After heat treatment, the large spur gear blank enters the processing stage. Before this link is officially carried out, it is necessary to select appropriate processing tools. CNC machining machine tool is the most critical tool in the modern processing of spur gears. It has the advantages of high precision and high efficiency. When applied to the processing and manufacturing of large spur gears, it can create more economic value for spur gear enterprises.
The general composition of NC machining machine tools includes industrial control computer (IPC), motion controller, servo driver, servo motor, photoelectric encoder, machine tool main body and other auxiliary equipment. In order to reduce the machining error when using the NC machining machine tool, the following four points should be paid attention to, namely, setting reasonable parameters, reasonably selecting cutting tools, reasonably selecting fixtures and determining the machining route according to the characteristics of the workpiece to be processed. The following is a specific analysis.
| Workpiece material department | Rough cutting speed / (M / min) | Roughing tool feed / (mm / R) | Rough cutting depth / mm | Finishing cutting speed / (M / min) | Finishing tool feed / (mm / R) | Finishing cutting depth / mm |
| Carbon steel | 220 | 0.2 | 3.0 | 260 | 0.10 | 0.4 |
| Low alloy steel | 180 | 0.2 | 3.0 | 220 | 0.10 | 0.4 |
| High alloy steel | 120 | 0.2 | 3.0 | 160 | 0.10 | 0.4 |
| Cast iron | 80 | 0.2 | 3.0 | 120 | 0.10 | 0.4 |
| Stainless steel | 80 | 0.2 | 2.0 | 60 | 0.10 | 0.4 |
| Titanium alloy | 40 | 0.2 | 1.5 | 150 | 0.10 | 0.4 |
| Grey cast iron | 120 | 0.2 | 2.0 | 120 | 0.15 | 0.5 |
| Ductile iron | 100 | 0.2 | 2.0 | 120 | 0.15 | 0.5 |
| Aluminium alloy | 1600 | 0.2 | 1.5 | 1600 | 0.10 | 0.5 |
1) Set reasonable processing parameters
With different gear materials, the required cutting speed, cutting amount and cutting depth are different, as shown in the table.
2) Reasonable selection of cutting tools
Due to the need for heat treatment of large spur gear blanks, the cutting temperature in the whole machining process is high, so the selected tools should have good heat resistance, high hardness, strong sharpness and good durability.
3) Reasonable selection of fixture
Fixture refers to the tool for clamping the spur gear blank to be processed. Due to the different types of gears processed, in order to avoid repeated replacement of fixtures and reduce costs, try to use general fixtures to clamp workpieces. In addition, in order to reduce the error, it is necessary to maintain the accurate positioning of the fixture.
4) Determine the processing route
Before formal machining, the operation route and cooperation degree of tools and fixtures shall be planned to ensure that the processing route can be carried out according to the planned route as far as possible. This can greatly reduce the machining error and improve the machining efficiency.