Fabricating High-Tonnage Press Structures
Straight-side H-Frame stamping presses are required to maintain near-zero parallel deviation during highly demanding, multi-ton striking operations. Any microscopic flexion in the machine frame leads to immediate degradation of stamped parts, excess tool and die wear, and premature bearing failure.
When our clients dictate reference press forces peaking up to 20,000 kN subject to rigorous Finite Element Analysis (FEA), the fabrication responsibilities move far beyond standard steelworking. For this 140-ton, 8-meter high structure, Openex manufactured massive reinforced columns, a specialized impact-resistant crown, and executed high-precision multi-axis machining across all machine bed interfaces.
Primary Manufacturing Challenges
The core columns and crowns utilize steel thicknesses reaching up to 120mm. Achieving 100% full-penetration welding on such dense A572 Gr50 materials poses extreme risks of internal stress cracks and Heat Affected Zone (HAZ) embrittlement if thermal envelopes aren't tightly controlled.
Measuring over 8,000 mm in height and possessing an operational clear opening of ~2,500 x 1,800 mm, rotating this massive box structure securely into the proper flat-position welding geometry demanded extreme heavy-crane logistics and internal lifting reinforcements.
Openex Machining & Fabrication Workflow
1. Pre-Machining and Beveling of Structural Elements
Proper weld penetration on S355 / Q355B plates requires extensive edge preparation. utilizing heavy profile CNC flame and laser cutting, massive side plates, stiffeners, and base beds were pre-machined with highly precise double-V grooves to ensure symmetrical welding deposition rates.
2. Strict Thermal Control & Welding (ISO Compliant)
Prior to joining, sections exceeding 80mm underwent regulated pre-heating arrays to mitigate temperature-differential shock. We implemented multi-layer, multi-pass submerged arc (SAW) and robotic flux-cored (FCAW) welding methodologies, allowing superior weld penetration depth while avoiding cold-cracking issues typical in extreme-gauge fabrications. Every structural critical joint cleared extensive Ultrasonic Testing (UT) criteria to eliminate unseen porosity or slag inclusion.
3. Post Weld Heat Treatment (PWHT) & Dimension Stabilization
Assembling 140 tons of interconnected heavy plating accumulates intense latent residual stresses. Before any surface machining could take place, the completed H-Frame assembly was hoisted into our oversized Heat Treatment Car-Bottom Furnace for controlled stress-relieving, physically resetting the crystalline lattice and yielding absolute dimensional stasis for decades of factory service.
4. Deep Precision CNC Surface Interface Milling
For a pressing die to execute flawlessly over millions of cycles, the crown mounts and the structural machine bed base interface cannot exhibit tolerance creep. Operating our giant multi-axis Waldrich Coburg Gantry CNC machines, our teams simultaneously bored, tapped, and faced the enormous interfaces on identical structural planes across an 8,000mm geometric envelope.
