Steel Wire Coiling Machine: Winding on a Collapsible Head

Executive summary An automatic steel wire coiling machine takes continuous wire feed from upstream drawing or annealing lines, winds it onto an expandable segmented mandrel, performs cut-to-length separation, and transfers consolidated coils for strapping. The accompanying operational video (duration: 72 s) details the mechanical sequence of a dual-mandrel coiling unit: high-speed winding, radial mandrel collapse, pneumatic coil-holding arm engagement, and automated reset. Engineered for heavy-duty industrial wire processing, this dual-head configuration supports line speeds from 200 to 800 m/min and delivers up to 40 strapped coils per hour under continuous operation.

Table of Contents

Kinematic Sequence Breakdown of the Coiling Cycle

The coiling system consists of three main sub-assemblies: an expandable four-segment coiling mandrel mounted on the driven headstock, an articulated swinging transfer arm for coil consolidation and offloading, and a heavy-duty structural base frame housing the drive train. A column-mounted HMI console and multi-tier stack light provide real-time status indication.

  1. 0 to ~9 s — High-Speed Rotary Winding: The segmented mandrel rotates at synchronized line speed. The servo-driven traverse guide executes reciprocal pitch-controlled strokes, building precision layered wire windings onto the expanded mandrel barrel.
  2. ~12 s — Coil Completion & Deceleration: As wire length approaches the pre-programmed target, the drive spindle decelerates smoothly to prevent outer-wrap slack and prepare for cut-off.
  3. ~15 to 42 s — Radial Mandrel Collapse & Clearance Generation: The segmented coiling mandrel collapses radially inward (moving from expanded winding diameter to collapsed unloading clearance). This mechanical collapse relieves radial hoop tension from the wire pack, allowing axial release.
  4. ~45 to 51 s — Dwell & Separation Phase: The mandrel remains fully collapsed with the completed coil suspended at dead center, verifying clearance before manipulator transfer.
  5. ~54 to 60 s — Transfer Manipulator In-Feed & Mandrel Reset: The pivoting transfer arm swings 90° inward to clamp the coil exterior. Concurrently, the mandrel core re-expands to its designated nominal winding diameter.
  6. ~63 to 69 s — Next-Coil Take-Up Engagement: The mandrel clamps the wire tail, accelerates back to line velocity, and resumes high-speed winding for the subsequent coil pack.
  7. ~72 s — Manipulator Retraction: The transfer arm withdraws the secured coil to the auxiliary staging position for automated ID strapping, returning to home standby.

Cycle Phase Timeline

The 72-second clip captures a transition between successive coil lots:

Operational Step Timestamp Window Duration Mechanical Execution
Precision Layer Winding 0 to ~12 s ~12 s Mandrel rotating at sync speed; servo traverse controlling coil build
Mandrel Radial Collapse ~15 to 30 s ~15 s Internal toggle/wedge links contract segments to collapse diameter
Release Dwell & Stabilization ~30 to 42 s ~12 s Full radial clearance maintained; coil core tension relieved
Transfer Arm In-Feed ~45 to 51 s ~6 s Manipulator swings into axial alignment with mandrel centerline
Coil Clamping & Re-Expansion ~54 to 63 s ~9 s Mechanical jaws secure coil outer profile; mandrel returns to winding diameter
Winding Resumption ~63 to 69 s ~6 s Wire tail clamped, spindle accelerates into synchronous speed
Arm Retraction & Offload ~72 s — Coil stripped axially to ID strapping station

Note: Data derived from 3-second frame-sampling intervals. The recorded cycle isolates the coil offload and mandrel reset sequence rather than total gross wind time.

System Architecture: How the Wire Coiling Line Operates

A fully integrated steel wire coiling and packaging line combines continuous accumulation, precision winding, shearing, automated strapping, and exit logistics into a closed loop:

  1. Vertical Tension Wire Accumulator: Buffers 5 to 20 m of wire using a motorized dancer assembly. It absorbs speed differentials between upstream drawing machines and coiler index cycles, preserving constant tensile force and preventing line trips.
  2. Dual-Head Coiling Machine: Employs two independent segmented mandrels. While Head A completes high-speed winding and length metering via an optical encoder, Head B indexes to the strapping position.
  3. Servo Traverse Mechanism & Portal Shear: Coordinates traverse pitch with wire diameter to maintain flat, uniform coil sidewalls. Upon reaching preset length, a rigid hydraulic/pneumatic portal shear executes a clean square cut.
  4. Through-the-Eye Automatic Strapping Unit: Feeds high-tensile polypropylene (PP) strap directly through the inner diameter (ID) of the coil, applying friction-weld seals at multiple radial intervals.
  5. Downstream Unloading System: Discharges finished, strapped coils to walking beams, downenders, or automated turnstiles.
Sub-Assembly Engineering Function Primary Benefit
Tension Accumulator Buffers 5–20 m wire; maintains tension within ±5% Zero shutdown of upstream drawing lines
Dual Expandable Mandrels Alternate continuous winding and offloading Eliminates indexing downtime; doubles throughput
Length Encoder & Servo Traverse Optical metering down to 10 mm; dynamic stroke adjust Precise coil weight and flat sidewall formation
Heavy-Duty Portal Cutter Guillotine blade cut at full deceleration Clean end condition; zero wire snagging
Automated Radial Strapping Through-the-ID strapping (3 to 6 positions) Structural bundle integrity during transport
Coil Transfer Manipulator Axial coil stripping via pneumatic clamp Eliminates manual handling; protects surface finish

