In the manufacture of mineral fiber from molten material, it has been common practice to use a bushing made of precious metals including platinum, rhodium, palladium, ruthenium, iridium and alloys thereof. The bushings are electrically heated by their own resistance and are usually box-like, open on the top and comprise an orifice plate containing hundreds or thousands of orifices, with or without nozzles or tips welded or formed thereon, as shown by U.S. Pat. Nos. 4,207,086 and 4,078,413, which disclosures are hereby incorporated by reference. It is also known in flat plate bushings having no tips or nozzles such as disclosed in U.S. Pat. Nos. 3,905,790 and 4,229,198
Occasionally, and sometimes frequently, a fiber will break beneath the bushing for various reasons that are known. When a fiber break occurs, the loose fiber soon causes other fibers to break and soon all, or most, fibers being formed beneath the bushing are broken, a stoppage of desired fiberization. This is called a “breakout” in the industry. After a breakout begins, it is necessary to wait a short time, usually tens of seconds up to a few minutes, for beads of molten glass to form beneath each bushing orifice or tip, and become large enough that they break loose and fall from the bottom of the orifice plate or tip pulling a very coarse fiber, called a primary fiber, onto the floor, into a scrap bin, basement or scrap bin beneath the forming room floor. This is normally called “beading out” in the industry. Once beaded out, or as soon as the operator is available, the operator or starting equipment can then restart a strand containing the primary fibers into a chopper or winder and again begin making the desired product. Detectors for detecting when a breakout is occurring, and when desired fiberization is occurring, are known as evidenced by U.S. Pat. Nos. 4,130,406, 4,229,198, 4,342,579, 3,432,580, 4,401,452, and 4,925,471.
During normal operation of the bushing to make fiber products the fibers move away from the bushing at a high speed of thousands of feet per minute. The fibers are gathered into a strand of fibers, and the path of the strand is also often turned from a downward direction to a generally horizontal direction, using a pad wheel, a gathering wheel or shoe, hereinafter all referred to as a pad wheel. Some pad wheels are stationary and are simply rotated several degrees at frequent intervals to prevent wearing a flat place on the pad wheel. The fiber strand rubbing around 20-90 degrees of a stationary pad wheel substantially increases tension in the fiber strands versus a turning or rotating pad wheel. To reduce tension on the fiber strands, most pad wheels turn, but are plagued by what is referred to in the industry as strand wrap on the pad wheel. Strand wrap occurs because the fibers, being wet and usually also having a chemical sizing on the surface, tend to stick to the surface of the pad wheel and when the sticking becomes excessive, due to drying of residue on the wheel to tackiness, fibers tend to stay on the rotating wheel and wrap around the wheel. When this occurs the bushing has to be broken out, fiberization interrupted, the pad wheel cleaned and the bushing restarted making good fiber product. While an operator is tending to this time consuming act, other things needed doing are left undone and this causes additional bushing breakouts and lost production. Pad wheel wraps cause costly problems including scrap problems, quality problems and lost production.
U.S. Pat. No. 4,526,598 discusses the pad wheel wrap problem and discloses a rotating a rotating pad wheel designed to try to avoid pad wheel wrap. This pad wheel appears to be driven with a conventional motor, 120 volts, but there is no disclosure of RPM, driven direction or whether always driven. U.S. Pat. No. 4,692,178 discloses a pad wheel comprising a rotatable, generally disc-shaped hub that is provided with walls for supporting a plurality of generally cylindrical rods about the hub's peripheral edge with the rods spaced apart to provide surface contact reductions of more than 70 percent and up to as much as 95 percent. This latter pad wheel is free wheeling, i.e. driven by the moving fiber strands. Both pad wheels are or appear to be an improvement over what came before, but still have short-comings, particularly in how they are driven. The use of 120 volt motors in a forming room environment is dangerous because of the frequent or constant wet conditions around the pad wheel and have a short life in these conditions. On the other hand, a free wheeling pad wheel causes more tension on the fiber strands than necessary and, does not slow down quickly or stop quickly.
USPTO Backgrounds
USPTO Backgrounds