If your machine has a "real" machine tool spindle, it will have a taper socket for holding the tools. The rest of the spindle is hollow, or has a throuogh hole which will allow a drawbolt of some sort to pass through. This drawbolt can be actuated with an impact wrench, either electric, or air operated, to draw the tool tightly into the taper.
This is how the "Quickdraw" toolchanger works. It has a 24 tool chain carousel, with the tools standing on their threaded end in little pockets fastened to the carousel chain. This chain is indexed witha Geneva star-wheel indexing mechanism.
The electric impact wrench is run by a timer circuit which controls the on-time of the impact wrench. A short stroke air cylinder brings the impact wrench down onto the drawbolt, when the spindle is fully up at the top.
A two-finger claw arm grabs the toolholder by the flange out of the carousel, and then lifts it and swings 180 degrees to align the tool with the spindle. While the arm swings, the tool holder is also inverted so the the threaded end is up to fit into the spindle first.
It takes quite a bit of rigging to interface one of these units to your cnc controller. I've seen these units sell with old mills for $3000 or so on Ebay. I know that a factory refurbished Quickdraw can cost you $7500.00 This toolchanger is actually quite a fine piece of work. A bit dated perhaps, but it is still in use, and repairs are still available for it.
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(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management) |