Catalog components for idlers

SFIT idler elements are stored in a hierarchy. This image shows the hierarchy for metric idlers:

Under the STSE are categories for each of these required profiles:

• Trough idler

• Impact idler

• V idler

• Flat idler

To view an idler profile, select it or its parent STCA or CATA in the Catalogue Explorer. Then click Catalog in the Modify group on the Catalogue tab.

The model view for the selected profile is displayed:

Data Set (DTSE)

Click Data Set in the Model References pane. The Data References pane is displayed:

These parameters are fixed:

• Roller Diameter

• Plate Thickness

Set these according to your requirements.

With two exceptions, use the remaining parameters and rules (see Rules) to specify the dimensions of the idler.

The exceptions are:

• ANGL parameter
  There must be a parameter with a DKEY of ANGL. The values of ANGL must be the same as those the belt.
  

• OSEC parameter
  This parameter provides information to the idler about the belt that owns the idler. The default value must point to a valid belt SPRF.
  

Expressions

The CEMA standards define the dimensions of all idlers in a similar way.

In this example:

E is the height to the tops of the angled idlers from the base.

K is the height to the top of the flat idler from the base.

H is the width between the tops of the angled idlers.

The letters assigned to each dimension differ by manufacturer.

E and K are defined as DESPs on the SFIT in the catalog.

H is defined by this expression:

( 2 * ( DESP[3 ] - DESP[2 ] ) / TAN ( RPRO ANGL ) + OPAR[1 ] )

Where:

DESP[3] = E

DESP[2] = K

ANGL=Belt angle

OPAR[1] is the base width of the owning GENSEC belt.

It is important to understand why dimension H is defined by an expression, not a DESP. This understanding will help you to calculate the correct base width of the belt.

The following example explains why H is defined by an expression.

The belt profile must sit exactly on top of the idlers, as shown in this image:

If you use the values from the catalog for each angle, the base width of the belt and the width of the idler differ by several millimetres. If you modify the idler angle and re-run the rules, the side belts can be some millimetres above or below the idler roll.

To make the base width of the belt consistent with the width of the flat roller, the expression of value H includes an average value of the base width. This value is set on the owning belt.

This table shows the values of E, K, and H for a CEMA standard idler with 4 inch roll, 35 degree troughing angle and 24 inch belt width:

PTSE Point Set

Click Point Set in the Model References pane. The Point Set References pane is displayed:

The primary use of idler P points is to help in positioning the geometry elements. However, P points can also be used for measurements and dimensions.

The positions of the idlers are defined by fixed and design parameters.

P point 0 is the origin. P must always be at the center of the middle roller where it contacts the belt. All other P points are positioned in relation to P point 0.

GMSE Geometry Set

Click +ve Geometry or -ve Geometry in the Model References pane. The Geometry References pane is displayed:

An idler consists of catalog primitives. Their dimensions are defined by fixed and design parameters. The dimensions can be positioned with respect to the origin (P point 0) or with respect to P points defined in the point set (PTSE).

Category

Click Category in the Model References pane to view all parameter definitions for the idler. The Point Set References pane is displayed:

In the Catalog sample data, the idler type is defined in its own category, by roller diameter. The example above is of a three role in-line troughing idler.

Examples

To distinguish between the different types of idler, each type has a specific GTYP setting.

This table shows an example definition of a three-roll inline trough idler.

This image shows an example of a trough idler with a 127mm roller diameter.

Note: The roller diameter is a fixed parameter.

This table shows the dimensions of idlers for different belt widths and angles from an idler standards catalog:

There is only one component for each roll diameter. All dimensions for each different angle and belt width are defined by rules. The values in this example are used in the example rules below.

Rules

A rule set is associated with each component. Rules set the design parameters of the key idler dimensions. These parameters are based on the width and angle of the belt and on the manufacturing idler standards used.

To open the Rule Manager, click Rule Set in the References pane of the Model View, or click Rule Set in the Modify group on the Catalogue tab.

The Rule Manager is documented separately. However, two examples of rules follow.

This example shows a simple rule for the roller length, dimension B.

The first level of the rule is:

If the roller diameter is 127mm or 152mm then go to the next level down. This is because the roller length does not change with different roller diameters.

The second level rules are:

If the belt width is 600mm then the design parameter for the roller length is 240mm.

If the belt width is 900mm then the design parameter for the roller length is 340mm.

If the belt width is 1200mm then the design parameter for the roller length is 390mm.

If the belt width is 1500mm then the design parameter for the roller length is 560mm.

The roller length does not change with the angle of the belt.

This image shows the rules for setting the design parameter for the height to the top of the rollers, dimension E.

The first level rule is:

If the roller diameter is 127mm then go to the next level down.

The second level rules are:

If the belt width is 600mm and the Angle is 20 degrees then the design parameter is set to 332mm.

If the belt width is 600mm and the Angle is 35 degrees then the design parameter is set to 388mm

.......

Because dimension E is not consistent between roller diameters 127mm and 158mm there is a different set of rules for 152mm diameter rollers.