In order to accommodate for the high demand in accuracy, quality and yield, it is essential to optimize the existing operating equipment. In the past Vollmer has supplied and been known for their high performance thickness gauges in conjunction with the automation of the screwdown system. Today, Vollmer offers a step by step optimization process. To achieve optimal results, all relevant parameters are automatically read-in, analyzed and controlled. The schedule for the optimization of rolling quality and yield is divided in five phases: I Installation of continuous strip thickness gauges with an accuracy of (plus or minus) 1 micrometer using very short response times and state of the art technology.

II Re-building of the existing screwdown system to a hydraulic screwdown system, in combination with automatic roll gap and mass flow controls. III Installation of the Vollmer Shapemeter Roll, which measures the strip's shape as the material is being rolled, and displays it on-line via a monitor. IV Installation of a shape control system, which utilizes all possible correction elements in order to achieve the desired shape of the material from the beginning to the end of the coil. V Utilization of SPC-systems (Statistical Process Control), which collect data during production in order to produce the necessary quality and quantity information as hard copies or files. This can be done after each coil or pass.

Phase 1
Thickness Gauge Measurement

The use of Vollmer thickness gauges allows to inspect the current status of product quality and to make a statistical machine capability check of the mill.

This first phase leads to one of the following conclusions: Either the mill is not economical and the quality needs improvement, whereby it is required that the hydraulic screwdown system is retrofitted. On the other hand the quality is sufficient and can be held constant with little intervention, i.e. with the thickness measurement gauges and the installation of a simple feedback system.

Phase 2:
Hydraulic Screwdown Components

After the installation of a servo valve controlled hydraulic screwdown system, the roll gap can be controlled via the automatic Vollmer roll gap control. This enables for the production to be independent of the following: Strip hardness faults Structure changes in the material Thickness deviations Back-up roll eccentricity These errors can only be compensated via a very fast closed loop control working with the roll gap. This thickness regulation system controls and regulates the output of the material. Existing rolling mills are generally designed to enable an installation of a flat short-stroke cylinder (pancake cylinder) between the existing screwdown spindles and the upper back-up roll bearings. The other option would be to replace the entire spindle assembly with a new hydraulic cylinder. The most important facts about this modification are listed below: Available options such as: roll force control, mass flow control, feedforward, feedback, elongation, etc., are all possible (integrated within the control system). Heavy duty hydraulic aggregates with the necessary components such as a cooling device, filter, and accumulator (within the scope of supply). The complete controlling and logistic functions are taken care of by the Programmable Logic Controller (PLC). Direct roll gap control measurement systems are custom fit for the existing roll table and the actual mill stand including the position sensors, which display the absolute roll gap.

Vollmer will help with the necessary mechanical engineering design changes and will send a specialist on-site for the modification of the mechanics. The operators will be trained by Vollmer and we will relay the know-how to your operators for the operation of the fast and precise control system. Vollmer will support the customer regarding the maintenance and service. After these first two phases of the optimization program we can assure the customer the highest quality with increased yield in production. Over the years we have proven to be a leader in the field for thickness controlling. This also applies to the roll gap control, position control, mass flow, feedforward, feedback, roll force control, and elongation control. Within just a decade we have in-stalled and commissioned over 300 systems of the previous mentioned measurement and controlling devices. The fast Vollmer controlling systems are PC or microprocessor based. Since the developments in the computer industry are so fast, we always bring our systems up to date with state of the art technology. This also includes pass schedule information storage, crash protocols and software diagnostics.

Phase 3:
Strip Shape Measurement

After the Vollmer shapemeter system was built in, the operator can observe and control the shape of the material during production. The highly dangerous and time consuming procedure of tapping and feeling the material while being rolled has been eliminated. The objective shape evaluation ensures improved constant material quality and increases the yield in production substantially. The shape of the material can be optimized by selecting nominal curves which are of the desired shape. The operator can easily make modifications by using a keyboard and the self explanatory user friendly dialogue programming, which is displayed on the monitor. This means that during the start up we will not require the on-site assistance of a programmer. In addition, the generally feared know-how loss due to the unwanted transfer of details about the technical procedure is eliminated.

Phase 4:
Strip Shape Controlling

With a Vollmer shapemeter system already present in a mill and providing that the mill is equipped with a fast and powerful servo-hydraulic screwdown, it then is possible to set up an automatic shape control system. Vollmer has over 20 years of experience in programming for the controlling of shape systems for cluster mills with 20 or 12 rolls, as well as six-high, four-high or two-high mills. All of our programs are set up in a fashion that every parameter can be set very easily via the shape control PC. The operator can easily adjust the preset values to fit the individual characteristics of the mill's correction elements, e.g. power crowning, roll bending, roll tilting, lateral shifting of tapered rolls or zone cooling. When using electronic storage devices it is possible to save, overwrite and call up at will, any parameter which has been requested. The system has the option to call up a number of different programs which cover the complete range for thickness, width and quality. For each program it is possible to adapt to the required tolerances by setting or choosing a

nominal curve which best fits the product. This curve can be sent directly to the control system. During the rolling process all activities of the controlling devices, including the actual position, are displayed on the monitor. As the complete range of adjustable parameters is available, our shape control covers all possible operation modes of the mill. This ensures the best possible strip shape controlling. All nominal and actual shape data, as well as the parameters, are continuously put out and can be printed as a hardcopy by pushing a button.

Phase 5:
Statistic Process Control

When using a SPC or MIS (Management Information Systems) the collected data, i.e. strip thickness, strip speed, strip shape, can be stored and a protocol can be made once the coil end has been reached. The protocol consists of a histogram and a probability calculation, the standard deviation and the process capability as well as the machine capability for the final product. If the possible and absolute tolerances have been exceeded they are documented as well.

The determined data can be individually stored (order no.) and called up at any time. The title of the page has the following headers: Order no., coil no., pass schedule, date, time, run-time, measured strip length, measured weight, etc. The data is stored under each one of these headers. This eases the search at a later date when the information is required. There are several standard programs to choose form as well as options for the protocol and layouts. We will discuss and realize the customers needs and wants. Since the data protocol is given out continuously, the company receives a basis for a permanently documented, objective statement about the quality of its rolling process. These protocols are also accepted by the end customer as a certificate of quality. The specialists of the Friedrich Vollmer FeinmeBgeratebau GmbH and their entire know-how are available to the customer throughout all the phases of the optimization.