Innovative Air-Turbine Cleaning Tool for BHS Corrugator Vacuum Flutting Holes – Comprehensive Study Notes

Overview of Corrugated-Box Packaging and the Flutting Stage

• Packaging protects product quality, simplifies storage/transport, and raises logistical efficiency.
• Corrugated boxes are made of corrugated fiberboard (flute) sandwiched between outer/inner brown‐kraft liners.
• Choice of flute depends on: material weight, self-stacking ability, fragility of contents, presence of inner cartons, vibration/shock requirements, and stacking load.
• Commercial flute codes and average corrugation counts:
– E-flute ≈ 128 flutes / linear foot
– B-flute ≈ 49 flutes / linear foot
– C-flute ≈ 41 flutes / linear foot
• Main corrugator modules: flutting rolls, auto-splicer, press roll, pre-heater, glue roll, slitter.
• Flutting process: glue is heated to 180\,^{\circ}\mathrm{C} and pressed through corrugating rolls (Fig. 2). Heat + glue leave frozen glue lumps and paper chips in the vacuum holes of the flutting rolls.

Problem Statement: Clogged Vacuum Flutting Holes

• BHS corrugator flutting rolls contain 16 straight vacuum holes:
– Inside radius r = 10\,\mathrm{mm} (Ø 20 mm)
– Length t = 2700\,\mathrm{mm}
• Debris occlusion leads to poor flute definition, higher reject rate, and machine downtime.
• Manual cleaning with an L-key requires 5\,\text{h} 25\,\text{min} for all 16 holes and risks scratching the bore.

Research Objective

Design, build, and test an innovative compressed-air-driven tool that:

1. Fits inside Ø 20 mm × 2700 mm holes.

2. Removes both frozen glue and paper chips quickly without damaging tungsten-carbide roll surfaces.

3. Functions as a preventive-maintenance (PM) tool to secure productivity.

Methodology (Experimental)

1. Gather geometrical/physical data of holes and debris.

2. Calculate minimum airflow/pressure to dislodge material.

3. Prototype an air-turbine-driven cleaning head (Archimedes screw turbine + sandpaper).

4. Measure rotational speed, cleaning time, debris mass removed.

5. Perform stress analyses (SolidWorks 2014) on shaft, turbine, and assembly.

Physical & Operating Parameters of the Flutting Holes

• Hole volume
V = \pi r^{2} t = \pi (10\,\text{mm})^{2} (2700\,\text{mm})
= 8.48 \times 10^{5}\;\text{mm}^{3} = 8.48\times10^{-4}\;\text{m}^{3}
• Air density \rho_{udara}=1.2\,\text{kg/m}^{3} (ambient).
• Friction factor (smooth bore) f = 0.004.

Air‐Velocity Relation

V_{udara}=\frac{Q}{A}
A=\pi\frac{D^{2}}{4}

Pressure-Drop Components

1. Wall friction (Darcy–Weisbach)
   \Delta P{g}=\frac{4 f L \rho{udara} V_{udara}^{2}}{2 D}

2. Material acceleration
   \Delta P{acc}=W V{p}

3. Suction/entrainment of debris
   \Delta P{s}=\Delta P{g} \; K R
   • Required total pressure
   \Delta P{total}=\Delta P{g}+\Delta P{acc}+\Delta P{s}=111.52\,\text{Pa}\;\left(1.12\times10^{-3}\,\text{bar}\right)
   → Significantly lower than shop air (7.5 bar) → ample margin for power transmission.

Innovative Cleaning-Tool Design

Pneumatic Supply Path

• Compressor discharge: 7.5\,\text{bar}.
• 2.5-inch galvanized pipe (6 m) → PU hose (10 m).
• Delivered pressure at nozzle ≈ 7.5-2.82=4.68\,\text{bar} (after line losses), still >> \Delta P_{total}.

Overall Dimensions

• Cleaning head Ø 19\,\text{mm} (1 mm clearance)
• Hexagonal shaft length 72\,\text{mm}
• Total tool length sized to reach 2700 mm bore via extension rods.

Main Components & Functions

3-D Printing Parameters for PLA Turbine

• Extruder 225\,^{\circ}\mathrm{C}; bed 70\,^{\circ}\mathrm{C}.
• Resulting tensile strength 34\,\text{N/mm}^{2}.

Mechanical & Structural Analyses

• Hex-shaft Von Mises stress \sigma{max}=4.58\,\text{kN/m}^{2} (tip near bearing), \sigma{min}=1.44\,\text{kN/m}^{2} (mid-span) → well below hardened-steel yield.
• Turbine stresses: \sigma{max}=8.86\,\text{kN/m}^{2} at blade root; \sigma{min}=2.56\,\text{kN/m}^{2} mid-blade → below PLA yield.
• Assembly stresses: \sigma{max}=4.23\,\text{kN/m}^{2} (shaft tip/blade root); \sigma{min}=3.85\,\text{kN/m}^{2} (mid-shaft) → safe.
• Hex-profile offers higher torque transfer and easier wrench engagement versus round shafts (supported by literature [6]).

