Introduction to Industrial Automation

Figure 5.27  Automation circuit of the object’s classification arrangement shown in Figure 5.26.

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184

 

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  Introduction to Industrial Automation

M

5.2.  In a process station, a cylinder pushes objects (one object at a time) from position 1 to positions 

2, 3, and 4, in order to undergo the corresponding treatment. After the end of the treatment, the 

cylinder returns to its initial position. You are prompted to resolve only this part of the automa-

tion relating to the movement of the cylinder, according to the following specifications:

 

a.  The piston rod slides one place at each press of the button b. 

 

b.  The sliding is sequential, cyclic, and non-reversible and therefore from the rest position 1,

with 

the

1

st

pressing of the 

button ‘b’ the 

piston rod

slides to 

position

‘2’

-//-

2

nd

-//-

-//-

‘3’

-//-

3

rd

-//-

-//-

‘4’

-//-

4

th

-//-

returns back to

‘1’

-//-

5

th

-//-

slides to

‘2’ and so on.

 

c.  The position sensing of the piston rod is achieved via the magnet M situated inside the 

cylinder and the reed switches mounted outside of the cylinder. When the magnet is in 

front of a reed switch, its NO contact closes.

    Select a suitable pneumatic directional valve and design the required automation circuit.

1

2

3

4

1

2

3

4

M

b

Reed switch

Magnet

  5.3. The figure shows an assembly station. The devices to be assembled are forwarded to technicians 

through the conveyor belt M and the pneumatic cylinders C

1

, C

2

, and C

3

. On the side of the 

first (second, third) technician there is the push-button X (Y, Z), in which the technician can 

request a device, when he has finished the assembly of the previous one. Then, the conveyor 

operates until a device comes in front of sensor a (b, c). Subsequently, the conveyor stops and 

the corresponding cylinder is extended. The cylinder pushes the device to the work location 

until the point 1 (2, 3) where a suitable proximity switch triggers the retraction of the cylinder. 

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Elements of Electro-Pneumatic Components 

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185

Then the system is on stand-by to accept a new request by another technician for the forwarding 

of another device. Design the required automation circuit using the state diagram method.

X

Y

Z

a

b

c

1

2

3

C

1

C

2

C

3

M

Note:

 In possible questions such as “How would the automation circuit have to act in a case where 

a new device request is triggered while simultaneously another one is forwarded?” or any similar 

one, state whichever answer you consider to be technically correct in order for the station to pres-

ent maximum effectiveness.

  5.4. Objects differing in height are separated in the conveyor system shown in the figure. There are 

three kinds of objects, two of which will be forwarded to conveyors M

2

 and M

3

 with the help 

of cylinders C

1

 and C

2

, while the third one will continue to the main conveyor M

1

. Each cylin-

der forwards objects of only one kind. The number and order of arrival of objects are random. 

The desired mode of operation of the system must satisfy the following specifications:

 

a.  The conveyor system takes effect in standby mode and hence the automation circuit is in 

operation through a two-position rotary switch RS

0-1

.

 

b.  Then, the three conveyors M

1

, M

2

, and M

3

 start to operate continuously, but conveyor 

M1 must stop every time a cylinder pushes an object or retracts.

 

c.  Define the placement height of the photoelectric switches PEC

1

 and PEC

2

 depending 

on which object you want to detect. In other words, select which cylinder will forward 

which object.

    After selecting the required additive electro-pneumatic equipment, such as the kind of 

cylinders, directional valves, and additive sensors for detecting the motion of piston rods, 

design the electric automation circuit. 

C

2

C

1

h

2

h

1

M

1

M

2

M

3

PEC

2

PEC

1

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