When the Reaming Bit is adjusted correctly without catastrophic processing failures, the low production efficiency caused by frequent drill changes is unacceptable. Through inspection, it was found that the back drilling surface of the cutting edge of the drilling tool was excessively worn. However, excessive or rapid wear of the back drill face can be misdiagnosed. Generally, excessively long cutting time, intermittent cutting or cutting vibration will cause chipping at the cutting edge and be regarded as wear of the back face. The wear of the rear face may be caused first by the built-up edge on the front face. This is because the cutting heat and cutting pressure weld the chips to the front face of the drill to form a built-up edge. At some point during the cutting, the chips will Take away the built-up edge, and at the same time take away the alloy material on the front drilling surface of the drilling tool. When the chip removes the built-up edge and the alloy material on the drilling tool, the built-up edge can be misdiagnosed as wear of the back drill face In order to determine the true cause of the wear of the rear face, you can check whether there are built-up edges or chipping after machining one or two holes in the reaming bit. Reducing cutting pressure and cutting heat can reduce built-up edge, cutting pressure is related to cutting depth and feed speed. Reducing the cutting depth and feed speed can reduce the cutting pressure and cutting heat, but it also reduces the production efficiency. One way to improve production efficiency is to use coated drills. When the chip flow passes through the cutting face of the drill, the coating can reduce the cutting heat. AlTiN's PVD film coating is more effective than CVD film coating, because too thick coating will deteriorate the cutting performance of the cutting edge. Cutting cooling Coolant is usually used to reduce cutting heat. This is simple and easy for turning the outer circle, but it is very difficult for boring the inner hole, because there are boring bars and chips that need to be cooled in the hole when boring. Positioning the coolant nozzle close to the orifice will prevent cutting. Therefore, the way is to provide internal coolant through the boring bar, providing a sufficient flow of coolant along the circumference of the boring bar is an ideal solution, so that the coolant resistance is small and can reach the bottom of the bored hole, which usually needs to be in multiple places Place coolant nozzles, such as at the main rear drilling face, front drilling face and auxiliary rear drilling face. If chipping occurs after machining several parts, the possible cause is that intermittent cutting is encountered, such as cross holes or keyways. For this situation, it is necessary to choose a drill with enhanced edge. If chipping is not caused by intermittent cutting, cutting vibration may be the cause. As with intermittent cutting, cutting vibration will force the drill tool to bend downward, and then rebound as the force disappears, thereby impacting the cutting edge of the drill tool. A possible solution is to increase the feed rate, which increases the feed rate by 10%, which can increase the cutting pressure sufficiently to keep the drilling tool under pressure to avoid the impact of rebound on the cutting edge.
