In the previous article we introduced two milling methods of the milling machine. Today we come to introduce the milling mechanism to achieve these two milling methods.
In reverse milling, the horizontal force component Fx of the cutting force F is opposite to the feed motion f; if the table is left and right feeding, the left of the screw thread contacts the nut thread, and the other side of the thread has a gap. The horizontal cutting component Fx of the milling cutter acting on the workpiece is opposite to the feed motion f. The left of the screw thread is always contacted with the right side of the nut thread, so the workpiece is stable during the milling process. The direction of the horizontal force Fx of the cutting force F is the same as that of the feed motion f. If the table is still fed to the right, the gap between the right side of the screw thread and the left side of the nut thread is still present. The horizontal cutting force Fx on the workpiece is the same as the direction of the feed movement.
The force Fx through the table to drive the screw to the right of the channel, and because the cutter is a multi-blade tool, milling cutting force is constantly changing, so this horizontal cutting force Fx is also changing, the screw will be in the gap In the range of back and forth, so that the table vibration, affecting the stability of cutting, and even cause milling cutter teeth break phenomenon, this time milling machine table feed screw and nut between, must be equipped with smooth milling mechanism The reasonable milling machine can eliminate the gap between the screw, the gap between the nuts, will not produce axial movement phenomenon, to ensure smooth milling smoothly; in reverse milling or fast moving, can automatically make the screw and nut release.Reduce the nut on the screw on the compression force to reduce the screw and nut between the unnecessary wear and tear.
The figure shows the structure of the milling mechanism used in the X6132 milling machine. This milling mechanism consists of right screw 3, left nut 1, right nut 2, crown gear 4, rack 5 and spring 6 and so on. The working principle is as follows: the rack 5 is moved to the right by the action of the spring 6 to push the crown gear 4 and rotate in the direction of the arrow in the figure to drive the left nut 1 and the right nut 2 to rotate in the opposite direction so that the left side of the left nut 1 close to the right side of the screw thread, right nut 2 on the right side of the screw thread on the left side of the screw thread. When the machine tool is working, the work force of the table is forced by the left nut 1 through the lead screw; the left force is borne by the right nut 2.
When the machine is in the reverse milling, the horizontal cutting force Fx of the milling cutting tool acting on the workpiece is opposite to the direction of the feed movement f, and the nut 2 is subjected to the axial force of the screw. The friction between the thread of the nut 2 and the screw thread is large, and the nut 2 has a tendency to rotate with the lead screw. The nut 1 is driven by the gear 4 so that the nut 1 has a tendency to rotate in the opposite direction to the lead screw. A gap is created between the left side of the thread of the nut 1 and the right side of the screw thread to reduce the wear of the screw.