ROLLER TABLE PROGRAM

This section outlines the format / type of knowledge contained in the manual and describes stages of the roller table expert system's creation.

3.3.1 Roller Table Design Manual

Figure 3.1 shows the drive side half of the roller used on a roller table. The diagram shows the important dimensions needed to describe a completed roller design.

cn a p ter 3 - c o m p o n e n t u e s ig n rrogram

Barrel Length

Roller width

Figure 3.1 The design manual describes the systematic approach needed to design a roller. The manual also provides brief guidelines about how to select the accessories needed by the roller; i.e. motors to drive the rollers, couplings to transmit the motor power to the rollers, bearings to support the rollers, seals to protect the end of the rollers from scale or debris from the plant.

An example of the heuristics used to design roller tables is in the selection of the roller. The type of roller selected depends upon the position of the roller table in the mill, together with the width.

Table 3.1 is an extract of the knowledge used in the procedure which selects the roller diameter and pitch for a Hot Strip mill 1420mm (56") wide. Where:

• D is the outer diameter of the roller

• d is the inner diameter of the roller if it is hollow

• Pitchl is the pitch between the rollers. When both Pitchl and Pitch2 exist they represent the length the pitch needs to fall within

cn a p ter 6 - c o m p o n e n t u e s ig n rrogram

• Turndown is the front end drop below the top of the last roller, see figure 3.2. The greater the turndown the greater the impact force on the following roller.

Turndown

Figure 3.2

Location in the Mill D (mm) d (mm) Pitchl (mm) Pitch2 (mm) Roller Type Mass Distr'b Turndown (mm ) Furnace entry table 400 0 950 0 solid 2 10 Furnace delivery table 400 0 870 950 solid 2 20 Approach table to reversing rougher 400 0 950 0 solid 0.5 50 Ingoing main table 400 0 750 0 solid 2 50 Outgoing main table 400 0 750 0 solid 2 50 Outgoing extension table 350 0 850 0 solid 0.5 50 Entry table to crop shear/coil box 350 0 950 0 solid 0.5 -1 Runout table to downcoiler(min thk 1.5mm) 305 255 460 0 hollow 0.5 -1 Runout table to downcoiler(min thk 1.2mm) 305 255 420 0 hollow 0.5 -1

Table 3.1 In the mass distribution column, figures less than or equal to 1.0 represent the PERCENTAGE (e.g., 0.5=50%) of rollers that the product rests on; figures greater than 1 represent the NUMBER of rollers that the product rests on. For example on the approach table to reversing rougher, the product rests on two rollers ( See figure 3.3 ). The turndown value will be 20 if the product is travelling at transport speed. The value of 50 is for product

cn a p ter 6 - c o m p o n e n t u e s ig n rrogram travelling at mill speed. -1 in the turndown column means the turndown value is not given in the Roller Table Design Manual.

The values for the diameter of the roller have been specified using the engineers experience. The rollers have to withstand impact loads, retain heat ( to reduce cooling of the strip as it passes ) and accelerate the strip to the desired velocity.

Pitch

Figure 3.3

The program uses the knowledge in the Design Manual to design the complete roller and selects components need for its installation. It does not design the table beds or any housings needed.

The main area of contention with the current design is how the impact loads on the roller are modelled. There is no accurate data to which can be used to validate the mathematical models used. It is suspected that the impact loads are to high and as consequence the roller is being over engineered.

3.3.2 Expert System Software Selection

The design manual was written in a form similar to a rule based approach. Each section contained conditional if... then... statements which

^ napter a - c o m p o n e n t JL^esign rrogram reference the next section. Each section represented a stage in the design of a roller table. Because of the use of the if... then... statements the use of rule based system is desirable.

It was decided to use a PC based piece of software to generate this program, to maximise its availability. The extracts from independent reviews of Xi Plus (Lydiard, 1989; Brown, 1990), Art-Im (Lydiard) and Kappa-Pc (Lydiard, 1990) were used to construct table 3.2. This table aims to highlight the features considered when selecting which piece of E.S. software to use.

Product Features

Rule

Capabilities Similarity of Rulesyntax with K nowledge syntax

External Links Ease of Interface Generation Supplied 'C

Interface

Xi Plus Yes Good Good Yes Good

Kappa-Pc Limited Average Good Yes Good

Art-Im Yes Average Good /

Difficult in practice

Yes Average

Table 3.2 Having fulfilled the basic criteria of having a rule base capability and being able to link with external programs, the main selection criterion was the similarity of the rule and knowledge syntax. This ensures that no unnecessary translation is done, which reduces the chance of the meaning being corrupted. As a result Xi Plus seemed the most suitable software to use.

Chapter 3 - C om p onent D e sig n rrogram