Top Former for Paper Machine Wire Part

The top former is an integral component of the paper machine (PM) wire part, installed between the under-pressure and suction boxes, approximately in the second third of the wire table. Its primary feature is a three-chamber suction box with varying under-pressure values in each chamber, connected to the vacuum system through separators. The cantilever bearing structure supports various elements including a driving roll, guide roll with positioning, wire run regulator, wire stretching device, spraying showers, and a wire cleaning system. All rolls come with doctors. Additionally, white water trays with discharge branches are installed under the bottom wire for splashing, and the top former includes service bridges. It is particularly useful in new and reconstructed PM wire sections with operating speeds up to 1,500-1,600 m/min, achieving dryness on the bottom wire of 10-12%.

Design

The key part of the top former is its suction box, which has diverse vacuum capacities and gradually increasing under-pressure values.

Under the suction box of the top former and beneath the bottom wire, a forming box is installed with height-adjustable and pneumatically controlled bars to enhance paper formation on the wire. Behind the forming chamber, a suction box keeps the paper web on the bottom wire where the top and bottom wires separate.

Main Parts

1. Supporting Structure: Cantilever design
2. Guide Rolls
3. Wire Stretching Units
4. Wire Run Regulator
5. Suction Box (Top Former)
6. Forming Box (Bottom Wire)
7. Oscillating System
8. Suction Box for Wire Cleaning
9. Suction Box (Bottom Wire)
10. Wire Stroke Sensing
11. Collecting Tanks
12. Covering and Walkways

Accessories

• Under-pressure system
• Drive
• Control system with control panel
• Dewatering wire
• System for vapor suction
• Fixtures for rolls and wire replacement

The construction design and machine safety comply with EU and EAC standards.

Technical Parameters

• Max. Paper Width: 7500 mm
• Max. Working Speed: 1500 m/min
• Production Range: 35 – 200 g/m² (depending on the paper grade)
• Dewatering Efficiency: 30 – 60% (flow rate from headbox)

Advantages

• High dewatering efficiency
• Space-saving placement
• Improved paper symmetry
• Enhanced web strength and reduced/eliminated porosity
• Better fiber formation in paper sheets
• Enhanced dewatering capacity monitoring

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