Apparatus for drilling printed circuit boards

An apparatus for automatically forming openings of predetermined sizes and locations in printed circuit boards comprising:

• a movable work table for supporting printed circuit boards to have openings drilled;
• at least one drilling unit provided with means for opening and closing a collet thereof, said drilling unit being movable relative to said work table;
• driving means for moving said work table and said drilling unit relative to each other;
• first tool holding means mounted on said work table to hold a plurality of drills each having a collar fitted around its shank at a predetermined position;
• second tool holding means of a magazine type removably mounted above said work table for holding a plurality of the drills arranged parallel to each other;
• tool transferring means operative to push a desired drill out of said second tool holding means, hold the desired drill that has been pushed out of the second tool holding means and convey the same to a position where said pushed-out desired drill is in alignment with said drilling unit;
• tool attaching means located on said work table for applying pressurized gas to the collar of the drill to move the same axially thereof;
• and
• a control unit operative to control operations of the component parts of the apparatus in a predetermined order that a desired drill is selected according to a diameter of an opening to be drilled, the drilling unit is brought into alignment with the selected drill either directly when the same is held in the first tool holding means or through the tool transferring means when the selected drill is held in the second tool holding means, after the selected drill is gripped by the collet of the drilling unit, the drilling unit is moved to a position in which the selected drill held thereby is aligned with the tool attaching means, the selected drill is temporarily released from gripping engagement with the collet and applied with pressurized gas to its collar by the tool attaching means, the selected drill is gripped by the collet again with the collar of the drill contacting the collet, and the drilling unit with the selected drill is moved to a predetermined position above the printed circuit boards to effect drilling of an opening.

An apparatus for automatically forming openings of predetermined sizes at predetermined positions in printed circuit boards, comprising:

• a stationary base member;
• a work table movably mounted on said stationary base member for supporting printed circuit boards in which openings are to be drilled;
• at least one drilling unit including a collet for gripping a drill, and drive means for opening and closing said collet;
• a housing mounted on said base member for supporting said drilling unit for movement relative to said work table;
• drive means for moving said work table and said drilling unit relative to each other;
• first tool holding means mounted on said work table for holding a plurality of drills each having a collar fitted around its shank at a predetermined position, each said drill being arranged with its tip directed downwardly;
• second tool holding means of a magazine type removably mounted on said housing above said work table for holding a plurality of the drills arranged parallel to each other, said second tool holding member including a cassette provided with a plurality of stepped through-holes into each of which the shank and collar of each drill are slidably fitted;
• tool transferring means for taking a desired drill out of the associated stepped through-hole of said second tool holding means and holding the desired drill so as to transfer the same between the second tool holding means and the drilling unit;
• tool attaching means provided on said work table, said tool attaching means including a bore for loosely receiving the collar of the drill, and a source of pressurized gas connected with said bore for selectively supplying pressurized gas to said bore;
• a control unit for controlling operations of the component parts of the apparatus in a predetermined manner that a desired drill is selected according to a diameter of an opening to be drilled, the drilling unit is brought into alignment with the selected drill either directly when the same is held in the first tool holding means or through the tool transferring means when the selected drill is held in the second tool holding means, after the selected drill is gripped by the collet of the drilling unit, the drilling unit is moved to a position in which the selected drill is aligned with the bore of the tool attaching means, at this position the selected drill is temporarily released from gripping engagement with the collet of the drilling unit and applied with pressurized gas to its collar by the tool attaching means to move lengthwise thereof toward the collet, the selected drill is gripped by the collet again with the collar of the drill contacting the collet, and the drilling unit with the selected drill is moved to a predetermined position above the printed circuit boards to effect drilling of an opening;
• and
• sensing means for detecting the position of the tip of the drill gripped by the collet to ascertain that the tip of the drill is accurately extending from the collet by a predetermined length and/or that the tip of the drill gripped by the collet is free from damage, said drill tip sensing means being associated with the tool attaching means and connected to the control unit so that, when the sensing means detects abnormality in the position of the tip of the drill, an warning is given and the apparatus is rendered inoperative.