DTI-1098 Crosslink & Expansion Conveyor Oven

CUSTOMER DIRECTIVE

The customer requested that we provide a continuous conveyor oven with variable speed operation and communication capabilities to allow synchronization with the entire production line speeds. The foam manufacturing process required a unique temperature profile to crosslink the material initially followed by additional heating to expand the web. The web is actually “expanded” by heating gassing ( or “blowing”) agents included in the material formulation. The heat must be applied to the material with uniform velocity and temperature across the web width and along the length of the oven system.

PROCESS DESCRIPTION

The DTI-1098 Continuous Conveyor Expanding Oven is designed to provide six (6) zones of temperature control along the length of the system. All zones are heated by independently controlled modulating natural gas fired burners. All zones include independent circulation fans and specialized air distribution systems as designed for the overall process.

In total, the heated chamber includes eighteen (18) access doors with nine (9) located on each side of the chamber. These access doors provide easy access to the heated chamber for inspection and maintenance requirements. The doors also include viewing windows to allow the product to be viewed during process operation.

An exhaust system is included to purge the chamber to meet NFPA requirements for gas-fired equipment and to exhaust byproducts of the process. A high percentage of the oven components are located on the top of the oven and handrail is included around the entire top perimeter for safety considerations.

The actual product conveyor includes a stainless steel wire mesh belt equipped with an automatic belt tension system and an automatic belt tracking system. A separate cleaning burner is used to burn-off byproducts of the process from the conveyor belt followed by a powered rotary brush that operates continuously to maintain a clean belt surface during operation.

At the exit of the system, the expanded foam material web passes through a series of cooling rolls to cool the product. The cooling rolls are chilled by continuous circulation of chilled water inside of the rolls. The cooling rolls are pre-ground, hard chrome–plated, finished ground, and polished to provide a very smooth roll surface. The entire cooling roll support structure is fabricated from stainless steel.

As part of this system, pinch rolls are included prior to the entrance of the oven to control the input speed of the extruded, unexpanded web. Pinch rolls are also included after the cooling rolls to control the output speed of the expanded foam exiting the system so that it can enter the downstream conversion equipment, which is also manufactured by Davron.

The overall oven system and additional components are controlled by PLC. All machine functions are controlled from the operator HMI (touch screen) located at the exit of the oven chamber. The control system is unique in the fact that the intent of the process is to expand the extruded web into foam. During the expanding process in the oven the extruded material multiplies several times in thickness and width. In addition to this expansion, the length of the moving material web also increases greatly in length. With this in mind, speed control of the movement of the web through the process is extremely critical. The PLC system provided includes the capability for proper speed control of all equipment included in the system to compensate for the required speed variation required during the expansion process.

The entire system is fully assembled and factory tested for operational verification prior to shipment.

DAVRON’S CAPABILITIES

In general, foam manufacturing processes vary greatly depending on the type of foam and specifically the formulation of particular products. These variations require specialized equipment to provide proper operation for the expanding process. Davron Technologies, Inc. designs and manufactures ovens of this type to meet many unique process requirements, including but not limited to, the following:

Industries Served: Aerospace, Aviation, Automotive, and general web-manufactured products.

Materials Processed: Various web products including Polyolefin,Polyethylene,Copolymers, Fluoropolymers, and Elastomer-based products requiring thermal processing for crosslinking and expansion. The system can also be used for many other types of products that require specific thermal processing during manufacturing and can be designed in any size required.

Other Processes: Preheating, Curing, Drying, Solvent Drying, Bonding