continuous casting experience

A repository for a creative life. One of the things I do is change.

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letter of recommendation

   Precision Tube embarked on an ambitious project just as I started working full time. The intention was to produce 3/8"OD x .016 wall, DHP copper tubing for the airconditioning / refrigeration market. This would leap the company from a position of a redraw mill to primary mill but just for this product. It was based on solving two technical challenges; continuously casting DHP copper strip 5" wide x 1/2", hot rolling in line to .035", coiling on 12,000lb capacity reels on one line and transferring to another, forming the strip into a 1 1/2"OD tube, non-vacuum electron beam welding the seam, and stretch reducing in line to 1 1/4"OD. Neither technology was mature, in fact, the non-vacuum electron beam welder (from Hamilton Standard) never became a viable machine tool anywhere and was quickly eclipsed by laser welding. The continuous caster was a wheel-belt machine, a 'one of a kind' from Hazelett Strip Casting, None of the engineers currently working at the company had hot metal experiance, we had been cold drawing big tubes into little tubes or were just out of school. Here is a link to a Picasa album of photos of a 'pour' as we called our experiments.

   No one had tried this approach and we took a year to cast metal into the machine successfully but it came out too cold to hot roll. I took part in all of the experiments and offered suggestions on approaches based on what I was learning from the process and from what I read. I went to five University librarys and accumulated in eight volumes, all the knowledge that had been published and that I could find on continuous casting. There were no books on continuous casting at the time and what information I gleaned was from other novel approaches, some similiar, like the Properzi wheel-belt for trapezoidal shapes (ending up as electric wire) in tough-pitch copper. I collected and read patents, including Sir Henry Bessemer's of 1854, the first patent for continuous casting. I borrowed one technique developed in 1908 to control the level of molten metal over a fixed orfice. I used the molten metal as ground and spectroscopic electrodes, sharpened like pencils, to touch the metal without sculling. My original addition to the body of knowledge was to develop an ablative coating for the 7' diameter, forged cu-cr ring closed with a .035" steel belt that made the mold using buckey balls before the material was out of academia. I discovered that acetylene soot (the first source of bucky balls) repulsed water (10,000 gal./min. on the exterior of the mold) and provided a smooth thin surface strong enough to protect the mold surface. The ablative part was to remove the coating on each revolution with wire wheels. The surface was satisfactory for rolling without conditioning, i.e. no surface defects.

   I was promoted to lead engineer and re-engineered the caster by turning it 180 deg., and shortening the capture area of the mold. The strip came out hot, but, with cracks. I was convinced that the cracking came from P2O5, a phosphoric slag created when the residual phosphorous in the molten metal reacted with O2. I discovered that the casting ring also reacted from the thermal cycling and could pinch the strip in its solidification causing cracks. We cast almost 500 tons of metal in 2 ton batches from a coreless induction furnace. I designed and built a holding furnace to convey the strip and keep it hot to the rolling mills which could be threaded easily along the serpantine bend of 35' to the rolling mills. I assisted in the design of the third generation in line chopper in front of the rolling mills, necessary for beginning cold strip, and strip unsatisfactory to roll. I designed and built an elliptical forced convection reheat furnace to reheat the strip, after the chopper before entering the mills.

   The rolling mills were purchased with hydraulic motors which used speed sensors that I discovered were effected by the vibrations in a 2 high, five stand tandem rolling mill rendering them useless. Since casting speed varied, it was a draw back never overcome. I successfully tested the penultimate properties of the process on a sample; casting, rolling, forming, welding and drawing to finished size. The non-vacuum welder produced a rooster tail of metal from the keyhole technique and could not achieve the speeds necessary to make the operation economically viable. The economic recession coupled with our understanding of the limitations inherent in the machines curtailed the project

The entire five years I worked on this project I was a 'hands on' engineer. I operated all of the equipment along with the intended plant operators(who also doubled as millwrights) and physically aided in the making, often designing, the equipment that was ancilliary but not purchasable, tundishes, launders, spoons and other devices necessary for a foundry. I became proficient with refractories of all kinds; building molds and forms, kilns, and burners. I wrote the reports for each experiment after my promotion to lead and analyzed results. I set up a test for residual phosphorus (range - .015 -.040) following a laboratory report from Noranda and using a wet chemistry/ colorimeter quick check at the melting furnace before casting. In order to learn more about foundrys in general, I apprenticed myself to the Artcaster, E.J. Harper, helping him mold, cast (in brass or aluminum), and clean 10 tons of Albany00 green sand every Tuesday evening for the commercial articles he designed. We worked with match plate patterns, squeeze jolt and floor molds. He traced his knowledge to apprenticing and working at the Baldwin Locomotive Works, Chester, Pa.. This lead me into casting my own sculpture at a foundry I built at my home and eventually to the Johnson Atelier, Technical Institute for Sculpture, Mercerville, N.J.

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