Automatic Pipe Coiling and Strapping Machine: Dual-Station Continuous Extrusion Packaging

Executive Summary

Flexible corrugated conduit, PE pipe, and industrial hose discharge from the extrusion cooling line as an uninterrupted, continuous strand. An automatic dual-station pipe coiling and strapping machine coils this continuous feed to target dimensions, shears it automatically at exact preset lengths, and straps the coil directly through its center eye. While station A executes precision indexing and strapping, station B immediately begins coiling the subsequent run. The extrusion downstream operates at full production speed with zero accumulator blowout and zero manual handling.

Each winding station comprises an expandable radial mandrel fitted with bilateral flange plates. The radial core arms adjust mechanically or pneumatically to establish the inner diameter (ID), while the flange plates define coil face width, delivering dense, square-sided coils ready for commercial shipment. Positioned alongside the coiler, a dedicated strapping unit with an integrated split-ring orbital track opens, penetrates the core aperture, indexes around the coil cross-section, and secures the package through the eye with heat-sealed PP strapping at programmable intervals.

Table of Contents

Why Two Stations

Continuous plastic extrusion lines cannot pause or decelerate without causing wall-thickness fluctuations, thermal degradation, or pipe ovality inside the vacuum calibration bath.

A single-station coiler introduces forced downtime during coil cutting, indexing, eye-strapping, and pneumatic unloading. With a dual-station configuration:

  • Station A handles active continuous winding synchronized with line extrusion speed.
  • Station B simultaneously handles final strap compression, strap joint welding, coil discharge, and reset.
Station A: [====== WINDING (100% LINE SPEED) ======] -> Shear & Transfer
Station B: [ STRAP EYE 1 ]-[ STRAP EYE 2 ]-[ EJECT ]-[ RESET & STANDBY ]

The pipe feed transfers instantaneously between spools at production speed. Line cycle time only needs to absorb the instantaneous shear and transfer phase, which standard dancer arms or compact accumulator loops manage seamlessly.

Machine Sequence

  1. High-Precision Meter Counting: An optical encoder or synchronized surface measuring wheel tracks continuous linear footage as pipe enters Spool A.
  2. Servo Traverse Layering: A ball-screw driven traverse guide oscillates transversely across the coil width, laying each conduit turn precisely adjacent to the last to prevent strand crossing.
  3. Pneumatic Cut and Automatic Transfer: Upon reaching the target length counter value, an integrated guillotine or orbital shear cuts the pipe square, while an automated clamping gripper secures the newly formed leading tail onto empty Spool B.
  4. Spool A Deceleration & Radial Indexing: Spool A halts rotation; the servo-driven strapping head articulates forward, closing its orbital ring track through the core eye to tension, weld, and sever the strap.
  5. Flange Retraction and Push-Off: The outer flange opens outward, the radial mandrel segments collapse radially to relieve hoop tension, and an integrated pusher transfers the strapped coil onto an outfeed gravity roller or motorized conveyor.
  6. Station Reset: Spool A expands its core arms, closes its flanges, and enters standby mode well before Spool B reaches its preset footage.

Machine Data

Engineering Parameter Standard Specification High-Capacity Range
Coil Inner Diameter (ID) 350–550 mm (Expandable core) 200–800 mm (Custom core)
Coil Outer Diameter (OD) 500–800 mm Up to 1,200 mm
Coil Face Width 150–300 mm 100–500 mm
Permissible Coil Weight 5–35 kg Up to 80 kg
Linear Coiling Speed 1–60 m/min Up to 100 m/min
Station Configuration 2 Independent Spools 2 Synchronized Spools
Installed Power 4.5 kW 7.5 kW (Heavy-gauge lines)
Strapping Material Polypropylene (PP), 12–13 mm 0.60–0.75 mm thickness
Pneumatic Requirement 0.6–0.8 MPa (Clean dry air) 0.6–0.8 MPa

Note: Allowable pipe outer diameter (OD), radial strap placement count (2, 3, 4, or 6 radial ties), dynamic strap tension, and auxiliary infeed accumulator integration are confirmed at technical review. For comparison, the heavy-duty vertical FCL-Y1200 coiler handles conduit OD 16–32 mm, applies 4 to 6 straps per coil, and maintains an eye-strapping cycle of 14–19 seconds per strap.

Coil Length and Winding Time Calculations

To verify whether your extrusion cycle matches the dual-spool strapping window, use the fundamental coil packing equations below:

Turns per Layer = Coil Face Width ÷ Pipe Effective OD
Number of Layers = (Coil OD − Coil ID) ÷ (2 × Pipe Effective OD)
Total Coil Length ≈ π × [(Coil OD + Coil ID) ÷ 2] × Turns per Layer × Number of Layers

Engineering Example:

  • Pipe Specification: 25 mm OD corrugated conduit
  • Target Dimensions: ID = 400 mm, OD = 600 mm, Width = 200 mm
  • Turns per Layer: 200 mm ÷ 25 mm = 8 turns
  • Total Layers: (600 mm − 400 mm) ÷ (2 × 25 mm) = 4 layers
  • Mean Turn Diameter: (600 mm + 400 mm) ÷ 2 = 500 mm (0.5 m)
  • Total Packaged Length: π × 0.5 m × 8 turns × 4 layers ≈ 50.2 meters

At a continuous line extrusion speed of 60 m/min, this 50-meter coil winds completely in 50.2 seconds. This 50-second window represents the total allowable time for the alternate station to index, strap, collapse the core, and discharge.

