Here’s a step-by-step guide to producing **flat five-layer corrugated board** (also called double-wall corrugated board), with a focus on achieving optimal flatness and structural integrity:
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### **Key Steps to Produce Flat Five-Layer Corrugated Board**
#### 制作平整五层瓦楞纸板的关键步骤
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### **1. Material Preparation 材料准备**
- **Linerboard (面纸/里纸):**
Use **symmetrical linerboard** (same weight for top and bottom layers).
**Example:** 200 gsm kraft paper for both outer layers.
- 选择对称的箱板纸（面纸和里纸克重相同），如外层均用200克牛皮纸。
- **Corrugated Medium (瓦楞芯纸):**
Combine two flutes (e.g., **B-flute + C-flute**) for balanced rigidity.
- 选用两种楞型组合（如B楞+C楞），平衡挺度和缓冲性。
- **Adhesive (粘合剂):**
Use **cornstarch-based glue** with controlled viscosity (20-30 sec Ford Cup #4) to prevent warping.
- 使用玉米淀粉胶，粘度控制在20-30秒（福特杯4号），防止翘曲。
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### **2. Corrugating Process 瓦楞成型**
- **Preheating (预热):**
Heat linerboard and medium to **160–180°C** to remove moisture and improve flexibility.
- 将面纸和芯纸预热至160–180°C，去除水分，提升柔韧性。
- **Flute Formation (压楞):**
Pass the medium through corrugating rolls under **35–50 kN/m pressure**.
Ensure uniform flute height (e.g., B-flute: 2.5–3.0mm; C-flute: 3.5–4.0mm).
- 芯纸经瓦楞辊压楞，压力35–50千牛/米，确保楞高均匀（如B楞2.5–3.0mm，C楞3.5–4.0mm）。
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### **3. Lamination 复合工艺**
- **Single-Facer Bonding (单面机粘合):**
Bond the first flute (e.g., B-flute) to a liner using starch glue (4–6 g/m²).
- 用单面机将第一层芯纸（如B楞）与面纸粘合，淀粉胶涂布量4–6克/平方米。
- **Double-Wall Formation (双瓦楞复合):**
Add the second flute (e.g., C-flute) and middle liner.
Use **hot plates (180–200°C)** and pressure rollers (**0.5–0.8 MPa**) for even bonding.
- 叠加第二层芯纸（如C楞）和中层衬纸，用热板（180–200°C）和压力辊（0.5–0.8兆帕）确保均匀粘合。
- **Final Lamination (最终复合):**
Bond the top liner under controlled tension to prevent warping.
- 复合顶层衬纸时控制张力，防止翘曲。
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### **4. Flattening Techniques 平整化技术**
- **Cooling Section (冷却段):**
Pass the board through **cooling rollers** or a ventilation system to stabilize temperature and moisture.
- 使用冷却辊或通风系统稳定纸板温湿度。
- **Moisture Balance (湿度平衡):**
Maintain liner moisture at **8–10%**. Uneven moisture is a major cause of warping.
- 保持面纸/里纸含水率8–10%，湿度不均会导致翘曲。
- **Pressure Calibration (压力校准):**
Adjust pressure rollers to ensure even compression across all layers.
- 校准压力辊，确保各层均匀受压。
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### **5. Quality Control 质量控制**
- **Flatness Test (平整度测试):**
Place the board on a flat surface; gaps should be **< 2mm/m²** (per ISO 3037).
- 将纸板置于平面，间隙应小于2毫米/平方米（ISO 3037标准）。
- **Warping Prevention (防翘曲):**
- Symmetrical material structure (面纸/里纸对称).
- Avoid rapid temperature changes during production.
- 对称结构，避免生产过程中温湿度突变。
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### **Troubleshooting 常见问题解决**
- **Problem: Warping (翘曲)**
- **Solution:** Adjust moisture in liners or reduce glue temperature.
- 解决方案：调整面纸湿度或降低胶水温度。
- **Problem: Uneven Layers (层间不平)**
- **Solution:** Recalibrate corrugating roll pressure and glue application.
- 解决方案：重新校准瓦楞辊压力和胶水涂布量。
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### **Equipment Parameters 设备参数参考**
- Line Speed: 100–200 m/min
- Steam Pressure: 1.0–1.2 MPa
- Drying Time: ≥ 30 seconds
By balancing materials, process parameters, and cooling, you can produce flat five-layer boards compliant with **FEFCO** or **GB/T 6544** standards.
通过平衡材料、工艺参数和冷却，可生产出符合FEFCO或GB/T 6544标准的平整五层瓦楞纸板。
