Adjustment Steps for CNC Gear Hobbing Machine
- Before debugging, carefully check the parts related to machining: such as the tool holder, tool boss, mandrel, and whether the runout of the fixture’s positioning end face meets the machining requirements, and whether the workpiece’s fit clearance is reasonable. Specific requirements:
1) Fixture end face runout between 0.006 and 0.013 (depending on the end face size);
2) Mandrel radial runout less than 0.01, upper and lower center cone surface runout less than 0.01;
3) Hob tool holder end face and radial runout less than 0.01, hob spindle radial runout less than 0.01;
- Check whether the angle between the tool holder and the tool shaft is within ±λ angle required for machining the product (subtract for same direction, add for opposite directions; for example, subtract the angle of the right-hand workpiece and the right-hand tool, otherwise add).
- Calculate the gear train, differential train, and feed train according to the product parameters and correctly install and lock them.
- Before starting the machine, double-check the hob, ensuring the workpiece is securely clamped and locked, and the hob is in a safe position.
- After starting the machine, ensure the hob’s axial (vertical) initial feed (safety) position stop is locked.
- Manually feed radially. When the hob contacts the workpiece’s outer diameter (allowing a depth of cut of 0.1mm for observation), this position is the effective feed starting point. Based on this, perform an initial trial cut using the following formula: When α = (17.5 ~ 22.5), the feed amount is: L = Mn × 2. After one machining stroke, measure the tooth thickness (common normal). The difference between this and the required thickness, ΔSn × 1.5, is the machining feed amount. Continue machining until the acceptable tooth thickness is achieved. This is the final machining position. For sprockets, the feed amount is calculated by subtracting 1mm from the full tooth depth and performing a trial cut. Once the machining position allows for tooth root inspection, perform the inspection and then proceed with further inspection until the final dimensions are determined.
- Secure the tool holder to the correct position of the travel stop (limit switch) and perform cyclic machining.
- Hob usage: Hobs have incomplete edge tooth profiles and are not allowed during machining. When starting machining, the hob should begin from the first tooth excluding the edge tooth and gradually move towards the other end until it reaches the next edge tooth. If chipping or scoring occurs on the product’s tooth surface, the hob should be moved immediately to avoid causing a large batch of defective products.
- During machining, constantly monitor the machine’s operation and inspect the products promptly, correcting any problems immediately.
