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Auto Variable Step Length Machining Tool Disclosure Number: IPCOM000255115D
Publication Date: 2018-Aug-31

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The Prior Art Database


In machining, thread features are commonly made using different operations, mainly hole making (predrill) and tapping. Selection of the predrill is done based on the tap specification and the tap depth. In machined parts we have different tap depths for same tap specification. Commonly step drills are used to predrill these tap holes. Step drills have main hole feature and chamfer feature at fixed step length. Normally there are step drills in which chamfer feature is integral part of the drill itself and another type chamfer insert body is attached to drill body. In all cases the step lengths are fixed before machining operation outside the machining centers. Due to this fixed step length we need separate step drills for different hole depths. This will increase the number of tools in machining operation. Multiple cutting tool increases the cycle time and tool inventory which intern increases the total machining cost. In below given example the hole feature is M6 x 1, however the depth is different. In this case we need two set of step drills, one for depth of 27mm and another for 20 mm.