[ Winding Window: 50.2 Seconds ]
======================================================
[ 4 Straps × 14s = 56s ] -> EXCEEDS WINDING TIME (Line Bottleneck)
[ 3 Straps × 14s = 42s ] + 6s Eject = 48s -> BALANCED CYCLE

Corrugated Wall Factor: Unlike smooth HDPE, corrugated conduit ridges interlock and wander slightly across the traverse span. Always add a 5% to 8% pitch clearance factor over the nominal pipe OD when programming the servo traverse pitch (Traverse Pitch = 1.05 to 1.08 × Conduit OD). Failure to include this pitch allowance causes the final turn of each layer to bind forcefully against the flange plate, driving up coiling motor torque and producing an uneven coil wall.

The Strapping Window Rule: If applying 4 straps at 14–19 seconds per strap (56–76 seconds total), cycle time exceeds the 50-second coiling time. The line must either run longer coil packages, utilize 2 to 3 straps instead of 4, or implement a high-speed strapping head. All cycle synchronizations are modeled and validated at quotation stage.

Strapping Through the Eye Mechanics

Passing a strap through a closed coil eye requires an automated split-ring orbital track. Once the coiling station reaches length and stops, the strapping unit advances:

  1. Track Insertion: A cantilevered track arm passes directly through the internal eye aperture, latching onto the outer track receiver to form a continuous guide ring.
  2. Strap Feed & Reverse Tensioning: The strap feed motor pushes PP strap completely around the loop. Upon entering the sealing block, the motor reverses to draw the strap tight against the conduit surface.
  3. Controlled Wall Tension: Strap tension is adjustable via torque limiter or servo current monitoring (20–250 N). This prevents over-tensioning from collapsing the thin-walled corrugations of electrical conduit while ensuring firm coil consolidation.
  4. Sealing & Indexing: An ultrasonic or electric heating element seals the PP joint; the track separates, the mandrel indexes 90° or 120°, and the cycle repeats for subsequent straps.

Engineering Selection Checklist

Prepare the following technical data to size the coiling and strapping downstream equipment:

  1. Conduit Profile: Pipe material (HDPE, LDPE, PVC, PA), outer diameter (OD), wall thickness, and minimum bend radius.
  2. Finished Coil Dimensions: Required inner diameter (ID), maximum allowable outer diameter (OD), and face width.
  3. Extrusion Line Parameters: Target linear speed (m/min), continuous output rate (kg/h), and batch length per coil (meters).
  4. Securing Requirements: Number of straps per coil (2, 3, 4, or 6 radial ties) and strap width preference (9 mm, 12 mm).
  5. Downstream Finishing: Direct carton packing, heat shrink tunnel, or in-line orbital stretch film wrapping.
  6. Discharge Layout: Manual take-off table, driven accumulating roller conveyor, or robotic palletizing pick-and-place.

Normative Safety Standards

All dual-station coiling systems are manufactured in compliance with international machinery directives:

  • EN ISO 12100:2010: Safety of machinery – Basic concepts and general principles for risk assessment and risk reduction.
  • EN 415-10: Safety requirements for packaging machines – Modular automated coiling and strapping machinery.
  • EN 60204-1: Safety of machinery – Electrical equipment of machines, industrial control enclosures, and emergency stop circuits.

The rotating mandrels, traverse screws, and indexing strapping heads reside within a fully interlocked extruded aluminum and polycarbonate safety enclosure. Opening any service access door trips safety-rated Category 4 dual-channel safety relays, dropping pneumatic pressure and bringing all rotating axes to an immediate Category 0 stop.

Engineering FAQ

Q: Can a single machine accommodate multiple pipe diameters without hardware changeovers? A: Yes. As long as the pipe falls within the minimum bend radius and fits between the flange boundaries, recipe changeovers are handled entirely from the HMI touch screen. The PLC stores servo traverse pitch, length cutoff, and radial indexing angles. Adjusting the coil width requires only repositioning the locking collars on the flange shaft.

Q: What is the primary cause of uneven or conical coil edges? A: Conical or unlevel coils stem directly from a mismatch between the linear traverse travel speed and the spool rotational velocity. If traverse pitch is smaller than pipe OD, turns overlap irregularly; if too wide, adjacent turns fall into gaps. Our machine synchronizes the traverse ball screw to the coiler spindle via real-time electronic gearing.

Q: Can this dual-station unit integrate with automated stretch wrapping? A: Yes. Strapped coils discharged from the spool outfeed directly integrate into an inline horizontal or eye-through orbital stretch wrapping system to apply PE film or woven polypropylene tape for complete transit moisture protection.

Next Step & RFQ Submission

  1. Submit Line Parameters: Email your pipe OD, target coil dimensions (ID × OD × Width), cutting length per coil, and extrusion line speed to info@fhopepack.com.
  2. Engineering Layout: Our packaging engineers determine mandrel arm geometry, traverse drive sizing, and calculate the exact strapping window balance.
  3. Formal Proposal Delivery: Receive a detailed 2D/3D layout, functional specification, and budget quote within 24 hours.

Sources

  • FHOPEPACK Technical Engineering Documentation: Dual-Spool Series Auto-Coiler Design Guidelines
  • ISO 12100:2010 / EN 415-10 Packaging Machinery Harmonized Safety Standards
  • IEC 60204-1 Industrial Machine Electrical Assemblies Compliance

Last reviewed: 2026-10-20

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