Experimental Testing Procedure

1. Pre-inspection: verify air-line integrity and part functionality.

2. Insert cleaning tool into first bore, supply air.

3. Record rotation with contact-less tachometer.

4. Time each bore until visually clean.

5. Collect and weigh expelled debris.

6. Repeat for all 16 holes.

Measured Rotational Speed

Tachometer reading: N = 12{,}413\,\text{rpm} at 7.5 bar input.

Cleaning-Time Log per Hole (Table 2 Abbreviated)

\big[3'21'',\;3'32'',\;2'43'',\;\ldots,\;2'54'',3'43''\big] → cumulative t_{total}=51'46''.

Debris Mass Removed

m_{debris}=2.82\,\text{g} of glue-paper chips (Fig. 10).

Performance Discussion

• Time reduced from 5\,25\,\mathrm{h} (manual) → 51.77\,\mathrm{min} (tool): \approx 84\% reduction.
• Compressed-air demand ((<5 \text{bar})) is negligible relative to plant capacity.
• Sandpaper + turbine combination simultaneously scours and pneumatically ejects debris, preventing re-deposit.
• Tool surfaces (sandpaper grit 169 HV) non-aggressive to tungsten-carbide roll yet sufficient for adhesion removal.
• Elevated roller temperature (≈ 200\,^{\circ}\mathrm{C}) underscores need for abrasion-and-heat-resistant cleaning media.
• Structural simulations confirm safe stress margins, ensuring longevity under 12k rpm service.
• Preventive-maintenance implication: shorter PM windows, higher OEE (Overall Equipment Effectiveness), lower scrap rates.

Ethical, Practical, & Industrial Implications

• Enhances operator ergonomics—eliminates prolonged manual scraping in a hot zone.
• Reduces downtime, supporting Just-In-Time (JIT) customer schedules.
• Extends roll life by avoiding scratch damage.
• Energy cost trade-off: compressed air vs. labor cost; given minute airflow need, air consumption cost is marginal.
• Intellectual-property potential: a compact air-turbine abrasive cleaner adaptable to any bored industrial component (heat-exchanger tubes, firearm bores, etc.).

Key Equations Recap

1. Hole volume
   V = \pi r^{2} t

2. Air velocity
   V_{udara}=\frac{Q}{A},\;A=\pi \frac{D^{2}}{4}

3. Frictional pressure drop
   \Delta P_{g}=\frac{4 f L \rho V^{2}}{2 D}

4. Acceleration pressure drop
   \Delta P{acc}=W V{p}

5. Suction pressure
   \Delta P{s}=\Delta P{g} K R

6. Total required pressure
   \Delta P{total}=\Delta P{g}+\Delta P{acc}+\Delta P{s}\approx111.52\,\text{Pa}

Conclusions

• A Ø 19\,\text{mm} air-turbine cleaning head clears 16 flutting holes (Ø 20 mm × 2700 mm) in 51\,46\,\text{min}—an 84\% efficiency gain over manual scraping.
• Line air at 7.5\,\text{bar} produces shaft speed \approx12.5\,\text{kRPM}, well above what is needed (theoretical requirement <1.12\times10^{-3}\,\text{bar}).
• Structural and material analyses validate durability of hardened-steel hex shaft, PLA Archimedes turbine, and Al-oxide sandpaper under thermal & mechanical loads.
• The device provides an effective PM tool, aligns with lean manufacturing goals, and demonstrates transferable technology to other bore-cleaning tasks. • A Ø 19\,\text{mm} air-turbine cleaning head effectively clears 16 challenging flutting holes, each measuring Ø 20 mm × 2700 mm, in a total time of 51\,46\,\text{min}. This represents a significant efficiency gain of approximately 84\% compared to the previously manual scraping method, which required 5\,\text{h}\;25\,\text{min} to clean all holes. • The cleaning tool operates robustly, with shop line air supplied at 7.5\,\text{bar} generating a shaft rotational speed of approximately 12.5\,\text{kRPM}. This operational pressure and speed are well above the theoretical minimum requirement, which was calculated to be less than 1.12\times10^{-3}\,\text{bar}, indicating ample power margin and reliable performance. • Comprehensive structural and material analyses confirm the exceptional durability of the tool's components under typical operating conditions. Specifically, the hardened-steel hex shaft, the 3D-printed PLA Archimedes turbine, and the Al-oxide sandpaper (grit 169 HV) are validated to withstand the combined thermal loads (due to elevated roller temperature, approx. 200\,\text{°C}) and mechanical stresses (such as those from rotation and abrasion) encountered during the cleaning process. • The developed device serves as a highly effective Preventive Maintenance (PM) tool, significantly reducing machine downtime and improving operational efficiency. Its design aligns well with lean manufacturing principles by minimizing waste and enhancing productivity. Furthermore, the demonstrated technology is highly transferable and adaptable for similar bore-cleaning tasks across various industrial sectors, such as cleaning heat-exchanger tubes or even firearm bores.

