Geometrical instruments – Gauge – Collocating
Reexamination Certificate
1999-07-30
2001-03-13
Hirshfeld, Andrew H. (Department: 2859)
Geometrical instruments
Gauge
Collocating
C033S645000, C033S638000
Reexamination Certificate
active
06199290
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of this invention relates to registration devices used for positioning work pieces on a work table and holding the same in place while the work piece is operated on. More particularly, this invention relates to registration devices that are attached to the tooling plate of the work tables of numeric controlled machine tools for automatically loading and unloading printed circuit boards and other work pieces for drilling or other machine operations.
2. Description of the Related Art
Printed circuit board (PCB) drilling machines are computer controlled machines having a table that moves in any X, Y plane; and a spindle that moves perpendicular to the table in the Z direction to drill holes in the PCB. On the X, Y table is a mounted plate, commonly called a tooling plate, onto which stacks of one or more PCBs are placed.
PCBs come in a variety of lengths, widths and thicknesses. However, PCBs always have at least two registration pins which are mounted in or through the PCB, so that the pins can be used to precisely mount the board into a known position after the board has been manually or automatically loaded onto the tooling plate. For automatic loading, the tooling plate has at least two types of clamps. A registration pin clamp is used to clamp the PCB's registration pin into a known registration position. The other clamp is a straight edge pin clamp, which is used to clamp the second registration pin into aligmnent with the known registration position at some point spaced apart from the registration position, dependent on the size of the PCB, to prevent rotation of the PCB on the tooling plate.
The registration pin clamping mechanism includes a registration block, which is aligned to the drilling machine for receiving the registration pin into a known registration position, enabling the programmer to use the registration position as a starting datum for creating a drilling program for the PCB. The registration pin clamping mechanism also includes a registration pin clamp which is a moving part that is biased against the registration pin and holds the pin in place against the registration block in the registration position. In order to achieve accuracy, the registration block must be securely mounted to the tooling plate.
The straight edge pin clamp includes a registration bar that is mounted to the tooling plate and aligned to the pin clamp registration block, and a moving edge clamp that clamps and unclamps the anti-rotation PCB pin at some point along the straight edge. Because PCBs come in many different sizes, the straight edge pin clamp must be in the shape of an elongated bar with a straight edge on the side which engages the registration pin so that it can clamp the anti-rotation PCB pin at any distance, regardless of the size of the PCB.
Drilling machines of this type are either automatically or manually loaded and unloaded. Automatic loaded machines come in two different designs. One design loads the PCB by lifting the PCB off of a stack and placing the PCB on top of the tooling plate. The other design slides one or more PCBs on top of the tooling plate into the designated position. In this type of design, the registration block moves out of position in order to enable the PCBs to be loaded into the proper position. Once the PCBs are in the proper position, the registration block will move back into position, and the PCBs will be clamped into place. As a result, maximum accuracy is not always achieved. The movement of the registration block can result in a slight misalignment of the registration block leading to random registration errors. The registration errors are detectable in the sub-micron level precision required for the accurate drilling of PCBs resulting in holes drilled in the wrong locations. Correcting the registration errors is a time consuming process that requires unloading the PCB and adjusting the registration block and registration bar.
For the foregoing reasons, there is a need for a registration system that will eliminate the registration errors introduced by movement of the registration block that are present when a PCB is automatically loaded onto a drilling machine.
SUMMARY
The present invention provides a method and apparatus for automatic loading and registration of work pieces, such as printed circuit boards, and registering against fixed registration points to overcome many of the shortcomings associated with prior art of automatic loading moveable registration systems.
In accordance with one aspect of the present invention, a registration apparatus includes a tooling plate having an angled slot and a main slot, a registration pin clamp, and a fixed position registration block. A PCB having two registration pins is loaded onto the tooling plate such that the first registration pin is clamped against a fixed registration bar and the second registration pin is clamped by a registration apparatus against the fixed position registration block.
According to another aspect of the present invention, a PCB is translated from a cart onto the tooling plate such that the first registration pin enters the angled slot of the tooling plate and moves into the main slot. The second registration pin then enters the angled slot of the tooling plate. When the second registration pin is positioned in the angled slot between the registration pin clamp and the fixed position registration block, translation of the PCB stops. The registration pin clamp then slides across the angled slot, and pushes the registration pin against the fixed position registration block. The second registration pin is now clamped into position against the right-angled end of the registration block. The first registration pin is then clamped into position by a straight edge pin clamp that is mounted along the main slot. The line between the first registration pin and the second registration pin is parallel to the main slot of the tooling plate.
In accordance with yet another aspect of the present invention, a linear motion device, such a pneumatic cylinder, is used to effect movement of the pin clamp towards and away form the angled slot. The linear motion device retracts to push the pin clamp toward and away from the angled slot.
In accordance with a further aspect of the present invention, the angled slot is angled such that the first registration pin passes by the fixed position registration block without requiring movement of the fixed position registration block. In this matter, the first registration pin passes by the fixed registration block and into the main slot of the tooling plate.
In accordance with still a further aspect of the present invention, the registration pin clamp in the fixed position registration block has an angled opening to accommodate any size registration pin. The registration pin clamp pushes the registration pin against the right angled opening of the registration block.
These and other aspects of the present invention are described in full detail in the following description, attached drawings and claims.
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Excellon Automation Co.
Guadalupe Yaritza
Hirshfeld Andrew H.
Kohlmann Henry G.
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