Generally, the use of magnetic chucks greatly speeds production rates and also serve as an operating convenience for a wide variety of surface grinding operations. Their successful use, however, is contingent on a number of things. One is the keeping of the working surface of the chuck both smooth and clean. Careless handling of workpieces on and off a chuck can mar its surface and cause trouble. Tools or work dropped on chuck can cause damage. Sliding rough material across a chuck can also cause marring.
If dents are inadvertently made in a chuck surface, any raised metal caused by such peening usually can be removed with an abrasive stone. Between grinding loads, swarf should be wiped off the chuck.
On a rotary multiple-spindle single-pass type grinder, keeping a magnetic chuck clean is a more difficult matter. However, when they are equipped with a sectional magnetic chuck, a specially developed chuck cleaner can be applied, which takes care of the cleaning function automatically. Mounted on the machine frame at a point between the two grinding spindles is a rotary-brush cleaner. The device carries a horizontal-axis rotary brush that overhangs the chuck, so as to remain in contact with it as it revolves. The brush is four inches in diameter and is carried on a horizontal spindle. The other end of the spindle has a directly mounted, 1800 rpm motor driving the brush.
A flexible, non-metallic scraper is mounted ahead of the brush, the purpose of which is to loosen any swarf which may tend to cling to the surface. The brush itself revolves while almost totally enclosed in a small hood, which is attached to a high-volume vacuum. To avoid pulling coolant through the vacuum disposal, a series of compressed air jets is arranged to blow the coolant back from the area directly around the vacuum space. Toward the rear of the machine, adjacent to the coolant tank, is a 50-gallon drum, equipped with a 1 ½ hp suction motor, which serves as a vacuum tank.
This arrangement allows a single pass machine to surface grind to closer tolerances at high production, ensuring closer accuracies. Swarf between work and chuck cannot affect tolerances adversely.
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