Eye Vertical Coil Stretch Wrapper for Copper Tube Coils

Executive Summary An eye-vertical orbital coil wrapping machine packages annealed and hard-drawn copper tube coils positioned eye-to-sky on driven support rollers. Packaging material—such as stretch film, crepe paper, woven PE, or VCI tape—is applied continuously through the coil eye via a rotating orbital shuttle ring while motorized polyurethane-coated rollers rotate the coil around its central axis. The mechanical overlap percentage must always be calibrated at the outer diameter (OD): because the coil circumference at the inside diameter (ID) is significantly shorter, material overlap naturally increases at the eye, ensuring full encapsulated coverage without voids.

Table of Contents

Machine Operation and Mechanical Motion

The eye-vertical orbital wrapper (eye-to-sky configuration) processes pancake and level-wound copper tube coils seated horizontally on a motorized dual-roller cradle.

+-------------------------------------------------------+
|                    ORBITAL RING                       |
|   ...<- - - - - - - [ Film Roll ] - - - - - - -...    |
|  :                                             :      |
|  :         +-------------------------+         :      |
|  :         |    Copper Tube Coil     |         :      |
|  :  Eye -> |   (Eye-to-Sky / Flat)   |         :      |
|  :         +-------------------------+         :      |
|  :              |               |              :      |
|  :...- - - - - [ PU Drive Rollers ] - - - - - -:      |
+-------------------------------------------------------+
  1. Rotational Kinematics: Dual ground rollers, vulcanized with shore A 75–85 polyurethane (PU), rotate the copper coil circumferentially along its centerline.
  2. Orbital Path: A dynamic shuttle ring traverses through the open inner eye of the coil, applying wrapping tape or film along the toroidal cross-section.
  3. Coil Protection: Soft-annealed copper tubes (e.g., Cu-DHP grade) are susceptible to surface scoring; thus, guide rollers are fitted with non-marking nylon or engineering plastic covers to eliminate metal-to-metal contact during loading, rotation, and discharge.

Step-by-Step Packing Sequence

  1. Coil Placement: The operator loads the unbanded or pre-strapped copper coil onto the roller station using an overhead jib crane with a C-hook or pneumatic coil lifter. The coil rests flat (eye vertical).
  2. Material Anchoring: The operator pulls the film or tape tail and attaches it to the coil periphery with low-tack adhesive or a secure mechanical tuck.
  3. Automatic Wrapping Cycle: The operator leaves the perimeter safety zone and activates cycle start via a dual-hand control or foot switch. The rotating ring ramps up via a variable frequency drive (VFD), while the base drive rollers rotate the coil concurrently.
  4. Cut and Finish: Once the preset revolution counter finishes the wrap cycle, the ring parks at the top dead-center home position. The film is cut automatically by a pneumatic blade or manually by the operator during offline inspection.
  5. Discharge: The packaged coil transfers off the table to downstream inspection or crating pallets.

(Note: For continuous multi-coil facilities, driven roller conveyors and automated cut-and-clamp grippers can replace manual loading and cutting steps).

Kinematic Principle: Differential Overlap Ratio

Wrapping tape is applied along the toroidal surface. Because the angular displacement per second is uniform across the entire coil, the linear travel distance per ring turn differs between the inner and outer diameters.

  • Linear travel per revolution at OD = π × OD
  • Linear travel per revolution at ID = π × ID

When wrap overlap is set to 50% at the outer diameter, the material advance pitch equals half the tape width (W_tape / 2). Because the inner perimeter is shorter, each pass covers a greater percentage of the circumference.

Overlap Variance Matrix (100 mm Tape, 50% OD Overlap Target)

Parameter Outer Diameter (OD) Inside Diameter (ID / Eye) Engineering Note
Coil Dimension 700 mm 400 mm Target standard commercial coil
Circumference 2,199 mm 1,257 mm π × Diameter
Circumferential Advance per Turn 50 mm 28.6 mm Base ratio: Advance_ID = Advance_OD × (ID / OD)
Effective Overlap Percentage 50.0% 71.4% Overlap = (1 - (Advance / Tape_Width)) × 100%
Material Layer Buildup 2.0 Layers 3.5 Layers Eye carries 75% more packing material

Operational Rule: Always calibrate tension and overlap at the outer diameter. If overlap is calibrated at the coil eye, the outer circumference will experience tape separation, leaving bare copper exposed to ambient air and handling abrasion.

