means of a rack having a number of pack supporting trays. The rack is located at the rear of the machine, and the pack is pushed along the Y axis of the tray onto a pack aligning and clamping fixture having a groove for housing the pins.
At each loading and unloading cycle, the device must transfer the machined pack back onto the original tray and remove another pack from the next tray. Moreover, in the case of a number of machining heads, an equal number of racks are required, which means this device, too, is fairly complicated and expensive.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a pack of printed circuit boards, which may be so stacked as to reduce storage space. It is a further object of the present invention to provide a highly straightforward, reliable pack loading and unloading device for a machine tool, designed to eliminate the aforementioned drawbacks typically associated with known devices.
According to the present invention, there is provided a method of stacking packs of printed circuit boards, wherein each pack comprises a pair of opposite edges, and a pair of locating elements located along the center line of the pack and adjacent to said edges; characterized by providing each pack with at least one pair of holes separated by a distance equal to that between said locating elements; and by placing a further pack on each pack so as to insert the locating elements of said further pack inside the holes of the underlying pack.
The device for loading and unloading packs of printed circuit boards on and off a table of a machine tool comprises a loading station for loading the packs to be machined, and an unloading station for unloading the machined packs; said table comprising at least one aligning and clamping fixture acting on said pair of locating elements to align and clamp a pack of printed circuit boards during machining; and the device being characterized in that a transfer device for transferring said packs is movable between said fixture and at least one of said stations.
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Borgotec Technologie per l'Automazione S.p.A.
Krizek Janice L.
Sheridan & Ross P.C.
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