1. Introduction
- CNC machine tools are important for manufacturing, and China is increasing support for the industry.
- The demand for CNC machine tools is growing, with an expected production value of 620 billion yuan in 2026.
- CNC machine tools require safety protection doors to prevent chip and coolant splashing.
- Existing protective doors have issues such as manual operation and reliability problems.
- This article designs an electric push rod type protective door to address these issues.
2. Design Principle of Electric Push Rod Type Protective Door
- The door operates by converting rotary motion to linear motion using a worm gear mechanism.
- Key components include the drive motor, reduction gearbox, screw, and contact switch.
- The gearbox is the core part, and components are made with anti-oxidation treatment.
- The worm gear provides high reduction and low noise in a compact space.
- Technical requirements: push rod load ≥ 60kg, speed ≥ 20mm/s.
3. Hardware Structure
3.1 Screw Design of Electric Push Rod
3.1.1 Screw Parameters
| Parameter | Value |
|---|---|
| Thread Type | Trapezoidal Thread |
| Number of Threads | 4 |
| Pitch Circle Diameter | 16.10mm |
| Axial Pitch | 4.45mm |
| Thread Angle | 30° |
3.1.2 Screw Efficiency
3.1.3 Shear Strength Check of Screw
3.1.4 Bending Strength Check of Screw
3.2 Worm Gear Parameter Design
3.2.1 Parameter Design of Worm Gear
3.2.2 Force Relationship between Worm Gear and Worm
4. Testing and Results
- After manufacturing, the components are assembled and tested.
- The screw rotates right-handed, so the upper nut must be left-handed to prevent loosening.
- A waterproof plastic housing is used to protect the screw from coolant and extend the device’s life.
- The device is installed at the top of the protective door.
- During testing, the worm gear shows some wear on the tooth roots. Solutions include lubrication, surface roughness control (), hardening the worm gear material, and increasing the tooth thickness.
- After optimization, the worm gear and screw operate stably with reduced noise and vibration compared to traditional devices.
- The cylindrical worm gear transmission has an efficiency ≥ 90%, higher load capacity, and advantages such as small size, light weight, and compact structure.
5. Conclusion
- The electric push rod device is the core of the protective door.
- The worm gear and screw are designed, and key component dimensions are calculated.
- The plastic housing protects the mechanism from chips and coolant.
- The device improves automation, efficiency, and safety, with low manufacturing and maintenance costs.
- It can be applied to various mechanical equipment and provides a reference for the industry.