PHC Spun Pile Machine Accessories FAQ

A: Button-head fracturing or dynamic anchoring failure during pre-tensioning stem from asymmetrical plastic displacement or pre-existing material defects.

• Root Causes:

  1. Excessive Hydraulic Forging Force: Exceeds the steel bar's radial expansion limits, fracturing the material grain boundaries.

  2. Punch Face Wear: Deformed or heavily worn flat working faces unevenly distribute the extrusion load, causing eccentric upsetting.

  3. Shearing Micro-Cracks: Ragged cut faces from worn blades act as stress concentration roots that expand into open cracks during cold forging.

• Shop-Floor Remedies:

  1. Lower Forging Pressure: Calibrate the hydraulic actuator backpressure to balance material displacement.

  2. Inspect Shearing Quality: Ensure the incoming bar end-face is clean and burr-free. Replace worn fixed blades immediately if cut angles drift.

  3. Replace Tooling: If the upset profile becomes irregular, swap out the flat-face heading punch and check the induction-hardened V-groove clamping jaws for internal rebar slippage.

A: Standard cutting tools fail because they lack the required matrix to handle induction-hardened, high-tensile PC bars (1275–1420 MPa). Ordinary blades dull after a few hundred cuts under continuous mechanical stress. Furthermore, poor-quality shearing deforms the bar end-face, producing heavy burrs and micro-cracks that cause button-heading fractures or anchoring slippage during pre-tensioning.

To prevent this, our dynamic GB Cr12MoV moving blades absorb impact shock without edge chipping, while companion fixed blades utilize AISI D2 tool steel to resist sliding abrasion.

A: Brittle edge chipping or fracture results from heavy micro-mechanical interference and stress under hydraulic pressure.

• Root Causes:

  1. Insufficient Shearing Clearance: Causes heavy tool rubbing and severe frictional heat.

  2. Material Defects: Microscopic segregation or hardness spikes in the PC bars.

  3. Improper Heat Treatment: Over-quenched tool steel exceeding 62 HRC that lacks impact toughness.

• Shop-Floor Remedies:

  • Fixed Blade Chipping: The fixed blade acts as rigid support. If it cracks, replace it immediately; do not regrind.

  • Moving Blade Chipping: If the GB Cr12MoV moving blade shows minor chipping, grind 0.10 mm to 0.20 mm and rotate to a fresh edge.

  • Adaptive Adjustment: Reset initial clearance to 0.05 mm – 0.10 mm. If heavy thuds occur, adjust clearance to 0.10 mm – 0.15 mm for buffer space.