Abstract: The gear shaving process for spiral face gears, a critical aspect of improving surface finish and enhancing the operational performance of these gears. Through a combination of theoretical analysis, simulation, and experimental verification, this research proposes and validates a novel shaving method for spiral face gears.
1. Introduction
1.1 Research Background and Significance
Spiral face gears are widely used in various industrial applications due to their compact structure, smooth transmission, and high load-bearing capacity. However, the surface quality of spiral face gears manufactured through die-casting is often subpar, leading to vibration and noise issues during operation. To address these concerns, this thesis investigates the gear shaving process for spiral face gears, aiming to improve their surface finish and overall performance.
1.2 Research Status at Home and Abroad
Researchers have explored various methods for processing spiral face gears. Staniek R [22] proposed a method where the tool axis is parallel to the tooth surface of the large gear being processed. Litvin et al. [25-28] conducted extensive research on worm face gear transmissions, addressing issues such as tooth root undercutting and tooth tip sharpening. While significant advancements have been made, there is still a lack of research on the finishing methods for die-cast spiral face gears.
1.3 Main Research Content of This Thesis
This thesis presents a gear shaving method for spiral face gears, including theoretical analysis, simulation, tool design, and experimental verification. The objectives are to improve the surface finish of spiral face gears and validate the feasibility of the proposed shaving method.
2. Tooth Surface Generation of Spiral Face Gear
Based on the forming principle of involute cylindrical spiral gears, the tooth surface equation of an involute spiral pinion is derived. Using differential geometry and spatial meshing principles, a generating coordinate system for spiral face gears is established. The tooth surface equation of the spiral face gear is then derived from the tooth surface equation of a hypothetical involute pinion tool through coordinate transformation and meshing equations.
Table 2.1 Parameters and Equations for Tooth Surface Generation
| Parameter | Description | Equation |
|---|---|---|
| rb | Base radius of the pinion | – |
| θ | Angular position of the tooth | – |
| β | Helix angle | – |
| x,y,z | Coordinates in the generating coordinate system | Derived from the tooth surface equation |
3. Principle of Gear Shaving for Spiral Face Gear
3.1 Introduction
Based on the characteristics of die-cast spiral face gears, this chapter proposes a gear shaving method. A hypothetical involute spiral pinion, which meshes with the spiral face gear, is used as the shaving tool, with slots cut into its spiral tooth surface to form the shaving cutter.
3.2 Gear Shaving Principle
The shaving process involves the interaction between the shaving cutter and the spiral face gear, removing material from the gear’s tooth surface to improve its finish.
3.3 Shaving Processing Kinematics Model
A spatial coordinate system is established for the shaving process, and the relative velocities at the cutting points are calculated. Through coordinate transformation, the tooth surface equation of the shaved spiral face gear is derived.
3.4 Tool Structure Design
The geometric dimensions of the shaving cutter are calculated based on its basic parameters. The chip pocket structure is designed based on shaving tool design experience and relevant tool design manuals.
Table 3.1 Parameters for Shaving Cutter Design
| Parameter | Description | Value |
|---|---|---|
| D | Diameter of the shaving cutter | – |
| B | Axial width of the shaving cutter | – |
| N | Number of teeth on the shaving cutter | – |
| h | Depth of the chip pocket | – |
4. NC Machining Simulation of Gear Shaving for Spiral Face Gear
4.1 Introduction
NC machining simulation is conducted using VERICUT software to verify the feasibility of the proposed shaving method and optimize the machining parameters.
4.2 Machine Tool Model for Gear Shaving
A machine tool model is created in Pro/E and imported into VERICUT for the simulation.
4.3 Shaving Processing Simulation
The simulation process includes establishing the shaving cutter and blank models, programming the NC code, and running the simulation to obtain the solid model of the shaved spiral face gear.
Table 4.1 Steps for Shaving Processing Simulation
| Step | Description |
|---|---|
| 1 | Create machine tool, shaving cutter, and blank models in Pro/E |
| 2 | Import models into VERICUT |
| 3 | Select the appropriate machine tool control system |
| 4 | Calculate the tool path for shaving simulation |
| 5 | Program NC code for shaving simulation |
| 6 | Run the simulation to obtain the solid model of the shaved spiral face gear |
5. Experimental Research on Gear Shaving
Using the designed axial-slotted shaving cutter, shaving experiments are conducted on a CNC machine tool. The surface roughness of the spiral face gears before and after shaving is measured using an Infinite Focus 3D optical measuring instrument.
Table 5.1 Basic Parameters for Gear Shaving
| Parameter | Symbol | Value |
|---|---|---|
| Number of teeth on the spiral face gear | N | – |
| Shaving cutter speed | vc | – |
| Feed rate | f | – |
| Depth of cut | ap | – |
The experimental results show a significant reduction in surface roughness after shaving, with the roughness of the concave surface decreasing from 0.8365 μm to 0.6311 μm.
6. Conclusion and Outlook
This thesis proposes and validates a gear shaving method for spiral face gears, demonstrating its feasibility and effectiveness in improving surface finish. The main conclusions are as follows:
- A generating coordinate system for spiral face gears is established, and the tooth surface equation is derived.
- A gear shaving method for spiral face gears is proposed, including the design of the shaving cutter and the establishment of a kinematics model.
- NC machining simulation is conducted using VERICUT software to verify the feasibility of the shaving method.
- Experimental results show a significant reduction in surface roughness after shaving, proving the correctness and feasibility of the proposed method.
Future research could focus on the tooth surface modification design of the shaving cutter to improve the meshing characteristics of spiral face gear transmissions and reduce vibration and noise. Additionally, experimental research on spiral face gear transmission dynamics and vibration could be conducted to determine their service life.