Introduction to Industrial Automation

Figure 10.6  Retentive reciprocating movement of a workable.

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  Introduction to Industrial Automation

operation. Write a program for a PLC to achieve the continuous reciprocating movement of the 

worktable, and present the retentive property, either by modifying the LAD program suitably or 

writing a new one.

10.7   Wooden Plate Stacking, Painting and Transferring Process

Figure 10.7 shows an arrangement for stacking, painting, and transporting wooden plates. After 

pressing an ON button, the feeder FD of wooden plates starts to operate. This means that a stack 

of 12 plates is created at point A, with each plate being counted by the photo switch F

1

. Then the 

feeder stops and the conveyor belt M operates until it brings the stack from point A to the location 

B, with the last detected by F

2

. Then the spray painting nozzles (PN

1

 and PN

2

) are energized for 

a time interval of 18 s. At the end of the time interval of 18 s, the painting nozzles are deactivated 

and the conveyor belt transfers the stack to location C, the last detected by F

3

. By pressing the 

OFF button at any time instant, the operation of the arrangement stops immediately. Write the 

required program for a PLC.