Tube Mills is fine-tune, rolled-form machines which are fine-tune to run at a specified speed (see Figure 1), usually in fast mode. Diameters of the circular or elliptical products being produced are specified because a thin tube mill welding process is used for producing these products. A thin, circular metal slice is cut by the machine into various shapes, as desired. When the desired cuts are made, a series of metal pieces with similar dimensions are pushed through the welding pore. These pieces are guided and aligned along the inside of the tube mill by hand, following the inside of the products’ cross section.
The purpose of this process is to weld a small circle into a larger circle, and thus to create a semi-circular profile with a greater diameter than the original circle. Because each of the resulting pieces has a different diameter, each must be trimmed to a different thickness depending on the diameter difference between the two pieces of the circle. When the desired inner diameter of the product is determined, the welding process is begun.
During operation, the machine feeds balls into the feed pipe by way of a hoist. As each ball is fed into the hoist, the diameter of the portion of the circle must be increased by a small amount. The metal discs on either end of the inner edge of the tube mill may also be fed into the drum from the outside by way of a hoist. A small gap may be present, permitting the balls to be fed into the drum from the inside. Each piece of the circle must be fed into the drum by a different method.
Feeding each round product through the tube mill, a series of strips may be made along the edges of the feed pipe. Each strip is a quarter-inch in diameter. On both ends of the strip, welded holes may be drilled to accept the pins of the pin-feed mechanism. Once the pins are firmly seated, they may be turned and twisted into position by means of a turning tool attached to the inner end of the machine.
After the welding has been completed, the tube mill forming equipment is turned off and left to cool. The plastic strips will harden into the appropriate thickness. The strip is slid into one end of the hole in the center of the pin-feed mechanism. A clamp may then be placed on the other end of the strip to hold the strip in place. This clamp may be adjustable to maintain a tight fit around the circumference of the pipe.
To complete the soldering job, the strip and all of the tools used during the welding process must be removed from the machine. The mill forming tooling is then manually adjusted to the proper setting for the specific type of product being formed. Once the tooling is adjusted, the plastic strip will be inserted into the newly adjusted opening and the weld puddle formed. Once the product is cooled and ready for packaging, it is time to place everything back into the tube mill and make several runs to ensure the soldering of the tooling to the pipe will have properly set.