Machining method of turbine and spline

① At present, the external spline is mainly processed by spline milling, and the key teeth with high precision or high helix angle are also processed by hobbing machine, such as the input shaft spline of automobile transmission and the driving bevel gear spline of rear axle reducer after heavy truck. The external spline can also be grooved, such as the output shaft spline of heavy truck transmission. Chip-free machining of small modulus external spline is gradually considered as a new technology. Commonly used splinter-free machining includes cold extrusion and cold rolling. Its characteristic is high processing efficiency, which is helpful to improve the strength of splines, such as automobile semi-axle splines and camshaft splines.

(2) Broaching is the main processing method for internal splines, with good accuracy, high processing efficiency and low cost, such as various flange splines. In mass production, the conventional inspection method is basically used to measure the spline, and the accuracy of the spline is ensured by the gear ring jumping. Splines produced in small batches are controlled by measuring the span of the rod. Precision splines can also be sampled through the measurement center.

Worm gear machining:

When manufacturing precision worm gear, it can be finished by shaving, honing or grinding after hobbing or cutting.

Gear hobbing adopts a worm hob with the same basic parameters as the working worm, and the tooth profile is cut according to the principle of generating method (see gear machining) (Figure 1).

If the radial feed method is used for gear hobbing, the hob and the workpiece will be hobbed according to the transmission ratio of Z2/Z 1 (Z 1 is the number of thread heads of the working worm and Z2 is the number of teeth of the worm wheel), and they will gradually approach until their center distance is equal to the center distance when the working worm engages with the worm wheel. When hobbing with tangential feed method, the machine tool should have axial feed besides ensuring the rotation of the cutter; At the same time, the table of the machine tool should also increase the corresponding additional rotation to realize the generating movement, which requires the use of differential chains. Therefore, the machining accuracy of tangential feed method is generally not as good as that of radial feed method, but the quality of tooth surface is better and undercut will not occur. Generally, the accuracy of hobbing worm gear can reach 6 ~ 8 (JB 162-60).

The basic parameters of gear shaving cutter are the same as those of working worm. Gear hobbing machine is generally used for gear shaving of worm gear, which can be driven by gear shaving cutter to freely shave worm gear, or can be forced to shave under the control of machine tool transmission chain, thus improving the quality and accuracy of gear shaving tooth surface.

After gear honing and grinding, in order to improve the quality of tooth surface and improve the contact between worms, gear honing or grinding can be carried out on a gear hobbing machine. Gear honing tool is a kind of honing worm, which is made by casting a mixture of abrasive, plastic and resin on the substrate. When grinding teeth, the grinding worm and abrasive made of cast iron grind against the worm wheel.