A CNC automatic process line for double drilling, tapping, and marking of hollow square or rectangular section profiles is a highly specialized manufacturing system designed for the sheet metal and structural metalworking sectors. It integrates multiple machining and marking operations into a single continuous workflow, ensuring precision, repeatability, and productivity in the fabrication of structural parts such as fittings, gussets, and end plates.

Here’s a technical breakdown:

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1. Core Function

The system automates three critical processes:

• Double Drilling: Simultaneous drilling on opposite sides of hollow sections (square/rectangular tubes) to ensure precise hole alignment.
• Tapping: Automated thread cutting in drilled holes, enabling the direct fastening of bolts or screws without additional operations.
• Marking: Automatic part identification, reference marking, or layout marking using dot peen, laser, or inkjet systems for downstream assembly.

These processes are executed in-line on raw profiles or plates, eliminating manual handling and re-clamping between operations.

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2. Design & Integration for Profiles

• Profile Handling: Heavy-duty infeed/outfeed conveyors, automatic clamping, and servo-driven positioning units handle hollow tubes and rectangular sections with accuracy.
• Clamping & Positioning: CNC-controlled servo axes move profiles to exact coordinates for drilling/tapping cycles. Hydraulic or pneumatic clamps stabilize thin-walled tubes to prevent vibration or deformation.
• Dual-Spindle Units: Equipped with synchronized drilling heads on opposite sides, ensuring coaxial precision when drilling through both walls of a hollow profile.

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3. For Fittings, Gussets, and End Plates

• Flat Plate Processing: The same line (or integrated modules) can automatically drill, tap, and mark gussets and end plates used in structural frameworks.
• High-Precision Fixtures: Modular fixtures align plates for hole-to-hole repeatability and positional accuracy, critical for bolted or welded assemblies.
• Tapping Stations: Threads are cut directly into end plates or gussets, ready for assembly.
• Marking Systems: Part numbers, reference coordinates, or assembly marks are applied automatically for error-free installation.

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4. Control System

• CNC or PLC Control: Coordinates drilling, tapping, and marking with part programs stored in the control unit.
• CAD/CAM Integration: Part geometries and drilling layouts can be imported directly from CAD drawings.
• Automation Modules: Automatic tool changers, tapping heads, coolant delivery, and chip evacuation systems ensure continuous operation.

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5. Technical Benefits for Sheet Metal & Metalworking

• Accuracy: Double-side drilling ensures perfect alignment, critical for structural bolted joints.
• Productivity: Eliminates manual repositioning and multiple setups → faster cycle times.
• Consistency: CNC control maintains repeatability across thousands of identical parts.
• Flexibility: Can process both tubular profiles and flat sheet components in one line.
• Traceability: Marking systems provide permanent part IDs for quality control and assembly tracking.
• Reduced Errors: Integrated automation minimizes operator mistakes in drilling/tapping patterns.

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In summary:
An automatic process line for double drilling, tapping, and marking of square/rectangular hollow sections and for producing fittings, gussets, and end plates is an integrated CNC fabrication system. It is designed to meet the needs of the sheet metal and structural metalworking industries, where high-precision, high-volume, and fully traceable components are essential for steel structures, machinery frames, and modular assemblies.