Operation Analysis and Control of Helical Gear Cutting Operation

At the instant when the additional rotation changes direction (ie: t=n2T), the instantaneous acceleration of the shaper blade is infinite. If the usual mechanical differential is used, it will inevitably generate large impact and vibration, thereby reducing the machining accuracy. Because of the fact that the additional rotation of the gear shaping cutter is realized without relying on the spiral guide rail, it is the difficulty and key of the CNC gear shaping machine.
Motion Control As can be seen from the above analysis, the control of the forming motion and the additional rotation is the key to the design of the CNC system of the gear shaping machine. To this end, we use "electronic gear transmission" and "electronic differential transmission" technology to achieve their linkage control [3].
(1) The electronic gear transmission chain satisfies the molding and precision requirements of the involute busbar of the workpiece gear, and the movement relationship between the spindle of the gear shaping cutter and the spindle of the machining gear must be strictly guaranteed. The motion relationship between the gear teeth of the gear shaping tool spindle and the machining gear spindle can be expressed by the following formula: Nc=Nb×$b$c×KbKc(3) where: Nb is the spindle gear angular displacement detection or the number of command pulses ; Nc is the angular displacement detection or command pulse number of the machining gear spindle; $b spindle cutter spindle detection or command pulse equivalent; $c is the machining gear spindle detection or command pulse equivalent; Kb is the number of the cutter head or the number of teeth; Kc is Machine the number of gear spindle teeth.
Since the unsynchronization of the movement between the tool spindle and the machining gear spindle will be directly copied onto the machining gear, resulting in the movement error of the machining gear, the control of the machine tool movement is one of the keys to the design of the gearbox CNC system. We use the electronic gear transmission 1 chain (ie, the synchronous phase-locked servo control unit) to connect the spindle of the gear cutter with the spindle of the machining gear, which strictly guarantees the above relationship.
(2) Electronic differential drive chain During the forming process of the helical gear of the helical gear of the workpiece, the spindle gear and the machining gear must not only strictly maintain the movement of the component tooth, but also must complete the Z axis (the spindle of the gear shaping cutter) The additional rotation associated with the axial feed, the control of the additional rotation is another key to the design of the gearbox CNC system. The mathematical relationship is as follows: Nc=Nb×$b$c×KbKc±$z$c×sinBP×Mn×Kc(4) where: Nz is the Z-axis displacement detection or the number of command pulses; $z is Z Spindle detection or command pulse equivalent; B is the machining gear helix angle; Mn is the machining gear normal modulus.
In order to meet the molding and precision requirements of the helical gear of the helical gear of the workpiece, the numerical control system of the gear shaping machine adopts the "electronic differential transmission chain" technology to ensure the movement relationship between the additional rotation of the machining gear spindle and the axial feed.
Conclusion (1) The above proposed a new method for controlling the motion of helical gear cutting by using "electronic gear transmission" and "electronic differential transmission" technology. (2) The use of "electronic gear transmission" and "electronic differential transmission" instead of mechanical transmission can not only improve the accuracy of the machine tool, but also make the machine tool simple to manufacture, convenient for maintenance and adjustment.