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Drill Pressure Foot

IP.com Disclosure Number: IPCOM000044123D
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Hall, RR: AUTHOR [+4]

Abstract

Suspended, populated circuit boards of different thicknesses can be accurately and reliably drilled by using an evacuated, floating pressure foot on the drill. Referring to the figure, a vertically movable drill spindle 1, having a turbine 2 and drill 3 therein, supports a sleeve 4. The sleeve carries guide rods 5, on which a housing 6 can move vertically relative to sleeve 4. An air bearing is provided between the inner diameter of the housing and mating outer diameter of the sleeve to permit friction-free movement. Housing 6 carries a pair of opposed air cylinders 7, whose piston rods 8 are each attached to a reciprocable slide 9. Each slide is formed at its inner end as half a pressure foot 10. At its outer end, each slide carries a cam 11 that actuates either one of a pair of limit switches 12 as the slide is moved.

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Drill Pressure Foot

Suspended, populated circuit boards of different thicknesses can be accurately and reliably drilled by using an evacuated, floating pressure foot on the drill. Referring to the figure, a vertically movable drill spindle 1, having a turbine 2 and drill 3 therein, supports a sleeve 4. The sleeve carries guide rods 5, on which a housing 6 can move vertically relative to sleeve 4. An air bearing is provided between the inner diameter of the housing and mating outer diameter of the sleeve to permit friction-free movement. Housing 6 carries a pair of opposed air cylinders 7, whose piston rods 8 are each attached to a reciprocable slide 9. Each slide is formed at its inner end as half a pressure foot 10. At its outer end, each slide carries a cam 11 that actuates either one of a pair of limit switches 12 as the slide is moved. A disc 13 and dished baffle 14 are also supported in housing 6 and have openings to accommodate drill 3. The chamber 15 between the disc and shield leads to a vacuum source 16. In operation, air cylinders 7 are operated to close the two halves of pressure foot 10 and actuate appropriate limit switches 12. Spindle 1 then lowers rotating drill 3 toward workpiece 17. As pressure foot 10 strikes the workpiece, housing 6 becomes supported by the workpiece and drill spindle 1 continues downwardly to drill a hole. Any debris from the drill is drawn into the vacuum chamber and discharged. The venturi effect produced by the disc 13 and...