Engine connecting rods must be lightweight, strong and have very high tolerances at the crank bearing for long life. Originally, the crank bearing opening on the forged rod was machined separately and measured so a suitable ‘mate’ could be found to produce the correct tolerance. This required two separate machining and measurement operations and the end result had lower total tolerances than desired.
With powder metallurgy there is a better option. Machine the bottom bearing opening on the entire con-rod, Laser scribe a line at the separation point on each side of the opening, and then ‘crack’ the con-rod into two mating pieces that can be bolted back together.
The Laser scribe is easy to automate with no contact or tool wear. A coaxial gas nozzle with air assist blows the debris out of the scribe line creating a narrow stress riser for a good break with near zero elongation.
The Laser can employ a time-share multiplexer to allow sequential scribing at two separate stations or an energy-share for simultaneous scribing. Even a time-share between two pairs of energy-share systems can be configured from a single Laser to switch between simultaneous scribing sets. Scribing speeds of 1m/min to over 3m/min are possible for a typical scribe time of about 0.5-1.0 seconds per side.
Pulsed Fiber Lasers produce the pulse energy and peak power for efficient scribing. A high power beam quality unit with a small fiber optic produces the best and narrowest scribe. Coaxial air or oxygen is used to aid in the drilling process.
Product Solution – redENERGY
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