What is Worm External Thread
Purpose: The steering worm is the core component of the electric power steering (EPS) system, which converts motor torque into steering force and determines the lightness and accuracy of steering. Geometric characteristics: complex thread tooth shape (trapezoidal/ball screw tooth shape), high lead accuracy requirements, sensitive tooth surface roughness; Common risks: steering stuttering due to tooth shape errors, rough surfaces that aggravate wear, and lead deviations that cause abnormal noises.
Worm External Thread Grinding Core Pain Point
There are three major bottlenecks in traditional processing equipment: (1) insufficient precision (such as P5 level ball screw accuracy), resulting in poor steering system meshing, and the scrap rate is as high as 5%. (2) low efficiency (only 80 pieces in a single shift), unable to meet the delivery of bulk orders; (3) High maintenance cost (short grinding wheel dressing cycle), increasing long-term operating burden.
Worm External Thread Grinding Process
Blank (forgings/castings) → roughing (removal of allowances) → finishing (SWM1507 multi-axis linkage grinding) → surface treatment (in-line grinding wheel trimming optimization roughness) → testing (according to JB2886-92/GB/T17587.3 standard)
Key points of the sub-link
Rough machining: adopt a large allowance rapid removal strategy, X-axis fast movement speed of 8m/min, reduce the early machining time; Key equipment: SWM1507 CNC system (precise control of feed volume).
Finishing:
- Tooth grinding: The A-axis adjusts the grinding wheel angle (±30°~-160°) to match the tooth angle, and the C-axis and Z-axis are linked (resolution 0.001°/mm) to ensure the lead accuracy;
- Online trimming: The diamond roller spindle (rotation speed 10000min⁻¹) trims the contour of the grinding wheel in real time to ensure that the tooth shape is continuously accurate;
- Cooling control: 500L cooling water tank circulates to avoid workpiece deformation; Key equipment: SWM1507 multi-axis linkage unit, diamond roller dresser.
Testing: Use a coordinate measuring instrument to verify the accuracy (P2 grade ball screw/5 level trapezoidal screw), and the roughness meter to detect whether Ra 0.4μm meets the standard.
SWM1507 CNC Worm Screw External Thread Grinding Machine
Worm External Thread Grinding Earnings Data
| Indicator | Traditional Equipment | SWM1507 | Improvement Range |
|---|---|---|---|
| Ball Screw Precision | Grade P5 | Grade P2 | 3 grades improved |
| Surface Roughness | Ra1.6μm | Ra0.4μm | 75% reduction |
| Scrap Rate | 5% | 0.5% | 90% reduction |
| Single-shift Output | 80 pcs | 105 pcs | 31% increase |
| Grinding Wheel Service Life | 500 pcs/wheel | 600 pcs/wheel | 20% extension |
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