Selected Reference Links for Further Study

1. Fadiji et al. (2018)—Mechanical design of corrugated packaging.

2. Julianti & Nurminah (2006)—Packaging technology fundamentals.

3. Pranowo (2019)—Maintenance systems.

4. Kumbarasari et al. (2021)—Vacuum material handling design.

5. Qian et al. (2007)—Wear resistance of corrugated rollers.

6. Zhou et al. (2021)—Hex-shaft design & quality function deployment.

7. Hanafi et al. (2020)—Mechanical properties of PLA + ESUN for FDM.

8. Widnyana et al. (2018)—Archimedes screw turbine performance.

Key Equations Recap

1. Hole volume

   V = \pi r^{2} t

   • Where r is the inside radius and t is the length of the vacuum hole.

   • For the BHS corrugator flutting rolls, r = 10\,\text{mm} and t = 2700\,\text{mm}.

   • The calculated volume is V = \pi (10\,\text{mm})^{2} (2700\,\text{mm}) = 8.48 \times 10^{5}\;\text{mm}^{3} = 8.48\times10^{-4}\;\text{m}^{3}.

2. Air velocity

   V_{\text{udara}}=\frac{Q}{A},\;A=\pi \frac{D^{2}}{4}

   • V_{\text{udara}} represents the air velocity inside the hole.

   • Q is the volumetric flow rate of air.

   • A is the cross-sectional area of the hole, with D being the diameter of the hole.

3. Frictional pressure drop (Darcy–Weisbach Equation)

   \Delta P{\text{g}}=\frac{4 f L \rho{\text{udara}} V_{\text{udara}}^{2}}{2 D}

   • This equation calculates the pressure drop due to wall friction within the bore.

   • f is the friction factor (for a smooth bore, f = 0.004).

   • L is the length of the hole.

   • \rho_{\text{udara}} is the density of air (ambient air density is 1.2\,\text{kg/m}^{3}).

   • V_{\text{udara}} is the air velocity.

   • D is the diameter of the hole.

4. Acceleration pressure drop

   \Delta P{\text{acc}}=W V{\text{p}}

   • This component accounts for the pressure needed to accelerate the debris.

5. Suction pressure

   \Delta P{\text{s}}=\Delta P{\text{g}} K R

   • This term relates to the pressure required for suction and entrainment of debris.

6. Total required pressure

   \Delta P{\text{total}}=\Delta P{\text{g}}+\Delta P{\text{acc}}+\Delta P{\text{s}}\approx111.52\,\text{Pa}\;\left(1.12\times10^{-3}\,\text{bar}\right)

   • This is the total calculated pressure required to dislodge and clear the debris from the vacuum holes.

   • This value is significantly lower than typical shop air pressure (7.5\,\text{bar}), indicating ample margin for power transmission and effective cleaning with existing plant pneumatic systems.

Physical & Operating Parameters of the Flutting Holes

• Hole volume (V):

  The volume of the cylindrical vacuum holes in the flutting rolls is calculated using the standard formula for the volume of a cylinder:

  V = \pi r^{2} t

  • Where:

    • r represents the inside radius of the hole, given as 10\,\text{mm}.

    • t represents the length of the hole, given as 2700\,\text{mm}.

  • Substituting these values into the formula:

    V = \pi (10\,\text{mm})^{2} (2700\,\text{mm})

  • This calculation yields a volume of 8.48 \times 10^{5}\;\text{mm}^{3}.

  • For consistency with other units (e.g., in pressure calculations), this volume is converted to cubic meters:

    V = 8.48 \times 10^{-4}\;\text{m}^{3}

• Air density (\rho_{\text{udara}}):

  The density of the ambient air within the operating environment is a crucial parameter for fluid dynamic calculations, particularly in determining pressure drops and air velocity. It is specified as:

  \rho_{\text{udara}}=1.2\,\text{kg/m}^{3}\text{ (ambient)}

  This value is typical for air at standard atmospheric pressure and moderate temperatures, and it is used in the Darcy-Weisbach equation to account for the mass of the air flowing through the holes.

• Friction factor (f):

  The friction factor, denoted as f, is a dimensionless quantity used in the Darcy-Weisbach equation to describe the frictional losses in pipe flow. For the conditions within the flutting holes, which are considered to have a 'smooth bore' (meaning the inner surface is relatively free from significant roughness):

  f = 0.004

  This low value indicates minimal resistance to airflow due to surface roughness, contributing to the overall pressure drop calculation.