BELT POLISHING

摘要

Basically, to run a coated abrasive belt requires a power source, a tracking and tensioningdevice, and a method or unit to transfer the power into driving the belt. A unit, therefore, consists of (Fig. 1) the following: (A) a power source, (B) a drive wheel or contact wheel, (C) an idler for tensioning and tracking the belt, and (D) the proper coated abrasive belt. In the vast majority of off-hand belt applications (in this context, "off-hand" does not imply "careless"; rather, it means with a hand-held workpiece), the amount of power consumed is directly related to the operation being performed on the workpiece and/or the operator's ability to apply pressure to the work. Naturally, an operation requiring greater amounts of stock removal will require more pressure and, hence, consume more power than will a fine-finishing operation; however, since the same equipment with slight modification can accomplish both extremes (i.e., removing excess metal or fine polishing), the horsepower (hp) requirement must be ample enough to encompass the most severe operating conditions. Originally, the power source to drive coated abrasive belts was a converted buffing lathe, running at a fixed speed. As the industry progressed, proper belt speeds have been taken into consideration, and today a wide variety of variable speed, single- or double-spindle "polishing jacks" are available to fit production needs. It is seldom necessary to exceed 7(1/2) hp for driving a single-spindle unit or to use more than 15 hp for a double-spindle jack having a common power source and utilizing an operator simultaneously on each spindle. If the spindles are powered separately, 7(1/2) hp on each will normally suffice. Generally speaking, 1-2 hp per inch of belt width is sufficient; however, special application conditions may need up to 5 hp per inch of belt width. Power-assisted, work-holding devices will change horsepower requirements drastically, and 25-50 hp machines are not uncommon.