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An automatic machine drill chuck design is shown which indicates to the machine operator when the drill in the chuck is dull and needs to be changed.
English (United States)
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Pressure Sensing Drill Chuck
An automatic machine drill chuck design is shown which indicates to the
machine operator when the drill in the chuck is dull and needs to be changed.
When automatic machines are used for drilling holes, a drill bit may become
dull and break without giving the machine operator any indication of a pending
failure. Often the part being drilled must be scrapped as a result. A new drill
chuck design will give the machine operator an early warning of a dull drill
condition in time for the operator to replace or sharpen the drill before a failure
A dull drill bit requires more pressure than a sharp drill bit when performing a
drilling operation. By utilizing a non-contact measurement transducer such as the
one manufactured by the Electro Corporation, and a spring that carries a certain
spring rating, a drill chuck design is shown that indicates the condition of the drill
bit in use. For example, a .020" diameter drill bit requires a 7.2-inch pound spring
at a feed rate of .0002" per revolution of the bit when sharp without collapsing the
spring. A dull drill bit will cause the spring to collapse and result in a small
movement which is picked up by the measurement transducer. Spring
adjustments may have to be made with a change in drill size.
Referring to the figure, a cross-section of the pressure sensing drill chuck
assembly is shown along with a voltmeter used to indicate to the operator the
condition of the drill in use. The trans...