GB/T 38959-2020: High-Strength Steel Power Spinning Process Specification - Technical Deep Dive

# GB/T 38959-2020: High-Strength Steel Power Spinning Process Specification ## 1. Standard Overview - **Standard Number:** GB/T 38959-2020 - **English Title:** Power spinning of high-strength steel -- Technological specification - **Issuing Body:** State Administration for Market Regulation - **Publication Year:** 2020 ## 2. Core Scope and Definitions This standard specifies the process content, process preparation, spinning formation, and post-spinning treatment for high-strength steel power spinning. ### Applicable Objects - **Material:** Alloy structural steel with yield strength above 800MPa - **Workpieces:** Conical parts and cylindrical parts - **Process Type:** Power spinning process (not applicable to hot spinning) ### Key Technical Terms - Circular arc spinner - Double conical surface spinner - Limit thinning rate - Half cone angle ## 3. Technical Comparison: Shear Spinning vs. Flow Forming | Comparison Item | Shear Spinning | Flow Forming | |----------------|----------------|--------------| | Applicable workpieces | Conical parts (half-cone angle > 5 degrees) | Cylindrical parts / small cone angle parts | | Typical thinning rate | 500mm, select Cr12MoV material - Hardness requirement: HRC 58-62 **Roller Parameter Settings:** - Shear roller: Corner radius of 1-3 times wall thickness - Flow forming roller: Lead-in angle range of 15-30 degrees ## 5. Recommended Equipment ### Three-Roller Frame-Type Power Spinning Machine - **Application:** Preferred equipment for cylindrical parts and conical parts with half-cone angle < 5 degrees - **Suitable Process:** Shear spinning ### Double-Roller Power Spinning Machine - **Application:** Optional equipment for conical parts with half-cone angle > 5 degrees - **Suitable Process:** Flow forming ## 6. Typical Problem Solutions and Optimization Cases ### Diameter Overshoot Correction - For cylindrical part diameter overshoot issues, adjust the feed ratio for correction - **Empirical Data:** For each 0.1 mm/r increase in feed ratio, diameter decreases by approximately 0.2-0.3 mm ### Specific Material Process Optimization (42CrMo) - Use 2-3 passes for spinning - Intermediate annealing temperature controlled at 650 +/- 10 degrees C ## 7. Process Preparation Requirements Prior to spinning operations, ensure: - Blank material meets specification requirements - Proper tooling (mandrel and rollers) is selected and in good condition - Equipment parameters are correctly set for the specific material and geometry - Environmental conditions are suitable for precision forming ## 8. Post-Spinning Treatment After spinning is complete: - Allow workpiece to cool under controlled conditions - Perform dimensional inspection to verify compliance with specifications - Conduct any required heat treatment (stress relief, annealing) - Perform final quality verification including mechanical property testing ## Conclusion GB/T 38959-2020 provides a comprehensive framework for high-strength steel power spinning, covering process preparation, equipment selection, parameter optimization, and quality control. Following these specifications ensures consistent, high-quality results in flow forming operations.