Better regulation for a phosphating line

An established international manufacturer of rolled titanium zinc based in the Netherlands required the installation of a control system to regulate a coil cleaning and phosphating line for substrates. The coated zinc coils were to be used for architectural purposes, such as cladding, panels and roofing sheets. They provided both aesthetic and anti-corrosion properties, where the quality standards are very high and a consistent colour essential.

 

Our Solution

We worked closely with Siemens to deliver a control system split into two main elements – strip transport and chemical process. The strip transport system consisted of 14 Master Drives, all connected to a common DC BUS supply. The chemical section required control of temperature, flow, pressure, level and conductivity within the seven process tanks through which the strip passed. After the process section, an anti-fingerprint coat was applied to the strip using a reverse roll coater driven by four further Master Drive inverters.

An S7 400 programmable controller coordinated the system and extensive use of distributed I/O was employed to reduce installation time. Profibus, spread over three separate networks, supplied 53 drops, which were made up of drives, intelligent valve stands, ET200M/S remote I/O, absolute encoders and strip steering units. The PLC’s multi-processing capability provided separate processors for the strip transport and chemical sections, with sufficient integral profibus ports to cover the number of nodes and enable parallel software development.

 

Results

• Improved product quality standards
• Greater output consistency