Wrapping Material Consumption Formula

To calculate consumable demand per coil, determine the toroidal perimeter of the coil cross-section:

  • Radial wall thickness: W_radial = (OD - ID) / 2 = (700 mm - 400 mm) / 2 = 150 mm
  • Coil axial height: H = 200 mm
  • Cross-section perimeter (P_cross): 2 × (W_radial + H) = 2 × (150 mm + 200 mm) = 700 mm (approx. 0.70 m)

Consumable Demand Comparison

Overlap Setting at OD Outer Advance Pitch Total Ring Turns Required Material Consumed per Coil (Net)
50% Overlap 50 mm 44 Turns (2,199 / 50) 30.8 meters (44 × 0.70 m)
66% Overlap 33.3 mm 66 Turns (2,199 / 33.3) 46.2 meters (66 × 0.70 m)
75% Overlap 25 mm 88 Turns (2,199 / 25) 61.6 meters (88 × 0.70 m)

(Allow an engineering safety scrap factor of 5–8% per coil for starting tails, cut leads, and final anchoring).

Damage Prevention for Thin-Walled Copper Coils

HVAC/R and plumbing tubes require dedicated packaging controls to eliminate transit and storage deterioration:

Risk Mode Mechanism of Damage Machine Engineering Countermeasure
Outer Wall Denting & Flattening Excessive film roll tension acting on soft-annealed copper tube layers. Mechanical friction brake or active magnetic particle clutch calibrated between 15 N and 35 N.
Atmospheric Oxidation / Tarnish Humid air, salt fog, or sulfur gas entering interstitial coil gaps. Interleaving polyethylene (PE) film or VCI (Vapor Corrosion Inhibitor) wrap at minimum 50% OD overlap.
Layer Scuffing & Abrasion Vibration-induced friction during sea-container transit. Elastic stretch wrap maintains structural hoop pressure, binding nested turns into a monolithic block.
Bore Ingress & Contamination Dust, moisture, and debris accumulating on open tube ends. Total toroidal encapsulation protects open tube tips without requiring separate end-caps.

Machine Safety and Industrial Compliance

High-speed orbital rings create significant rotating pinch points. Safe integration must comply with international machinery directives:

  • Machinery Safety Standards: Design conforms to EN ISO 12100:2010 (Risk assessment and risk reduction) and EN 415-10:2014 (Safety requirements for packaging machines).
  • Physical Guarding & Light Curtains: Operating zones must feature sheet-steel or mesh perimeter guards with interlocked access doors (Category 3 / PLd according to EN ISO 13849-1).
  • Hazardous Interventions Prohibited: Operators must never reach into the eye or touch the coil while the shuttle ring is rotating. Starting tape leads must be smoothed only when the ring is stationary and LOTO (Lockout/Tagout) protocols are observed during reel swaps.

Engineering Selection Checklist

Prepare the following mechanical parameters prior to specifying machine frame size:

  • Coil Dimensional Envelope: Minimum and maximum Outer Diameter (OD), Inside Diameter (ID), and Coil Width/Height.
  • Mass Profile: Minimum and maximum coil weight (determines support roller bearing specs).
  • Tube Specification: Outer wall diameter, wall thickness, and copper temper (soft annealed vs. hard drawn).
  • Packaging Material: LLDPE stretch film (17–35 µm), HDPE reinforced woven tape, VCI crepe paper, or compound film.
  • Throughput Target: Required finished coils per hour / per shift.
  • Integration Mode: Standalone semi-automatic unit or full line integration with infeed/outfeed powered conveyors.

Engineering FAQ

Q: What coil configurations can this eye-vertical wrapper handle? A: It is designed for level-wound coils (LWC), pancake coils, smooth plumbing coils, and grooved AC tube bundles loaded flat (eye perpendicular to the floor).

Q: Why does wrapping material accumulate more thickly at the inside diameter? A: Because circumferential linear travel per degree of ring rotation is lower at the ID than at the OD (Circumference = π × D). Consequently, adjacent tape wraps land closer together inside the eye.

Q: What is the optimal tape tension for thin-walled copper coils? A: Packaging tension is typically maintained between 15 N and 35 N. Excessive tension collapses outer tube turns, while insufficient tension causes packaging slack during transit.

Q: Can one wrapper handle both stretch film and crepe paper? A: Yes. Dual-purpose wrapping shuttles can accommodate standard film cores (76 mm / 3 in) and handle both high-stretch polymer films and non-stretch paper with mechanical brake adjustments.

Project Consultation & Quotation Process

  1. Dimensional Submission: Send your coil dimensional envelope (ID, OD, Height, Weight) and target cycle times to info@fhopepack.com.
  2. Engineering Proposal: Receive an official layout diagram, shuttle ring sizing calculation, and equipment quotation within 48 business hours.
  3. Application Verification: Coordinate factory acceptance trials using sample coils at our testing facility to finalize tension and overlap parameters.

Standards and References

Last reviewed: 2026-10-04

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