What is the main processing technology for the double helical gear ?
A double helical gear is a cylindrical gear with right-handed teeth on a certain part of the tooth width and left-handed teeth on another part of the tooth width. It is widely used in the transmission system of heavy machinery.
Advantages of double helical gear:
1. The double helical gear has a high degree of coincidence, and at least 2 teeth are engaged at any time.
2. The double helical gear has high bearing capacity and works smoothly
3. The double helical tooth theory has no or very small axial force due to the opposite direction of the tooth helix angle in the symmetrical direction.
The two sides of the double helical gear can be manufactured separately and then combined according to the needs; or although the two sides are made into one, the necessary overtravel grooves are left between the effective tooth surfaces on both sides; Or gear shaping is used, but it is also necessary to break the tooth surfaces on both sides. Compared with the processing of ordinary gears, the processing technology of double helical gear is more complicated and difficult. The commonly used processing methods include gear shaping, gear hobbing and gear milling. Hobbing has higher requirements on the width of the undercut, and gear shaping has lower requirements on the width of the undercut. However, for the double helical tooth without relief groove, currently only milling can be selected.
Double helical gear shaping and hobbing are similar to helical gear processing, and both use the principle of generating method to process gears. The difference is that when processing double helical teeth, it is necessary to swing the angle twice, and the symmetry of the left-handed and right-handed teeth needs to be strictly controlled. If the error is too large, it will affect the assembly and meshing of the double helical teeth.
Next, let's take a look at the milling and processing double helical teeth. The tooth milling process is generally to process the tooth shape on a tooth milling machine or machining center by using a forming module disc milling cutter or a finger milling cutter with an involute edge. After each tooth profile of the gear is milled, the indexing mechanism rotates one tooth by the manual or mechanical linkage indexing plate, and then mills out another tooth slot, and this cycle is repeated until all milling is completed.
Our company mostly uses end mills for processing, and uses four-axis linkage or semi-linkage to process the tooth profile. After rough milling, semi-finishing and fine milling, the tooth profile requirements of the drawings are finally achieved. Compared with the forming cutter, it has low processing cost and is not limited by the cutter. It can process gears from 6 to 50 molds.
Comparison between gear milling and gear hobbing and gear shaping:
advantage:
1. The gear milling equipment is simple and the tool cost is low.
2. Milling gear is suitable for single piece and small batch production.
3. double helical gears without undercuts can be processed.
4. The requirements for the hardness of the gear base material are not high, and materials with a hardness below HRC36 can be processed.
5. It can process large modulus and non-standard modulus gears.
6. The left-handed and right-handed gears of the gear are processed and formed at one time, and the symmetry is good.
Luoyang Yujie Industry and Trade Co., Ltd.has 3m, 4m, 6m, 13m, large CNC gantry milling, CNC machining center VMC850, VMC650, large CNC floor boring, and other advanced equipment, can process double helical teeth and other non-standard mechanical parts, If you have any Machining needs, please feel free to contact us!
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