Technical Specifications & Line Data

Parameter Operational Range / Value Engineering Notes
Wire Diameter Range 1.2 mm to 8.0 mm (Customizable) Low, medium, and high carbon steel, galvanized or annealed
Maximum Line Speed 200 to 800 m/min Synchronized via closed-loop dancer feedback
Production Capacity 40 coils/h (Dual-Head) / 20 coils/h (Single-Head) Dependent on coil weight, wire gauge, and strapping cycles
Centerline Elevation 1,000 mm from finished floor Standard ergonomics for cross-line integration
Electrical Rating 380 V / 440 V, 3-Phase, 50/60 Hz Inverter-driven spindle motors with dynamic braking units
Accumulator Buffer Length 5 to 20 m capacity Tuned to line speed and mandrel switchover duration
Strapping Material Polypropylene (PP), 10 mm × 0.8 mm Optional polyester (PET) or steel strap on request
Strapping Configurations 3, 4, or 6 radial straps Symmetrically spaced through coil core
Joint Weld Efficiency 75% to 80% of base strap tensile strength Thermally regulated friction vibration weld

Takt Time & Output Kinematics

Line takt time governs line balance with upstream wire processing equipment:

Takt Time = 3600 s ÷ Target Hourly Output

  • Dual-Head Configuration (40 coils/h): Takt Time = 3600 ÷ 40 = 90 s per coil
  • Single-Head Configuration (20 coils/h): Takt Time = 3600 ÷ 20 = 180 s per coil

Kinematic Validation

Consider a wire drawing line operating at a linear velocity of 600 m/min winding a 900 m coil pack:

Winding Time (t_wind) = (Coil Length ÷ Linear Velocity) × 60 t_wind = (900 m ÷ 600 m/min) × 60 = 90 s

In a Dual-Head configuration, t_wind (90 s) matches the 90-second takt. Head A winds wire continuously while Head B executes mandrel collapse, coil stripping, ID strapping, and re-expansion within that same 90-second window.

In a Single-Head configuration, strapping and handling time (approximately 90 s) occurs sequentially after winding, yielding:

Total Cycle Time = t_wind + t_handling = 90 s + 90 s = 180 s

This kinematic constraint explains why single-mandrel setups operate at half the capacity of dual-mandrel lines.

Engineering Selection Checklist

  • Wire Feed Characteristics: Grade, tensile strength (MPa), and inlet diameter range.
  • Upstream Line Speed: Continuous output speed (m/min) and emergency stop ramp duration.
  • Target Coil Geometry: Inner core diameter (ID mm), outer diameter (OD mm), coil build height (width mm), and target mass (kg).
  • Head Architecture: Dual-mandrel continuous winding (≤ 40 coils/h) vs. single-mandrel non-continuous system (≤ 20 coils/h).
  • Strapping Specifications: Radial strap count (3, 4, or 6), seal type (friction weld vs. mechanical seal), and strap width/thickness.
  • Take-Away Interface: Direct discharge to gravity roller table, chain conveyor, tilting downender, or C-hook overhead monorail.

Machine Safety & Electrical Standards

High-speed wire coiling machines combine heavy rotational inertia, high-tensile wire tension, and multi-axis automated clamping. Perimeter interlocks and dedicated safety logic prevent operator exposure during high-speed rotation and mandrel manipulation:

  • Wire Break Mitigation: Sudden wire fractures upstream trigger the accumulator’s multi-switch dancer limit sensors within 50 ms. Dynamic braking resistors arrest spindle rotation immediately, mitigating loose wire whipping.
  • Pinch-Point & Crush Safeguards: The collapsing mandrel segments and pivoting transfer manipulator are guarded behind fixed physical fencing and interlocked perimeter access doors.
  • Maintenance Lockout (LOTO): Complete isolation and zero-energy state verification must precede manual wire restringing, shear blade servicing, or strap head maintenance.
  • Regulatory Harmonization:
    • ISO 12100:2010: Risk assessment and risk mitigation hierarchy.
    • EN 415-10:2014: Packaging machines — General safety requirements.
    • ISO 13849-1 (PLd / Cat. 3): Dual-channel safety circuit architectures for emergency stop and access gate interlocks.

Engineering FAQ

Q: What is the maximum linear entry speed for the dual-head coiling system? A: Nominal speeds range from 200 to 800 m/min, determined by wire tensile class, coil weight, and traverse pitch stability.

Q: Can the mandrel handle variable internal coil diameters (ID)? A: Mandrels are engineered for specific nominal IDs (e.g., 300 mm, 400 mm, or 500 mm). Modular bolt-on segment shoes allow rapid field conversions between standard industry diameters.

Q: How does the system prevent slack when cutting wire at high speeds? A: The line decelerates along a synchronized S-curve; the vertical dancer accumulator absorbs upstream wire flow while a dedicated pneumatic snubber clamps the tail against the mandrel prior to portal cutting.

Q: What type of strapping heads are utilized for through-the-eye bundling? A: Industrial friction-weld strapping heads feeding 10 mm to 12 mm PP straps through an indexing strap track, achieving joint efficiencies of 75% to 80%.

Project Sizing & Quotation Workflow

We engineer steel wire coiling lines tailored to exact plant footprints and metallurgical criteria:

  1. Submit Line Parameters: Send drawing exit speed, wire diameter, finished coil dimensions (ID/OD/Width), and daily throughput targets to info@fhopepack.com.
  2. Technical Engineering Proposal (48 Hours): Receive a customized machine footprint drawing, dual vs. single-head cycle simulation, and accumulator sizing calculation.
  3. Plant Layout & Integration Audit: Our packaging systems engineers verify take-away conveyor centerline clearances, electrical drops, and safety fencing envelopes for turn-key commissioning.

Sources & References

Last reviewed: 2026-10-05

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