Step 15.7: Index the Chain

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Step 15.7: Index the Chain

Background:

The chain moves with constant velocity. Now, we want the chain to index.

An index motion has:

1.An Index-Period: The chain moves to a new position.

2.A Dwell-Period: The chain does not move.

We must change the motion-values that we give to the kinematic-chains.

We connect new Function-Blocks to the input-connector of the existing Motion-FBs that control the motions to Slider-X and Slider-Y.

tog_plusStep 15.6: Video of Pattern

Indexing Belt 

tog_minusFunction-Blocks for a Constant Velocity Chain
tog_minusFunction-Blocks for an Indexing Chain
tog_plusOPTION 1

12 × index and dwell motion periods in one machine cycle.

Advantage: Less complexity of the Function-Blocks.

Disadvantage: If you want to edit the Motion-Law, or the Index-Period, you must edit a complex motion.

12x Index and Dwell

12x Index and Dwell

This is an example motion that has 12 identical index-periods and 12 dwell-periods in one machine-cycle.

The Motion-Width (X-axis) is 360, and the Motion displacement (Y-axis) is 360.

If you want to change the motion-law or the index-period, you must edit all 24 segments, and not make any mistakes!

FBs for 12x Index motion

FBs for 12x Index motion

These are the Function-Blocks. There is 1 x Motion FB. It has a link to the Motion with 12 x indexes - see above.

The motion controls the Slider-X and Slider-Y directly.

We add 30º to the motion output so that the input to Slider-X2 and Slider-Y2 is advanced by 30º.

The pulleys rotate by 72º each index rather than 30º. Thus the input to the Pulley's is multiplied by 2.4.

tog_plusOPTION 2

1 × Index and Dwell motion

Advantage: If you want to edit the Motion-Law, the Index-Period or the Dwell-Period, you can edit a simple motion with two segments.

Disadvantage: The Function-Blocks are more complex.

1 x Index and Dwell

1 x Index and Dwell

This example Index motion has 2 segments.

Segment 1: Indexing

Segment 2: Dwell

The Motion-Width is 360º, and the Motion displacement is 30º.

If you want to change the motion-law or the index-period, you only need to edit 2 segment.

FBs for 12x Index motion

FBs for 12x Index motion

These are the Function-Blocks.

The Motion FB with the name 1×Index has the link to Index Motion - see above.

The output of 1×Index increases from 0 to 30º as the input increases from 0 to 360º.

If we increase the input from 0 to 4320º (12×360º), the output from 1xIndex (0 to 30º) will repeat 12x.

We can accumulate the output of 0 to 30º : 0-30, 30-60, 60-90, ... 330-360º.

To provide an input to 1×Index of 0 to 4320º, we use a Gearing FB and enter 12 as the Gearing Ratio.

GST-15-710-MotionFB-dialog

Motion FB (1xIndex)

You must use Accumulate Output radio-button in the Motion FB dialog.

1.Open the Motion FB dialog

2.Enable After each Motion-Cycle : Accumulate.