Sponge Slabstock Foaming Machine--Conveyor Belt Block Foaming Machine

The basic process in a foaming production line typically includes:

1. Transporting reactants from storage tanks to the metering system.
2. Precisely measuring and thoroughly mixing the materials.
3. Continuously pouring the mixed liquid onto a paper mold.
4. Reacting and foaming the material in the mold on the conveyor belt, with the foam block being continuously transported out of the foaming tunnel.
5. Extracting volatile harmful gases from the production area through an exhaust system.
6. Removing the mold paper after the foam block has solidified.
7. Cutting the continuous foam block into required lengths and sending them to the curing storage area.

To meet these process requirements, a foaming machine unit consists of essential components such as a paper feeder, metering system, bridge frame with a mixing head, control panel, conveyor belt with an exhaust duct, paper collection system, cutting device, and block conveying equipment.

Figure 1 illustrates a typical conveyor belt foam block production line. Due to the hindering effect of the side paper during foaming, the sides of the foam block are lower than the middle, forming an arched cross-section. The typical material yield ranges from 80% to 88%. With continuous innovations in foam production techniques, various flat-top foaming technologies have emerged, allowing foam block cross-sections to be nearly rectangular or fully rectangular. Notable techniques include the Draka-PCTzetakis method (side film lifting), Hennecke-Planibloc method (balanced pressure plate), Maxfoam method (overflow foaming), and hybrid techniques like the EC/TopFoam method (drop plate), RS film-lifting method (overflow trough with side film lifting), Pintomax method (overflow trough with floating cover press plate), and QFM method (balanced pressure plate with drop plate).

Figure 1: Schematic Diagram of Conveyor Belt Foam Block Production Line

The vertical foaming machine, developed in the early 1980s, enables the production of large-section foam blocks using small-flow foaming technology. It is suitable for manufacturing both rectangular and cylindrical foam blocks for rotary cutting. Additionally, specialized horizontal foaming machines, such as Romax, produce cylindrical foam blocks for continuous foam sheeting applications.

With growing environmental concerns, new foaming methods have been developed, such as E-Max (sealed mold foaming), VPF (variable pressure foaming), and Cardio/NovaFlex (CO₂ foaming). These methods incorporate improvements like enclosed foaming environments, foaming agent recovery, pressure adjustments, and the use of eco-friendly foaming agents. Corresponding production equipment has also evolved to accommodate these advancements.

Due to the development of flat-top foaming technologies and equipment, polyether-based foams are rarely produced using traditional conveyor belt foaming machines. Instead, these machines are primarily used for producing polyester-based soft foam blocks, where high material viscosity prevents the use of flat-top foaming techniques. Recent innovations in mixing head nozzles have enabled polyester foam blocks to be produced using fixed mixing heads. Figure 2 illustrates the process flow of a conveyor belt high-pressure foaming machine used for polyester foam production.

Figure 2: Schematic Diagram of Conveyor Belt High-Pressure Foaming Machine Process